CN115972081A - Megasonic-assisted lapping disk and lapping assembly - Google Patents

Abstract

The invention provides a megasonic-assisted grinding disc and a grinding assembly. The megasonic-assisted abrasive disk comprises: the first surface of the grinding disc body is provided with an accommodating groove; the upper disc covers the first surface of the grinding disc body and is detachably connected with the grinding disc body; a megasonic generator; the energy converter is arranged in the accommodating groove and is electrically connected with the megasonic generator; the matching layer is fixedly connected with the surface of one side, facing the upper disc, of the transducer in the accommodating groove and is abutted against the upper disc; the transmission shaft is fixedly connected with the grinding disc body; and the driving assembly is in driving connection with the transmission shaft and drives the transmission shaft to rotate. According to the invention, the megasonic is used for driving the grinding disc body and the grinding pad fixed on the grinding disc body to vibrate at high frequency, so that the grinding fluid in the grinding pad nest chamber vibrates at high frequency, the grinding effect which can be achieved by the traditional large flow of the grinding fluid is achieved under the condition of smaller flow, and meanwhile, large-particle impurities in the grinding pad nest chamber leave the grinding pad under the action of high-frequency vibration and micro-flow of the grinding fluid, so that the wafer scratch is reduced.

Description

Megasonic-assisted lapping disk and lapping assembly

Technical Field

The invention relates to the technical field of semiconductor integrated circuit chip manufacturing, in particular to a megasonic-assisted grinding disc and a grinding assembly.

Background

In the last two decades, the semiconductor industry has rapidly progressed according to moore's law, and the feature sizes of integrated circuits have been shrinking. Line widths from 0.18 μm to 5/7nm have marked the entry of integrated circuits into the nanoscale era. The nanoscale chip requires high performance, high integration level, high speed and stability, and the flatness requirement of the interconnection layer material of the integrated circuit also enters the nanoscale.

Techniques for the deposition of layers of material in modern integrated circuit wafers include Physical Vapor Deposition (PVD), chemical Vapor Deposition (CVD), plasma Enhanced Chemical Vapor Deposition (PECVD), and electrochemical plating (ECP), among others. Due to the technical limitations of the deposition technique itself, the surface of the deposited material is subsequently planarized. Planarization techniques are effective in removing surface topography and surface defects, such as height unevenness, surface roughness, material agglomeration, lattice damage, scratches and contamination, etc., that do not meet circuit requirements during material deposition. Chemical mechanical planarization or Chemical Mechanical Polishing (CMP) is a common technique used to polish or planarize workpieces, such as semiconductor wafers. In conventional Chemical Mechanical Polishing (CMP), a wafer is fixed on a polishing head, a polishing pad is fixed on a polishing disk, the wafer and the polishing pad are in direct contact during polishing, controllable pressure is provided between the wafer and the polishing pad, a polishing liquid supply arm delivers polishing liquid, and the wafer and the polishing pad rotate in the same direction at different rotating speeds, and a film on the wafer is polished under the action of relative motion of the polishing pad and the polishing head until a preset thickness is reached. In this process, the lapping liquid is retained in the lapping pad nest chamber in a large number, the utilization ratio is lower, and large particle impurities are easily hidden in the lapping pad nest chamber, can cause the damage to the wafer.

Disclosure of Invention

Accordingly, the present invention provides a megasonic-assisted abrasive disk and assembly. Drive the grinding miller body and go up fixed grinding pad high-frequency oscillation with the help of the megasonic, then the lapping liquid high-frequency oscillation in the grinding pad nest room reaches the grinding effect that the large-traffic can reach of traditional lapping liquid under the condition of less flow, increases operation rate, and the large granule impurity in the grinding pad nest room leaves the grinding pad under the effect that high-frequency oscillation and lapping liquid flow a little simultaneously, reduces the wafer scratch.

The invention provides a megasonic-assisted abrasive disk comprising: the grinding disc comprises a grinding disc body, wherein a first surface of the grinding disc body is provided with an accommodating groove; an upper disc, which covers the first surface of the grinding disc body and is detachably connected with the grinding disc body; a megasonic generator; the transducer is arranged in the accommodating groove and is electrically connected with the megasound generator; the matching layer is fixedly connected with one side surface, facing the upper disc, of the transducer in the accommodating groove and is abutted against the upper disc; the transmission shaft is fixedly connected with the grinding disc body; and the driving assembly is in driving connection with the transmission shaft and drives the transmission shaft to rotate.

Optionally, the megasonically-assisted abrasive disk further comprises: and the grinding pad is fixedly connected with the surface of one side, back to the accommodating groove, of the upper disc.

Optionally, an adhesive layer is disposed on a side surface of the polishing pad facing the upper disc, and the polishing pad is adhesively connected to the upper disc.

Optionally, the megasonically-assisted abrasive disk further comprises: and the end point detection device is used for monitoring the thickness of the film layer on the surface of the wafer and is arranged in the accommodating groove.

Optionally, the endpoint detection device comprises at least one of an optical endpoint detection device and an eddy current endpoint detection device.

Optionally, the transducer, matching layer and abrasive disk body are coaxially arranged.

Optionally, the megasonic generator emits megasonic at a frequency of 850KHz to 1.4MHz.

Optionally, the upper disc is bolted to the abrasive disc body.

Optionally, a surface of the matching layer facing the transducer is provided with an adhesive layer, and the matching layer and the transducer are adhesively connected.

The invention also provides a grinding assembly, which comprises a grinding head, a grinding fluid supply arm, a grinding pad dresser and the megasonic-assisted grinding disc.

Compared with the prior art, the technical scheme provided by the invention at least has the following beneficial effects:

by adopting the megasonic-assisted grinding disc and the grinding assembly, the megasonic drives the grinding disc body and the grinding pad fixed on the grinding disc body to vibrate at high frequency, so that the grinding fluid in the grinding pad nest chamber vibrates at high frequency, the grinding effect which can be achieved by the traditional grinding fluid at large flow can be achieved under the condition of smaller flow, the utilization rate is improved, and meanwhile, large-particle impurities in the grinding pad nest chamber leave the grinding pad under the action of high-frequency vibration and micro-flow of the grinding fluid, and the wafer scratch can be reduced.

Drawings

FIG. 1 is a schematic view of a megasonic-assisted abrasive disk in accordance with one embodiment of the invention;

FIG. 2 is a schematic view of a polishing assembly according to one embodiment of the present invention.

Reference numerals:

1: a grinding disk body; 2: hanging the plate; 3: a megasonic generator; 4: a transducer; 5: a matching layer; 6: a drive shaft; 7: a drive assembly; 8: a grinding head; 9: a grinding fluid supply arm; 10: a polishing pad dresser.

Detailed Description

The embodiments of the present invention will be further described with reference to the accompanying drawings. In the description of the present invention, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc., indicate orientations or positional relationships based on the orientations or positional relationships shown in the drawings, and are only for convenience of description of the present invention, and do not indicate or imply that the device or assembly referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus, should not be construed as limiting the present invention. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance. Wherein the terms "first position" and "second position" are two different positions.

Fig. 1 is a schematic view of a megasonic-assisted abrasive disk in accordance with one embodiment of the invention. As shown in fig. 1, the megasonically-assisted abrasive disk includes an abrasive disk body 1, an upper disk 2, a megasonic generator 3, a transducer 4, a matching layer 5, a drive shaft 6, and a drive assembly 7.

The first surface of the grinding disc body 1 is provided with an accommodating groove; the upper disc 2 covers the first surface of the grinding disc body 1 and is detachably connected with the grinding disc body 1; the transducer 4 is arranged in the accommodating groove and is electrically connected with the megasonic generator 3; the matching layer 5 is fixedly connected with one side surface of the transducer 4 facing the upper disc 2 in the accommodating groove and is abutted with the upper disc 2; the transmission shaft 6 is fixedly connected with the grinding disc body 1; the driving component 7 is in driving connection with the transmission shaft 6 and drives the transmission shaft 6 to rotate.

When the polishing pad is used, the transducer 4 is placed in the accommodating groove, the matching layer 5 is attached to and fixed on the surface of the transducer 4, the upper disc 2 is connected with the polishing disc body 1, the upper disc 2 covers the first surface of the polishing disc body 1 where the accommodating groove is located, the upper disc covers the accommodating groove and abuts against the matching layer 5, and a polishing pad (not shown) is fixed on the surface of the upper disc 2. And in the grinding stage, the driving assembly 7 drives the transmission shaft 6 to rotate so as to drive the grinding disc body 1 and a grinding pad fixed on the grinding disc body 1 to rotate, the grinding head drives a wafer to abut against the grinding pad and rotate in the same direction, a grinding fluid supply arm conveys grinding fluid to the grinding pad, the megasonic generator 3 is started at the same time, the megasonic generator 3 sends megasonic driving signals and transmits the megasonic driving signals to the transducer 4 through a lead, the transducer 4 converts the megasonic driving signals into megasonic energy to drive the matching layer 5 to vibrate, so as to drive the upper disc 2 abutting against the matching layer 5 to vibrate, the upper disc 2 vibrates to drive the grinding pad fixed on the upper disc 2 to vibrate, so that the grinding fluid and large-particle impurities in the grinding pad chamber vibrate along with the upper disc, the grinding fluid realizes micro-flow through high-frequency vibration, the grinding effect which can be achieved by the traditional large-flow grinding fluid is achieved under the condition of smaller flow, and the large-particle impurities leave the grinding pad chamber under the action of high-frequency vibration and the micro-flow of the grinding fluid.

By adopting the megasonic-assisted grinding disc, the megasonic drives the grinding disc body 1 and the grinding pad fixed on the grinding disc body to vibrate at high frequency, so that the grinding fluid in the grinding pad nest chamber vibrates at high frequency, the grinding effect which can be achieved by the large flow of the traditional grinding fluid can be achieved under the condition of smaller flow, the utilization rate is improved, and meanwhile, large-particle impurities in the grinding pad nest chamber leave the grinding pad under the action of high-frequency vibration and micro-flow of the grinding fluid, and the wafer scratch can be reduced.

As shown in fig. 1, in this embodiment, the polishing disc body 1 is a cylinder, the receiving groove is formed in a first surface of the polishing disc body 1, that is, the upper surface of the polishing disc body 1 in fig. 1, the transducer 4 and the matching layer 5 are sequentially placed in the receiving groove, the transducer 4 is connected to the external megasonic generator 3 through a wire, the upper disc 2 is a circular plate body matched with the cross section of the polishing disc body 1, covers the upper surface of the polishing disc body 1, and is detachably connected to the polishing disc body 1, and the polishing pad is fixed to the upper surface of the upper disc 2. The transmission shaft 6 with the lower surface fixed connection of abrasive disc body 1, drive assembly 7 can only include the motor, make the output shaft of motor direct with transmission shaft 6 is connected and drives its rotation, also can set up to the complex transmission form between the subassembly part, for example, the output shaft of motor and the axle center fixed connection of first drive wheel in the drive assembly 7, the second drive wheel cover is established transmission shaft 6, the conveyer belt is established to the cover between first drive wheel and second drive wheel, then the first drive wheel of motor output drive rotates, and first drive wheel rotates and drives the conveyer belt and rotate, and the conveyer belt rotates and drives the second drive wheel and rotate, and final second drive wheel drive transmission shaft 6 rotates. The megasonic-assisted grinding disc of the invention is started up with a grinding program of a random table, and the machine is not started up in a standby state, so that the megasonic-assisted grinding disc can be suitable for 4-inch, 6-inch, 8-inch, 12-inch or other wafer-size machines. The shape of the matching layer 5 and the transducer 4 may be, but is not limited to, a circular, square, triangular, rectangular, etc. symmetrical geometric figure, and the material of the matching layer 5 and the transducer 4 may be, but is not limited to, a piezoceramic material and an epoxy material. The matching layer 5 can select different materials and thicknesses according to different megasonic action strength requirements, the highest sound transmission efficiency or the lower sound transmission condition is ensured, finally megasonic acts on the grinding disc body 1, the upper disc 2 and the grinding pad fixed on the upper disc 2, so that the grinding pad vibrates at high frequency and small amplitude, and indirectly acts on grinding fluid and large-particle impurities in the grinding pad nest chamber, and the grinding fluid generates micro-flow.

Optionally, the megasonic-assisted polishing disk further comprises a polishing pad (not shown), and the polishing pad is fixedly connected with a side surface of the upper disk 2, which faces away from the accommodating groove. The grinding pad is preset on the upper disc 2, so that the field operation efficiency is improved.

Optionally, an adhesive layer is disposed on a side surface of the polishing pad facing the upper disc 2, and the polishing pad is adhesively connected to the upper disc 2. And the grinding pad is connected with the upper disc 2 by gluing, so that the fixed connection mode between the grinding pad and the upper disc is simplified, the operation is convenient, and the operation efficiency is improved.

Optionally, the megasonic-assisted polishing disk further comprises an end point detection device (not shown) for monitoring the thickness of the film layer on the surface of the wafer, and the end point detection device is disposed in the accommodating tank. The end point detection device is arranged, the film thickness of the surface of the wafer is judged according to the change of the received signal, the partition pressure of the grinding program is adjusted according to the film thickness, so that a better flattening effect is achieved, and meanwhile, when the film thickness reaches the preset thickness of the grinding program, the continuous grinding is stopped, so that the grinding precision is accurately controlled.

According to the practical application condition, the end point detection device can adopt any end point detection structural form which is commercially available and meets the condition of monitoring the thickness of the wafer film layer.

Optionally, the endpoint detection device comprises at least one of an optical endpoint detection device and an eddy current endpoint detection device. The optical end point detection device and the eddy current end point detection device have high sensitivity and high detection precision.

Only one type of end point detection device can be arranged in the accommodating groove, two types of end point detection devices can be arranged in the accommodating groove at the same time, and when the detection result of any type of end point detection device indicates that the thickness of the ground wafer film layer reaches the preset thickness, the grinding is stopped. Optical end point detection devices and eddy current end point detection devices are mature prior art, and the specific working principle thereof is not described herein again.

Optionally, the transducer 4, the matching layer 5 and the abrasive disc body 1 are arranged coaxially.

In this embodiment, the transducer 4, the matching layer 5 and the cross section of the grinding disc body 1 are all set to be circular, and the three are coaxially arranged, and simultaneously the transmission shaft 6 and the three are coaxially arranged. The transducer 4 and the matching layer 5 may also be provided in other shapes than the abrasive disc body 1, depending on the application.

Optionally, the megasonic frequency emitted by the megasonic generator 3 is 850KHz-1.4MHz. The megasonic frequency is too low to enable the grinding disc body 1 to generate enough high-frequency vibration, so that the grinding liquid in the grinding pad nest chamber cannot generate enough high-frequency vibration, micro-flow cannot be realized, the use efficiency of the grinding liquid cannot be improved, and meanwhile, large particle impurities in the grinding pad nest chamber cannot leave the grinding pad under the action of the high-frequency vibration and the micro-flow of the grinding liquid; the megasonic frequency is too high, consuming higher energy, but not bringing more beneficial technical effects. The megasonic frequency is set within the above range, and the grinding disc body 1 can generate enough high-frequency vibration while keeping low energy consumption.

Optionally, the upper disc 2 is bolted to the abrasive disc body 1. Adopt bolted connection, simplified go up the dish 2 with the detachable connected mode between the abrasive disc body 1, be convenient for equipment and operation.

Optionally, the surface of the matching layer 5 on the side facing the transducer 4 is provided with an adhesive layer, and the matching layer 5 and the transducer 4 are adhesively connected. The arrangement simplifies the fixed connection mode between the matching layer 5 and the transducer 4, is convenient to operate and is beneficial to improving the assembly efficiency.

FIG. 2 is a schematic view of a polishing assembly according to one embodiment of the present invention. As shown in fig. 2, the present invention further provides a polishing assembly, which comprises a polishing head 8, a slurry supply arm 9, a polishing pad dresser 10, and a megasonic-assisted polishing disc according to any of the embodiments described above.

The megasonic-assisted grinding disc is matched with the grinding head 8, the grinding fluid supply arm 9 and the grinding pad dresser 10 in the grinding process, the grinding head 8 clamps a wafer and provides a downward pressure in the grinding stage, and the grinding head 8 can be fixed at a certain fixed position or a swinging position can be set according to a program; the grinding fluid supply arm 9 is used for conveying grinding fluid in a grinding stage, and can be fixed at a certain fixed position or set at a swinging position according to a program; the pad dresser 10 dresses the pad during polishing to increase pad roughness and remove polished impurities, which may be performed during the main polishing stage, or before or after polishing. Under the action of the megasonic generator 3, the transducer 4 and the matching layer 5, the upper disc 2 drives the grinding pad on the upper disc to vibrate at high frequency, so that grinding fluid in the grinding pad vibrates at high frequency to generate micro-flow, the micro-flow of the grinding fluid increases the contact and reaction between the grinding fluid and a wafer, the grinding efficiency and the utilization rate of the grinding fluid are improved, and the problem of unstable grinding rate of the edge of the wafer can be solved; vibrating large-particle impurities generated by grinding in an active region of the grinding pad dresser 10 to enable the large-particle impurities to be separated from a grinding pad nest chamber, and discharging the large-particle impurities separated from the grinding pad with waste liquid under the action of the grinding pad dresser 10; meanwhile, the grinding liquid flows slightly, so that the groove of the grinding pad does not need a wide-angle opening, the pressure of the grinding pad dresser 10 is reduced, and the service life of the grinding pad dresser 10 are prolonged.

The following are specific examples of the grinding assembly of the present invention:

example 1:

the grinding head 8 clamps a wafer, the grinding fluid supply arm 9 supplies grinding fluid, and the driving assembly 7 drives the transmission shaft 6 to rotate in the grinding process so as to provide rotating speed for the grinding disc body 1 and the upper disc 2 to rotate. In a main grinding stage, under program setting, the grinding pad dresser 10 starts to swing, the grinding head 8 swings at the same time, the grinding fluid supply arm 9 is fixed at a certain position and is fixed, the megasonic generator 3 is started at the same time, the megasonic generator 3 emits megasonic waves with the frequency of 1.7MHz, the matching layer 5 is made of a circular epoxy resin material, the transducer 4 is made of a circular piezoelectric ceramic material, and the center of the upper disc 2 generates amplitude of about 7nm under the action of the megasonic waves. The amplitude at the center of the upper disc 2 enables the grinding fluid to achieve the grinding rate effect which can be achieved by the traditional grinding fluid under the condition of smaller flow, and compared with the condition of not under the action of megasonic waves, the flattening effect is better.

Example 2:

the grinding head 8 clamps a wafer, the grinding fluid supply arm 9 provides grinding fluid, and the driving assembly 7 drives the transmission shaft 6 to rotate in the grinding process so as to provide rotating speed for the rotation of the grinding disc body 1 and the upper disc 2. In a main grinding stage, under program setting, the grinding pad dresser 10 starts to swing, the grinding head 8 and the grinding fluid supply arm 9 swing simultaneously, the megasonic generator 3 is started simultaneously, the megasonic generator 3 emits megasonic waves with the frequency of 1MHz, the matching layer 5 is made of an elliptical aluminum material, the transducer 4 is made of an elliptical piezoelectric ceramic material, and the center of the upper disc 2 generates an amplitude of about 10nm under the action of the megasonic waves. The amplitude of the upper disc 2 at the center enables the grinding fluid to achieve the grinding rate effect which can be achieved by the traditional grinding fluid under the condition of smaller flow, and compared with the condition of not under the action of megasonic waves, the flattening effect is better

Example 3:

the grinding head 8 clamps a wafer, the grinding fluid supply arm 9 supplies grinding fluid, the driving assembly 7 drives the transmission shaft 6 to rotate in the grinding process to provide rotating speed for the grinding disc body 1 and the upper disc 2 to rotate, and an eddy current end point detection device is arranged in a containing groove of the grinding disc body 1. At the main grinding stage, under the program set, lapping pad trimmer 10 begins swing work, the lapping liquid supplies liquid arm 9 swing work simultaneously, grinding head 8 is fixed at a certain position motionless, opens simultaneously megasonic generator 3, megasonic generator 3 sends the megasonic of frequency for 1.7MHz, circular epoxy material is selected for use to matching layer 5, square piezoceramics material is selected for use to transducer 4, under megasonic effect, go up 2 center production in the wall and be about 10 nm's amplitude. The amplitude at the center of the upper disc 2 enables the grinding fluid to achieve the grinding rate effect which can be achieved by the traditional grinding fluid under the condition of smaller flow, and compared with the condition of not under the action of megasonic waves, the flattening effect is better. Meanwhile, the eddy current end point detection device collects the film thickness of the surface of the metal film wafer, the partition pressure of the grinding procedure is adjusted according to the film thickness, so that a better flattening effect is achieved, and grinding is stopped after the film thickness reaches the set value of the grinding procedure.

By adopting the grinding assembly, the grinding disc body 1 and the grinding pad fixed on the grinding disc body are driven to vibrate at high frequency by megasonic, so that the grinding fluid in the grinding pad nest chamber vibrates at high frequency, the grinding effect which can be achieved by the large flow of the traditional grinding fluid can be achieved under the condition of smaller flow, and the utilization rate is improved; meanwhile, large-particle impurities in the grinding pad nest chamber leave the grinding pad under the action of high-frequency vibration and grinding liquid micro-flow, so that the wafer scratch can be reduced; the grinding pad dresser 10 does not need to cut a grinding pad groove, only needs to cut small holes on the surface of the grinding pad, reduces pressure, can prolong the service life of the grinding pad and the grinding pad dresser 10, and reduces production cost; under the assistance of megasonic, the grinding fluid is more uniformly contacted with the wafer, thereby being beneficial to the stability of the whole wafer removal rate and improving the wafer flatness.

Finally, it should be noted that: the above examples are only intended to illustrate the technical solution of the present invention, but not to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, it should be understood by those of ordinary skill in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some technical features may be equivalently replaced; and the modifications or the substitutions do not make the essence of the corresponding technical solutions depart from the scope of the technical solutions of the embodiments of the present invention.

Claims (10)

1. A megasonic-assisted abrasive disk, comprising:

the grinding disc comprises a grinding disc body, wherein a first surface of the grinding disc body is provided with an accommodating groove;

an upper disc, which covers the first surface of the grinding disc body and is detachably connected with the grinding disc body;

a megasonic generator;

the transducer is arranged in the accommodating groove and is electrically connected with the megasound generator;

the matching layer is fixedly connected with the surface of one side, facing the upper disc, of the transducer in the accommodating groove and is abutted against the upper disc;

the transmission shaft is fixedly connected with the grinding disc body;

and the driving assembly is in driving connection with the transmission shaft and drives the transmission shaft to rotate.

2. The megasonic-assisted abrasive disk of claim 1, further comprising:

and the grinding pad is fixedly connected with the surface of one side, back to the accommodating groove, of the upper disc.

3. The megasonic-assisted grinding disc of claim 2 wherein:

the surface of one side, facing the upper disc, of the grinding pad is provided with an adhesive layer, and the grinding pad is connected with the upper disc in an adhesive mode.

4. The megasonic-assisted abrasive disk of any of claims 1-3, further comprising:

and the end point detection device is used for monitoring the thickness of the film layer on the surface of the wafer and is arranged in the accommodating groove.

5. The megasonic-assisted grinding disc of claim 4 wherein:

the end point detection device includes at least one of an optical end point detection device and an eddy current end point detection device.

6. The megasonic-assisted lapping disc of any one of claims 1-3 wherein:

the transducer, the matching layer and the abrasive disk body are coaxially arranged.

7. A megasonic-assisted grinding disc as defined in any one of claims 1 to 3 in which:

the megasonic frequency emitted by the megasonic generator is 850KHz-1.4MHz.

8. The megasonic-assisted lapping disc of any one of claims 1-3 wherein:

the upper disc is connected with the grinding disc body through bolts.

9. The megasonic-assisted lapping disc of any one of claims 1-3 wherein:

and an adhesive layer is arranged on the surface of one side, facing the transducer, of the matching layer, and the matching layer is in adhesive connection with the transducer.

10. A polishing assembly comprising a polishing head, a slurry supply arm, and a pad conditioner, further comprising the megasonic-assisted polishing pad of any of claims 1-9.

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