A composite cutting process for a MEMS three-layer gyroscope wafer

Abstract

This invention discloses a composite cutting process for MEMS three-layer gyroscope wafers, involving alternating laser cutting and mechanical cutting. Advantages: It reduces the impact on the bonding layers between the multiple internal layers of the MEMS wafer and mitigates the edge collapse associated with mechanical cutting alone. This significantly reduces the likelihood of reliability failure and the high cost associated with using only mechanical or laser cutting methods to separate the wafers, effectively controlling costs while ensuring chip performance.

Description

Technical Field

[0001] The present invention relates to the field of wafer cutting, in particular to a composite cutting process for a gyroscope wafer with a MEMS three-layer structure. Background Art

[0002] The MEMS gyroscope disc with a three-layer structure using wafer-level vacuum bonding has a relatively thick total thickness. If only mechanical cutting methods are used, due to the high-speed impact generated by mechanical cutting, firstly, delamination between the discs is likely to occur, resulting in a reduction or disappearance of the vacuum degree, so that the performance of the chip after cutting will be reduced; secondly, there will be more edge collapse at the edge of the chip after cutting, which will easily increase the risk of reliability failure of the chip, and it is easy to cause failure under low temperature, high temperature or rapid temperature change conditions. If only laser cutting methods are used, due to the limitation of energy focusing, firstly, thicker chips cannot be cut, and secondly, as the cutting depth increases, the requirements for the width of the chip cutting groove will become more stringent (size width), which will lead to larger chip size, thereby reducing the number of chips on a single wafer, and then causing the price of the chip to rise, reducing the competitiveness of the chip.

[0003] In view of this, it is necessary to provide a composite cutting process for a gyroscope wafer with a MEMS three-layer structure. Summary of the Invention

[0004] The composite cutting process for a MEMS three-layer gyroscope wafer provided by the present invention effectively solves the problems of reduced performance, edge collapse, inconvenience in cutting and increased cost of existing MEMS gyroscope wafers after cutting.

[0005] The technical solution adopted by the present invention is: a composite cutting process for a gyroscope disc with a MEMS three-layer structure, comprising alternately performing laser cutting and mechanical cutting.

[0006] Furthermore, the laser cutting and mechanical cutting include the following steps:

[0007] S1, wafer film application;

[0008] S2, first glue coating and curing.

[0009] S3, first laser cutting.

[0010] S4, first degumming and cleaning.

[0011] S5. First mechanical cutting.

[0012] S6. First chip cleaning.

[0013] S7, second glue coating and curing.

[0014] S8, second laser cutting.

[0015] S9, second degumming and cleaning.

[0016] S10, second mechanical cutting.

[0017] S11, second chip cleaning.

[0018] Furthermore, the depth of the first laser cutting is controlled at 60%-95% of the thickness of the first layer of chip, the depth of the first mechanical cutting is controlled at 5%-40% of the thickness of the first layer of chip plus the thickness of the second layer of chip plus 5%-15% of the thickness of the third layer of chip, the depth of the second laser cutting is controlled at 25%-75% of the thickness of the third layer of chip, and the depth of the second mechanical cutting is controlled at 10%-70% of the thickness of the third layer of chip plus 10%-35% of the thickness of the cutting support film.

[0019] Furthermore, the wafer film attaching method is as follows: placing the wafer on the support film and then letting it stand for 5-10 minutes;

[0020] Furthermore, the rotation speed of the first mechanical cutting is 30,000 rpm-80,000 rpm, and the cutting step speed is 10 mm / s-80 mm / s; the rotation speed of the second mechanical cutting is 30,000 rpm-80,000 rpm, and the cutting step speed is 10 mm / s-80 mm / s.

[0021] Furthermore, the first degumming and cleaning is as follows: the degumming solution is continuously applied to the surface of the chip, and the speed is sequentially adjusted to 300-600 rpm for 2-3 minutes, 600-1000 rpm for 2-5 minutes, 500-800 rpm for 2-3 minutes, and 800-1100 rpm for 3-5 minutes; deionized water is used, and the speed is adjusted to 500-1500 rpm for 1-5 minutes, and the nitrogen blowing flow rate is 0.5 L / min-1.5 L / min for 1-3 minutes. The second degumming cleaning parameters are as follows: continuously applying the degumming solution on the surface of the chip, sequentially adopting 300-600 rpm for 2-3 minutes, 600-1000 rpm for 2-5 minutes, 500-800 rpm for 2-3 minutes, and 800-1100 rpm for 3-5 minutes; using deionized water, adopting 500-1500 rpm for 1-5 minutes, and nitrogen blowing flow rate 0.5 L / min-1.5 L / min, for 1-3 minutes.

[0022] Furthermore, the method for cleaning the chip for the first time is: using deionized water, using 600-1800 rpm for 1-3 minutes, and nitrogen blowing at a flow rate of 0.5 liters / minute to 1.5 liters / minute for 1-2 minutes; the method for cleaning the chip for the second time is: using deionized water, using 600-1800 rpm for 1-3 minutes.

[0023] Furthermore, it also includes S12 for drying the chip processed by S11. The drying method is: using a rotation speed of 800-1600 rpm, maintaining a nitrogen blowing flow rate of 0.5 liters / minute to 1.5 liters / minute, and maintaining it for 1-2 minutes; then standing for 0.5-1.5 minutes, and then taking it out and placing it.

[0024] Furthermore, the first coating and curing is to use a rotary coating method to apply the protective glue for cooling to cover and protect the cutting grooves on the chip surface, and the second coating and curing method is to use a rotary coating method to apply the protective glue for cooling to cover and protect the cutting grooves on the chip surface.

[0025] The invention's beneficial effects include reducing the impact on the bonding layers between multiple internal layers of a MEMS wafer and mitigating edge chipping issues associated with single mechanical cutting. This significantly reduces the likelihood of reliability failure and the high cost associated with using only mechanical or laser cutting methods to separate the wafers, effectively controlling costs while ensuring chip performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 This is a flow chart of the composite cutting process for the MEMS three-layer gyroscope wafer provided in the embodiment of the present application. DETAILED DESCRIPTION

[0027] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the specific embodiments of the present invention are described in detail below with reference to the accompanying drawings.

[0028] like Figure 1 As shown, a composite cutting process for a MEMS three-layer gyroscope wafer includes alternating laser cutting and mechanical cutting.

[0029] The above design can reduce the impact on the bonding layers between multiple internal layers of the MEMS wafer and also reduce the edge chipping problem caused by single mechanical cutting. This greatly reduces the possibility of reliability failure and high cost of the chips separated from the wafer by single mechanical cutting or laser cutting, effectively controlling costs while ensuring chip performance.

[0030] Specifically: Figure 1As shown, the laser cutting and mechanical cutting include the following steps:

[0031] S1. Wafer film application.

[0032] S2, first glue coating and curing.

[0033] S3, first laser cutting.

[0034] S4, first degumming and cleaning.

[0035] S5. First mechanical cutting.

[0036] S6. First chip cleaning.

[0037] S7, second glue coating and curing.

[0038] S8, second laser cutting.

[0039] S9, second degumming and cleaning.

[0040] S10, second mechanical cutting.

[0041] S11, second chip cleaning.

[0042] The above design can ensure that the debris of the MEMS wafer is not easily splashed when it is laser cut and can effectively clean the debris after it is mechanically cut.

[0043] Specifically: the depth of the first laser cutting is controlled at 60%-95% of the thickness of the first layer of chip, for example, it can be 60%, 75%, 95%, the depth H1 of the first mechanical cutting is controlled at 5%-40% of the thickness of the first layer of chip L1 plus the thickness of the second layer of chip L2 plus 5%-15% of the thickness of the third layer of chip L3, the depth of the second laser cutting is controlled at 25%-75% of the thickness of the third layer of chip, and the depth of the second mechanical cutting is controlled at 10%-70% of the thickness of the third layer of chip plus 10%-35% of the cutting support film.

[0044] That is, H1 = (5% - 40% L1) + L2 + (5% - 15% L3).

[0045] In the above design, the first laser cut depth is controlled at 60%-95% of the thickness of the first chip layer, leaving a sufficient thickness for mechanical cutting. This prevents delamination between the first and second chips, which could affect the bonding strength and performance of the chips. Setting the first mechanical cut depth at 5%-40% of the first chip thickness plus the second chip thickness plus 5%-15% of the third chip thickness prevents delamination at the junctions of the first and second chips, and the second and third chips, which could affect the bonding strength and performance of the chips, leading to product failure. Setting the second laser cut depth at 25%-75% of the third chip thickness prevents delamination at the junctions of the second and third chips, which could affect the bonding strength and performance of the chips, leading to product failure. Setting the second mechanical cut depth at 10%-70% of the third chip thickness plus 10%-35% of the cutting support film thickness effectively prevents delamination between the third chip and the cutting support film.

[0046] Specifically, the wafer film attaching method is: placing the wafer on the support film and then letting it stand for 5-10 minutes.

[0047] In the above design, the 5-10 minutes of standing is used to increase the adhesion between the disc and the membrane. If the time is too short, the bonding force is insufficient, which is not conducive to the removal of bubbles and may cause subsequent fragmentation.

[0048] Specifically: the rotation speed of the first mechanical cutting is 30,000 rpm-80,000 rpm, and the cutting step speed is 10 mm / s-80 mm / s; the rotation speed of the second mechanical cutting is 30,000 rpm-80,000 rpm, and the cutting step speed is 10 mm / s-80 mm / s.

[0049] In the above design, the rotational speed affects cutting capacity. The speed setting is, to a certain extent, related to the chip structure. A speed that is too low results in insufficient cutting capacity, causing oscillation and defects, while a speed that is too high generates additional impact and can cause excessive damage. A cutting speed range of 30,000 rpm to 80,000 rpm covers the range of our existing chips, ensuring smooth cutting without causing additional impact to the wafer. The stepping speed range of 10 mm / s to 80 mm / s not only impacts production efficiency but also works together with the rotational speed to ensure smooth cutting.

[0050] Specifically, the first degumming and cleaning is as follows: the degumming solution is continuously applied to the surface of the chip, and the speed is sequentially maintained at 300-600 rpm for 2-3 minutes, 600-1000 rpm for 2-5 minutes, 500-800 rpm for 2-3 minutes, and 800-1100 rpm for 3-5 minutes; deionized water is used, and the speed is maintained at 500-1500 rpm for 1-5 minutes, and the nitrogen blowing flow rate is 0.5 L / min-1.5 L / min, and it is maintained for 1-3 minutes. The second degumming and cleaning parameters are as follows: continuously apply the degumming solution on the surface of the chip, and keep it at 300-600 rpm for 2-3 minutes, 600-1000 rpm for 2-5 minutes, 500-800 rpm for 2-3 minutes, and 800-1100 rpm for 3-5 minutes; use deionized water, keep it at 500-1500 rpm for 1-5 minutes, and blow nitrogen at a flow rate of 0.5 L / min-1.5 L / min for 1-3 minutes.

[0051] In actual use, the chip is first debonded with a degumming solution, followed by a surface cleanse using deionized water. The debonding process is divided into two stages. The first stage, at 300-600 rpm, primarily involves initial immersion and dissolution. At 600-1000 rpm, the speed is increased to increase pressure and impact, accelerating dissolution. The second stage, at 500-800 rpm, further immersion and dissolution are achieved. At 800-1100 rpm, the speed is increased to increase pressure and impact, accelerating dissolution.

[0052] In the above design, the effectiveness of glue removal is influenced by both rotation speed and time. By gradually soaking and dissolving the glue in the first and second stages, glue removal is more effective. Nitrogen purge can prevent chip oxidation.

[0053] Specifically: the method for cleaning the chip for the first time is: using deionized water, using 600-1800 rpm for 1-3 minutes, and nitrogen blowing at a flow rate of 0.5 L / min-1.5 L / min for 1-2 minutes; the method for cleaning the chip for the second time is: using deionized water, using 600-1800 rpm for 1-3 minutes.

[0054] In the above design, the rotation speed and time of the deionized water can ensure that the residual protective glue can be cleaned.

[0055] Specifically, it also includes S12 for drying the chip after S11 processing. The drying method is: using a rotation speed of 800-1600 rpm, maintaining a nitrogen blowing flow rate of 0.5 liters / minute to 1.5 liters / minute, and maintaining it for 1-2 minutes; then let it stand for 0.5-1.5 minutes, and then take it out and place it.

[0056] In the above design, the rotational speed directly affects the force and range of the nitrogen gas on the wafer surface, ensuring that the nitrogen gas covers the wafer surface. The force of the nitrogen gas on the deionized water on the wafer surface can separate the deionized water from the wafer. A nitrogen flow rate of 0.5-1.5 L / min ensures effective removal and also affects the chip surface's anti-oxidation effect. A 0.5-1.5 minute standstill ensures that the chip surface is completely drained.

[0057] Specifically: the first coating and curing method is to use a rotary coating method to apply the protective glue for cooling to cover and protect the cutting grooves on the chip surface; the second coating and curing method is to use a rotary coating method to apply the protective glue for cooling to cover and protect the cutting grooves on the chip surface.

[0058] In the above design, the spin coating method can ensure that the glue effectively covers the cutting groove.

[0059] To explain in further detail, it should be understood that the above is only a specific embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A composite cutting process for a MEMS three-layer gyroscope wafer, characterized by: The method comprises alternating laser cutting and mechanical cutting, wherein the laser cutting and mechanical cutting comprise the following steps: S1, wafer film lamination; S2, first glue coating and curing; S3, first laser cutting; S4, first glue removal and cleaning; S5, first mechanical cutting; S6, first chip cleaning; S7, second glue coating and curing; S8, second laser cutting; S9, second degumming and cleaning; S10, second mechanical cutting; S11, second chip cleaning; the depth of the first laser cutting is controlled at 60%-95% of the thickness of the first layer of chip, the depth of the first mechanical cutting is controlled at 5%-40% of the thickness of the first layer of chip plus the thickness of the second layer of chip plus 5%-15% of the thickness of the third layer of chip, the depth of the second laser cutting is controlled at 25%-75% of the thickness of the third layer of chip, the depth of the second mechanical cutting is controlled at 10%-70% of the thickness of the third layer of chip plus 10%-35% of the thickness of the cutting support film.

2. The composite cutting process for the MEMS three-layer gyroscope wafer according to claim 1 is characterized in that: The method of attaching the disc to the film is as follows: placing the disc on the support film and then letting it stand for 5-10 minutes.

3. The composite cutting process for the MEMS three-layer gyroscope wafer according to claim 2 is characterized in that: The rotation speed of the first mechanical cutting is 30,000 rpm-80,000 rpm, and the cutting step speed is 10 mm / s-80 mm / s. The rotation speed of the second mechanical cutting is 30,000 rpm-80,000 rpm, and the cutting step speed is 10 mm / s-80 mm / s.

4. The composite cutting process for the MEMS three-layer gyroscope wafer according to claim 3 is characterized by: The first degumming and cleaning is as follows: continuously apply the degumming solution on the surface of the chip, and sequentially use 300-600 rpm to maintain for 2-3 minutes, 600-1000 rpm to maintain for 2-5 minutes, 500-800 rpm to maintain for 2-3 minutes, 800-1100 rpm to maintain for 3-5 minutes; use deionized water, use 500-1500 rpm to maintain for 1-5 minutes, and blow nitrogen at a flow rate of 0.5 L / min-1.5 L / min for 1-3 minutes. The second degumming and cleaning parameters are as follows: continuously apply the degumming solution on the surface of the chip, and use 300-600 rpm for 2-3 minutes, 600-1000 rpm for 2-5 minutes, 500-800 rpm for 2-3 minutes, and 800-1100 rpm for 3-5 minutes; use deionized water, use 500-1500 rpm for 1-5 minutes, and nitrogen blowing flow rate 0.5 L / min-1.5 L / min, and keep it for 1-3 minutes.

5. The composite cutting process for the MEMS three-layer gyroscope wafer according to claim 4 is characterized in that: The method for cleaning the chip for the first time is: using deionized water, using 600-1800 rpm for 1-3 minutes, and nitrogen blowing at a flow rate of 0.5 liters / minute to 1.5 liters / minute for 1-2 minutes; the method for cleaning the chip for the second time is: using deionized water, using 600-1800 rpm for 1-3 minutes.

6. The composite cutting process for the MEMS three-layer gyroscope wafer according to claim 5 is characterized in that: It also includes S12 for drying the chips processed by S11. The drying method is: use a rotation speed of 800-1600 rpm, maintain a nitrogen blowing flow rate of 0.5 liters / minute to 1.5 liters / minute, and maintain it for 1-2 minutes; then let it stand for 0.5-1.5 minutes, and then take it out and place it.

7. The composite cutting process for the MEMS three-layer gyroscope wafer according to claim 5 is characterized by: The first coating and curing method is to use a rotary coating method to apply the protective glue for cooling to cover and protect the cutting grooves on the chip surface. The second coating and curing method is to use a rotary coating method to apply the protective glue for cooling to cover and protect the cutting grooves on the chip surface.

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