WO2015023232A1

WO2015023232A1 - Apparatus And Method For Bonding A Plurality Of Semiconductor Chips Onto A Substrate

Info

Publication number: WO2015023232A1
Application number: PCT/SG2014/000382
Authority: WO
Inventors: Amlan Sen; Jimmy Hwee Seng Chew; Raymond Shoa Siong LIM
Original assignee: Orion Systems Integration Pte Ltd
Priority date: 2013-08-14
Filing date: 2014-08-14
Publication date: 2015-02-19
Also published as: CN105637626A; TW201515160A

Abstract

An apparatus and a method for bonding semiconductor a plurality of semiconductor chips to a substrate are provided. The apparatus comprises a frame; a plurality of bond heads coupled to the frame, each bond head being operable to obtain and release a chip; and a bond stage coupled to the frame and operable to receive a substrate; each bond head of the plurality of bond heads being relatively moveable with respect to the bond stage and operable to contact a chip obtained by the bond head with a substrate received on the bond stage and to release the chip to bond the chip to the substrate

Description

APPARATUS AND METHOD FOR BONDING A PLURALITY OF

SEMICONDUCTOR CHIPS ONTO A SUBSTRATE

TECHNICAL FIELD

Various embodiments relate to an apparatus for bonding semiconductor chips to a substrate and a method for bonding a plurality of semiconductor chips onto a substrate.

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BACKGROUND

Many electronic devices comprise electric circuits which control the manner in which the electronic device operates. The electric circuit may comprise a substrate onto which one or more semiconductor chips are bonded.

The process of bonding a semiconductor chip can include using an intermediate material, such as, for example, solder to adhere the chip to the substrate. Additionally, the intermediate material may be electrically conductive so that electrical signals can travel from the substrate to the chip. The substrate may include one or more electric tracks for transporting the electrical signals between different parts of the substrate and between different semiconductor chips bonded to the substrate. The process of bonding a semiconductor chip to a substrate may include contacting the semiconductor chip to the substrate and applying pressure and/or heat.

Over the past decades, there has been a continuing drive to miniaturize electronic devices. In turn, this has led to a need to bond ever smaller semiconductor chips onto substrates. As the size of the semiconductor chip becomes smaller, so do its connections with the substrate. Accordingly, the bonding process should position the semiconductor chip accurately on the substrate. If the substrate and semiconductor chip are misaligned, the semiconductor chip can malfunction or not function at all. Therefore, apparatuses for bonding semiconductor chips must be developed to accurately align and bond semiconductor chips to a substrate.

There are also drives to reduce the time taken to bond a semiconductor chip to a substrate. By reducing this time, it is possible to reduce the overall time taken to manufacture an electronic device. In turn, more electronic devices can be manufactured in the same period of time, which is obviously advantageous in mass-production applications. Therefore, apparatuses for bonding semiconductor chips must be developed to efficiently bond semiconductor chips to a substrate.

SUMMARY

According to an aspect of the present invention, there is provided an apparatus for bonding semiconductor chips to a substrate, the apparatus comprising:

a frame;

a plurality of bond heads coupled to the frame, each bond head being operable to obtain and release a chip; and

a bond stage coupled to the frame and operable to receive a substrate;

each bond head of the plurality of bond heads being relatively moveable with respect to the bond stage and operable to contact a chip obtained by the bond head with a substrate received on the bond stage and to release the chip to bond the chip to the substrate.

At least two bond heads of the plurality of bond heads may be operable to move chips obtained by the at least two bond heads as one with respect to the bond stage.

The at least two bond heads may be operable to move the chips obtained by the at least two bond heads as one in a plane parallel to a plane of the bond stage. The at least two bond heads may be operable to move the chips obtained by the at least two bond heads as one towards or away from the bond stage.

One bond head of the plurality of bond heads may be operable to move a chip obtained by the one bond head relatively with respect to a chip obtained by another bond head of the plurality of bond heads. The one bond head may be operable to move the chip obtained by the one bond head in a plane parallel to a plane of the bond stage independently from the chip obtained by the other bond head.

The one bond head may be operable to move the chip obtained by the one bond head towards or away from the bond stage independently from the chip obtained by the other bond head. The plurality of bond heads may be moveably coupled to the frame and the bond heads may be arranged linearly, and a spacing between adjacent pairs of bond heads may be adjustable.

The plurality of bond heads may be coupled to the frame via a rail and each bond head may be operable to slide on the rail to adjust the spacing between adjacent pairs of bond heads.

A length of the rail may be sized such that, when at least one bond head slides to an end portion of the rail, relative movement between the at least one bond head and the bond stage is limited such that the at least one bond head cannot contact a chip obtained by the at least one bond head with the substrate.

The rail may be moveably coupled to the frame and the rail may comprise a drive mechanism operable to move the rail towards or away from the bond stage to move the plurality of bond heads towards or away from the bond stage.

The frame may comprise a first platform and an opposing second platform, the first platform being spaced from and held parallel to the second platform by at least one pillar, the plurality of bond heads being coupled to the first platform and the bond stage being coupled to the second platform.

The bond stage may be moveably coupled to the second platform and the bond stage may comprise a drive mechanism operable to move the bond stage in a plane parallel to the second platform. The apparatus may further comprise a feeder moveably coupled to the frame, the feeder comprising a drive mechanism operable to move the feeder between a loading position, in which the feeder is configured to receive a chip, and a feeding position, in which the feeder is configured to present the chip to one of the plurality of bond heads so that the one bond head can obtain the chip from the feeder.

The feeder may be operable to receive at least two chips and to present each chip to a different one of the plurality of bond heads. The apparatus may further comprise a loading mechanism operable to load a chip onto the feeder from a wafer, when the feeder is in the loading position.

The apparatus may further comprise a camera moveably coupled to the frame, the camera comprising a drive mechanism operable to move the camera relative to the plurality of bond heads and the bond stage, the camera being configured in use to measure a position of at least one bond head with respect to the bond stage, wherein the at least one bond head and the bond stage are operable to move into alignment with each other in dependence on the position measured by the camera. The camera may be configured in use to move in-between the at least one bond head and the bond stage, the camera having a first lens for measuring a position of the at least one bond head with respect to a reference and a second lens for measuring a position of the bond stage with respect to the reference, wherein the at least one bond head and the bond stage are configured to move into alignment with each other in dependence on the positions measured by the first and second lenses.

At least one bond head of the plurality of bond heads may be operable to heat a chip obtained by the at least one bond head. At least one bond head of the plurality of bond heads may be operable to apply a predetermined pressure force to the chip when contacting the chip with the substrate.

At least one bond head of the plurality of bond heads may comprise a suction devices wherein, when a chip is presented to the at least one bond head, the suction device is configured to suck the chip onto the at least one bond head and to maintain suction to hold the chip on the at least one bond head, and wherein the suction device is configured to deactivate suction to release the chip from the at least one bond head. The apparatus may further comprise a controller in communication with the bond stage and each bond head of the plurality of bond heads, the controller being operable to control each bond head to move relatively with respect to the bond stage, to obtain a chip and to release the obtained chip.

The apparatus may further comprise an additional frame, an additional plurality of bond heads coupled to the additional frame, an additional bond stage coupled to the additional frame and an additional feeder moveably coupled to the additional frame, wherein each bond head of the additional plurality of bond heads is relatively moveable with respect to the additional bond stage and operable to contact a chip obtained by the bond head with an additional substrate received on the additional bond stage and to release the chip to bond the chip to the additional substrate, wherein the additional feeder comprises a drive mechanism operable to move the additional feeder between a loading position, in which the additional feeder is configured to receive a chip, and a feeding position, in which the additional feeder is configured to present the chip to one of the additional plurality of bond heads so that the one bond head can obtain the chip from the additional feeder, and

wherein the loading mechanism is operable to load a chip onto the feeder when in the loading position for presentation to a bond head of the plurality of bond heads, and to load a chip onto the additional feeder when in the loading position for presentation to a bond head of the additional plurality of bond heads.

According to a second aspect of the present invention, there is provided a method for bonding a plurality of semiconductor chips onto a substrate, the method comprising: a. receiving a substrate onto a bond stage;

b. obtaining a first chip by a first bond head;

c. moving the first bond head and the bond stage relative to each other to align the first chip on the first bond head with the substrate on the bond stage;

d. obtaining a second chip by a second bond head;

e. moving the first bond head towards the bond stage to contact the first chip with the substrate and releasing the first chip to bond the first chip to the substrate, and retracting the first bond head away from the bond stage;

f. moving the second bond head and the bond stage relative to each other to align the second chip on the second bond head with the substrate on the bond stage; and g. moving the second bond head towards the bond stage to contact the second chip with the substrate and releasing the second chip to bond the second chip to the substrate, and retracting the second bond head away from the bond stage.

The method may further comprise:

obtaining a third chip by the first bond head after retracting the first bond head away from the bond stage, and

obtaining a fourth chip by the second bond head after retracting the second bond head away from the bond stage.

The method may further comprise:

heating the first chip on the first bond head before releasing the first chip on the substrate; and

heating the second chip on the second bond head before releasing the second chip on the substrate.

The method may further comprise:

delaying the first bond head from obtaining the third chip after releasing the first chip on the substrate to allow the first bond head to cool down; and delaying the second bond head from obtaining the fourth chip after releasing the second chip on the substrate to allow the second bond head to cool down.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments of the invention will be better understood and readily apparent to one of ordinary skill in the art from the following written description, by way of example only, and in conjunction with the drawings, wherein like reference signs relate to like components, in which:

Figure 1 is a perspective view of an apparatus for bonding in accordance with an embodiment;

Figure 2 is a front view of a bond head in accordance with an embodiment; Figure 3 is a front view of parts of the apparatus for bonding of Figure 1 ;

Figure 4 is a further perspective view of the apparatus for bonding of Figure 1 ; Figures 5a and 5b are front views of apparatuses for bonding in accordance with two different embodiments;

Figure 6 is a perspective view of an apparatus for bonding in accordance with an embodiment;

Figure 7 is a perspective view of an apparatus for bonding in accordance with an embodiment;

Figure 8 is a perspective view of an apparatus for bonding in accordance with an embodiment;

Figure 9a is a front view of a portion of an apparatus for bonding in accordance with an embodiment, Figure 9b is a front view of a bond gang of the apparatus of Figure 9a, and Figure 9c is a bottom view of the bond gang;

Figure 10a is a front view of a bond head of the apparatus for bonding of Figure 9a, Figure 10b is a side view of the bond head, and Figure 9c is a bottom view of the bond head; Figure 11 a is a front view of a bond gang of the apparatus for bonding of Figure 9a in a first configuration, and Figure 9b is a front view of the bond gang in a second configuration;

Figure 12 is a plan view of an apparatus for bonding in accordance with an embodiment;

Figure 13 is a flow diagram of a method for bonding in accordance with an embodiment; Figure 14a-g are plan views of part of an apparatus for bonding in accordance with an embodiment when operating to perform the method for bonding of Figure 13; Figures 15a-d are plan views of part of an apparatus for bonding in accordance with an embodiment; Figure 16 is a flow diagram of a method for bonding in accordance with an embodiment.

Figure 17a-c are plan views of part of an apparatus for bonding in accordance with an embodiment when operating to perform the method for bonding of Figure 16;

Figure 18 is a plan view of the operation of a vision system in accordance with an embodiment; and

Figure 19 is a flow diagram of a method for bonding in accordance with an embodiment.

DETAILED DESCRIPTION

Various embodiments relate to an apparatus for bonding semiconductor chips to a substrate and a method for bonding a plurality of semiconductor chips onto a substrate. In an embodiment, a semiconductor chip may be referred to as a chip or a die.

Figure 1 shows an apparatus 2 for bonding semiconductor chips to a substrate in accordance with an embodiment. The apparatus 2 comprises two bond heads 4, 6, a bond stage 8 and a frame 10. The bond heads 4, 6 are coupled to the frame 10. The bond stage 8 is coupled to the frame 10. It is to be understood that the two bond heads 4, 6 represent a plurality of bond heads. In use, each bond head 4, 6 is operable to obtain and release a semiconductor chip, whereas the bond stage 8 is operable to receive a substrate. Additionally, each bond head 4, 6 is relatively moveable with respect to the bond stage 8 and operable to contact a chip obtained by the bond head 4, 6 with a substrate received on the bond stage 8 and to release the chip to bond the chip to the substrate. In an embodiment, the plurality of bond heads is moveable with respect to the bond stage 8 and/or the bond stage 8 is moveable with respect to the plurality of bond heads. The following describes further details of the apparatus 2 and its operation with reference to the specific embodiment of Figure 1. It is to be understood that at least some of these further details may be absent in some other embodiments. As seen more particularly on Figure 1 , the frame 10 supports various elements of the apparatus 2 including the bond heads 4, 6 and the bond stage 8. The frame 10 includes a lower platform 10b, an upper platform 10a and two pillars 10c and 10d. The pillars 10c and 10d hold the upper platform 10a above, and spaced apart from, the lower platform 10b. The precise spacing between the upper and lower platforms may vary between different embodiments. The upper platform 10a is held substantially parallel to the lower platform 10b.To ensure that the different elements of the apparatus 2 are stable in operation, the frame 10 may be made of a rigid material, such as, for example, metal. In an embodiment, the bond stage 8 is coupled to the lower platform 10b by an X-Y positioning system (i.e. drive mechanism). Specifically, the bond stage 8 is configured to move in a plane which is above and parallel to the lower platform 10b, by virtue of the X-Y positioning system. The X-Y positioning system includes a bar 12 having located thereon two rails 14a and 14b. An underside of the bond stage 8 is configured with cooperating grooves (not shown) in which the rails 14a and 14b slide. Accordingly, the bond stage 8 may be configured to slide up and down the bar 12. The apparatus 2 may further comprise a drive mechanism, such as a motor, to move the bond stage 8 on the bar 12. It is to be understood that the underside of the bond stage 8 is opposite to the side of the bond stage 8 which is configured to receive the substrate.

Additionally, the lower platform 10b includes two rails 16a and 16b. An underside of the bar 12 is configured with cooperating grooves (not shown) in which the rails 16a and 16b may slide. Accordingly, the bar 12 is configured to slide up and down the lower platform 10b. The apparatus 2 may further comprise a drive mechanism, such as a motor, to move the bar 12 on the lower platform 10b. It is to be understood that the underside of the bar 12 is opposite to the side of the bar 12 which is configured to receive the bond stage 8. It is also to be understood that the up and down sliding motion of the bond stage 8 is substantially normal to the up and down sliding motion of the bar 12 such that the bond stage 8 can move in an X and/or Y direction with respect to the lower platform 10b. The X and Y directions are indicated on Figure 1 by respective arrows. The apparatus 2 may comprise a controller (not shown) which is in communication with the X-Y positioning system. In use, the controller may exchange electrical signals with the X-Y positioning system in order to communicate with and control the X-Y positing— system. For example, the controller may control the X and Y movements of the bond stage 8. In an embodiment, the controller may send instructions to the X-Y positioning system which instruct the X-Y positioning system how to operate. The X-Y positing system may send feedback data to the controller to assist the controller in controlling the operation of the X-Y positing system.

The bond heads 4 and 6 are coupled to the upper platform 10a. The bond heads 4 and 6 may be identical.

The following describes the structure of a bond head 201 in accordance with the embodiment of Figure 2. It is to be understood that in an embodiment, the bond heads 4 and 6 are the same as the bond head 201 of Figure 2.

In an embodiment, the bond head 201 is operable to obtain and release a chip (not shown). For example, the chip may be contacted with a substrate received on the bond stage 8 and released to bond the chip onto the substrate. The bond head 201 comprises a bond actuator 204 which is coupled to a top side of the upper platform 10a. A drive shaft 208 is coupled between the bond actuator 204 and a bond plate 210 of the bond head 201. The drive shaft 208 is positioned through a bore (not shown) in the upper platform 10a and is slidable in the bore. The bond plate 210 is also moveably coupled to the upper platform 10a by at least two bond sliding guides 206a and 206b of the bonding device 201. Each bond sliding guide 206a, 206b slides within a respective bore (not shown) through the upper platform 10a. The bond actuator 204 and bond slide guides 206a and 206b form a system for controlling the vertical motion of the bond head 201 with respect to the bond stage 8 and the upper platform 10a. Specifically, the bond actuator 204 may vertically extend or retract the drive shaft 208 to move the bond plate 210 towards or away from the upper platform 10a. The bond sliding guides 206a and 206b ensure stability and alignment of the bond head 201 as it moves vertically. In an embodiment, a horizontal movement plate 212 may be coupled to an underside of the bond plate 210. In an embodiment, the horizontal movement plate 212 is configured to slide horizontally in an X-direction across the bond plate 210. This movement direction is indicated on Figure 2 by an arrow labelled X. Additionally, the horizontal movement plate 212 is configured to slide horizontally in a Y-direction across the bond plate 210. Considering Figure 2, this movement direction would be into and out of the page. It is to be understood that the underside of the bond plate 210 is opposite to the side of the bond plate 210 which faces the upper platform 10a. The bond head 201 may further comprise a drive mechanism, such as a motor, to move the horizontal movement plate 212 with respect to the bond plate 210 . In an embodiment, an angular movement plate 214 may be coupled to an underside of the horizontal movement plate 212 via a connecting plate 216. The connecting plate 216 is configured to move horizontally (in the X and/or Y directions) with the horizontal movement plate 212. The angular movement plate 214 is configured to rotate with respect to the connecting plate 216. The bond head 201 may further comprise a drive mechanism, such as a motor, to rotate the angular movement plate 214 with respect to the connection plate 216. It is to be understood that the angular movement (also known as rotational movement or Θ direction movement) permits a lower part (i.e. the angular movement plate 214 and below) of the bond head 201 to rotate with respect to an upper part (i.e. the connecting plate 216 and above) of the bond head 201 about an axis Z of the bond head 201. This axis is represented on Figure 2 by a dashed line labelled Z. In another embodiment, the connecting plate 216 may be omitted and the angular movement plate 214 is configured to rotate with respect to the horizontal movement plate 212. In an embodiment, a bonding heater 220 may be coupled to an underside of the angular movement plate 214 to allow the bond head 201 to heat a chip obtained by the bond head. A tip of the bond head 201 is provided by a bonding tool 218 which is coupled to an underside of the bonding heater 220. The bonding head 201 may be configured with a vacuum means, such as a suction device, to allow the bond tool 218 to obtain and release a chip. In another embodiment, mechanical means such as a gripping device, may be provided for obtaining and releasing the chip. For example, the suction device may be configured in use to suck a chip positioned just below the bonding head 201 onto the bonding tool 218 and to maintain suction to hold the chip in position. The suction device may be configured to deactivate to release the chip from the bond tool 218. It is to be understood that the bonding heater 220 is capable of heating a chip obtained by the bonding tool 2 8. In another embodiment, a joining plate (not shown) may be included between the bonding heater 220 and the angular movement plate 214.

It is to be understood that the bonding tool 218 is capable of moving vertically (i.e. Z direction) with respect to the upper platform 10a by virtue of the bond actuator 204 and the drive shaft 208. Also, the bonding tool 218 is capable of moving horizontally (i.e. X and Y directions) with respect to the upper platform 10a by virtue of the horizontal movement plate 212. Also, the bonding tool 218 is capable of rotating (i.e. Θ direction) with respect to the upper platform 10a by virtue of the angular movement plate 214. Also, movements with respect to the upper platform 10a may also translate to movements with respect to other aspects of the frame 10 and/or the bond stage 8.

It is to be understood that the bond head 201 of Figure 2 may be a fixed bond head because it is fixed to the upper platform 10a of the frame 10. Specifically, the bonding tool 218 of the bond head 201 may be capable of moving in the vertical, horizontal and Θ directions with respect to the upper platform 10a via the bond plate 210, the horizontal movement plate 212 and the angular movement plate 214. However, the bond actuator 204 and bond sliding guide 206a, 206b of the bond head 201 is not capable of moving with respect to the upper platform 10a, for example, the whole bond head 201 cannot slide along the upper platform 10a or move towards or away from it. Hence, the bond head 201 may be a fixed bond head.

As mentioned above, the apparatus 2 may comprise a controller. The controller may be in communication with the bond heads 4, 6. In use, the controller may exchange electrical signals with the bond heads 4, 6 in order to communicate with and control the bond heads 4, 6. For example, the controller may control the X, Y, Z and Θ movements of the bonding tool 218. In an embodiment, the controller may send instructions to the bond heads 4, 6 which instruct the bond heads 4, 6 how to operate. The bond heads 4, 6 may send feedback data to the controller to assist the controller in controlling the operation of the bond heads 4, 6.

Considering the apparatus 2 of Figure 1 , the above-described movements of the bond head 4 may be performed with corresponding movements of the bond head 6. Accordingly, the bond heads 4, 6 may move in the X, Y, Z and Θ directions as one, i.e. they may make the same movements at the same time. Additionally or alternatively, the bond head 4 may move in the X, Y, Z and Θ directions independently from the bond head 6.

Figure 3 illustrates an alternative view of some parts of the embodiment of Figure 1. In the embodiment of Figure 3, the bond heads 4 and 6 are similar to the bond head 201 of Figure 2.

In an embodiment, the bond heads 4 and 6 are adjacent each other on the upper platform 10a and are spaced apart from each other. The spacing between adjacent bond heads 4 and 6 may vary between different embodiments. The bond heads 4 and 6 are coupled to the upper platform 10a such that the respective bonding tools of the bond heads 4 and 6 are located between the upper platform 10a and the lower platform 10b. In this arrangement, the respective bond actuators and the respective bond slide guides of the bond heads 4 and 6 are coupled to the upper platform 10a. The frame 10 provides support and holds the bond heads 4 and 6 in place while the bond tools of the bond heads 4 and 6 move in the horizontal, vertical and angular directions with respect to the lower platform 10b and a bond stage positioned thereon (not shown).

Figure 4 illustrates an alternative view of some parts of the embodiment of Figure 1. In the embodiment of Figure 4, the bond heads 4 and 6 are similar to the bond head 201 of Figure 2.

In an embodiment, a fixed axis of each bond head 4, 6 is shown by reference lines 400a and 400b, respectively. The fixed axis of each bond head 4, 6 may be the axis about which the bonding tool of the corresponding bond head rotates. The bond head 4 may be spaced apart from the bond head 6 such that their respective fixed axes are a distance d apart. The value of d may vary between different embodiments. As described with reference to Figure 2, the bonding tools of bond heads 4, 6 are configured to make angular and vertical movements about and along their respective fixed axes 400a and 400b. The angular motion of bond head 4 is shown by arrow 402a and the angular motion of bond head 6 is shown by arrow 402b. The vertical motion of bond head 4 is shown by arrow 404a and the vertical motion of bond head 6 is shown by arrow 404b. In an embodiment, the bond head 4 may move vertically and/or angularly independently from the bond head 6. Additionally or alternatively, the bond head 4 may move vertically and/or angularly together as one with the bond head 6. Figures 5a and 5b show two apparatuses 500 and 502 in accordance with different embodiments.

In an embodiment, considering Figure 5a, the apparatus 500 is similar to the apparatus 2 as shown in Figure 3. However, the apparatus 500 includes only half of the apparatus 2. Specifically, the frame of apparatus 500 includes a upper platform 10a' and a lower platform 10b'. As before, the frame includes a pillar 10d' connecting the upper platform 10a' to the lower platform 10b'. However, no pillar is provided on the other side (i.e. right side) of the upper and lower platforms. This gives the apparatus 500 a cantilevered or C-shaped configuration that frees up additional work space. Additionally, the upper platform 10a' is held substantially parallel to the lower platform 10b' by the pillar 10d'. As before, the upper platform 10a' has coupled thereto a bond head 4'. In an embodiment, considering Figure 5b, the apparatus 502 is similar to the apparatus 2 as shown in Figure 3 and the apparatus 500 of Figure 5a. Specifically, the apparatus 502 comprises all the same features as the apparatus 500; however, the apparatus 502 includes the lower platform 10b from apparatus 2, instead of the lower platform 10b'. Furthermore, the apparatus 502 comprises a second upper platform 10a" which is substantially parallel to the first upper platform 10a', but is located in a different plane. Specifically, the second upper platform 10a" is closer to the lower platform 10b than the first upper platform 10a'. The apparatus 502 includes a pillar 10c" connecting the second upper platform 10a" to the lower platform 10b. Additionally, the second upper platform 10a" is held substantially parallel to the lower platform 10b by the pillar 10c". The second upper platform 10a" has coupled thereto a bond head 6". In an embodiment, more than one bond heads may be coupled to the first and/or the second upper platform.

Figure 6 shows an apparatus 600 for bonding semiconductor chips to a substrate (not shown) in accordance with an embodiment. The apparatus 600 is analogous to the apparatus 2 of Figure 1 ; however, the apparatus 600 comprises five bond heads 602a- e. Each bond head 602a-e may be the same as the bond head 201 of Figure 2. It is to be understood that the five bond heads 602a-e represent a plurality of bond heads (also known as a bond head gang). The following describes the differences between the apparatus 600 of Figure 6 and the apparatus 2 of Figure 1. In an embodiment, each of the five bond heads 602a-e is coupled to the upper platform 10a of the frame 10 in a similar manner to the way in which the bond heads 4, 6 of Figure . However, each bond head 602a-e of Figure 6 is orientated slightly differently to the bond heads 4, 6 of Figure 1. Specifically, each of the bond heads 602a-e are rotated about 90° with respect to the bond heads 4, 6. Hence, the bond actuators of the bond heads 602a-e can be positioned side by side with one another without any bond slide guide in-between. Accordingly, the distance between adjacent bond heads may be reduced and the bond heads 602a-e may be positioned closer together. For example, this can be clearly seen by comparing the bond heads of Figure 6 with those of Figure 1. Alternatively, each bond head 602a-e of Figure 6 may be oriented similarly to the bond heads 4, 6 of Figure 1. In an embodiment, the fixed axes of bond heads 602d and 602e can be closer together than the distance d of Figure 4. In Figure 6, the distance between adjacent bond heads may vary in different embodiments. Furthermore, the distance between bond heads in different pairs of adjacent bond heads may vary in different embodiments. For example, the distance between bond heads 602a and 602b may be different from a distance between bond heads 602c and 602d. In another embodiment, there may be more or less than five bond heads coupled to the upper platform 10a of the frame 10. In an embodiment, the shape of the bond stage 8 and the bar 12 may differ depending on the number of bond heads. For example, in the embodiment of Figure 1 , where there are only two bond heads 4, 6, the bond stage 8 may be relatively narrow because it has to bridge across two bond heads 4, 6. On the other hand, in the embodiment of Figure 6, where there are five bond heads 602a-e, the bond stage 8 may be relatively wide because it has to bridge across five bond heads 602a-e. In an embodiment, a length and/or width of the bond stage 8 may be dependent on the number and arrangement of bond heads. Also, the shape of the bar 12 may change in dependence on the shape of the bond stage 8. In an embodiment, a length/width of the bar 12 may be proportional to a length/width of the bond stage 8. For example, the bar 12 may be wide when the bond stage 8 is wide and the bar 12 may be narrow when the bond stage 8 is narrow. Additionally, the size of the frame 10 may change in dependence on the number of bond heads. For example, the upper platform 10a and the lower platform 10b may become wider or narrower to accommodate a greater or lesser number of bond heads. A larger number of bond heads may be used to speed up the bonding process and improve bonding efficiency. Further, the distance between adjacent bond heads may also be determined by the size of the substrate to be received on the bond stage 8. Figure 7 illustrates a apparatus 700 for bonding semiconductor chips to a substrate in accordance with an embodiment. The embodiment of Figure 7 may bond semiconductor chips to one or more substrates. The apparatus 700 may comprise two apparatuses 702a and 702b positioned side-by-side. Each of apparatuses 702a and 702b may be similar to the apparatus 600 of Figure 6. The following describes the additional features of apparatus 702a compared to apparatus 600 of Figure 6.

In an embodiment, the apparatus 702a comprises a feeder (or die feeder or chip feeder) 720a. The feeder 720a includes a chip tray 722a coupled to the frame 10 of the apparatus 702a by two supporting arms 724a and 726a. Specifically, the chip tray 722a is generally rectangular shape having a length which extends across the whole bond head gang, the arm 724a attaches to one end of the chip tray 722a and to pillar 10d of frame 10, and the arm 726a attaches to the other end of the chip tray 722a and to pillar 10c of frame 10. In use, the chip tray 722a may be configured to slide along the length of the arms 724a, 726a such that the chip tray 722a can move between a loading position and a feeding position. In the loading position, chips may be placed onto the chip tray 722a, as will be described below. In the feeding position, chips may be presented to the bond heads 602a-602e. Specifically, in the feeding position, the chip tray 722a may be positioned directly below the bond heads 602a-e such that the bond heads 602a-e may be activated to obtain chips positioned on the chip tray 722a onto the corresponding bonding tools (e.g. 218 of Figure 2). For example, each bonding head may include a suction device which when activated sucks a chip positioned on the chip tray 722a onto the respective bond tool. In this way, chips can be obtained by the bond heads 602a-e from the feeder 720a. In an embodiment, the feeder 720a may include a linear motor (i.e. drive mechanism) which is operable to slide the chip tray 722a along the arms 724a, 726a between the loading and feeding positions.

In an embodiment, the apparatus 700 may comprise a controller in communication with the feeder 720a. In use, the controller may exchange electrical signals with the feeder 720a in order to communicate with and control the feeder 720a. For example, the controller may control the movement of the chip tray 722a between the loading and feeding positions. In an embodiment, the controller may send instructions to the feeder 720a which instruct the feeder 720a how to operate. The feeder 720a may send feedback data to the controller to assist the controller in controlling the operation of the feeder 720a. In an embodiment, the apparatus 702b also comprises a corresponding feeder 720b which is analogous to feeder 720a of apparatus 702a. In use, apparatuses 702a, 702b may move as one or move independently of each other.

In an embodiment, the apparatus 700 comprises a loading mechanism for loading chips from a wafer 730 contained within a wafer container 732 onto the feeder 720a and the feeder 720b.

In an embodiment, the loading mechanism includes a flipper (or die flipper or chip flipper) 734. The flipper 734 has a rod-like shape with a first end portion 736a and a second end portion 736b. Each end portion 736a and 736b is fitted with means for obtaining a chip from the diced wafer 730. For example, the means may comprise a suction device configured in use to suck the chip from the diced wafer 730 onto the flipper 734 when the respective end portion 736a, 736b is positioned over the chip of the diced wafer 730. Additionally, the suction device may be configured to maintain suction to hold the chip on the flipper 734. Further, the suction device may be configured to deactivate suction to release the chip from the flipper 734. In another embodiment, the suction device may be replaced by mechanical means, such as a gripping device. The flipper 734 is coupled to a servo motor 738 at a mid-way portion of the flipper 734. In use, the servo motor 738 is configured to rotate the flipper 734, for example, by about 180°. Accordingly, the flipper 734 may be moved between first and second flipped positions. In the first flipped position, the first end portion 736a is positioned opposite the diced wafer 730, whereas the second end portion 736b is positioned opposite a placer (or die placer or chip placer) 740a or 740b of the loading mechanism. In the second flipped position, the first end portion 736a is positioned opposite the placer 740a or 740b, whereas the second end portion 736b is positioned opposite the diced wafer 730. The servo motor 738 is configured to actuate the flipper 734 between the first and second flipped positions.

In an embodiment, the wafer container 732 is operable to move the wafer 730. For example, the wafer container 732 may be operable to move the wafer with respect to the flipper 734 in order to cause a different chip to be picked up by the flipper 734 in separate operations.

In an embodiment, as mentioned above, the loading mechanism also includes the placers 740a and 740b. The placer 740a is configured to operate with the apparatus 702a, whereas the placer 740b is configured to operate with the apparatus 702b. The following describes with placer 740a in more detail.

In an embodiment, the placer 740a is fitted with means for obtaining a chip from the flipper 734. For example, the means may comprise a suction device configured in use to suck the chip from the first end portion 736a or second end portion 736b onto the placer 740a when the respective end portion 736a, 736b is positioned opposite the placer 740. Additionally, the suction device may be configured to maintain suction to hold the chip on the placer 740a. Further, the suction device may be configured to deactivate suction to release the chip from the placer 740a. In another embodiment, mechanical means, such as a gripping device, may be used instead of the suction device. The placer 740a is configured in use to transport chips from the flipper 734 to the chip tray 722a of apparatus 702a. Accordingly, the placer 740a is configured to slide along a rail 736 which runs parallel to and adjacent to the upper platforms of the apparatuses 702a and 702b.

In an embodiment, the apparatus 700 includes a casing 740 in which the apparatuses 702a and 702b are located. The casing 740 comprises a base 742 on which the lower platforms 10b of the apparatuses 702a and 702b rest. The rail 736 forms part of the casing and is attached to the casing by struts 744 and 746. The strut 744 is parallel with and preferably adjacent to the pillar 10d of the apparatus 702a, whereas the strut 746 is parallel with and preferably adjacent to the pillar 10c of the apparatus 702b.

In an embodiment, in use, the placer 740a slides along the rail 736 between a picking position and a placing position. In the picking position, the placer 740a is opposite either the first end portion 736a or the second end portion 736b of the flipper 734, depending on the orientation of the flipper 734. In the placing position, the placer 740a is opposite the chip tray 722a of apparatus 702a. Accordingly, it is to be understood that the chip tray 722a slides along its respective arms 724, 726 such that when in its loading position, it is opposite the placer 740a in its placing position. In an embodiment, according to the above described operation, a chip may be picked up from the diced wafer 730 by the flipper 734. The flipper 734 may be moved from the first flipped position to the second flipped position such that the chip is positioned opposite the placer 740a. The chip may then be transferred from the flipper 734 to the placer 740a by cooperating operations of their respective chip obtaining means (e.g. suction devices or gripping devices). The placer 740a may then be slid along the rail 736 from the picking position to the placing position so that the placer 740a opposes the chip tray 722a in its loading position. The chip may then be transferred from the placer 740a to the chip tray 722a. The chip tray 722a may then be moved from the loading position to the feeding position so that chip is presented to one of the bond heads 602a-e of the apparatus 702a. In this way, chips may be transferred from the wafer 730 to the bond heads 602a-e.

In an embodiment, it is to be understood that the placer 740a may position a chip on a particular portion of the chip tray 722a which is known to correspond to a certain one of bond heads 602a-e of apparatus 702a. In this way, a chip can be transferred to a particular one of the bond heads 602a-e of the apparatus 702a. In an embodiment, multiple chips may be positioned on the chip tray 722a before the chip tray 722a is moved from the loading position to the feeding position. Accordingly, chips can be loaded onto multiple ones of the bond heads 602a-e of apparatus 702a at the same time to improve efficiency.

In an embodiment, the placer 740a and the rail 736 have cooperating slots and grooves (not shown) to enable the placer 740a to slide along the rail 736. In an embodiment, the placer 740a may comprise a drive unit, such as a motor, to drive it to slide.

It is to be understood that the placer 740b and its operation with respect to the apparatus 702b is analogous to the placer 740a and its operation with respect to the apparatus 702a.

In an embodiment, the apparatus 700 may comprise a controller in communication with the loading mechanism and the wafer container. In use, the controller may exchange electrical signals with the loading mechanism and the wafer container in order to communicate with and control these two components. In an embodiment, the controller may send instructions to the loading mechanism and the wafer container which instruct these components how to operate. The loading mechanism and the wafer container may send feedback data to the controller to assist the controller in controlling their operation. In an embodiment, the apparatus 700 includes corresponding first vision systems 750a and 750b. The following describes the first vision system 750a in more detail.

In an embodiment, the first vision system 750a includes a camera which is preferably mounted to an arm extending from the pillar 10c of frame 10 of apparatus 702a. The camera may be orientated such that its field of view can be directed towards an underside of the placer 740a. In this way, when the placer 740a is carrying a chip from the picking position to the placing position, the first vision system 750a can capture an image of the chip on the placer 740a. Accordingly, the first vision system 750a can obtain an image of the orientation or position of the chip on the placer 740a.

In an embodiment, the first vision system 750a may be coupled to the controller (not shown). The controller may comprise a vision processor which determines an orientation of the chip. For example, the controller may compare the image taken of the chip on the placer 740a with a reference image. The difference in the chip position between the two images may be used by the controller to compute an offset in the chip position. For example, the controller may receive the image from the first vision system 750a and compare it to the reference image. Based on the comparison, the controller may determine that the chip is rotated clockwise by 2° compared to the reference. In an embodiment, the placer 740a may be further configured in use to rotate a chip held by the placer 740a. For example, the placer 740a may comprise a motor which is capable of rotating the chip. As mentioned above, the controller may be in communication with both the placer 740a and the first vision system 750a. Therefore, after determining the offset in the position of the chip on the placer 740a, the controller may transmit a signal to the placer 740a to cause the placer 740a to compensate for the offset. For example, if a 2° clockwise rotation offset is detected, the placer 740a may rotate the chip anti-clockwise by 2°. Accordingly, the orientation of the chip on the placer 740a may be adapted or changed to match the reference. In an embodiment, the reference image may comprise an earlier image taken by the first vision system 750a. In an embodiment, the reference image may comprise an image of a chip held by the placer 740a in a predetermined orientation, i.e. the chip is in the desired alignment with respect to the placer 740a.

It is to be understood that the first vision system 750b and its operation with respect to the controller, the placer 740b and the apparatus 702b is analogous to the first vision system 750a and its operation with respect to the, controller, the placer 740a and the apparatus 702a. However, it should be noted that the first vision system 750b is preferably mounted to an arm extending from the pillar 10d of frame 10 of apparatus 702b, as can be seen on Figure 7.

In an embodiment, the apparatus 700 includes corresponding second vision systems 756a and 756b. The following describes the second vision system 756a in more detail.

In an embodiment, the second vision system 756a includes a camera. The second vision system 756a is moveable relative to the plurality of bond heads 602a-e and the bond stage 8 of the apparatus 702a. The camera may be configured in use to measure a position of each bond heads 602a-e with respect to the bond stage 8. For example, the bond head 602a may be considered. Specifically, the second vision system 756a may be configured in use to move in-between the bond head 602a and the bond stage 8. The second vision system 756a may have a first lens for measuring a position of the bond head 602a with respect to a reference (e.g. a predetermined reference position). The second vision system 756a may have a second lens for measuring a position of the bond stage 8 with respect to the same reference. It is to be understood that in order for the second vision system 756a to move relative to the plurality of bond heads 602a-e and the bond stage 8 of the apparatus 702a, the second vision system 756a may be attached to an arm extending from the frame 10 of apparatus 702a. The arm may be extendible such that the second vision system 756a is capable of moving in a plane which is parallel to the bond heads 602a-e and bond stage 8 and in-between the bond heads 602a-e and bond stage 8. The second vision system 756a may comprise a drive mechanism to enable it to move relative to the bond heads 602a-e and bond stage 8.

In an embodiment, the second vision system 756a is in communication with the controller (not shown). The controller may comprise a vision processor which determines alignment between the bond head being measured (e.g. 602a) and the bond stage 8 of apparatus 702a, based on the images obtained by the second vision system 756a. Specifically, since the bond head 602a is operable to bond a chip onto a substrate received on the bond stage 8, the alignment is likely to be with reference to a specific position on the bond stage 8. This position may be identified by alignment marks on the bond stage 8 or on a substrate received on the bond stage 8. The specific position corresponds to the specific position on the substrate at which a chip obtained by the bond head 602a is to be bonded (also known as a bonding site).

For example, the controller may compare the two images taken by the second vision system 756a and compute two differences. The first difference may be the difference (i.e. offset) between the image of the bond head 602a and the reference. The second difference may be the difference (i.e. offset) between the image of the bond stage 8 and the reference. It is to be understood that the offset can be in terms of X, Y and/or Θ movements.

In an embodiment, the controller computes a total alignment offset for the bond head 602a and/or the bond stage 8. Additionally, the controller may be in communication with the bond head 602a and/or the bond stage 8 and may cause the bond head 602a and/or the bond stage 8 to move in accordance with the determined offset. The movement of the bond head 602a is described above with reference to bond head 201 of Figure 2. The movement of the bond stage 8 is described above with reference to Figure 1. For example, it may be determined that the bond head 604a should remain in its current position and the bond stage 8 should move into alignment with the bond head 602a based on the controllers image processing. Alternatively, the bond head 602a may move and the bond stage 8 may remain stationary. Alternatively, both the bond head 602a and the bond stage 8 may move.

In an embodiment, the bond stage 8 moves rather than the bond head 602a since the bond stage 8 may be capable of a greater amount of movement compared to the bond head 602a. In an embodiment, the bond stage 8 may perform any X and/or Y movement, whereas the bond head 602a may perform any Θ (i.e. angular) movement.

According to the above described operation, the bond stage 8 of apparatus 702a may be aligned with one or more of the bond heads 602a-e of apparatus 702a. Accordingly, it is possible to accurately control the exact position at which a chip obtained by a bond head is bonded to a substrate received on the bond stage. Furthermore, once each bond head 602a-e of apparatus 702a has obtained a chip from the feeder 720 and the bond heads 602a-e have been correctly aligned with a substrate received on the bond stage 8, each bond head 602a-e may be actuated in the vertical (i.e. Z) direction in order to bond the obtained chip onto the substrate. Specifically, the chip may be obtained and held on the bond head, for example, by suction or mechanically. Then, the bond head may move towards the substrate such that the chip contacts the substrate. Then, the bond head may release the chip, for example, by removal of the suction or actuation of the mechanical means. The step of releasing may involve pressing (e.g. with a predetermined pressure force) the chip onto the substrate to improve the strength of the bond. Also, as described above with reference to Figure 2, the bond head may heat the obtained chip before and during bonding to improve the strength of the bond. After bonding, the bond head may release the chip and retract away from the substrate in a vertical direction. It is to be understood that the second vision system 750b and its operation with respect to the controller and the apparatus 702b is analogous to the second vision system 750a and its operation with respect to the controller and the apparatus 702a.

In an embodiment, the apparatus 702a is separate from the apparatus 702b, although both may be serviced by the same loading mechanism. The loading mechanism may include the flipper 734, the servo motor 738 and the placers 740a and 740b. The apparatus 702a may have its own plurality of bond heads 602a-e which is separate from the plurality of bond heads 602a-e of apparatus 702b. The apparatus 702a may have its own feeder 740a which is separate from the feeder 740b of apparatus 702b. Therefore, the apparatus 702a may be used to bond chips to one substrate and the apparatus 702b may be used to bond chips to another substrate. However, the chips for both apparatus 702a and apparatus 702b may come from the same loading mechanism. Also, the chips may come from the same diced wafer. In different embodiments, the apparatus 700 may comprise more than two apparatuses according to Figure 6. For example, the apparatus 700 may comprise four such apparatuses 702a-d. The apparatuses may be arranged linearly or in a different manner, such as, in a square or circular formation. In accordance with the above description, the same loading mechanism may be shared between some or all of apparatuses 702a-d. Figure 8 illustrates an apparatus 750 for bonding semiconductor chips to a substrate in accordance with an embodiment. The embodiment of Figure 8 may bond semiconductor chips to one or more substrates. The apparatus 750 comprises two apparatuses 752a and 752b positioned side-by-side. Each of apparatuses 752a and 752b is similar to the apparatus 2 of Figure 1. Accordingly, the apparatuses 752a and 752b are similar to the apparatuses 702a and 702b of Figure 7, but include two bond heads rather than five.

The apparatus 750 of Figure 8 is similar to the apparatus 700 of Figure 7. The following describes the differences between the apparatus 750 compared to the apparatus 700.

In an embodiment, the apparatus 752a comprises two bond heads 4a and 6a, whereas the apparatus 752b comprises two bond heads 4b and 6b. In an embodiment, the apparatus 752a comprises two feeders 754a and 756a. The feeder 754a is configured to operate with the bond head 4a, whereas the feeder 756a is configured to operate with the bond head 6a. The apparatus 752b comprises two feeders 754b and 756b. The feeder 754b is configured to operate with the bond head 4b, whereas the feeder 756b is configured to operate with the bond head 6b. In an embodiment, the feeder 754a comprises a chip tray 760a attached to an arm 762a which extends from the pillar 10d of the apparatus 752a. In use, the chip tray 760a can move along the arm 762a between a loading position and a feeding position. Whilst in the loading position, the chip tray 760a may be at an end of the arm 762a furthest from the bond head 4a so that a corresponding placer may place a chip on the chip tray 760a. Whilst in the feeding position, the chip tray 760a may be at an end of the arm 762a closest to the bond head 4a so that the chip tray 760a is positioned directly below the bond head 4a.

In an embodiment, the feeder 756a is analogous to the feeder 754a, but relates to the bond head 6a rather than the bond head 4a. However, the arm of the feeder 756a extends from the pillar 10c of the apparatus 752a rather than the pillar 10c. The feeders 754b and 756b are analogous to the feeders 754a and 756a, respectively, but relate to the bond heads 4b and 6b, respectively, rather than the bond heads 4a and 6a. Figures 9a to 9c show a plurality of bond heads or bond head gang 801 in accordance with an embodiment. The bond head gang 801 may comprise five bond heads 801 a-e coupled to a rail 808 which is coupled to an upper platform 810. In other words, the plurality of bond heads is coupled to the frame via the rail 808. In use, each of the bond heads 801 a-e is capable of sliding along the rail 808 in order to change their position along the upper platform 810. Accordingly, in an embodiment, the plurality of bond heads is moveably coupled to the frame so that the spacing between adjacent pairs of bond heads is adjustable and the plurality of bond heads is arranged linearly. Figures 9a-9c aim to illustrate movements of the bond heads 801 a-e as one, i.e. each bond head 801 a-e makes the same movement(s) at the same time.

In an embodiment, each of the bond heads 801 a-e is spaced at a predetermined distance apart from adjacent bond heads in the bond head gang 801. The number of bond heads in the bond head gang 801 may be different in different embodiments and the distance between adjacent bond heads may be different in different embodiments.

In an embodiment, at a resting position, the bond head gang 801 is at a position above and spaced from a bond stage 802. As before, the bond stage 802 may slide on a bar 804 and the bar may slide on rails 805 positioned on a lower platform 806. In use, the bond stage 802 is configured to receive a substrate (not shown) and each bond head 801 a-e is configured to obtain a chip and bond the chip to the substrate.

In an embodiment, the bond head gang 801 is preferably configured to overlap an entire width of the bond stage 802, as shown in Figure 9a. As seen more particularly on Figure 9b, it can be seen that the bond head gang 801 is capable of moving as a single unit in a vertical (i.e. Z) direction towards the bond stage 802. In an embodiment, the rail 808 may be coupled to the upper platform 810 via a vertical actuation device (i.e. vertical drive mechanism). In use, the vertical actuation device may be configured to move the bond head gang 801 towards the bond stage 802, for example, to bond chips obtained on the bond heads to a substrate on the bond stage 802. Additionally, the vertical actuation device may be configured to move the bond head gang 801 away from the bond stage 802, for example, to retract the bond head gang away from a substrate after bonding chips to a substrate. It is to be understood that the vertical actuation device may act directly on the rail 808 in order to vertically move the bond head gang 801. Alternatively, a bracket may be present in-between the rail 808 and the vertical actuation device. The vertical actuation device may comprise a linear motor and a drive shaft. In operation, the linear motor may drive the shaft to extend the rail 808 towards the bond stage 802 (i.e. away from the upper platform 810), or retract the rail 808 away from the bond stage 802 (i.e. towards the upper platform 810). The vertical actuation device may be in communication with a controller. The controller may be configured in use to control the operation of the vertical actuation device. Accordingly, the bond heads 801 a-e may move vertically together as one, i.e. move vertically together in a gang 801 at the same time. In an embodiment, as seen more particularly on Figure 9c, the bond head gang 801 is capable of moving as a single unit in a horizontal (i.e. X and/or Y) direction with respect to the bond stage 802. The X and Y directions are indicated on Figure 9c by respective arrows. In an embodiment, the rail 808 may be coupled to a horizontal actuation device (i.e. horizontal drive mechanism). In use, the horizontal actuation device may be configured to move the bond head gang 801 with respect to the bond stage 802. It is to be understood that the horizontal actuation device may act directly on the rail 808 in order to horizontally move the bond head gang 801. Alternatively, a bracket may be present in-between the rail 808 and the horizontal actuation device. The controller may be configured in use to control the operation of the horizontal actuation device. Accordingly, the bond heads 801 a-e may move horizontally together as one, i.e. move horizontally together in a gang 801 at the same time.

The following describes the bond head 801a in further detail, but it is to be understood that this description applies equally to bond heads 801b-e. The bond head 801a can be seen more particularly in Figures 10a to 10c.

In an embodiment, the bond head 801a may comprise a linear drive unit 904a coupled to the rail 808. The linear drive unit may comprise of a motor and bearings which enable the bond head 902a to move or slide along the rail 808. This movement is represented on Figure 10a by an arrow labelled X. In an embodiment, the linear drive unit 904a is in communication with and controlled by the controller. The underside of the linear drive unit 904a is coupled to a horizontal movement plate 912a. In an embodiment, the horizontal movement plate 912a is configured to move horizontally (i.e. in an X-direction) with respect to the linear drive unit 904a. This movement direction is indicated on Figure 10a by an arrow labelled X. Alternatively and additionally, the horizontal movement plate 912a is configured to move horizontally (i.e. in a Y-direction) with respect to the linear drive unit 904a. This movement direction is indicated on Figure 10b by an arrow labelled Y. It is to be understood that this horizontal (X and/or Y) direction movement may be in addition to the horizontal (X and/or Y) direction movement provided by the linear drive unit 904a. For example, the linear drive unit 904a may be used to provide a coarse horizontal (X and/or Y) direction movement, whereas the horizontal movement plate 912a may be used to provide a fine horizontal (X and/or Y) direction movement. The bond head 801a may further comprise a drive mechanism, such as a motor, to move the horizontal movement plate 912a with respect to the linear drive unit 904a. In an embodiment, the drive mechanism is in communication with and controlled by the controller.

In an embodiment, an angular movement plate 914a is coupled to an underside of the horizontal movement plate 912a via a connecting plate 916a. The connecting plate 916a is configured to move horizontally with the horizontal movement plate 912a. The angular movement plate 914a is configured to rotate with respect to the connecting plate 916a. Alternatively, the connecting plate 916a may be omitted and the angular movement plate 914a is configured to rotate with respect to the horizontal movement plate 912a. This movement direction is indicated on Figure 10c by an arrow labelled Θ: The bond head 801a may further comprise a drive mechanism, such as a motor, to rotate the angular movement plate 914a with respect to the connection plate 916a. In an embodiment, the drive mechanism is in communication with and controlled by the controller. It is to be understood that the rotation or angular movement permits a lower part (i.e. the angular movement plate 914a and below) of the bond head 801a to rotate with respect to an upper part (i.e. the connecting plate 916a and above) of the bond head 801a about a vertical (i.e. Z) axis of the bond head 801a.

In an embodiment, a bonding heater 920a is coupled to an underside of the angular movement plate 914a to allow the bond head 801a to heat a chip obtained by the bond head 801a. A tip of the bond head 801a is provided by a bonding tool 918a which is coupled to an underside of the bonding heater 920a. The bonding head 801a is configured with means for obtaining a chip. The means may include a suction device or a gripping device to allow the bond tool 918a to obtain and release a chip. For example, the suction device may be configured in use to suck a chip positioned just below the tip onto the bond tool 918a and to maintain suction to hold the chip in position. The suction device may be configured to deactivate to release the chip from the bond tool 918a. It is to be understood that the bonding heater 920a is capable of heating a chip obtained by the bond tool 918a.

It is to be understood that the configuration of the horizontal movement plate 912a, the angular movement plate 914a and the bonding heater 920a in the bond head 801a may be different in different embodiments.

In an embodiment, multiple ones of the bond heads 801 a-e may move in the X, Y, Z and Θ directions as one, i.e. they may make the same movements at the same time. Additionally or alternatively, one or more of the bond heads 801 a-e may move in the X, Y, Z and Θ directions independently from one or more other ones of the bond heads 801 a-e. That is, each bond head may comprise independent horizontal, vertical and angular drive mechanisms controlled by the controller. Figures 11a and 11 b show the bond head gang 801 including bond heads 801 a-e. The bond head gang 801 may be used in an apparatus for bonding semiconductor chips to a substrate as described above.

As mentioned above, in an embodiment, the bond heads 801a-e of the bond head gang 801 are arranged linearly on the rail 808. Specifically each bond head 801 a-e is configured to slide on the rail 808. Each bond head 801 a-e comprises a linear drive unit, which enables it to slide along the rail 808 from one specific location to another specific location. Each bond head 801 a-e may be in communication with the controller. The controller may be configured in use to control the operation of the bond heads 801 a-e. Accordingly, each bond head 801 a-e may be controlled by the controller to slide along the rail 808 between two or more specific locations.

As seen more particularly on Figure 11a, in an embodiment, the bond heads 801 a-e of the bond head gang 801 slide on the rail 808 to change a spacing between adjacent bond heads, e.g. 801a and 801b. For example, a certain spacing may be necessary in order that chips bonded onto a substrate are that certain distance apart. Specifically, bonding sites on the substrate for the chips may be a certain distance apart and so the chips must be separated by that certain distance before bonding can be performed.

In an embodiment, the whole bond head gang 801 may slide as one along the rail 808. This operation may be thought of as a coarse horizontal movement. Alternatively, an individual bond head may slide independently of some or all other bond heads. A finer horizontal movement may be achieved by operation of the horizontal movement plates of each bond head 801a-e. These horizontal movement plates may move as one. Alternatively, the horizontal movement plates of different bond heads may move differently or independently from those of other bond heads. In a similar manner, all bond heads may perform the same angular movement courtesy of their respective angular movement plates. Alternatively, different bond heads may perform different angular movements. In an embodiment, the horizontal and angular movements of each bond head are controlled by the controller.

In an embodiment, the spacing out of the bond heads 801 a-e is performed after the bond heads 801 a-e have picked up chips from a feeder. The spacing out motion may be performed simultaneously while the bond stage 802 moves into position under the bond head gang 801. An advantage of this operation is that chips may be placed on the feeder in the same configuration regardless of the required spacing between the chips during bonding. For example, the chips can be placed close together on the feeder, but the chips may be more spaced out when bonded to the substrate. The increased spacing is achieved by the bond heads 801 a-e sliding on the rail 808. In an embodiment, as seen more particularly on Figure 11 b, when only bond heads 801a-d are required for a given bonding process, the bond head 801e may be moved to one end portion of the rail 808. Specifically, bond head 801e may slide along the rail 808 to one end portion which does not overlap a substrate received on the bond stage 802. The remaining bond heads 801 a-d may be spaced out as described above. In an embodiment, the rail 808 may be longer than the bond stage 802 and the substrate. In this way, bond heads which are slid to an end portion of the rail may be excluded from the bonding operation. In other words, a length of the rail is sized such that, when at least one bond head slides to an end portion of the rail, relative movement between the at least one bond head and the bond stage is limited such that the at least one bond head cannot contact the substrate.

In an embodiment, when all bond heads except one (e.g. 801a) have been slid to the end portion of the rail 808, the last remaining bond head 801a may be used to bond a chip to any portion of the bond stage 802. Specifically, the bond stage 802 is capable of moving horizontally relative to bond head gang 801 , as described with reference to Figures 1 and 9a. When the only one bond head (e.g. 801a) of the bond head gang 801 is not slide to an end portion of the rail 808, the bond stage 802 can move relative to that bond head in order to bond a chip anywhere on the bond stage. Further, in an embodiment, when all bond heads except two (e.g. 801a and 801b) have been slid to the end portion of the rail 808, the last two remaining bond heads 801a may be used to bond a chip to any portion of the bond stage 802. This principle may be applied to other numbers of remaining bond heads.

Figure 12 shows a top view of a bonding apparatus 1000 in accordance with an embodiment. The apparatus 1000 comprises an upper platform 1002a and a lower platform 1002b. Line 1004 denotes an edge of the upper platform 1002a. Accordingly, the upper platform 1002a is about the same width as the lower platform 1002b, but is about half as deep as the lower platform 1002b. Pillars 1006a and 1006b, shown in phantom, hold the upper platform 1002a parallel and spaced apart from the lower platform 1002b. The apparatus 1000 comprises two bond heads 1008a and 1008b, both of which are coupled to the upper platform 1002a. In an embodiment, the bond heads 1008a and 008b represent a plurality of bond heads.

Figure 12 shows a work region 1010 of the apparatus 1000. The work region 1010 comprises a plane which is parallel to the surface of the lower platform 1002b, above the surface of the lower platform 1002b, and in-between the two pillars 1006a and 1006b. The work area 1010 is divided into two areas 1012a and 1012b. The area 1012a corresponds with bond head 1008a, whereas the area 1012b corresponds with bond head 1008b. In an embodiment, the apparatus 1000 also comprises two bond stages 1014a and 1014b. The bond stage 014a corresponds with the bond head 1008a, whereas the bond stage 1014b corresponds with the bond head 1008b. In use the bond stages 1014a and 1014b are capable of moving relative to the bond heads 1008a and 1008b. Specifically, the bond stage 1014a is capable of moving anywhere within the area 1012a of the work region 1010. On the other hand, the bond stage 1014b is capable of moving anywhere within the area 1012b of the work region 1010. Accordingly, the bond stage 1014a is capable of moving relative to the bond head 1008a such that the bond head 1008a is capable of bonding anywhere on the bond stage 1014a. On the other hand, the bond stage 1014b is capable of moving relative to the bond head 008b such that the bond head 1008b is capable of bonding anywhere on the bond stage 1014b. According to the above-described embodiment, multiple bond stages may be provided, wherein each bond stage corresponds to certain bond heads. In an embodiment, each bond stage may correspond with a different bond head or different group of bond heads may correspond to each other bond stage. In an embodiment, each bond stage may correspond to at least some of the same bond heads as another bond stage.

Figure 13 illustrates a bonding sequence 1100 embodiment performed by an apparatus 1200 embodiment illustrated in Figures 14a-g. Figures 14a-g show only part of the apparatus 1200 so that the individual operations in the sequence can be clearly seen. However, the apparatus 1200 is similar to apparatus 2 of Figure 1 and apparatuses 752a and 752b of Figure 8. Accordingly, the apparatus 1200 comprises two bond heads 1202a and 1202b, which represent a plurality of bond heads. As in Figure 1 , the bond heads 202a and 1202b are coupled to an upper platform (not shown) of a frame. A lower platform 1203 of the frame is held parallel to and spaced from the lower platform 1203 by pillars 1205a and 1205b, shown in phantom. The lower platform 1203 includes a bond stage (not shown) onto which a substrate 1208 is positioned. The bond _; stage may move the substrate over the lower platform 1203, as described with reference to Figure 1. The bond heads may provide vertical, horizontal and angular movements as described above with respect to Figure 2. In an embodiment, bond head 1202a is capable of moving independently from bond head 1202b. In an embodiment, bond head 1202a is capable of moving as one with bond head 1202b.

The following describes some additional features of the apparatus 200 in more detail. In an embodiment, a feeder 1204a is provided for feeding chips to the bond head 1202a and a feeder 1204b is provided for feeding chips to the bond head 1202b. The feeder 1204a comprises a chip tray 1210a attached to an arm 1212a which extends from the pillar 1205b. In use, the chip tray 1210a can move along the arm 1212a between a loading position and a feeding position. Whilst in the loading position, the chip tray 1210a may be at an end of the arm 1212a furthest from the bond head 1202a so that a corresponding placer (not shown) may place a chip on the chip tray 1210a. Whilst in the feeding position, the chip tray 1210a may be at an end of the arm 1212a closest to the bond head 1202a so that the chip tray 1210a is positioned directly below the bond head 1202a. The feeder 1204b is analogous to the feeder 1204a, but relates to the bond head 1202b rather than the bond head 1202a. The feeders 1204a and 1204b are analogous to those of Figure 8. In an embodiment, a vision system 1206 is provided for aligning the chips which is obtained on the bond heads 1202a and 1202b with specific positions on the substrate 1208 which is received on the bond stage. The vision system 1206 is analogous to the second vision systems 756a and 756b of Figure 7.

Details of the bonding sequence 1100 of Figure 13 are provided as follows. It is to be understood that the operations of the apparatus 1200 may be controlled by a controller of the apparatus 1200.

Step 1101 may be seen more particularly on Figure 14a. At step 1101 , the substrate 1208 is received onto the bond stage. Also, the feeder 1204a is positioned in its loading position and a first chip 1220 is placed onto the feeder 1204a, for example, by a corresponding placer. The feeder 1204b is positioned in its loading position but no chip is placed onto it. The bond heads 1202a and 1202b are in an idle position fully retracted from the bond stage, i.e. fully moved to the upper platform. The vision system 1206 is in an idle position in the middle of the lower platform 1203 and away from either bond head 1202a or 1202b. Step 1102 may be seen more particularly on Figure 14b. At step 1102, the bond stage moves the substrate 1208 into position underneath the bond head 1202a. The position of the bond stage depends on the precise location on the substrate 1208 at which the first chip 1220 is to be bonded by the bond head 1202a. It can be seen on Figure 12b that, in this case, the first chip 220 is to be bonded to the bottom-right comer of the substrate 1208, as viewed on Figure 14b. Next, the feeder 1204a moves from its loading position to its feeding position underneath the bond head 1202a. Once in the feeding position, the bond head 1202a picks up the first chip 1220 from the feeder 1204a, for example, by suction. Alternatively, the bond stage moves the substrate 1208 into position underneath the bond head after the bond head 1202a has picked up the first chip 1220 from the feeder 1204a. Subsequently, a second chip 1222 is placed onto the feeder 1204b, for example, by a corresponding placer.

Step 1104 may be seen more particularly on Figure 14c. At step 1104, the empty feeder 1204a moves back to its loading position. The vision system 1206 moves in- between the bond head 1202a and the substrate 1208. The vision system 1206 in combination with the controller then determines the necessary movements of the bond stage and/or the bond head 1202a in order to bring the first chip 1220 into alignment with the first chip bonding site on the substrate 1208. The bond stage and/or the bond head 1202a then move to align the first chip and the first chip bonding site. Subsequently, the feeder 1204b moves from its loading position to its feeding position underneath bond head 1202b.

The process of aligning the first chip 1220 with the first chip bonding site is explained in more detail with reference to Figure 14d. Figure 14d illustrates how the vision system 1206 is operable to align the first chip 1220 obtained by the bond head with the first chip bonding site on the substrate 1208, in accordance with an embodiment. In an embodiment, the camera of the vision system 1206 may comprise two lenses. The first lens of the camera of the vision system 1206 is for measuring a position of the first chip 1220 on the bond head 1202a. The second lens of the camera of the vision system 1206 is for measuring a position of the first chip bonding site on the substrate 1208. As mentioned above, the bonding site may be identifiable by alignment marks (or fiduciary marks) on the substrate 1208. The alignment marks are shown on Figure 14d by crosses. As can be seen on Figure 14d, the first chip 1220 is intended to be bonded such that two diagonal corners 1220a and 1220b of the first chip 1220 are respectively aligned with two alignment marks 1208a and 1208b. Alternatively, alignment marks (or fiduciary marks) may also be present on the first chip 1220. The first chip 1220 is intended to be bonded such that the alignment marks of the first chip 1220 are respectively aligned with the alignment marks on the substrate 1208. Accordingly, in a first operation, the vision system 1206 moves to capture an image of the first chip 1220 on the bond head 1202a which is positioned over the substrate 1208. In a second operation, the vision system 1206 first moves to a position 1206a to capture an image of the first one of the two alignment marks 1208a. Subsequently, the vision system 1206 moves to position 1206b to capture an image of the second one of the two alignment marks 1208b. The vision system 1206 then returns to its idle position. Therefore, a total of three images are captured. Alternatively, the vision system 1206 may move to capture an image of the first diagonal corner 1220a of the first chip 1220. Next, the vision system 1206 moves to capture the second corner 1220b of the first chip 1220. Therefore, a total of four images are captured. Each image may be compared to a reference location in order to determine whether the first chip 1220 is aligned with the first chip bonding site. If alignment is not correct, an offset is calculated and the bond stage and/or bond head 1202a are/is moved into alignment.

Step 1106 may be seen more particularly on Figure 14e. At step 1106, the second chip is picked up from the feeder 1204b by the bond head 1202b, for example, by suction. The empty feeder 1204b then moves back to its loading position. The vision system 1206 moves in-between the bond head 1202b and the substrate 1208. The vision system 1206 in combination with the controller then determines the necessary movements of the bond stage and/or the bond head 1202b in order to bring the second chip into alignment with the second chip bonding site on the substrate 1208. The bond stage and/or the bond head 1202b then move to align the second chip and the second chip bonding site. This process is analogous to the above-described process relating to the alignment of the first chip with the first chip bonding site. Next, the first chip on the bond head 1202a is bonded onto the substrate 1208 at the first chip bonding site. Specifically, the bond head 1202a is moved vertically (i.e. in the Z direction) towards the substrate 1208 until the first chip contacts the substrate 1208. This operation bonds the first chip to the substrate 1208. Subsequently, the bond head 1202a releases the first chip, for example, by deactivating suction. The bond head 1202a then moves vertically upwards towards the upper platform and away from the substrate 1208. Next, a third chip 1224 is placed on the feeder 1204a which is located in its loading position.

In an embodiment, contact between the first chip and the substrate may be detected by a sensor device of the bond head 1202a, such as a displacement or force sensor. In use, the sensor device of the bond head 1202a may detect the point at which resistance to the downward vertical movement occurs. This point may indicate that the first chip has contacted the substrate. In an embodiment, the bond head 1202a is further configured to press the first chip 1220 down onto the substrate 1208, i.e. by applying a pressure force. For example, the sensor device may identify that the first chip 1220 has contacted the substrate, but this may then cause the bond head 1202a to increase the force with which it moves downwards. In this way, pressure may be applied to the first chip 1220 to improve the bond between the first chip 1220 and the substrate 1208. The operation of the bond head 1202a may be controlled by the controller. In an embodiment, pressure may be applied for a predetermined time period and/or at a predetermined force. The predetermined time period and/or force may be defined by the controller. The predetermined time period and/or force may vary between different embodiments and between different process steps in the same embodiment.

In an embodiment, the bond head -1202a is further configured to heat the first chip 1220 whilst it is being held by the bond head 1202a and/or whilst it is being bonded to the substrate 1208. The bond head 1202a may use a bonding heater as described above with respect to Figure 2. Heating the first chip 1220 may cause solder present on the first chip 1220 to enter a molten state before or whilst the first chip 1220 is brought into contact with the substrate 1208. The bonding heater of the bond head 1202a may be deactivated once the first chip 1220 has been released so that the bonding tool may cool down before obtaining another chip. Step 1108 may be seen more particularly on Figure 14f. At step 1108, the bond stage moves the substrate 1208 to the next bonding location underneath the bond head 1202b. Specifically, the next bonding location is the second chip bonding site which may be located in the bottom-left of the substrate 1208, as seen in Figure 14f. Therefore, the bond stage moves the substrate 1208 so that the second chip bonding site is located directly beneath the bond head 1202b. Next, the vision camera 1206 is used as described above to ensure that the second chip 1222 on the bond head 1202b is aligned with the second chip bonding site of the substrate 1208. If necessary, the bond stage and/or the bond head 1202b are moved to achieve alignment. Subsequently, the feeder 1204a moves from its loading position to its feeding position.

Step 1110 may be seen more particularly on Figure 14g. At step 1110, the third chip 1224 is obtained by the bond head 1202a from the feeder 1204a in its feeding position. The feeder 1204a then moves back to its loading position. The vision system 1206 then moves to the bond head 1202a in preparation for alignment of the bond head 1202a. Next, the second chip 1222 on the bond head 1202b is bonded onto the substrate 1208 at the second chip bonding site. Specifically, the bond head 1202b is moved vertically (i.e. in the Z direction) towards the substrate 1208 until the second chip 1222 contacts the substrate 1208. This operation bonds the second chip 1222 to the substrate 1208. Subsequently, the bond head 1202b releases the second chip 1222, for example, by deactivating suction. The bond head 1202b then moves vertically upwards towards the upper platform and away from the substrate 1208. The bonding of the second chip 1222 by the bond head 1202b is analogous to the bonding of the first chip 1220 by the bond head 1202a. Also, the feeder 1204b receives a fourth chip 1226 whilst in its loading position. The above-described operation completes one cycle of the bonding process. According to the above-described process, two chips have been bonded onto the substrate. The first chip 1220 was bonded by the bond head 1202a, whereas the second chip 1222 was bonded by the bond head 1202b. After step 1110, at step 1112, a decision is made regarding whether or hot other chips need to be bonded to the substrate. If no further bonding is required, the bonding process 1100 ends. However, if further bonding is required, the above-described operations 1104 to 1110 are repeated. However, to prepare the apparatus 1200 for operation 1104, the substrate 1206 moves underneath the bond head 1202a such that the third chip bonding site is directly below the third chip 1224.

When the steps 1104 to 1110 are repeated, the operations relating to the first chip 1220 now relate to the third chip 1224, and the operations relating to the second chip 1224 now relate to the fourth chip 1226. It is noted that the above described operations have already introduced both the third chip 1224 and fourth chip 1226. Furthermore, the operations will introduce a new fifth chip and a new sixth chip. Accordingly, it can be seen how the above-described bonding sequence could be used to bond any number of chips onto the substrate 208. Figure 15a shows a top view of an apparatus 300. Only part of the apparatus 1300 is shown so that the various operations of the apparatus 300 can be explained more clearly. The apparatus 1300 is analogous to the apparatus 1200 of Figures 14a-g. However, the apparatus 1300 has the following differences. In an embodiment, the apparatus 1300 comprises a bond head gang of five bond heads 1307a-e, rather than two bond heads 1202a and 1202b. Additionally, the bond head gang is similar to the bond head gang 801 of Figures 9a, 9b, 11a and 11b, and each of the bond heads 1307a-e is similar to the bond heads 902a-e of Figures 9a, 9b and 10a-c. Accordingly, the bond heads 1307a-e are mounted on a rail and are slidable on the rail. In this way, the spacing between pairs of adjacent bond heads is variable. In an embodiment, the apparatus 1300 comprises a feeder 1309 which is capable of feeding chips to each of the bond heads 1307a-e, rather than having an individual feeder (1204a and 1204b) for each bond head (1202a and 1202b). The feeder 1309 comprises a chip tray 13 0 which is generally rectangular shape having a length which extends across the whole bond head gang. One end portion of the chip tray 1310 is attached to an arm 1312a which extends from the pillar 1205a. The other end portion of the chip tray 1310 is attached to an arm 1312b which extends from the pillar 1205b. In use, the chip tray 1310 can move along the arms 1312a and 1312b between a loading position and a feeding position. Whilst in the loading position, the chip tray 1310 may be at an end of the arms 1312a and 1312b furthest from the bond heads 1307a-e so that a corresponding placer (not shown) may place chips on the chip tray 1310. Whilst in the feeding position, the chip tray 1310 may be at an end of the arms 1312a and 1312b closest to the bond heads 1307a-e so that the chip tray 1310 is positioned directly below the bond heads 1307a-e. The feeder 1309 may be the same as the feeders 720a and 720b of Figure 7.

In an embodiment, the apparatus comprises a substrate 1303, rather than the substrate 1208. These two substrates may be substantially the same. In an embodiment, in use, the apparatus 1300 may operate as follows.

In an embodiment, the feeder 1309 may be configured into its loading position. Chips may be placed onto the chip tray 1310, for example, by one or more corresponding placers (not shown). In an embodiment, five chips may be placed evenly-spaced along the chip tray 1310, wherein each chip corresponds to a different one of the bond heads 1307a-e. This can be seen on Figure 15a by the chips 1314a-e. In an embodiment, a spacing between adjacent chips 1314a-e may be the same as a spacing between adjacent bond heads 1307a-e. In an embodiment, the feeder 1310 may be moved from its loading position to its feeding position. At the feeding position the bond heads 1307a-e may obtain chips 1314a-e from the chip tray 1310, for example, by suction. The feeder 1310 may then return to its loading position. At this time, more chips may be loaded onto the chip tray 1310. In an embodiment, the bond stage may move the substrate 1303 into position underneath the bond heads 1307a-e. Specifically, each bond head 1307a-e is carrying a different one of chips 1314a-e and the substrate will have a corresponding chip bonding site for each chip 1314a-e. Therefore, the position of the substrate 1303 aims to line-up the chip bonding sites with their respective chips. This positioning may be controlled by the controller.

In an embodiment, although the above operation aims to align chip bonding sites with their respective chips, the alignment may not be sufficiently accurate. Therefore, vision system 1206 may move in-between the bond heads 1307a-e and the substrate 1303 to determine the alignment between each chip 1314a-e and its respective chip bonding site. As before, alignment marks on the substrate 1303 may be used to provide reference points on the substrate 1303. The result of this process may be the calculation of a series of offsets. An offset may be provided for each one of the bond heads 1307a-e and the bond stage. The offset may indicate the movement required by the bond heads to bring the chips 1314a-e into alignment with their respective bonding sites on the substrate 1303. Bond head offsets may define an X, Y and/or Θ movement. The X movement may be provided by moving the bond head on the rail and/or by using its horizontal movement plate. Bond stage offsets may define an X and Y movement. Once the necessary offset movements have been made, bonding can begin.

In an embodiment, each of the bond heads 1307a-e may move vertically towards the substrate 1303. For a given bond head (e.g. 1307a) the vertical movement may stop once the chip (e.g. 1314a) contacts its bonding site on the substrate 1303. The bond head may apply pressure (i.e. a pressing force) to the chip once it contacts the substrate to improve the bond strength. The bond head may heat the chip before and/or during the bonding operation to improve the bond strength. Once the chip has been bonded to the substrate, the bond head releases the chip, for example, by deactivating suction. The bond head then moves vertically away from the substrate 1303 and towards the upper platform to which the bond head is coupled. It is to be understood that the bond heads 1307a-e may move vertically together as one or independently of one another.

In an embodiment, once all of the bond heads 1307a-e have completed bonding, the feeder 1309 may be used again to feed new chips to the bond heads 1307a-e in anticipation for another bonding operation. In an embodiment, in a given bonding operation, all bond heads 1307a-e may be used to bond a chip to the substrate 1303. In another embodiment, one or more bond heads may not be used to bond a chip to the substrate. For example, a chip may not be loaded onto the feeder for certain bond heads and those certain bond heads may not perform any bonding operation.

Figure 15b illustrates a further operation of the apparatus 1300. Figure 15b illustrates only part of the apparatus 1300. Specifically, only the bond heads 1307a-e and the substrate 1303 are shown.

In an embodiment, a pre-bonding configuration of the bond heads 1307a-e is shown in phantom (i.e. dotted line). In the pre-bonding configuration, the spacing between the bond heads 1307a-e may be relatively small, i.e. the adjacent bond heads may be close together. A bonding configuration of the bond heads 1307a-e is shown in solid line. In the bonding configuration, the spacing between the bond heads 1307a-e may be wider than in the pre-bonding configuration, i.e. adjacent bond heads may be spaced further apart. It is to be understood that this operation may be achieved by the bond heads 1307a-e sliding on a rail, as described with reference to Figures 9 to 11.

In an embodiment, the spacing between adjacent bond heads 1307a-e may be set according to alignment marks on the substrate 1303. Specifically, the substrate 1303 may comprise a grid of cross shaped alignment marks. The grid may comprise multiple rows of alignment marks and multiple columns of alignment marks, for example, three rows and ten columns. Two exemplary alignment marks 1304a and 1304b are indicated on Figure 15b. The two alignment marks 1304a and 1304b may be adjacent alignment marks in the same row. A spacing between the two alignment marks 1304a and 1304b may define a unit pitch for the substrate 1303. The unit pitch may be about 20mm. The spacing between each pair of adjacent marks in the same row may equal the unit pitch. The spacing between each pair of adjacent marks in the same column may equal the unit pitch.

In an embodiment, each alignment mark may indicate the bonding site for a chip. Additionally or alternatively, multiple alignment marks may indicate the bonding site of a single chip (e.g. as in Figure 14d). Additionally or alternatively, only some alignment marks may indicate a bonding site or part of a bonding site. In the embodiment of Figure 15b, each alignment mark indicates the centre of a bonding site. The following explains how the apparatus 1300 performs bonding in this case.

In an embodiment, in the bonding configuration, the spacing between adjacent ones of bond heads 1307a-e is set to double the unit pitch. In a first bonding operation, each bond head 1307a-e may bond a chip to every other one of the top row of alignment marks of substrate 1303. Accordingly, after this first bonding operation is complete, every other alignment mark in the top row of alignment marks will have a chip bonded to it. In a second bonding operation, the gaps in the top row will be filled in such that each alignment mark in the top row of alignment marks will have a chip bonded to it. This process will then continue for each lower row of alignment marks. In this way, a chip may be bonded to each alignment mark on the substrate 1303 by the bond heads 1307a-e. In an embodiment, a different order may be used, for example, the first bonding operation may be performed for each row in turn and then the second bonding operation may be performed for each row in turn.

Figure 15c illustrates a further operation of the apparatus 1300, in accordance with an embodiment. Figure 15c shows a further substrate 1350 comprising three rows of alignment marks and eight columns of alignment marks. Since the apparatus 1300 comprises five bond heads 1307a-e, and there are eight columns, one of the bond heads may be excluded from the bonding operation. Therefore, in an embodiment, bond head 1307e may be removed from the bonding operation by sliding it to an end portion of the rail, as described above with reference to Figure 11b. Accordingly, the phantom lines indicate a pre-bonding configuration in which all bond heads 1307a-e are closely spaced together. However, the solid lines indicate a bonding configuration in which bond heads 1307a-d are spaced apart by double the unit pitch, and bond head 1307e has been moved away from the substrate 1350 so that it is not included in the bonding operation. Accordingly, analogous bonding operations may be performed, as described above with reference to Figure 15b, in order to bond a chip to each alignment mark on substrate 1350 using bond heads 1307a-d.

Figure 15d illustrates a further operation of the apparatus 1300, in accordance with an embodiment. Figure 15d shows a further substrate 1360 comprising three rows of alignment marks and eleven columns of alignment marks. Since the apparatus 1300 comprises five bond heads 1307a-e, and there are eleven columns, it is efficient to use all five bond heads 1307a-e, rather than move one or more bond heads to the end portion of the rail. The bonding operation will be identical to the bonding operation of Figure 15b; however, the bond head 1307e will have to bond three columns and the other bond heads 1307a-d will have to bond two columns. Accordingly, in an embodiment, different bond heads may perform a different number of bonding operations. For example, to bond the final chip of each row (i.e. the rightmost column) only one chip may be placed on the chip tray 1309. The chip may be at the same position as chip 13 4e.

In an embodiment, the spacing between the bond heads 1307a-e may be determined by the controller based on a predetermined algorithm. The algorithm may receive as inputs the number of bond heads of the apparatus, the number of bonding sites on the substrate, the spacing between adjacent bonding sites, the arrangement of the bonding sites on the substrate. Some or all of these inputs may be predefined to the controller, for example, by an operator of the apparatus. Some or all of these inputs may be determined by a vision system of the apparatus. In any case, based on these inputs, the controller may determine the number of bond heads to be used, the spacing between adjacent bond heads and the number of bonds to be performed by each bond head being used. Figure 16 illustrates a bonding sequence 1400 embodiment performed by the apparatus 1300 embodiment illustrated in Figures 17a-d. Before the bonding sequence starts, the apparatus 1300 is in the configuration as described above with reference to Figure 17a. Step 1402 may be seen more particularly on Figure 17a. At step 1402, the bond stage moves the substrate 1303 into position underneath the bond heads 307a-e so that the chips are opposite their respective bonding sites. The substrate 1303 comprises three rows of alignment marks and eleven columns of alignment marks. Since the apparatus 1300 comprises five bond heads 1307a-e, and there are eleven columns, it is efficient to use all five bond heads 1307a-e. The bonding operation will be similar to the bonding operation of Figure 15d. Accordingly, the bond head 1307e will have to bond three columns and the other bond heads 1307a-d will have to bond two columns. As can be seen on Figure 17a, the bond heads 1307a-e are positioned directly over the lowest row of alignment marks on the substrate 1303. Further, there is a bond head positioned over every other alignment mark on the lowest row, but there are two uncovered alignment marks on the rightmost end of the lowest row. Also at step 1402, the feeder 1309 moves from the loading position to the feeding position. Once in the feeding position, the bond heads 1307a-e pick up a different one of chips 1314a-e from the chip tray 1310.

Step 1404 may be seen more particularly on Figure 17b. At step 1404, the feeder 1309 returns to its loading position. The vision system 1206 then checks the alignment of each chip 1314a-e on its respective bond head with the chips corresponding bonding site (i.e. alignment mark). For each chip and bonding site pair, an offset is determined by the controller using the images captured by the vision system. The offset indicates what movements are necessary by the bond head and/or the bond stage to bring the chip into alignment with its corresponding bonding site. For example, the vision system 1206 may first capture an image of the chip 1314a on the bond head 1307a. Next, the vision system may capture an image of the bonding site on the substrate 1303. The required X, Y and/or Θ movements required by the chip to bring it into alignment with the bonding site may be computed by the controller. The controller may then cause the bond head 1307a to move by the required amounts in the X, Y and/or Θ directions to align the chip with the bonding site. This process may then be repeated for other bond heads 1307b-e. In an embodiment, images for multiple chips and bonding sites may be captured and, subsequently, multiple offsets may be determined and alignment movements performed. At the end of this process, each chip 1314a-e is aligned with its corresponding bonding site on the substrate 1303. In an embodiment, the bond stage may move in addition to the bond heads 1307b-e. Step 1406 may be seen more particularly on Figure 17c. At step 1406, the vision system 1206 moves away from the bond head 1307a-e to its idle position. Each bond head 1307a-e performs a vertical movement to bond their chip to the substrate. Each bond head 1307a-e then releases its chip and moves vertically away from the substrate and towards the upper platform. The bond heads 1307a-e may move vertically as one. This operation may be analogous to the operation as described above, with reference to step 1106 of Figure 11. Next, new chips 1370a-e are placed onto the feeder 1309 in preparation for a subsequent bonding operation. For example, the new chips 1370a-e may be bonded to the same row of alignment marks or a different row of alignment marks. A decision block 1408 is present after the step 1406. At the decision block 1408, it is decided if bonding is complete or not. If bonding is complete, the bonding process ends. Alternatively, if bonding is not complete, the bonding process returns to step 1402.

It is to be understood that each bond head 1307a-e may move together as one or bond heads may move independently from each other. For example, all bond heads 1307a-e may perform movements in the X, Y and/or Θ directions at the same time, i.e. together. Alternatively, one bond head may perform movements in the X, Y and/or Θ directions independently from at least one other bond head. Alternatively, movements in one direction may be performed by bond heads together, but movements in another direction may be performed by different bond heads independently. For example, vertical (i.e. Z-direction) movements may be performed by all bond heads together as one. However, horizontal (i.e. X and/or Y) and/or angular (i.e. Θ) movements may be performed by each bond head independently of other bond heads.

Figure 18 illustrates an alternative operation of the vision camera 1206 of apparatus 1300, in accordance with an embodiment. This operation is analogous to the operation of Figure 14d. However, whereas the operation of Figure 14d relates to the alignment of a single chip to its respective chip bonding site, the operation of Figure 18 relates to the alignment of five chips ( 314a-e) to their respective bonding sites on substrate 1600.

In an embodiment, as can be seen on Figure 18, the chip 1314a is intended to be bonded such that two diagonal corners of the chip 1314a are respectively aligned with two alignment marks on substrate 1600. Accordingly, in a first operation, the vision system 1206 moves to capture an image of the chip 1314a on the bond head 1307a which is positioned over the substrate 1600. In a second operation, the vision system 1206 first moves to position 1602 to capture an image of the first one of the two alignment marks. Subsequently, the vision system 1206 moves to position 1604 to capture an image of the second one of the two alignment marks. At this point, the vision system 1206 then moves on to perform a similar process for the chip 1314b and its bonding site. Following this, the process is repeated for each remaining chip, i.e. chips 1314c, 1314d and 1314e. The vision system 1206 then returns to its idle position. The path of the vision system 1206 is indicated on Figure 18 by arrows. In view of the above, a total of three images are captured for each chip and bonding- site pair. Each image may be compared to a reference location in order to determine whether the chip is aligned with its corresponding bonding site. If the two are not aligned, an offset is calculated and the bond stage and/or corresponding bond head are moved to achieve alignment. This process is analogous to the process as described with reference to Figure 14d.

It is noted that the controller may cause each bond head to move into alignment as soon as its corresponding images have been captured. Alternatively, the controller may cause some or all bond heads to wait for the image capturing to complete for all bond heads before causing them to move into alignment.

Figure 19 is a flow diagram of a method 1700 for bonding in accordance with an embodiment. The method 1700 may be suitable for bonding a plurality of semiconductor chips onto a substrate. The method 1700 may be performed using the apparatus of Figure 1 or the apparatus of Figures 14a-g. For the sake of clarity the method will be described with reference to Figure 1.

At step 1702, a substrate is received on to the bond stage 8. For example, the substrate may be placed onto the bond stage manually or by some mechanical device.

At step 1704, a chip is obtained by the first bond head 4. The chip may be the first chip to be bonded in accordance with this method. The chip may be obtained by the bond head 4 as described above. For example, a loading mechanism may be used to transfer a chip from a wafer to a feeder and the feeder may be used to present the chip to the bond head.

At step 1706, the first bond head 4 and the bond stage 8 move relative to each other to align the first chip on the first bond head 4 with the substrate on the bond stage 8. The bond head 4 and/or the bond stage 8 may move. A vision system may be used to determine what movements are necessary to achieve alignment. This is described in detail above.

At step 1708, a next chip is obtained by the second bond head 6. The next chip may be the second chip to be bonded in accordance with this method. The chip may be obtained by the bond head 6 as described above. For example, a loading mechanism may be used to transfer a chip from a wafer to a feeder and the feeder may be used to present the chip to the bond head.

At step 171.0, the first chip is bonded to the substrate. Specifically, the first bond head 4 is moved towards the bond stage 8 to contact the first chip with the substrate. Next, the bond head 4 releases the first chip. Subsequently, the first bond head 4 is retracted away from the bond stage.

At step 1712, the second bond head 6 and the bond stage 8 move relative to each other to align the second chip on the second bond head 6 with the substrate on the bond stage 8. The bond head 6 and/or the bond stage 8 may move. A vision system may be used to determine what movements are necessary to achieve alignment. This is described in detail above. At step 1714, the second chip is bonded to the substrate. Specifically, the second bond head 6 is moved towards the bond stage 8 to contact the second chip with the substrate. Next, the bond head 6 releases the second chip. Subsequently, the second bond head 6 is retracted away from the bond stage. At step 1716, if bonding is finished, i.e. only two chips are to be bonded to the substrate, the method ends. On the other hand, if further bonding is necessary, processing flows back to step 1704. However, this phase of the method bonds a third chip and a fourth chip to the substrate. Additional phases of the method may be performed to bond additional chips to the substrate. For example, the method may be used to bond ten, twenty or one hundred chips to the substrate. Furthermore, some method steps may not be performed in some phases so that an odd number of chips can be bonded to the substrate.

In an embodiment, the third chip is obtained on the first bond head 4 after the first bond head 4 retracts away from the bond stage following bonding of the first chip. In an embodiment, the fourth chip is obtained on the second bond head 6 after the second bond head 6 retracts away from the bond stage following bonding of the second chip.

In an embodiment, the first bond head 4 heats chips obtained thereby before releasing the chips after bonding. For example, the bond head 4 may begin heating up a chip as soon as the chip has been obtained. Alternatively, the bond head 4 may begin heating the chip after alignment of the chip is underway or completed. The second bond head 6 may operate in a corresponding manner. In an embodiment, the first bond head 4 may delay obtaining a subsequent chip after a bonding step is performed, i.e. after releasing a chip. For example, the first bond head 4 may need to cool down so that it is not too hot when it obtains a new chip. Being too hot may thermally shock the new chip, which may cause damage to the chip. The second bond head 6 may operate in a corresponding manner.

In an embodiment, some of the steps of the method 1700 may be rearranged. For example, the first bond head 4 may obtain a chip (e.g. the third chip) before or during step 1712 and/or step 1714. In an embodiment, the first bond head 4 may obtain a chip in-between steps 1712 and 1714. Also, the second bond head 6 may delay obtaining a chip (e.g. the fourth chip) until after step 1710.

An advantage of the method of 1700 is that one bond head can be cooling-down and/or heating-up whilst the other bond head is aligning, bonding or obtaining a chip. In this way productivity can be maximised. Specifically, time is not wasted waiting for a bond head to cool-down or heat-up because this time is being used by another bond head to complete bonding related operations.

In the above-described embodiments, the bond stage is configured in use to receive a substrate. In some embodiments, the bond stage may include means for ensuring that the substrate is received in a certain orientation. Additionally, the bond stage may include means for ensuring that the substrate does not move once received. For example, a surface of the bond stage may include a recessed portion which is sized and shaped to match a substrate. Accordingly, the substrate may fit into the recess to ensure its orientation. Additionally or alternatively, the bond stage may include additional mechanical means (e.g. a clip or a fastening) which is configured in use to hold the substrate to the bond stage. Also, the bond stage may comprise magnetic means which is configured in use to attract the substrate to the bond stage.

The above-described embodiments, relate to an apparatus or method for bonding a chip to a substrate. In an embodiment, the chip is an integrated circuit or monolithic integrated circuit (also referred to as an IC or a microchip). In an embodiment, the chip is a set of electronic circuits on one small plate of semiconductor material, for example silicon and gallium arsenide (GaAs). In an embodiment, the substrate may be a strip of material such as silicon, gallium arsenide (GaAs), ceramic, BT resin, epoxy resin, FR4 or polymer. In an embodiment, the substrate serves as a foundation upon which semiconductor chips are deposited. In an embodiment, the substrate may comprise one or more electrically conductive tracks to transport charge around the substrate and between different chips bonded to the substrate.

In an embodiment, the chip and/or the substrate may contain an intermediate material which works to bond the chip to the substrate. For example, the intermediate material may be solder. In operation, the intermediate material may mechanically adhere the chip to the substrate. Additionally, the intermediate material may protect a portion of the chip and/or substrate from physical damage. Additionally, the intermediate material may be electrically conductive to facilitate charge flow between the chip and the substrate.

The above-described embodiments relate to an apparatus for bonding semiconductor chips to a substrate. The apparatus includes a plurality of bond heads and a bond stage. Each bond head of the plurality of bond heads is operable to obtain and release a chip. The bond stage is operable to receive a substrate. Also, each bond head of the plurality of bond heads is relatively moveable with respect to the bond stage and operable to contact a chip obtained by the bond head with a substrate received on the bond stage and to release the chip to bond the chip to the substrate. In an embodiment, the apparatus may further include a controller in communication with the bond stage and each bond head of the plurality of bond heads. Additionally, the controller may control each bond head of the plurality of bond heads to move relatively with respect to the bond stage, to contact a chip obtained by the bond head with a substrate received on. the bond stage, and to release the chip to bond the chip to the substrate.

It is to be understood that one or more features from one of the above-described embodiments may be combined with one or more features from one or more other ones of the above-described embodiments to form one or more new embodiments which covered by the scope of the appended claims. It will be appreciated by a person skilled in the art that numerous variations a d/or modifications may be made to one or more of the above-described embodiments without departing from the scope of the appended claims. The above-described embodiments are, therefore, to be considered in all respects to be illustrative and not restrictive.

Claims

1. An apparatus for bonding semiconductor chips to a substrate, the apparatus comprising:

a frame;

a bond stage coupled to the frame and operable to receive a substrate;

2. The apparatus of claim 1 , wherein at least two bond heads of the plurality of bond heads are operable to move chips obtained by the at least two bond heads as one with respect to the bond stage.

3. The apparatus of claim 2, wherein the at least two bond heads are operable to move the chips obtained by the at least two bond heads as one in a plane parallel to a plane of the bond stage.

4. The apparatus of claim 2 or claim 3, wherein the at least two bond heads are operable to move the chips obtained by the at least two bond heads as one towards or away from the bond stage.

5. The apparatus of any preceding claim, wherein one bond head of the plurality of bond heads is operable to move a chip obtained by the one bond head relatively with respect to a chip obtained by another bond head of the plurality of bond heads.

6. The apparatus of claim 5, wherein the one bond head is operable to move the chip obtained by the one bond head in a plane parallel to a plane of the bond stage independently from the chip obtained by the other bond head.

7. The apparatus of claim 5 or claim 6, wherein the one bond head is operable to move the chip obtained by the one bond head towards or away from the bond stage independently from the chip obtained by the other bond head.

8. The apparatus of any preceding claim, wherein the plurality of bond heads is moveabiy coupled to the frame and the bond heads are arranged linearly, and wherein a spacing between adjacent pairs of bond heads is adjustable.

9. The apparatus of claim 8, wherein the plurality of bond heads is coupled to the frame via a rail and each bond head is operable to slide on the rail to adjust the spacing between adjacent pairs of bond heads.

10. The apparatus of claim 9, wherein a length of the rail is sized such that, when at least one bond head slides to an end portion of the rail, relative movement between the at least one bond head and the bond stage is limited such that the at least one bond head cannot contact a chip obtained by the at least one bond head with the substrate.

11. The apparatus of claim 9 or 10, wherein the rail is moveabiy coupled to the frame and the rail comprises a drive mechanism operable to move the rail towards or away from the bond stage to move the plurality of bond heads towards or away from the bond stage.

12. The apparatus of any preceding claim, wherein the frame comprises a first platform and an opposing second platform, the first platform being spaced from and held parallel to the second platform by at least one pillar, the plurality of bond heads being coupled to the first platform and the bond stage being coupled to the second platform.

13. The apparatus of claim 12, wherein the bond stage is moveabiy coupled to the second platform and the bond stage comprises a drive mechanism operable to move the bond stage in a plane parallel to the second platform.

14. The apparatus of any preceding claim, further comprising a feeder moveabiy coupled to the frame, the feeder comprising a drive mechanism operable to move the feeder between a loading position, in which the feeder is configured to receive a chip, and a feeding position, in which the feeder is configured to present the chip to one of the plurality of bond heads so that the one bond head can obtain the chip from the feeder.

15. The apparatus of claim 14, wherein the feeder is operable to receive at least two chips and to present each chip to a different one of the plurality of bond heads.

16. The apparatus of claim 14 or 15, further comprising a loading mechanism operable to load a chip onto the feeder from a wafer, when the feeder is in the loading position.

17. The apparatus of any preceding claim, further comprising a camera moveably coupled to the frame, the camera comprising a drive mechanism operable to move the camera relative to the plurality of bond heads and the bond stage, the camera being configured in use to measure a position of at least one bond head with respect to the bond stage, wherein the at least one bond head and the bond stage are operable to move into alignment with each other in dependence on the position measured by the camera.

18. The apparatus of claim 17, wherein the camera is configured in use to move in- between the at least one bond head and the bond stage, the camera having a first lens for measuring a position of the at least one bond head with respect to a reference and a second lens for measuring a position of the bond stage with respect to the reference, wherein the at least one bond head and the bond stage are configured to move into alignment with each other in dependence on the positions measured by the first and second lenses.

19. The apparatus of any preceding claim, wherein at least one bond head of the plurality of bond heads is operable to heat a chip obtained by the at least one bond head.

20. The apparatus of any preceding claim, wherein at least one bond head of the plurality of bond heads is operable to apply a predetermined pressure force to the chip when contacting the chip with the substrate.

21. The apparatus of any preceding claim, wherein at least one bond head of the plurality of bond heads comprises a suction device, wherein, when a chip is presented to the at least one bond head, the suction device is configured to suck the chip onto the at least one bond head and to maintain suction to hold the chip on the at least one bond head, and wherein the suction device is configured to deactivate suction to release the chip from the at least one bond head.

22. The apparatus of any preceding claim, further comprising a controller in communication with the bond stage and each bond head of the plurality of bond heads, the controller being operable to control each bond head to move relatively with respect to the bond stage, to obtain a chip and to release the obtained chip.

23. The apparatus of claim 16, further comprising an additional frame, an additional plurality of bond heads coupled to the additional frame, an additional bond stage coupled to the additional frame and an additional feeder moveably coupled to the additional frame,

wherein each bond head of the additional plurality of bond heads is relatively moveable with respect to the additional bond stage and operable to contact a chip obtained by the bond head with an additional substrate received on the additional bond stage and to release the chip to bond the chip to the additional substrate, wherein the additional feeder comprises a drive mechanism operable to move the additional feeder between a loading position, in which the additional feeder is configured to receive a chip, and a feeding position, in which the additional feeder is configured to present the chip to one of the additional plurality of bond heads so that the one bond head can obtain the chip from the additional feeder, and

24. A method for bonding a plurality of semiconductor chips onto a substrate, the method comprising:

a. receiving a substrate onto a bond stage;

b. obtaining a first chip by a first bond head;

d. obtaining a second chip by a second bond head; e. moving the first bond head towards the bond stage to contact the first chip with the substrate and releasing the first chip to bond the first chip to the substrate, and retracting the first bond head away from the bond stage;

f. moving the second bond head and the bond stage relative to each other to align the second chip on the second bond head with the substrate on the bond stage; and

g. moving the second bond head towards the bond stage to contact the second chip with the substrate and releasing the second chip to bond the second chip to the substrate, and retracting the second bond head away from the bond stage.

25. The method of claim 24, further comprising:

26. The method of claim 24 or 25, further comprising:

27. The method of claim 26 when dependent on claim 25, further comprising:

delaying the first bond head from obtaining the third chip after releasing the first chip on the substrate to allow the first bond head to cool down; and

delaying the second bond head from obtaining the fourth chip after releasing the second chip on the substrate to allow the second bond head to cool down.