Wafer wet thinning device and thinning method

Abstract

The invention discloses a wafer wet-process thinning device and method, and relates to the technical field of wafer processing, and the method comprises the following steps: S1, preparing equipment and materials; s2, loading and protecting the wafer; s3, heating and stabilizing the solution; s4, corrosion execution; s5, thickness monitoring and termination are carried out; s6, cleaning, drying and quality detection. Through the liquid storage frame, the stirring mechanism and the hole protection frame, a NaOH solution in the liquid storage frame is stirred, sodium silicate precipitates are not easy to coagulate in the NaOH solution through stirring, and then through protection of the hole protection frame outside the stirring mechanism, the wafer can be prevented from being in contact with the stirring mechanism in the thinning process, so that the wafer is prevented from being damaged. And the NaOH solution is kept to flow uniformly by dynamic stirring, so that the formation of sodium silicate precipitates is effectively inhibited. And the hole protection frame adopts a honeycomb-shaped titanium alloy structure, so that the physical isolation between the stirring mechanism and the wafer is realized while the fluid passing rate is ensured to be more than 85%.

Description

Technical Field

[0001] The present invention relates to the technical field of wafer processing, and in particular to a wafer wet thinning device and a wafer thinning method. Background Art

[0002] Wafer thinning refers to the process of reducing the thickness of the wafer from the initial hundreds of microns to tens of microns by mechanical or chemical means. This process is mainly used in the back-end packaging link of chip manufacturing. After the chip thickness is thinned, the path for heat to be transferred from the inside of the chip to the packaging heat dissipation structure is shortened, which significantly reduces thermal resistance and avoids performance degradation or device failure due to high temperature. Thin chips are easier to achieve high-density packaging, meeting the miniaturization needs of mobile devices, wearable electronics, etc. Thick wafers are also prone to stress concentration due to differences in thermal expansion coefficients during cutting, packaging or operation. Thinning can reduce the risk of cracking and improve reliability.

[0003] However, in the existing wafer thinning process, a diamond grinding wheel is used to grind the back of the wafer layer by layer, and chemical mechanical polishing is used to repair surface damage. Although the process is mature and suitable for large-size wafers, the grinding process is prone to produce microcracks and edge collapse, and the damaged layer can reach 1 to 2μm, requiring additional polishing and repair. In the existing chemical thinning process, alkaline solutions are used to anisotropically corrode silicon, and the silicate precipitates generated by the reaction need to be frequently filtered, which greatly increases the complexity of the process.

[0004] There are related invention patents related to wafer thinning, as follows:

[0005] Chinese patent application number: CN202110645550.9, the name of the invention patent is: A wafer thinning method, the invention relates to the field of wafer processing technology, specifically to a wafer thinning method, taking a substrate for pretreatment; covering the surface of the wafer to be processed with a colloid layer, measuring the thickness of the colloid layer, and controlling the thickness of the colloid layer within a predetermined range; bonding the wafer to the substrate and thinning the wafer, and separating the wafer and the substrate after the thinning process is completed. In this way, the wafer is first bonded to the substrate and then thinned, so that the substrate can provide support for the wafer during the thinning process, which can effectively reduce the risk of wafer breakage during thinning, improve the production quality of the wafer, and help improve the yield rate of the product.

[0006] However, in the above-mentioned existing patents, although the risk of wafer breakage during thinning can be effectively reduced, sodium silicate precipitates will be generated due to chemical reactions during the thinning process, which requires frequent filtering and cleaning. The sodium silicate precipitates need to be cleaned regularly, which will increase the downtime in the production process and reduce production efficiency. Moreover, the cleaning of the precipitates is not only time-consuming, but may also cause certain wear and tear on the equipment, increasing the maintenance cost of the equipment. Summary of the invention

[0007] The purpose of the present application is to provide a wafer wet thinning device and a thinning method, which are used to solve the problem that the existing sodium silicate precipitates need to be cleaned regularly.

[0008] The core of the present invention is to use a high-concentration NaOH solution (48%) to etch the wafer on both sides at high temperature (80°C), and to achieve a high-efficiency, low-damage thinning effect by precisely controlling the reaction parameters. The single processing time is short, the reagent cost is only 25% of physical thinning, and there is no mechanical stress introduced, which is suitable for ultra-thin wafers.

[0009] In order to achieve the above object, the present invention adopts the following technical solutions:

[0010] A wafer wet thinning device includes a liquid storage frame, the bottom end of the liquid storage frame is fixedly connected to a rotating motor, the top output end of the rotating motor is fixedly connected to a stirring mechanism, and the stirring mechanism is used to continuously stir a high-concentration NaOH solution. The NaOH solution can be rotated and flowed by stirring, so that the chemical reaction can be more complete, so that the generation of sodium silicate precipitates can be limited.

[0011] As a further improvement of the present invention, two sliding grooves are symmetrically provided on both sides of the inner wall of the liquid storage frame, an inlet is provided on one side of the inner wall of the liquid storage frame corresponding to the right angle of the sliding groove, an oblique liquid outlet is provided on the bottom of the inner wall of the liquid storage frame close to the inlet, a rod groove is provided on one side of the outer surface of the liquid storage frame, an expansion groove is provided on the outer surface of the liquid storage frame at the middle of the rod groove, a hole protection frame is provided on the outside of the stirring mechanism, and the bottom of the hole protection frame is fixedly connected to the bottom surface of the liquid storage frame. This can prevent the wafer from being damaged due to the stirring of the stirring mechanism when the wafer is thinned.

[0012] As a further improvement of the present invention, a waterproof frame is provided outside the rotating motor, the bottom end of the waterproof frame is fixedly connected to the bottom surface of the liquid storage frame, a waste tank is provided inside the liquid storage frame near the inlet, a filter plate is fixedly connected inside the oblique liquid outlet, an outlet tank is provided outside the liquid storage frame at the side corresponding to the rod tank, and two directional tanks are symmetrically provided inside the liquid storage frame at the side of the sliding tank near the inlet. So the sodium silicate precipitate can be collected centrally.

[0013] As a further improvement of the present invention, a gripping rod is clamped inside the rod groove, a push-pull gripping handle is fixedly connected to one end of the gripping rod away from the waste tank, a rotating block is rotatably connected to the middle of one side of the gripping rod away from the push-pull gripping handle, a unidirectional rod is fixedly connected to one end of the rotating block away from the gripping rod, and a push plate is fixedly connected to one end of the unidirectional rod away from the rotating block. The sodium silicate precipitate inside the waste tank can be pushed out by the push plate.

[0014] As a further improvement of the present invention, a rotating spring is fixedly connected to one side of the waste tank away from the push plate, the other end of the rotating spring is fixedly connected to a baffle door, a series rod is slidably connected to the inside of the directional groove and the sliding groove, and a cleaning rod is fixedly connected to one end of the series rod close to the inside of the liquid storage frame. This makes it convenient to centrally clean the sodium silicate precipitates.

[0015] As a further improvement of the present invention, a pulling handle is fixedly connected to the outer surface of the tandem rod away from the cleaning rod, and two pressing springs are symmetrically fixedly connected to the side of the cleaning rod close to the tandem rod, and the ends of the two pressing springs away from the cleaning rod are respectively fixedly connected to the inside of the two sliding grooves. Thus, the generated sodium silicate precipitate can be pushed into the inside of the waste tank.

[0016] A wafer wet thinning method, the specific steps comprising:

[0017] S1, equipment and material preparation: prepare a constant temperature reaction tank, ultrasonic cleaning machine, thickness measuring instrument, protective equipment, 48% NaOH solution, deionized water, dilute hydrochloric acid and nitrogen gun in advance;

[0018] S2, wafer loading and protection: select single-sided or double-sided etching according to the needs, and apply film protection to the non-etched area;

[0019] S3, solution heating and stabilization: 48% NaOH solution was heated to 80°C and stabilized for 10 minutes to ensure temperature uniformity;

[0020] S4, etching execution: immerse the wafer, start the timer, shake the wafer slightly every 30 seconds to eliminate bubbles, and start the stirring mechanism to prevent the formation of sodium silicate precipitation;

[0021] S5, thickness monitoring and termination: sampling and measuring thickness every 90 seconds, and terminating the reaction when the target value is reached;

[0022] S6, cleaning, drying and quality inspection: Clean the wafer surface according to the processing flow to avoid residues affecting subsequent processes, then use a microscope to check surface defects and measure TTV and thickness uniformity.

[0023] 8. As a further improvement of the present invention, in the steps S3-S4, the chemical reaction formula of the wafer and the NaOH solution is as follows:

[0024] Si+2NaOH+H2O=Na2SiO3+2H2↑.

[0025] As a further improvement of the present invention, in the steps S3-S6, the front and back sides of the silicon wafer are both etched, the thinning method can thin the wafer by 4um every 90s, and the thinning method can reduce the wafer diameter by 0.01um every 90s. The TTV refers to the difference between the maximum thickness and the minimum thickness of the silicon wafer, and the increase of the TTV is equivalent to physical thinning. Thus, the thinning speed can be fast, thereby shortening the production cycle and reducing production costs.

[0026] As a further improvement of the present invention, in the steps S3-S6, the NaOH solution is placed in a constant temperature reaction tank, the constant temperature reaction tank adopts a closed-loop temperature control system to ensure the stability of the temperature of the NaOH solution, and the wafer surface cleaning is performed by ionized water washing to completely remove residual NaOH and reaction products. The ionized water washing process is fast and effective, which can shorten the cycle time of wafer cleaning, thereby improving the overall efficiency of semiconductor production and reducing production costs.

[0027] Compared with the prior art, the present invention has the following beneficial effects:

[0028] 1. Through the liquid storage frame, stirring mechanism and hole protection frame, the stirring mechanism is driven to rotate by starting the rotating motor, thereby achieving the effect of stirring the NaOH solution inside the liquid storage frame. The stirring will make it difficult for the NaOH solution to condense sodium silicate precipitate. Then, the hole protection frame is protected outside the stirring mechanism, so that the wafer will not come into contact with the stirring mechanism during the thinning process. Dynamic stirring keeps the NaOH solution flowing evenly, effectively inhibiting the formation of sodium silicate precipitation. The hole protection frame adopts a honeycomb titanium alloy structure, which ensures a fluid pass rate of more than 85% while achieving physical isolation between the stirring mechanism and the wafer. Moreover, stirring the NaOH solution helps to improve the thinning efficiency. The evenly stirred solution can act more evenly on the wafer surface, thereby achieving a more uniform thinning effect, which helps to reduce the unevenness of the wafer surface and improve the quality of the wafer. The design of the stirring mechanism and the hole protection frame jointly improves the stability and reliability of the wafer thinning process. Stirring ensures uniformity of the solution, while the protective frame prevents damage to the wafer. Together, they make the wafer thinning process more controllable and reliable.

[0029] 2. Through the inlet, waste tank, cleaning rod and series rod, when sodium silicate precipitate is precipitated on the surface of NaOH solution, the operator pulls the series rod to make the cleaning rod scrape the sodium silicate precipitate along the surface of NaOH solution into the waste tank, thereby achieving the effect of cleaning the sodium silicate precipitate generated by the reaction of wafer and NaOH solution. Through the scraping operation of the cleaning rod, it can be ensured that the sodium silicate precipitate is removed from the surface of NaOH solution in a timely and effective manner, avoiding pollution of the wafer and reaction environment. The pure reaction solution can ensure the stability of the reaction conditions between the wafer and NaOH solution, thereby improving the efficiency of the reaction and the processing quality of the wafer. The continuous scraping action of the cleaning rod ensures the continuous cleaning of sodium silicate precipitate during the reaction process, avoiding production interruptions caused by the accumulation of precipitates.

[0030] 3. Through the grip, rotating block, unidirectional rod and push plate, when there is too much sodium silicate precipitate accumulated inside the waste tank, the operator will bend the grip to take it out by expanding the tank. The bent grip can also ensure the overall consistency of the device. Then the grip pushes the push plate into the waste tank, so that the push plate pushes the sodium silicate precipitate along the bottom of the waste tank. When the sodium silicate precipitate contacts the baffle door, the baffle door will be opened under the action of the thrust. The above operation can be repeated to remove the sodium silicate precipitate inside the waste tank. Regular cleaning of the sodium silicate precipitate inside the waste tank helps to keep the equipment clean and hygienic, and prevents the accumulation of precipitates from damaging the equipment or affecting the subsequent process. Moreover, the cleaning of the waste tank can be achieved through simple operation, which reduces the difficulty and cost of maintenance. The bent grip design allows the operator to operate the push plate more conveniently, reducing the physical exertion during maintenance. Moreover, removing the sodium silicate precipitate inside the waste tank can prevent safety hazards such as equipment blockage or leakage caused by excessive precipitates.

[0031] 4. Thinning the wafer through the chemical reaction between NaOH solution and wafer. The chemical thinning method usually involves immersing the wafer in NaOH solution and removing part of the material on the surface of the wafer through chemical reaction. The operation is relatively simple and does not require complex physical equipment and mechanical movement. Using NaOH solution as a thinning agent, the solution composition is single and the ratio is relatively simple, which helps to reduce variables in the production process and improve production stability and controllability. Moreover, since the chemical thinning method is simple to operate and the solution ratio is single, it is very suitable for large-scale production. By adjusting parameters such as the concentration, temperature and time of the NaOH solution, the wafer thinning thickness can be precisely controlled to meet the needs of large-scale production. Compared with the physical thinning method, the chemical thinning method can usually remove the material on the surface of the wafer faster, thereby reducing the production time. At the same time, since a large amount of physical equipment and energy consumption are not required, the production cost is also reduced. The main cost of the chemical thinning method is the cost of the chemical reagent of the NaOH solution. Compared with the complex equipment and maintenance costs required for the physical thinning method, the cost is lower and easier to control. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For those skilled in the art, other drawings can be obtained based on these drawings without paying any creative work.

[0033] Figure 1 It is a schematic diagram of the three-dimensional structure of the present invention.

[0034] Figure 2 It is a schematic diagram of the three-dimensional structure of the liquid storage frame, the material discharging slot and the pulling handle in the present invention.

[0035] Figure 3 For the present invention Figure 2 Schematic diagram of the three-dimensional structure from another angle.

[0036] Figure 4 For the present invention Figure 2 Schematic diagram of the three-dimensional structure from another angle.

[0037] Figure 5 It is a schematic diagram of the three-dimensional structure of the sliding groove, the material inlet and the oblique liquid outlet in the present invention.

[0038] Figure 6 It is a three-dimensional structural schematic diagram of the cleaning rod, the series rod and the pressing spring in the present invention.

[0039] Figure 7 It is a schematic diagram of the cross-sectional three-dimensional structure of the liquid storage frame located at the waste tank in the present invention.

[0040] Figure 8 For the present invention Figure 7 Schematic diagram of the enlarged three-dimensional structure at point A in the middle.

[0041] Fig. 9 The present invention is a three-dimensional structural schematic diagram of the grip rod, push plate and push-pull handle.

[0042] Fig.10 It is a schematic diagram of the cross-sectional three-dimensional structure of the liquid storage frame and the waterproof frame in the invention.

[0043] In the figure: 101, liquid storage frame; 102, sliding slot; 103, inlet; 104, oblique liquid outlet; 105, rod slot; 106, rotating motor; 107, stirring mechanism; 108, waterproof frame; 109, waste slot; 110, filter plate; 111, outlet slot; 112, directional slot; 113, expansion slot; 114, hole protection frame; 201, grip; 202, rotating block; 203, same direction rod; 204, push plate; 205, baffle door; 206, rotating spring; 207, cleaning rod; 208, series rod; 209, pressing spring; 210, pulling handle; 211, push-pull handle. DETAILED DESCRIPTION

[0044] 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.

[0045] A wafer wet thinning device, as shown in the figure, includes a stirring mechanism 107, a waste tank 109, a push plate 204, a baffle door 205, a cleaning rod 207, a series rod 208, a pressing spring 209 and a pulling handle 210.

[0046] like Figure 1-Figure 10As shown, it includes a liquid storage frame 101, the inner bottom end of the liquid storage frame 101 is fixedly connected to a rotating motor 106, and the top output end of the rotating motor 106 is fixedly connected to a stirring mechanism 107, and the stirring mechanism 107 is used to continuously stir the high-concentration NaOH solution. Two sliding grooves 102 are symmetrically provided on both sides of the inner wall of the liquid storage frame 101, and an inlet 103 is provided on the side of the inner wall of the liquid storage frame 101 corresponding to the right angle of the sliding groove 102, and an oblique liquid outlet 104 is provided at the bottom of the inner wall of the liquid storage frame 101 close to the inlet 103. A rod groove 105 is provided on the outer surface of one side of the liquid storage frame 101, and an expansion groove 113 is provided on the outer surface of the liquid storage frame 101 at the middle of the rod groove 105. A hole protection frame 114 is provided on the outside of the stirring mechanism 107, and the bottom of the hole protection frame 114 is fixedly connected to the bottom surface of the inside of the liquid storage frame 101. A waterproof frame 108 is provided outside the rotating motor 106, and the bottom end of the waterproof frame 108 is fixedly connected to the bottom surface of the liquid storage frame 101. A waste tank 109 is provided inside the liquid storage frame 101 near the inlet 103, and a filter plate 110 is fixedly connected inside the oblique liquid outlet 104. An outlet tank 111 is provided outside the liquid storage frame 101 at the corresponding side of the rod slot 105, and two directional slots 112 are symmetrically provided inside the liquid storage frame 101 at the side of the sliding slot 102 near the inlet 103. This can prevent the wafer from contacting the stirring mechanism 107 during the thinning process, and the dynamic stirring keeps the NaOH solution flowing evenly, effectively inhibiting the formation of sodium silicate precipitation. The hole protection frame 114 adopts a honeycomb titanium alloy structure, which realizes the physical isolation of the stirring mechanism 107 and the wafer while ensuring a fluid pass rate of more than 85%. Moreover, stirring the NaOH solution helps to improve the thinning efficiency.

[0047] like Figure 6-Figure 9As shown, a gripping rod 201 is clamped inside the rod groove 105, and the end of the gripping rod 201 away from the waste slot 109 is fixedly connected to a push-pull handle 211, and a rotating block 202 is rotatably connected to the middle part of the side of the gripping rod 201 away from the push-pull handle 211, and the end of the rotating block 202 away from the gripping rod 201 is fixedly connected to a unidirectional rod 203, and the end of the unidirectional rod 203 away from the rotating block 202 is fixedly connected to a push plate 204. A rotating spring 206 is fixedly connected to the side of the waste tank 109 away from the push plate 204, and the other end of the rotating spring 206 is fixedly connected to the baffle door 205. A series rod 208 is slidably connected to the inside of the directional groove 112 and the sliding groove 102, and a cleaning rod 207 is fixedly connected to the end of the series rod 208 close to the inside of the liquid storage frame 101, and a drag handle 210 is fixedly connected to the outer surface of the series rod 208 away from the cleaning rod 207. Two pressing springs 209 are symmetrically fixedly connected to the side of the cleaning rod 207 close to the series rod 208, and the ends of the two pressing springs 209 away from the cleaning rod 207 are respectively fixedly connected to the inside of the two sliding grooves 102. It can ensure that the sodium silicate precipitate is removed from the surface of the NaOH solution in a timely and effective manner, avoiding pollution to the wafer and the reaction environment. It can also achieve the effect of removing the sodium silicate precipitate inside the waste tank 109. Regularly cleaning the sodium silicate precipitate inside the waste tank 109 helps to keep the equipment clean and hygienic, and prevents the accumulation of precipitates from damaging the equipment or affecting subsequent processes.

[0048] The present invention also provides a wafer wet thinning method, comprising the following steps:

[0049] S1, equipment and material preparation: prepare in advance a constant temperature reaction tank, an ultrasonic cleaner, a thickness gauge, protective equipment, 48% NaOH solution, deionized water, dilute hydrochloric acid, and a nitrogen gun.

[0050] S2, wafer loading and protection: select single-sided or double-sided etching according to the needs, and apply film protection to the non-etched area.

[0051] S3, solution heating and stabilization: heat the 48% NaOH solution to 80°C and stabilize for 10 minutes to ensure temperature uniformity.

[0052] S4, etching execution: immerse the wafer, start the timer, slightly shake the wafer every 30 seconds to eliminate bubbles, and start the stirring mechanism 107 to prevent the generation of sodium silicate precipitation.

[0053] In steps S3-S4, the chemical reaction formula between the wafer and the NaOH solution is as follows:

[0054] Si+2NaOH+H2O=Na2SiO3+2H2↑.

[0055] S5, thickness monitoring and termination: Sampling and thickness measurement are performed every 90 seconds, and the reaction is terminated when the target value is reached.

[0056] S6, cleaning, drying and quality inspection: Clean the wafer surface according to the processing flow to avoid residues affecting subsequent processes, then use a microscope to check surface defects and measure TTV and thickness uniformity.

[0057] In steps S3-S6, both the front and back sides of the silicon wafer are corroded. The thinning method can thin the wafer by 4um every 90s. The thinning method can also reduce the wafer diameter by 0.01um every 90s. TTV refers to the difference between the maximum thickness and the minimum thickness of the silicon wafer. The increase in TTV is equivalent to physical thinning. The NaOH solution is placed in a constant temperature reaction tank. The constant temperature reaction tank adopts a closed-loop temperature control system to ensure the stability of the NaOH solution temperature. The wafer surface is cleaned by rinsing with ionized water to completely remove residual NaOH and reaction products. Removing part of the material on the surface of the wafer by chemical reaction is relatively simple to operate, does not require complex physical equipment and mechanical movement, uses NaOH solution as a thinning agent, the solution composition is single, and the ratio is relatively simple, which helps to reduce variables in the production process and improve production stability and controllability. Moreover, since the chemical thinning method is simple to operate and the solution ratio is single, it is very suitable for large-scale production.

[0058] Finally, it should be noted that the above are only preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, it is still possible for those skilled in the art to modify the technical solutions described in the aforementioned embodiments or to make equivalent substitutions for some of the technical features therein. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A wafer wet thinning device, comprising a liquid storage frame (101), characterized in that: The inner bottom end of the liquid storage frame (101) is fixedly connected to a rotating motor (106), and the top output end of the rotating motor (106) is fixedly connected to a stirring mechanism (107), and the stirring mechanism (107) is used to continuously stir the high-concentration NaOH solution.

2. A wafer wet thinning device as claimed in claim 1, characterized in that: Two sliding grooves (102) are symmetrically provided on both sides of the inner wall of the liquid storage frame (101); an inlet (103) is provided on one side of the inner wall of the liquid storage frame (101) corresponding to a right angle with the sliding groove (102); an oblique liquid outlet (104) is provided at the bottom of the inner wall of the liquid storage frame (101) close to the inlet (103); a rod groove (105) is provided on the outer surface of one side of the liquid storage frame (101); an expansion groove (113) is provided on the outer surface of the liquid storage frame (101) at the middle of the rod groove (105); a hole protection frame (114) is provided on the outside of the stirring mechanism (107); the bottom of the hole protection frame (114) is fixedly connected to the bottom surface of the inside of the liquid storage frame (101).

3. A wafer wet thinning device as claimed in claim 2, characterized in that: A waterproof frame (108) is provided on the outside of the rotating motor (106), the bottom end of the waterproof frame (108) is fixedly connected to the bottom surface of the liquid storage frame (101), a waste trough (109) is provided on the inside of the liquid storage frame (101) on a side close to the inlet (103), a filter plate (110) is fixedly connected to the inside of the oblique liquid outlet (104), an outlet trough (111) is provided on the outside of the liquid storage frame (101) on a side corresponding to the rod groove (105), and two directional grooves (112) are symmetrically provided on the inside of the liquid storage frame (101) on a side of the sliding groove (102) close to the inlet (103).

4. A wafer wet thinning device as claimed in claim 3, characterized in that: A gripping rod (201) is clamped inside the rod groove (105); one end of the gripping rod (201) away from the waste trough (109) is fixedly connected to a push-pull grip (211); a rotating block (202) is rotatably connected to the middle of one side of the gripping rod (201) away from the push-pull grip (211); one end of the rotating block (202) away from the gripping rod (201) is fixedly connected to a unidirectional rod (203); and one end of the unidirectional rod (203) away from the rotating block (202) is fixedly connected to a push plate (204).

5. A wafer wet thinning device as claimed in claim 4, characterized in that: A rotating spring (206) is fixedly connected to one side of the waste trough (109) away from the push plate (204), and a baffle door (205) is fixedly connected to the other end of the rotating spring (206). A series rod (208) is slidably connected to the inside of the directional groove (112) and the sliding groove (102), and a cleaning rod (207) is fixedly connected to one end of the series rod (208) close to the inside of the liquid storage frame (101).

6. A wafer wet thinning device as claimed in claim 5, characterized in that: A pulling handle (210) is fixedly connected to the outer surface of the serial rod (208) on the side away from the cleaning rod (207), and two pressing springs (209) are symmetrically fixedly connected to the side of the cleaning rod (207) close to the serial rod (208), and one end of the two pressing springs (209) away from the cleaning rod (207) is respectively fixedly connected to the inside of the two sliding grooves (102).

7. A thinning method comprising the thinning device according to any one of claims 1 to 6, characterized in that: The specific steps include: S1, equipment and material preparation: prepare a constant temperature reaction tank, ultrasonic cleaning machine, thickness measuring instrument, protective equipment, 48% NaOH solution, deionized water, dilute hydrochloric acid and nitrogen gun in advance; S2, wafer loading and protection: select single-sided or double-sided etching according to the needs, and apply film protection to the non-etched area; S3, solution heating and stabilization: 48% NaOH solution was heated to 80°C and stabilized for 10 minutes to ensure temperature uniformity; S4, etching execution: immersing the wafer, starting the timer, slightly shaking the wafer every 30 seconds to eliminate bubbles, and starting the stirring mechanism (107) to prevent the generation of sodium silicate precipitation; S5, thickness monitoring and termination: sampling and measuring thickness every 90 seconds, and terminating the reaction when the target value is reached; S6, cleaning, drying and quality inspection: Clean the wafer surface according to the processing flow to avoid residues affecting subsequent processes, then use a microscope to check surface defects and measure TTV and thickness uniformity.

8. A wafer wet thinning device and a wafer thinning method as claimed in claim 7, characterized in that: In the steps S3-S4, the chemical reaction formula between the wafer and the NaOH solution is as follows: Si+2NaOH+H2O=Na2SiO3+2H2↑.

9. A wafer wet thinning device and a wafer thinning method as claimed in claim 7, characterized in that: In the steps S3-S6, the front and back sides of the silicon wafer are both etched, and the thinning method can thin the wafer by 4um every 90s. The thinning method can also reduce the wafer diameter by 0.01um every 90s. The TTV refers to the difference between the maximum thickness and the minimum thickness of the silicon wafer, and the increase of the TTV is equivalent to physical thinning.

10. A wafer wet thinning device and a wafer thinning method as claimed in claim 7, characterized in that: In the steps S3-S6, the NaOH solution is placed in a constant temperature reaction tank, and the constant temperature reaction tank adopts a closed-loop temperature control system to ensure the stability of the temperature of the NaOH solution. The wafer surface is cleaned by rinsing with ionized water to completely remove residual NaOH and reaction products.

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