CN117995773A - Wafer cutting method and die - Google Patents

Abstract

The embodiment of the disclosure provides a wafer cutting method and a die, wherein the method comprises the following steps: providing a wafer and a shielding ring, wherein the edge area of the wafer is provided with a preset fixed area; forming a positive photoresist layer on a first surface of a wafer; placing a shielding ring on the positive photoresist layer, wherein the position of the shielding ring corresponds to the position of a preset fixed area; exposing the positive photoresist layer; removing the shielding ring; developing the exposed positive photoresist layer, and patterning the positive photoresist layer; cutting the wafer by adopting a plasma cutting process to form a plurality of cutting grooves on the wafer; and removing the positive photoresist layer, and thinning and expanding the cut wafer to form a plurality of grains. The positive photoresist layer of the shielding area of the shielding ring is not exposed, so that the positive photoresist layer can be completely reserved in the preset fixing area of the wafer after development, and the preset fixing area can be protected from being cut in the plasma cutting process, so that the strength of the edge area of the wafer is ensured, and the wafer cutting effect is improved.

Description

Wafer cutting method and die

Technical Field

The embodiment of the disclosure belongs to the technical field of semiconductors, and particularly relates to a wafer cutting method and a die.

Background

In order to increase the utilization rate of the wafer, the design of a cutting path developed in the current radio frequency identification product is reduced from the width of 30um to 80um to the width of less than 10um, and the current cutting tool cutting cannot meet the requirement, and a plasma cutting process is adopted for cutting operation.

And carrying out a wafer thinning and film expanding process on the wafer after the plasma cutting process. The wafer thinning stage needs to be carried out with a film on the front surface of the wafer, and the wafer edge is adsorbed and fixed through a vacuum adsorption device. In order to increase the structural strength of the wafer edge, a part of area needs to be reserved at the wafer edge without plasma cutting, so that the wafer edge area can be conveniently fixed in the wafer thinning process.

At present, the shielding ring is added on the plasma cutting machine table to shield the process gas during cutting, so that the edge of the wafer is not cut, but the shielding ring is not in strong contact with the surface of the wafer, and the process gas still permeates to the bottom of the shielding ring to cut the wafer in the plasma cutting process, so that the edge area of the wafer is completely cut, the strength of the edge area of the wafer is further influenced, and the cutting effect of the wafer is affected.

In view of the above, it is necessary to provide a wafer dicing method and die that are reasonably designed and effectively solve the above problems.

Disclosure of Invention

The embodiments of the present disclosure aim to solve at least one of the technical problems in the prior art, and provide a wafer dicing method and a die.

An aspect of an embodiment of the present disclosure provides a wafer dicing method, including:

Providing a wafer and a shielding ring, wherein the edge area of the wafer is provided with a preset fixing area;

Forming a positive photoresist layer on the first surface of the wafer;

Placing the shielding ring on the positive photoresist layer, wherein the position of the shielding ring corresponds to the position of the preset fixing area;

exposing the positive photoresist layer;

Removing the shielding ring;

Developing the exposed positive photoresist layer to pattern the positive photoresist layer;

Cutting the wafer by adopting a plasma cutting process to form a plurality of cutting grooves on the wafer;

And removing the positive photoresist layer, and thinning and expanding the cut wafer to form a plurality of grains.

Optionally, an exposure lens module is provided, and the exposure lens module is provided with a telescopic clamp;

The placing the shadow ring on the positive photoresist layer comprises:

Fixing the second surface of the wafer to a chassis;

Clamping the shielding ring through the telescopic clamp, and moving the shielding ring to the upper part of the wafer, wherein the shielding ring and the exposure lens module are coaxially arranged;

aligning the shielding ring and the wafer so that the position of the shielding ring corresponds to the position of the preset fixed area;

and loosening the telescopic clamp to place the shielding ring on the positive photoresist layer.

Optionally, the aligning the shielding ring and the wafer includes:

The exposure lens module performs center point location on the wafer according to a preset mark of the wafer;

and moving the chassis to enable the center of the exposure lens module to coincide with the center point of the wafer, and completing the alignment of the shielding ring and the wafer.

Optionally, the removing the shielding ring includes:

And the exposure lens module is lowered to the shielding ring, and the shielding ring is clamped by the telescopic clamp and taken away.

Optionally, after the fixing the second surface of the wafer to the chassis, the method further includes:

and aligning the center position of the wafer with the center position of the chassis.

Optionally, the shielding ring includes a supporting portion and a shielding portion connected to the supporting portion;

the supporting part is supported on the chassis;

The shielding part is covered at the position of the positive photoresist layer corresponding to the preset fixing area.

Optionally, the width range of the preset fixing area is 1mm plus or minus 0.1mm.

Optionally, the thinning the diced wafer includes:

A protective film layer is arranged on the first surface of the wafer;

Adsorbing the preset fixing area of the wafer through a vacuum adsorption device so as to fix the wafer;

and thinning the second surface of the wafer to a preset thickness, and removing the protective film layer.

Optionally, the dicing wafer is subjected to film expansion to form a plurality of grains;

Setting an expansion film layer on the second surface of the thinned wafer;

and performing film expansion treatment on the expansion film layer so that the wafer is divided along the cutting grooves to form a plurality of grains.

Another aspect of embodiments of the present disclosure provides a die cut using the method described above.

In the wafer cutting method and the crystal grain, a wafer and a shielding ring are provided firstly, and the edge area of the wafer is provided with a preset fixing area; then forming a positive photoresist layer on the first surface of the wafer; then placing a shielding ring on the positive photoresist layer, wherein the position of the shielding ring corresponds to the position of a preset fixed area; and exposing the positive photoresist layer. The positive photoresist layer of the shielding area of the shielding ring is not exposed, so that the positive photoresist layer can be completely reserved in the preset fixing area of the wafer after development, the positive photoresist layer is in strong contact with the preset fixing area, the preset fixing area can be protected from being cut in the plasma cutting process, the structural strength of the wafer edge area is ensured, the wafer edge area can be better fixed in the wafer thinning process, and the wafer cutting effect is improved.

Drawings

FIG. 1 is a schematic diagram of a prior art process for dicing a wafer using a plasma dicing process;

FIG. 2 is a flow chart of a wafer dicing method according to an embodiment of the disclosure;

FIG. 3 is a schematic process diagram of a wafer dicing method according to another embodiment of the disclosure;

FIG. 4 is a schematic process diagram of a wafer dicing method according to another embodiment of the disclosure;

FIG. 5 is a schematic view of a shielding ring according to another embodiment of the disclosure;

FIG. 6 is a schematic diagram of test results of a feasibility test on a dummy wafer using the wafer dicing method according to another embodiment of the disclosure;

FIG. 7 is a schematic diagram of test results of performing an effect test on a dummy wafer using the wafer dicing method according to another embodiment of the disclosure;

Fig. 8 is a schematic diagram of test results of performing a stability test on a dummy wafer using the wafer dicing method according to another embodiment of the disclosure.

Detailed Description

In order to enable those skilled in the art to better understand the technical solutions of the embodiments of the present disclosure, the embodiments of the present disclosure are described in further detail below with reference to the accompanying drawings and detailed description.

As shown in fig. 1, in the prior art, a wafer dicing process using a plasma dicing process is as follows: a photoresist layer is formed on the front surface of the wafer A, and the photoresist layer is sequentially exposed and developed to pattern the photoresist layer, so that a pattern of a cutting groove B is formed on the photoresist layer. Before cutting, a shielding ring C is placed on the patterned photoresist layer, and the shielding ring C is located in the edge area of the wafer A. The wafer a is diced using a plasma dicing process to form a plurality of dicing grooves B on the wafer a. Although the shielding ring C is added to shield the process gas in the plasma cutting stage to achieve the effect of not being cut, the shielding ring C is not in strong contact with the surface of the wafer a, and the process gas still permeates into the bottom of the shielding ring C to cut the wafer a in the cutting process, so that the phenomenon that the local edge of the wafer a is completely cut in the rightmost diagram shown in fig. 1 is caused, the strength of the edge area of the wafer is further affected, and the cutting effect of the wafer is affected.

Based on the foregoing technical problems of the prior art, as shown in fig. 2, an aspect of an embodiment of the disclosure provides a wafer dicing method S100, where the method S100 includes:

S110, providing a wafer and a shielding ring, wherein the edge area of the wafer is provided with a preset fixing area.

As shown in fig. 3, a wafer 110 and a shadow ring 120 are provided, wherein an edge region of the wafer 110 has a predetermined fixing region 111. Specifically, the predetermined fixing area 111 is a ring area located at the edge area of the wafer 110.

S120, forming a positive photoresist layer on the first surface of the wafer.

In the present embodiment, the first surface of the wafer 110 represents the front surface of the wafer 110, and the second surface of the wafer 110 is the back surface of the wafer 110. That is, as shown in fig. 3, a positive photoresist layer 130 is coated on the front surface of the wafer 110. Wherein the exposed areas of positive photoresist layer 130 are dissolved in a developer after development, the unexposed areas remain. In this embodiment, the material of the positive photoresist layer is not particularly limited, and for example, it may be common Diazonaphthoquinone (DNQ) or the like, and may be selected according to actual needs.

S130, placing the shielding ring on the positive photoresist layer, wherein the position of the shielding ring corresponds to the position of the preset fixed area.

As shown in fig. 4c, in this embodiment, an exposure lens module 140 is further provided, and the exposure lens module 140 is provided with a telescopic clamp 150. The exposure lens module 140 is used for exposing the positive photoresist layer 130. The telescoping clamp 150 is used to grasp the shadow ring 120. In this embodiment, the telescopic clamp 150 may be a telescopic clamping jaw, and the type of the telescopic clamp 150 is not limited in this embodiment, and may be selected according to actual needs.

Illustratively, placing the shadow ring 120 on the positive photoresist layer 130 specifically comprises the steps of:

Step S131, fixing the second surface of the wafer on the chassis.

As shown in fig. 4a and 4b, the back side of the wafer 110 is secured to a chassis 160. Specifically, in the present embodiment, the wafer 110 is transferred to the vacuum chuck of the exposure machine by the robot, and the back surface of the wafer 110 is fixed on the vacuum chuck of the exposure machine by suction, so as to fix the wafer 110.

And S132, clamping up the shielding ring through the telescopic clamp, and moving the shielding ring to the upper part of the wafer, wherein the shielding ring and the exposure lens module are coaxially arranged.

Specifically, as shown in fig. 4d, the exposure lens module 140 is moved to the upper portion of the shadow ring 120, the shadow ring 120 is clamped by the telescopic clamp 150, and the shadow ring 120 is moved to the upper portion of the wafer 110 by moving the exposure lens module 140. The shielding ring 120 and the exposure lens module 140 are disposed coaxially.

And S133, aligning the shielding ring and the wafer so that the position of the shielding ring corresponds to the position of the preset fixed area.

The aligning the shielding ring 120 with the wafer 110 specifically includes the following steps:

As shown in fig. 4c, the exposure lens module 140 performs center point positioning on the wafer 110 according to the preset mark 112 of the wafer 110. Specifically, the lens in the exposure lens module 140 captures a specific mark on the wafer 110 to determine the center point of the wafer 110.

As shown in fig. 4d, after the center point of the wafer 110 is located, the chassis 160 is moved to make the center of the exposure lens module 140 coincide with the center point of the wafer 110. Since the shielding ring 120 and the exposure lens module 140 are coaxially arranged, after the center of the exposure lens module 140 coincides with the center point of the wafer 110, the center of the shielding ring 120 coincides with the center of the wafer 110, so that the positioning of the shielding ring 120 and the wafer 110 is completed, the position of the shielding ring 120 corresponds to the position of the preset fixed area 111, and the shielding ring 120 is ensured to accurately cover the preset fixed area 111 of the wafer 110.

Step S134, loosening the telescopic clamp to place the shielding ring on the positive photoresist layer.

Specifically, as shown in fig. 4e, after the alignment of the shadow ring 120 and the wafer 110 is completed, the telescopic jig 150 is released to place the shadow ring 120 on the positive photoresist layer 130. Wherein, the position of the shielding ring 120 corresponds to the position of the preset fixing area 111.

It should be noted that, in the wafer thinning process, the wafer 110 is fixed by attaching a film on the crystal face and then vacuum-adsorbing the preset fixing area 111 on the edge of the wafer 110, so that in order to increase the structural strength of the edge of the wafer 110, a part of area needs to be reserved in the preset fixing area 111 on the edge of the wafer, and plasma cutting is not performed. In addition, the effect of die separation is required to be achieved by stretching the back film in the film expansion process, so that the structural strength of the preset fixing area 111 at the edge of the wafer 110 is not easily excessive.

According to the above requirements, in the present embodiment, the width of the preset fixing region 111 ranges from 1mm±0.1mm. Accordingly, the width of the shielding ring 120 is the same as the width of the preset fixing area 111, so that the preset fixing area 111 can be blocked in the plasma cutting process, and the preset fixing area 111 is not cut.

Further, as shown in fig. 5, the shielding ring 120 includes a supporting portion 121 and a shielding portion 122 connected to the supporting portion 121. The support portion 121 is supported by the chassis 160. The shielding portion 122 covers the positive photoresist layer 130 and corresponds to the preset fixing region 111. The width of the shielding portion 122 is the same as the width of the preset fixing area 111. The shielding ring 120 can be better supported on the chassis 160 through the supporting part 121, so that the stability of the whole shielding ring 120 is improved; the positive photoresist layer 130 on the preset fixing region 111 is shielded from being developed by the shielding part 122, so that the preset fixing region 111 is ensured not to be cut during plasma cutting, and the strength of the preset fixing region 111 is ensured.

And S140, exposing the positive photoresist layer.

The specific steps for exposing the positive photoresist layer 130 are as follows:

step S141, after the shielding ring is placed on the positive photoresist layer, lifting the exposure lens module to a set focusing height.

Specifically, as shown in fig. 4f, after the shadow ring 120 is placed on the positive photoresist layer 130, the exposure lens module 140 is lifted to the set focusing height of the machine.

Step S142, a mask plate is placed between the positive photoresist layer and the exposure lens module.

Specifically, as shown in fig. 4f, a mask plate 170 is placed between the positive photoresist layer 130 and the exposure lens module 140, wherein the mask plate 170 is provided with a pattern of cut grooves.

And step S143, moving the chassis, taking the mask plate as a mask, and exposing the positive photoresist layer through the exposure lens module.

Specifically, as shown in fig. 4f, the positive photoresist layer 130 is exposed by the exposure lens module 140 by moving the chassis 160 and using the mask plate 170 as a mask. Wherein the positive photoresist layer 130 blocked by the blocking ring 120 is not exposed to light and may remain after development.

S150, removing the shielding ring.

Specifically, as shown in fig. 4g, after the exposure of the positive photoresist layer 130 is completed, the exposure lens module 140 is lowered to the position of the shielding ring 120, and the shielding ring 120 is clamped by the telescopic clamp 150 and removed.

And S160, developing the exposed positive photoresist layer to pattern the positive photoresist layer.

Specifically, as shown in fig. 3, the exposed positive photoresist layer 130 is developed, and the positive photoresist layer 130 is patterned to transfer the pattern of the cut grooves on the mask plate 170 to the positive photoresist layer 130.

As shown in fig. 3, since the positive photoresist layer 130 blocked by the blocking ring 120 is not exposed, the positive photoresist layer 130 blocked by the blocking ring 120 is not dissolved in the developing solution and remains when the positive photoresist layer 130 is exposed.

S170, cutting the wafer by adopting a plasma cutting process to form a plurality of cutting grooves on the wafer.

Specifically, as shown in fig. 3, the wafer 110 is diced according to the dicing groove pattern on the patterned positive photoresist layer 130 using a plasma dicing process to form a plurality of dicing grooves 180 on the wafer 110. Since the preset fixing area 111 of the wafer 110 has the positive photoresist layer 130, the process gas does not permeate into the preset fixing area 111 during the dicing process of the plasma dicing process, as shown in fig. 3, so that the preset fixing area 111 can be ensured not to be diced.

S180, removing the positive photoresist layer, and thinning and expanding the cut wafer to form a plurality of grains.

Specifically, after dicing the wafer 110 by the plasma dicing process, the positive photoresist layer 130 remaining on the front surface of the wafer 110 is removed, and the diced wafer is thinned and spread in sequence to form a plurality of dies.

Thinning the cut wafer specifically comprises the following steps:

First, a protective film layer is provided on a first surface of the wafer 110. That is, a protective film layer is attached to the front surface of the wafer 110, and the protective film layer is used to protect the wafer.

Next, the predetermined fixing area 111 of the wafer 110 is sucked by the vacuum suction device to fix the wafer 110. Since the preset fixing area 111 is not cut, the strength of the preset fixing area 111 is better, and the wafer 110 can be better fixed.

Finally, the second surface of the wafer 110 is thinned to a predetermined thickness, and the protective film is removed. That is, according to the requirement of the die, the back surface of the wafer 110 may be thinned to a predetermined thickness by a polishing process or the like, and the protective film layer may be removed.

The method for forming the wafer comprises the steps of performing film expansion on the wafer after cutting to form a plurality of crystal grains, and specifically comprises the following steps:

First, an extended film layer is provided on the second surface of the thinned wafer 110. That is, an extension film layer is attached to the back surface of the thinned wafer 110.

Then, the expanding film layer is subjected to film expanding treatment so that the wafer is divided along the cutting grooves to form a plurality of grains.

Specifically, the wafer 110 may be placed on a platform of the film expander, where the moving part of the platform is lifted, so that the middle part of the extended film layer is lifted, and the extended film layer is extended and stretched, so that the wafer 110 is divided along the dicing groove 180 to form a plurality of dies, and the effect of die separation is achieved.

For example, the wafer dicing method S100 is performed on a dummy wafer for feasibility test, and the test result is shown in fig. 6. As can be seen from fig. 6, the manner of adding the shadow ring 120 when the positive photoresist layer 130 is exposed before the plasma dicing can realize that the predetermined fixing area of the wafer 110 is not diced, that is, 1mm of the edge area of the wafer 110 is not diced.

For example, the wafer dicing method S100 is performed to perform an effect test on a dummy wafer, and the test result is shown in fig. 7. As can be seen from fig. 7, the manner of adding the shadow ring 120 when exposing the positive photoresist layer 130 before the plasma dicing can ensure that the predetermined fixing area 111 of the wafer 110 is completely preserved, and the dicing condition does not occur, so that the dicing uniformity is better.

For example, the wafer dicing method S100 is performed for stability testing on a dummy wafer, and the test results are shown in fig. 8. As can be seen from fig. 8, by adding the shadow ring 120 to the exposure of the positive photoresist layer 130 prior to plasma dicing, and continuously testing 25 wafers, it is possible to achieve that the edge 1±0.1mm is not diced, and no significant decentration occurs.

The wafer cutting method of the embodiment of the disclosure includes the steps of firstly providing a wafer and a shielding ring, wherein the edge area of the wafer is provided with a preset fixing area; then forming a positive photoresist layer on the first surface of the wafer; then placing a shielding ring on the positive photoresist layer, wherein the position of the shielding ring corresponds to the position of a preset fixed area; and exposing the positive photoresist layer. The positive photoresist layer of the shielding area of the shielding ring is not exposed, so that the positive photoresist layer can be completely reserved in the preset fixing area of the wafer after development, the positive photoresist layer is in strong contact with the preset fixing area, the preset fixing area can be protected from being cut in the plasma cutting process, the structural strength of the wafer edge area is ensured, the wafer edge area can be better fixed in the wafer thinning process, and the wafer cutting effect is improved.

Another aspect of the disclosed embodiments provides a die cut using the wafer cutting method S100 described above. The specific process of the wafer dicing method S100 is described in detail above, and will not be described herein.

The crystal grain of the embodiment of the disclosure is cut by the wafer cutting method, so that the quality of the crystal grain can be improved.

It is to be understood that the above implementations are merely exemplary implementations employed to illustrate the principles of the disclosed embodiments, which are not limited thereto. Various modifications and improvements may be made by those skilled in the art without departing from the spirit and substance of the embodiments of the disclosure, and these modifications and improvements are also considered to be within the scope of the embodiments of the disclosure.

Claims (10)

1. A method of dicing a wafer, the method comprising:

Providing a wafer and a shielding ring, wherein the edge area of the wafer is provided with a preset fixing area;

Forming a positive photoresist layer on the first surface of the wafer;

Placing the shielding ring on the positive photoresist layer, wherein the position of the shielding ring corresponds to the position of the preset fixing area;

exposing the positive photoresist layer;

Removing the shielding ring;

Developing the exposed positive photoresist layer to pattern the positive photoresist layer;

Cutting the wafer by adopting a plasma cutting process to form a plurality of cutting grooves on the wafer;

And removing the positive photoresist layer, and thinning and expanding the cut wafer to form a plurality of grains.

2. The method of claim 1, wherein an exposure lens module is provided, the exposure lens module being provided with a telescopic clamp;

The placing the shadow ring on the positive photoresist layer comprises:

Fixing the second surface of the wafer to a chassis;

Clamping the shielding ring through the telescopic clamp, and moving the shielding ring to the upper part of the wafer, wherein the shielding ring and the exposure lens module are coaxially arranged;

aligning the shielding ring and the wafer so that the position of the shielding ring corresponds to the position of the preset fixed area;

and loosening the telescopic clamp to place the shielding ring on the positive photoresist layer.

3. The method of claim 2, wherein the aligning the shadow ring and the wafer comprises:

The exposure lens module performs center point location on the wafer according to a preset mark of the wafer;

and moving the chassis to enable the center of the exposure lens module to coincide with the center point of the wafer, and completing the alignment of the shielding ring and the wafer.

4. The method of claim 2, wherein exposing the positive photoresist layer comprises:

After the shielding ring is placed on the positive photoresist layer, the exposure lens module is lifted to a set focusing height;

placing a mask plate between the positive photoresist layer and the exposure lens module;

And moving the chassis, taking the mask plate as a mask, and exposing the positive photoresist layer through the exposure lens module.

5. The method of claim 4, wherein the removing the shadow ring comprises:

And the exposure lens module is lowered to the shielding ring, and the shielding ring is clamped by the telescopic clamp and taken away.

6. The method of any one of claims 2 to 5, wherein the shielding ring comprises a support portion and a shielding portion connected to the support portion;

the supporting part is supported on the chassis;

The shielding part is covered at the position of the positive photoresist layer corresponding to the preset fixing area.

7. The method according to any one of claims 1 to 5, wherein the width of the predetermined fixing area ranges from 1mm ± 0.1mm.

8. The method of any of claims 1 to 5, wherein the thinning the diced wafer comprises:

A protective film layer is arranged on the first surface of the wafer;

Adsorbing the preset fixing area of the wafer through a vacuum adsorption device so as to fix the wafer;

and thinning the second surface of the wafer to a preset thickness, and removing the protective film layer.

9. The method of claim 8, wherein the dicing the wafer is spread to form a plurality of dies;

Setting an expansion film layer on the second surface of the thinned wafer;

and performing film expansion treatment on the expansion film layer so that the wafer is divided along the cutting grooves to form a plurality of grains.

10. A die cut using the method of any one of claims 1 to 9.