Wafer cutting method
Through diamond knife marking and wet etching methods, the problem of wafer collapse caused by traditional cutting methods is solved, high-precision wafer cutting is achieved, and bad products are reduced.
Patent Information
- Application Number
- CN202311076162.9
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2023-08-24
- Publication Date
- 2025-02-25
AI Technical Summary
Traditional semiconductor wafer cutting methods are prone to cause wafer collapse and it is difficult to achieve sufficient precision.
The wafer is scribed by a diamond knife, the depth of the marking is smaller than the thickness of the wafer, and a protective layer is formed in the non-scribing area after the marking, and then wet etching is performed in the corrosion tank, and etching is performed using etching liquids of nitric acid, hydrofluoric acid and glacial acetic acid.
Effective wafer cutting is achieved, which avoids wafer collapse caused by diamond knife cutting, reduces bad products, and maintains a smooth finish on the wafer surface.
Smart Images
Figure CN119517846A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the technical field of semiconductor processing, and in particular to a wafer cutting method. Background Art
[0002] Cutting is an important method of semiconductor mechanical physical processing. The traditional method of cutting semiconductor wafers is mainly through the grinding wheel. However, due to the control of various factors such as the wheel, axial guide and grinding fluid, the product often breaks down. With the development of the semiconductor industry, it needs to be processed more and more precisely. Therefore, an effective cutting method has become an urgent problem to be solved. Summary of the invention
[0003] In view of the deficiencies in the prior art, an embodiment of the present invention provides a wafer cutting method, comprising:
[0004] The wafer is scribed with a diamond knife, and the depth of the scribe line is less than the thickness of the wafer;
[0005] Forming a protective layer on the surface of the wafer after scribing, wherein the protective layer covers the non-scribable area of the wafer;
[0006] The wafer is placed in an etching tank for wet etching; wherein the etching depth is 0.05-0.15 mm, wherein the etching solution in the etching tank includes nitric acid, hydrofluoric acid and glacial acetic acid, and the temperature of the etching solution is 0-5°C.
[0007] As a preferred solution, the ratio of the scribing depth to the corrosion depth is 37:3-39:1.
[0008] As a preferred solution, the thickness of the wafer is 2 mm, and the scribing depth is 1.85-1.95 mm.
[0009] As a preferred embodiment, the volume ratio of the nitric acid, the hydrofluoric acid and the glacial acetic acid is 8:1:1.
[0010] As a preferred solution, the wet etching time is 15-25 minutes.
[0011] As a preferred solution, the protective layer is photoresist.
[0012] As a preferred solution, after placing the wafer in the etching tank for wet etching, the method further comprises:
[0013] The protective layer is removed.
[0014] As a preferred embodiment, the diamond knife includes a plurality of diamond particles and a binder; the plurality of diamond particles are classified according to length into: a first diamond particle, a second diamond particle and a third diamond particle; the length of the first diamond particle is less than or equal to a first length threshold and greater than or equal to a second length threshold; the length of the second diamond particle is less than the second length threshold and greater than or equal to a third length threshold; the length of the third diamond particle is less than the third length threshold and greater than or equal to a fourth length threshold, the first length threshold is greater than the second length threshold, the second length threshold is greater than the third length threshold, and the third length threshold is greater than the fourth length threshold;
[0015] The number of the first diamond particles accounts for 40% of the total number of diamond particles, the number of the second diamond particles accounts for 30% of the total number of diamond particles, and the number of the third diamond particles accounts for 30% of the total number of diamond particles.
[0016] As a preferred solution, the diamond knife is mounted on a rotating spindle, and the number of the first diamond particles gradually decreases from the tip of the diamond knife toward the rotating spindle.
[0017] As a preferred solution, the number of the second diamond particles and the third diamond particles gradually increases from the tip of the diamond knife toward the rotating spindle.
[0018] Compared with the prior art, the beneficial effect of the embodiments of the present invention is that: the wafer cutting method provided by the embodiments of the present invention uses a diamond knife to scribe the wafer, and the scribe depth is less than the thickness of the wafer. At this time, the wafer has not been separated, and then a protective layer is formed in the non-scribe area of the wafer surface after scribe, and then the wafer is placed in an etching tank for wet etching, wherein the etching depth is 0.05-0.15mm, wherein the etching solution in the etching tank includes nitric acid, hydrofluoric acid and glacial acetic acid, and the temperature of the etching solution is 0-5°C. In this way, a part of the wafer is first removed by scribe, and then the scribe wafer is etched with the etching solution, thereby achieving effective cutting, avoiding problems such as wafer collapse caused by the use of a diamond knife for cutting throughout the process, thereby reducing defective products, and being able to complete the production operation under the premise of wafer surface smoothness. BRIEF DESCRIPTION OF THE DRAWINGS
[0019] Figure 1 It is a schematic flow chart of a wafer cutting method in an embodiment of the present invention. DETAILED DESCRIPTION
[0020] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.
[0021] See also Figure 1 , which is a flow chart of the wafer cutting method in an embodiment of the present invention.
[0022] The wafer cutting method according to the embodiment of the present invention comprises:
[0023] Step S101, scribing a wafer with a diamond knife, wherein the scribing depth is less than the thickness of the wafer;
[0024] Step S102, forming a protective layer on the surface of the scribed wafer, wherein the protective layer covers the non-scribed area of the wafer;
[0025] Step S103, placing the wafer in an etching tank for wet etching; wherein the etching depth is 0.05-0.15 mm, wherein the etching solution in the etching tank includes nitric acid, hydrofluoric acid and glacial acetic acid, and the temperature of the etching solution is 0-5°C.
[0026] In an embodiment of the present invention, a diamond knife is used to scribe a wafer, and the scribe depth is less than the thickness of the wafer. At this time, the wafer has not been separated. Then, a protective layer is formed in the non-scribe area of the wafer surface after scribe, and then the wafer is placed in an etching tank for wet etching, wherein the etching depth is 0.05-0.15 mm, wherein the etching solution in the etching tank includes nitric acid, hydrofluoric acid and glacial acetic acid, and the temperature of the etching solution is 0-5°C. In this way, a portion of the wafer is first removed by scribe, and then the scribed wafer is etched with the etching solution, thereby achieving effective cutting, avoiding problems such as wafer collapse caused by the use of a diamond knife for cutting throughout the process, thereby reducing defective products, and being able to complete the production operation under the premise of wafer surface smoothness.
[0027] In an optional embodiment, in the step S101 "marking the wafer with a diamond knife, the marking depth is less than the thickness of the wafer", when marking, the inclination angle of the diamond knife is 30°, and a non-crack extension type crack line can be successfully drawn on a wafer with a thickness of 2.0 mm. The pneumatic pressure is 1000-1200 MPa. If it exceeds 1200 MPa, the wafer will be broken. In this embodiment, the marking depth is 1.85-1.95 mm, for example, it can be 1.85 mm, 1.86 mm, 1.87 mm, 1.88 mm, 1.89 mm, 1.9 mm, 1.91 mm, 1.92 mm, 1.93 mm, 1.94 mm, 1.95 mm, etc. Of course, the marking depth can also be set according to actual use requirements, and no further details are given here.
[0028] In a specific implementation, the scribing depth accounts for 92.5%-97.5% of the thickness of the wafer. The scribing depth of the wafer scribed by a diamond knife can reach more than 90% of the thickness of the wafer without causing the wafer to separate automatically.
[0029] In the embodiment of the present invention, the corrosion depth is 0.05-0.15mm, for example, it can be 0.05mm, 0.06mm, 0.07mm, 0.08mm, 0.09mm, 0.1mm, 0.11mm, 0.12mm, 0.13mm, 0.14mm, 0.15mm, etc. Of course, the corrosion depth can also be set to other values according to actual use requirements, which will not be described in detail here. The temperature of the etching solution is 0-5°C, for example, it can be 0°C, 1°C, 2°C, 3°C, 4°C, 5°C, etc. Of course, the temperature of the etching solution can also be set to other values according to actual use requirements, which will not be described in detail here.
[0030] In an optional implementation, the ratio of the scribing depth to the corrosion depth is 37:3-39:1.
[0031] In an optional embodiment, the volume ratio of the nitric acid, the hydrofluoric acid and the glacial acetic acid is 8:1:1, and the corrosion time of the wet etching is 15-25 min, for example, it can be 15 min, 16 min, 17 min, 18 min, 19 min, 20 min, 21 min, 22 min, 23 min, 24 min, 25 min, etc. Of course, the corrosion time of the wet etching can also be set to other values according to actual use requirements, which will not be elaborated here.
[0032] In an optional embodiment, in the step S102 "forming a protective layer on the surface of the wafer after scribing, wherein the protective layer covers the non-scribe area of the wafer", the protective layer may be, for example, a photoresist. In a specific implementation, exposure and development operations are performed through the photoresist to form a protective layer of a desired shape to cover the non-scribe area of the wafer, i.e., the chip area in the wafer. As for the scribed area, it may be exposed to the outside to facilitate subsequent wet etching, thereby separating the wafers.
[0033] In this embodiment, a portion of the wafer is first removed by scribing, and then very little etching solution can be used for etching, thereby reducing costs, reducing the occurrence of defective products, and completing the production operation under the premise of ensuring the surface smoothness of the wafer.
[0034] In an optional implementation, after placing the wafer in the etching tank for wet etching, the method further includes:
[0035] The protective layer is removed.
[0036] In an optional embodiment, the diamond knife includes a plurality of diamond particles and a binder; the plurality of diamond particles are classified according to length into: a first diamond particle, a second diamond particle and a third diamond particle; the length of the first diamond particle is less than or equal to a first length threshold and greater than or equal to a second length threshold; the length of the second diamond particle is less than the second length threshold and greater than or equal to a third length threshold; the length of the third diamond particle is less than the third length threshold and greater than or equal to a fourth length threshold, the first length threshold is greater than the second length threshold, the second length threshold is greater than the third length threshold, and the third length threshold is greater than the fourth length threshold;
[0037] The number of the first diamond particles accounts for 40% of the total number of diamond particles, the number of the second diamond particles accounts for 30% of the total number of diamond particles, and the number of the third diamond particles accounts for 30% of the total number of diamond particles.
[0038] In the embodiment of the present invention, the length of the diamond particles refers to the maximum length among the diamond particles.
[0039] It should be noted that the specific values of the first length threshold, the second length threshold, the third length threshold and the fourth length threshold can be set according to actual usage requirements, and no further details are given here.
[0040] In practical applications, the larger the diamond particles, the stronger the cutting ability of the diamond knife, the slower the wear of the diamond particles, and the longer the service life of the diamond knife. However, the larger the diamond particles, the greater the impact force on the cutting surface during the cutting process, which is easy to introduce greater mechanical stress and cause serious defects such as wafer cracks and edge collapse. Smaller diamond particles can reduce the impact force on the cutting surface during cutting and reduce the risk of larger cutting defects. However, smaller diamond particles are not easy to fall off. If they cannot be shed and updated in time, the knife is prone to wrapping, which will cause a sharp drop in the cutting ability of the diamond knife and serious defects. This embodiment designs three kinds of diamond particles, which are first diamond particles, second diamond particles and third diamond particles in descending order of length. This embodiment ensures that the diamond tool has sufficient cutting ability by setting the number of first diamond particles to account for 40% of the total number of diamond particles, the number of second diamond particles to account for 30% of the total number of diamond particles, and the number of third diamond particles to account for 30% of the total number of diamond particles, and thereby does not generate a large impact force on the cutting surface of the wafer during cutting, so as to avoid defects such as wafer cracks and edge collapse. At the same time, the first diamond particles can ensure that there are enough diamond particles to fall off and be updated in time.
[0041] In an optional embodiment, the diamond knife is mounted on a rotating spindle, and the number of the first diamond particles gradually decreases from the tip of the diamond knife toward the rotating spindle.
[0042] In the specific implementation, the diamond knife is usually roughly circular in shape, and the diamond knife is driven to cut by driving the rotating spindle. For details, reference can be made to the prior art, and no further details are given here. In this embodiment, the number of the first diamond particles gradually decreases from the tip of the diamond knife toward the rotating spindle, so that after a small amount of the first diamond particles near the tip fall off, some first diamond particles are added to the adjacent areas of the fallen diamond particles to ensure that there is still sufficient cutting ability after the diamond particles fall off.
[0043] Furthermore, the number of the second diamond particles and the third diamond particles gradually increases from the tip of the diamond knife toward the direction of the rotating spindle. When the first diamond particles fall off, in order to further ensure that the diamond tool has sufficient cutting ability and does not form a large impact force on the cut surface of the wafer during cutting, the number of the second diamond particles and the third diamond particles is gradually increased from the tip of the knife toward the direction of the rotating spindle to cooperate with the first diamond particles to provide cutting force, while avoiding defects such as easy cracks and edge collapse of the wafer.
[0044] Compared with the prior art, the beneficial effect of the embodiments of the present invention is that: the wafer cutting method provided by the embodiments of the present invention uses a diamond knife to scribe the wafer, and the scribe depth is less than the thickness of the wafer. At this time, the wafer has not been separated, and then a protective layer is formed in the non-scribe area of the wafer surface after scribe, and then the wafer is placed in an etching tank for wet etching, wherein the etching depth is 0.05-0.15mm, wherein the etching solution in the etching tank includes nitric acid, hydrofluoric acid and glacial acetic acid, and the temperature of the etching solution is 0-5°C. In this way, a part of the wafer is first removed by scribe, and then the scribe wafer is etched with the etching solution, thereby achieving effective cutting, avoiding problems such as wafer collapse caused by the use of a diamond knife for cutting throughout the process, thereby reducing defective products, and being able to complete the production operation under the premise of wafer surface smoothness.
[0045] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and substitutions can be made without departing from the technical principles of the present invention. These improvements and substitutions should also be regarded as the scope of protection of the present invention.
Claims
1. A wafer cutting method, characterized in that: include: The wafer is scribed with a diamond knife, and the depth of the scribe line is less than the thickness of the wafer; Forming a protective layer on the surface of the wafer after scribing, wherein the protective layer covers the non-scribable area of the wafer; The wafer is placed in an etching tank for wet etching; wherein the etching depth is 0.05-0.15 mm, wherein the etching solution in the etching tank includes nitric acid, hydrofluoric acid and glacial acetic acid, and the temperature of the etching solution is 0-5°C.
2. The wafer cutting method according to claim 1, characterized in that: The ratio of the scribing depth to the corrosion depth is 37:3-39:
1.
3. The wafer cutting method according to claim 1, characterized in that: The thickness of the wafer is 2 mm, and the scribing depth is 1.85-1.95 mm.
4. The wafer cutting method according to claim 1, wherein: The volume ratio of the nitric acid, the hydrofluoric acid and the glacial acetic acid is 8:1:
1.
5. The wafer cutting method according to claim 1, wherein: The wet etching process takes 15-25 minutes.
6. The wafer cutting method according to claim 1, wherein: The protective layer is photoresist.
7. The wafer cutting method according to claim 1, characterized in that: After placing the wafer in the etching tank for wet etching, the method further comprises: The protective layer is removed.
8. The wafer cutting method according to any one of claims 1 to 7, characterized in that: The diamond knife includes a plurality of diamond particles and a binder; the plurality of diamond particles are classified according to length into: a first diamond particle, a second diamond particle and a third diamond particle; the length of the first diamond particle is less than or equal to a first length threshold and greater than or equal to a second length threshold; the length of the second diamond particle is less than the second length threshold and greater than or equal to a third length threshold; the length of the third diamond particle is less than the third length threshold and greater than or equal to a fourth length threshold, the first length threshold is greater than the second length threshold, the second length threshold is greater than the third length threshold, and the third length threshold is greater than the fourth length threshold; The number of the first diamond particles accounts for 40% of the total number of diamond particles, the number of the second diamond particles accounts for 30% of the total number of diamond particles, and the number of the third diamond particles accounts for 30% of the total number of diamond particles.
9. The wafer cutting method according to claim 8, characterized in that: The diamond knife is mounted on a rotating spindle, and the number of the first diamond particles gradually decreases from the tip of the diamond knife toward the rotating spindle.
10. The wafer cutting method according to claim 9, characterized in that: The number of the second diamond particles and the third diamond particles gradually increases from the tip of the diamond knife toward the rotation spindle.