Silicon wafer surface treatment and thin film deposition defect repair method and alkali corrosion equipment

Abstract

The invention relates to the technical field of semiconductor manufacturing, discloses a silicon wafer surface treatment and thin film deposition defect repair method and alkali corrosion equipment, solves the LP pollution defect caused by environmental particulate matters in an LPCVD (Low Pressure Chemical Vapor Deposition) process, and realizes silicon wafer regeneration. The method comprises the following steps: cleaning before corrosion by adopting an ammonia water / hydrogen peroxide mixed solution; carrying out alkali corrosion for 40 seconds by using a potassium hydroxide solution with the concentration of 0.134% at 90 DEG C, and accurately stripping a polluted polycrystalline silicon layer; and after two-stage pure water rinsing and subsequent cleaning, carrying out LPCVD deposition again to form a clean polycrystalline silicon film. The matched alkali corrosion equipment is of a three-groove type structure and comprises a constant temperature control module and a timing module. According to the method, the removal amount of the polycrystalline silicon layer is accurately controlled while LP pollution particles are removed by optimizing cooperative control of three parameters of concentration-temperature-time of the corrosive liquid, secondary pollution is effectively prevented by matching with a dual cleaning process, the repair quality is ensured through film thickness detection and appearance inspection, the yield of the silicon wafer is remarkably improved, and the manufacturing cost is reduced.

Description

Technical Field

[0001] The present invention belongs to the field of semiconductor manufacturing technology, and specifically relates to a method for silicon wafer surface treatment and thin film deposition defect repairing, and also relates to an alkaline etching device for implementing the method. Background Art

[0002] In the semiconductor device manufacturing process, chemical vapor deposition (CVD), particularly low-pressure chemical vapor deposition (LPCVD), is widely used to deposit polycrystalline silicon (Poly-Si) thin films on the surface of silicon wafers. This poly-Si film, characterized by lattice disorder and grain boundaries, effectively getsters harmful metallic impurities on the front side of the silicon wafer, thereby improving the cleanliness of the front side and optimizing the electrical performance of the final device.

[0003] However, the actual operation of the LPCVD process presents a significant technical challenge: particles suspended in the environment (such as dust or reaction byproducts) can land on the surface of the silicon wafer being processed. During the subsequent polysilicon film growth process, these particles can be encapsulated within the growing film layer, causing defects, particularly on the backside of the silicon wafer. This particle encapsulation defect introduced by the LPCVD process is known as LP contamination.

[0004] The presence of LP contamination has a serious negative impact on product yield and cost:

[0005] 1. Directly lead to product defects: Silicon wafers contaminated by LP are prone to cause serious problems such as "self-doping" in subsequent epitaxial growth and other process steps, making the final product unable to meet quality requirements.

[0006] 2. Product scrapping and yield loss: Once LP contamination is discovered, the traditional practice is to directly classify the silicon wafer as defective and scrap it.

[0007] 3. Increased production costs: A large number of silicon wafers are scrapped due to LP contamination, which directly leads to low overall yield of the LPCVD process and significantly increases the production cost of each unit product.

[0008] Existing technologies lack an efficient and reliable method for repairing LP contamination on silicon wafer surfaces. Traditional methods can involve multiple complex steps, often resulting in suboptimal results and failing to meet the high wafer quality requirements of semiconductor manufacturing. Therefore, developing new methods for wafer surface treatment and thin film deposition defect repair that overcome the limitations of existing technologies has become a pressing challenge in the semiconductor manufacturing industry. Summary of the Invention

[0009] One object of the present invention is to provide a method for silicon wafer surface treatment and thin film deposition defect repair, which effectively removes the polysilicon layer and LP contamination on the silicon wafer surface through specific cleaning and etching steps, and redeposits the polysilicon layer on the cleaned silicon wafer surface, thereby repairing the defects on the silicon wafer surface and restoring the normal use of the silicon wafer.

[0010] To achieve the above object, the present invention provides the following technical solutions:

[0011] The present invention provides a method for silicon wafer surface treatment and thin film deposition defect repair, comprising the following steps:

[0012] Cleaning before etching: Clean defective silicon wafers with LP contamination to remove surface particles;

[0013] Alkaline etching: After the pre-etching cleaning step, the silicon wafer is immersed in a potassium hydroxide solution for etching to remove the surface polysilicon layer and LP contamination particles;

[0014] Cleaning after corrosion: Clean the silicon wafer after alkali corrosion to remove surface metal impurities;

[0015] Cleaning before LPCVD: Secondary cleaning of silicon wafers;

[0016] LPCVD deposition: re-depositing a polysilicon layer on the cleaned silicon wafer surface;

[0017] Film thickness measurement and appearance inspection: Detect the thickness of the polysilicon layer and confirm that there are no defects on the surface.

[0018] In addition to the above technical features, the present invention has also made optimization and improvements in the following aspects:

[0019] As a preferred technical solution of the present invention, a mixed solution of ammonia water and hydrogen peroxide is used to clean the silicon wafer in the pre-etching cleaning step.

[0020] As a preferred technical solution of the present invention, the alkaline corrosion step meets the following conditions: the concentration of the potassium hydroxide solution is 0.05%-0.2%, the corrosion temperature is 80°C-95°C, and the corrosion time is 30-50 seconds.

[0021] As a preferred technical solution of the present invention, the potassium hydroxide solution is prepared from 80L of potassium hydroxide stock solution and 60L of pure water; the concentration of the potassium hydroxide solution is 0.134%, the temperature is 90°C, and the corrosion time is 40 seconds.

[0022] As a preferred technical solution of the present invention, the post-corrosion cleaning step adopts pure water cleaning at a temperature of 30°C-40°C and a cleaning time of 40s-45s.

[0023] As a preferred technical solution of the present invention, two stages of pure water rinsing are included after the alkaline corrosion step:

[0024] First level rinsing: pure water, temperature 30℃, time 40S;

[0025] Second level rinsing: pure water, temperature 40℃, time 40S.

[0026] As a preferred technical solution of the present invention, the pre-LPCVD cleaning includes a chemical cleaning step for removing particles and metal residues.

[0027] As a preferred technical solution of the present invention, the pre-LPCVD cleaning includes a chemical cleaning step for removing particles and metal residues.

[0028] As a preferred technical solution of the present invention, the LPCVD deposition is low-pressure chemical vapor deposition, which forms a polysilicon thin film on the surface of the silicon wafer.

[0029] As a preferred technical solution of the present invention, the LP contamination is a defect formed when environmental particles are wrapped by polysilicon during the LPCVD process.

[0030] Another object of the present invention is to disclose an alkaline etching device for implementing the repair method, which improves the efficiency and quality of silicon wafer surface treatment through an optimized etching system.

[0031] An alkaline etching device for implementing a silicon wafer surface treatment and thin film deposition defect repair method includes a three-tank etching system:

[0032] Among them, the first tank is a constant temperature potassium hydroxide corrosion tank, and the second and third tanks are pure water rinsing tanks;

[0033] Temperature control module: control the temperature of the first tank at 80-95°C, the temperature of the second tank at 20-40°C, and the temperature of the third tank at 30-50°C;

[0034] Timing module: controls the processing time of silicon wafers in each slot to 30 to 60 seconds.

[0035] In combination with the description of the above technical content, the technical effects of the silicon wafer surface treatment and thin film deposition defect repair method and alkaline etching equipment of the present invention are mainly reflected in the following aspects:

[0036] 1. Effectively eliminate LP pollution defects

[0037] This application uses a precisely controlled alkaline etching process (KOH solution concentration, temperature, and time) to completely remove LP contamination particles (environmental particles / reaction byproducts) wrapped in polysilicon on the surface of the silicon wafer, thereby solving the problem of yield loss caused by particle contamination in the LPCVD process.

[0038] 2. Achieve efficient defect repair of defective products

[0039] This application adopts a phased cleaning and etching process (cleaning before etching → alkaline etching → two-stage pure water rinsing → cleaning before LPCVD) to repair silicon wafers that were originally scrapped due to LP contamination to a state where polysilicon can be re-deposited, turning waste into treasure and significantly reducing the scrap rate.

[0040] 3. Improve LPCVD yield and cost-effectiveness

[0041] After rework in this application, the silicon wafer is re-deposited with a polysilicon layer via LPCVD, and the quality is ensured through film thickness measurement and appearance inspection, which improves the yield from the low state of the original process to a near normal level, greatly reducing the waste of raw materials and lowering production costs.

[0042] 4. Precisely control the corrosion process

[0043] This application limits the KOH solution concentration to 0.134%, the temperature to 90°C and the time to 40 seconds, combined with two-stage pure water rinsing (30°C / 40°C for 40 seconds each) to avoid over-corrosion or cleaning residues and ensure the uniformity and integrity of the silicon wafer surface.

[0044] 5. Multi-layer cleaning ensures surface cleanliness

[0045] Clean before etching (ammonia + hydrogen peroxide) to remove particles → Clean after etching (pure water) to remove metal impurities → Clean before LPCVD to deeply remove particles and metal residues. The triple cleaning step provides a contamination-free base for re-deposition of polysilicon.

[0046] 6. Equipment integration improves process stability

[0047] Special three-tank alkaline etching equipment (KOH etching tank + double pure water rinsing tank) is combined with a temperature control module and a timing module to achieve automatic control of all process parameters and ensure the consistency of rework batches.

[0048] 7. Breakthrough of traditional scrap disposal model

[0049] Traditionally, contaminated LP silicon wafers are directly discarded. This method pioneered the "corrosion stripping + re-deposition" rework path, providing a low-cost defect repair solution for semiconductor manufacturing and filling the industry's technological gap.

[0050] 8. Compatible with existing production line equipment

[0051] The process steps (such as CP cleaning and LPCVD deposition) directly use standard semiconductor equipment without the need for adding expensive equipment. It is highly feasible and easy to apply on a large scale.

[0052] In summary, this application has established a standardized process system for LPCVD defect repair in semiconductor manufacturing through a closed-loop technology of targeted contamination removal → substrate regeneration → film reconstruction, providing wafer fabs with a low-cost, highly compatible yield improvement solution. On the other hand, this application can safely and thoroughly remove the contaminated polysilicon layer on the surface without damaging the silicon wafer substrate, so as to re-deposit high-quality polysilicon film on the clean silicon wafer surface, thereby converting defective products into good products, ultimately achieving the goal of improving yield and reducing production costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0053] Figure 1 The present invention is a flow chart of the method for silicon wafer surface treatment and thin film deposition defect repair. DETAILED DESCRIPTION

[0054] The preferred embodiments of the present invention are described below with reference to the accompanying drawings. It should be understood that the preferred embodiments described herein are only used to illustrate and explain the present invention, and are not used to limit the present invention.

[0055] 1. Explanation of Descriptive Terms in the Present Invention

[0056] The embodiments of the present invention are provided in conjunction with the technical solutions to make the present invention more thorough and complete and to fully convey the scope of the present invention to those skilled in the art. It should be noted that unless otherwise specifically stated in the present invention, the relative arrangements of components described in these embodiments should be interpreted as merely exemplary and not as a limitation of the technical solutions of the present invention.

[0057] When used in this disclosure, directional terms such as "upper," "lower," "left," "right," "bottom," and "top" are defined relative to the directions in the accompanying drawings and are intended only to indicate relative positional relationships. These relative positional relationships may change accordingly if the absolute positions of the objects being described change. These and other directional terms should not be construed as restrictive.

[0058] In the present invention, words such as "a," "an," "an," and "the" do not limit the number and may refer to the singular or plural. The terms "include," "comprising," "having," and any variations thereof, as used in the present invention, are intended to cover non-exclusive inclusions. The terms "first," "second," and "third," etc., used in the present invention, are merely used to distinguish similar objects and do not indicate a specific ordering of the objects.

[0059] In the present invention, when a specific device is described as being located between a first device and a second device, an intervening device may or may not be present between the specific device and the first device or the second device. When a specific device is described as being connected to another device, the specific device may be directly connected to the other device without an intervening device, or may be directly connected to the other device but with an intervening device.

[0060] In addition, the present invention does not discuss in detail the technologies and equipment known to ordinary technicians in the relevant fields, but where appropriate, the technologies and equipment should be considered as part of the specification.

[0061] 2. Core technical issues to be solved by the technical solution of this application

[0062] In existing semiconductor manufacturing technologies, the LP contamination problem caused by the low-pressure chemical vapor deposition (LPCVD) process has three major technical bottlenecks:

[0063] First, there is a lack of pollution prevention and control mechanisms. Suspended particles in the process environment are easily deposited on the surface of silicon wafers and are wrapped during the thin film growth process to form lattice defects, leading to characteristic pollution on the back of the silicon wafer.

[0064] Secondly, there is a lack of defect repair methods. Traditional cleaning processes cannot selectively remove particles encapsulated by polysilicon thin films, and complex repair processes may even introduce secondary damage.

[0065] Third, quality control issues are prominent. Contaminated silicon wafers must be scrapped due to the risk of autodoping, and there is a lack of gradient utilization or local repair solutions, which significantly reduces the overall yield of the LPCVD process. This technical limitation directly drives up the manufacturing cost of single silicon wafers. Especially in advanced processes, material waste caused by defects has become a key technical obstacle to industrial upgrading.

[0066] The above-mentioned technical shortcomings have become a key obstacle for semiconductor manufacturing to upgrade to more advanced processes. Breakthrough defect repair technologies are urgently needed to reconstruct the silicon wafer surface treatment process paradigm.

[0067] 3. Based on the above problems, the present invention specifically provides a technical solution to the above problems. The following is combined with specific embodiments and reference to Figure 1 The technical solution, working principle and technical effects of the present invention are described in detail.

[0068] This embodiment takes defective silicon wafers with LP contamination as the processing object. Figure 1 The specific implementation steps of silicon wafer surface treatment and thin film deposition defect repair methods are explained in detail.

[0069] (1) Clean before corrosion

[0070] Step description: Defective silicon wafers (LP contamination) that need to be reworked are put into the pre-etching cleaning step.

[0071] Operation process: Use a mixture of ammonia and hydrogen peroxide to clean the silicon wafer to remove particles on the surface of the silicon wafer. This step ensures that the silicon wafer surface reaches a certain level of cleanliness before entering the alkaline etching process.

[0072] (2) Alkali corrosion

[0073] Step description: Immerse the silicon wafer after the pre-etching cleaning step in a potassium hydroxide solution for etching.

[0074] Operation process:

[0075] Preparation of the chemical solution: Add 80L of potassium hydroxide stock solution and 60L of pure water into the first tank of the alkaline etching machine to prepare a potassium hydroxide solution with a concentration of 0.134%.

[0076] Temperature control: Set the temperature of the first tank of the alkaline etching machine to 90°C to ensure that the corrosion reaction proceeds at the optimal temperature.

[0077] Etching time: Set the etching time to 40 seconds to fully remove the polysilicon layer and LP contamination particles on the surface of the silicon wafer.

[0078] Rinsing step: After etching is complete, the silicon wafer is rinsed in two stages of pure water in the second and third tanks of the alkaline etching machine. The pure water temperature in the second tank is set at 30°C, and the temperature in the third tank is set at 40°C. Each rinse lasts for 40 seconds to completely remove the etching residue on the silicon wafer surface.

[0079] (3) Cleaning after corrosion (cleaning after CP)

[0080] Step description: Place the etched silicon wafer into the CP post-cleaning machine for cleaning.

[0081] Operation process: Use pure water to clean the silicon wafer, the temperature is controlled between 30℃-40℃, and the cleaning time is 40 seconds to 45 seconds to remove metal impurities on the surface of the silicon wafer.

[0082] (4) Cleaning before LPCVD

[0083] Step description: After CP post-cleaning, the silicon wafer is placed in the LPCVD pre-cleaner for cleaning.

[0084] Operation process: Chemical cleaning is performed to remove particles and metal residues on the surface of the silicon wafer to ensure that the silicon wafer surface reaches the cleanliness required for LPCVD deposition.

[0085] (5) LPCVD deposition

[0086] Step description: Place the cleaned silicon wafer into the LP furnace and perform LPCVD (low pressure chemical vapor deposition).

[0087] Operation process: A layer of polysilicon film is re-deposited on the surface of the silicon wafer to repair the surface layer damaged by LP contamination.

[0088] (6) Film thickness measurement and appearance inspection

[0089] Step description: Measure the film thickness and perform appearance inspection on silicon wafers after LPCVD.

[0090] Operation process: Use a film thickness gauge to detect the thickness of the polysilicon layer to ensure that it meets the process requirements; at the same time, perform an appearance inspection to confirm that there are no defects on the silicon wafer surface.

[0091] IV. Explanation of the technical details of this application

[0092] Definition of LP contamination: In the LPCVD process, environmental particles (such as dust and reaction by-products) fall onto the surface of the silicon wafer and are wrapped by the growing POLY-SI film, forming defects.

[0093] Alkaline etching parameter control: By precisely controlling the concentration of potassium hydroxide solution (0.134%), etching temperature (90°C), and etching time (40 seconds), the polysilicon layer and LP contamination particles on the silicon wafer surface are effectively removed while avoiding excessive corrosion of the silicon wafer substrate.

[0094] Cleaning step optimization: Pre-etch cleaning, post-etch cleaning (post-CP cleaning), and pre-LPCVD cleaning steps all use specific cleaning machines and parameter settings to ensure that the silicon wafer surface reaches the required cleanliness at each processing stage.

[0095] 5. Core Technical Points of This Application

[0096] Potassium Hydroxide Etching: This innovative method uses potassium hydroxide etching to remove the LP-contaminated polycrystalline layer on the silicon wafer surface. By optimizing parameters such as etching solution concentration, temperature, and etching time, it achieves efficient and precise removal of silicon wafer surface contamination.

[0097] Three-tank etching system: A three-tank etching system was designed and adopted, consisting of a constant-temperature potassium hydroxide etching tank and a two-stage pure water rinsing tank. This system ensures the stability and repeatability of the etching process by precisely controlling the temperature and processing time of each tank.

[0098] Rework process integration: Integrating pre-etch cleaning, alkaline etching, post-etch cleaning, pre-LPCVD cleaning, and LPCVD deposition steps into the complete rework process, achieving full-process treatment of silicon wafer surface contamination.

[0099] VI. Technical Effects of This Application

[0100] Improve yield: Through this method, defective products that were originally discarded due to LP contamination can be converted into good products, effectively improving the yield of the LPCVD process.

[0101] Reduce costs: Avoid the economic losses caused by directly discarding defective products and reduce production costs.

[0102] Improved product quality: By redepositing the polysilicon layer, the surface quality of the silicon wafer is optimized, improving the electrical performance and reliability of the product. This method also reduces the risk of product failure due to surface contamination, further enhancing overall product quality.

[0103] To further illustrate the technical solution of this application, the following describes the steps of the silicon wafer surface LP contamination repair process in combination with specific application scenarios:

[0104] Step 1: Clean before etching

[0105] Take 10 defective 8-inch silicon wafers with LP contamination (defect characteristics: particles on the back are wrapped by polysilicon);

[0106] Place in a pre-corrosion cleaning machine and use a mixed solution of ammonia and hydrogen peroxide = 1:5 (volume ratio) at 60°C for 120 seconds to remove surface particles.

[0107] Step 2: Alkaline Corrosion

[0108] Prepare potassium hydroxide solution: 80L potassium hydroxide solution + 60L pure water (concentration 0.134%);

[0109] Immerse the silicon wafer in a 90°C potassium hydroxide solution (first tank) for 40 seconds;

[0110] Graded rinsing:

[0111] Second tank: pure water, 30℃, 40 seconds;

[0112] The third tank: pure water, 40℃, 40 seconds.

[0113] Effect: The polysilicon layer is completely removed and the LP contamination particles disappear.

[0114] Step 3: Clean after corrosion

[0115] Use a post-CP cleaning machine (containing dilute hydrochloric acid + megasonic waves) to remove residual metal ions (Fe and Cu content <0.1ppb) caused by alkaline corrosion.

[0116] Step 4: Clean before LPCVD

[0117] SC-1 solution (NH4OH / H2O2 / H2O) was used for cleaning to simultaneously remove particles (≤0.1μm) and metal residues.

[0118] Step 5: LPCVD deposition

[0119] SiH4 gas was introduced into a low-pressure furnace (pressure 100 Pa) and a polysilicon film (target thickness 1.2 μm) was redeposited at 620°C.

[0120] Step 6: Detection

[0121] Film thickness measurement: Ellipsometer shows thickness deviation <±3%;

[0122] Appearance inspection: no particles attached, uniform surface

[0123] VII. Description of the application principles of each step of this application:

[0124] 1. Clean before etching (SC1 cleaning)

[0125] Function: Remove initial particles on the surface of silicon wafers to provide a clean base for subsequent etching.

[0126] Method: Use a mixed solution of ammonia (NH3·H2O) and hydrogen peroxide (H2O2) with a volume ratio of 1:5 and clean at 60℃ for 120 seconds.

[0127] Principle: Hydrogen peroxide's strong oxidizing properties decompose organic matter, and ammonia complexes metal ions. The two work synergistically to achieve efficient cleaning.

[0128] 2. Alkali corrosion (KOH selective corrosion)

[0129] Function: Accurately remove the surface polysilicon layer and LP contamination particles while retaining the SiO2 substrate.

[0130] Method: Immerse the silicon wafer in 0.134% wt KOH solution and etch it at 90°C for 40 seconds.

[0131] principle:

[0132] Concentration control: 0.05%-0.2% low concentration KOH achieves selective corrosion to avoid excessive damage to the SiO2 substrate.

[0133] Temperature-time synergy: High temperature accelerates the reaction kinetics and precisely controls the etching rate, ensuring complete removal of the polysilicon layer (approximately 500nm) while retaining the 50nm SiO2 buffer layer.

[0134] Chemical reaction: Si+2KOH+H2O→K2SiO3+2H2↑, polysilicon reacts with KOH to form soluble silicate.

[0135] 3. Clean after corrosion (two-stage countercurrent rinsing)

[0136] Function: Remove residual KOH and metal impurities to prevent secondary pollution.

[0137] method:

[0138] First stage rinse: Rinse with 30℃ ultrapure water for 40 seconds to remove most of the KOH.

[0139] Second stage rinsing: Rinse with 40°C ultrapure water and megasonic waves (1.2MHz, 30W) for 40 seconds to remove particles and metal residues.

[0140] principle:

[0141] Temperature gradient design: low temperature to high temperature rinsing to reduce metal ion redeposition.

[0142] Megasonic wave assistance: cavitation effect generates microjets to remove particles from the surface of silicon wafers.

[0143] 4. Cleaning before LPCVD (SC2 cleaning)

[0144] Function: Remove metal residue and passivate the surface to improve deposition adhesion.

[0145] Method: Use SC2 solution with a volume ratio of hydrochloric acid (HCl) to hydrogen peroxide of 1:10 and clean at 75°C for 180 seconds.

[0146] Principle: HCl dissolves metal oxides, hydrogen peroxide oxidizes and passivates the surface, reducing the contact angle from 65° to 15° and improving wettability.

[0147] 5.LPCVD deposition (low pressure regeneration)

[0148] Function: Re-deposit a high-quality polysilicon layer on the surface of a clean silicon wafer.

[0149] Method: pressure 100Pa, temperature 620℃, SiH4 flow rate 50sccm, deposition time 60 minutes.

[0150] principle:

[0151] Low pressure environment: inhibits gas phase nucleation, promotes surface diffusion, and improves film density.

[0152] In-situ doping: Resistivity uniformity (±3%) controlled by gas ratio.

[0153] 6. Film thickness measurement and appearance inspection

[0154] Function: Ensure that the quality of the regenerated film layer meets the standards.

[0155] method:

[0156] Ellipsometer: Measure film thickness (target value 1.2 μm, uniformity ± 2.5%).

[0157] Laser scanning microscope (LSM): Detect surface roughness (Ra≤0.5nm) and defect density (<0.5 particles / cm 2 ).

[0158] The present application also discloses an alkaline etching device for implementing a method for silicon wafer surface treatment and thin film deposition defect repair. The structure and working principle of the alkaline etching device are as follows:

[0159] The three-tank corrosion system consists of three tanks: the first, second, and third. The first tank (constant temperature corrosion tank) utilizes a 316L stainless steel body with a built-in PTFE heating tube. The temperature control module utilizes PID control with an accuracy of ±0.5°C. The stirring system features a bottom-mounted magnetic stirrer with an adjustable speed of 50-200 rpm.

[0160] The second tank (primary rinsing tank) can be temperature-controlled and can be used to adjust the temperature value between 20-40°C. It is equipped with an N2 bubbling device. The liquid level is monitored by a photoelectric liquid level sensor with an error of ±2mm.

[0161] The third tank (secondary rinsing tank) can be temperature-controlled and can be used to adjust the temperature value between 30-50°C. It is integrated with a megasonic generator.

[0162] The control module includes a timing module, which is controlled by PLC and the processing time of each slot is independently set (30 to 60 seconds).

[0163] In summary, this invention, through comprehensive innovations in the process, equipment, and testing, has established a highly efficient and controllable silicon wafer defect repair system. Its core approach is to leverage the selective etching properties of KOH, combined with precise process parameter control and advanced cleaning technology, to achieve efficient removal of LP contamination and precise regeneration of the silicon wafer surface.

[0164] The above description is only a preferred 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.

[0165] In addition, the technical solutions between the various embodiments can be combined with each other, but they must be based on the fact that ordinary technicians in this field can implement them; when the combination of technical solutions is mutually contradictory or cannot be implemented, it should be deemed that such a combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

Claims

1. A method for silicon wafer surface treatment and thin film deposition defect repair, characterized in that: The following steps are involved: Cleaning before etching: Clean defective silicon wafers with LP contamination to remove surface particles; Alkaline etching: After the pre-etching cleaning step, the silicon wafer is immersed in a potassium hydroxide solution for etching to remove the surface polysilicon layer and LP contamination particles; Cleaning after corrosion: Clean the silicon wafer after alkali corrosion to remove surface metal impurities; Cleaning before LPCVD: Perform secondary cleaning on silicon wafers to remove surface particles and metal residues; LPCVD deposition: re-depositing a polysilicon layer on the cleaned silicon wafer surface; Film thickness measurement and appearance inspection: Detect the thickness of the polysilicon layer and confirm that there are no defects on the surface.

2. The method for silicon wafer surface treatment and thin film deposition defect repair according to claim 1, characterized in that: In the cleaning step before etching, a mixed solution of ammonia and hydrogen peroxide is used to clean the silicon wafer.

3. The method for silicon wafer surface treatment and thin film deposition defect repair according to claim 1, characterized in that: The alkaline corrosion step satisfies the following conditions: Potassium hydroxide solution concentration is 0.05%–0.2%; The corrosion temperature is 80℃–95℃; The corrosion time is 30–50 seconds.

4. The method for silicon wafer surface treatment and thin film deposition defect repair according to claim 3, characterized in that: The potassium hydroxide solution is prepared by mixing 80 L of potassium hydroxide stock solution with 60 L of pure water; the concentration of the potassium hydroxide solution is 0.134%, the temperature is 90° C., and the corrosion time is 40 seconds.

5. The method for silicon wafer surface treatment and thin film deposition defect repair according to claim 1, characterized in that: The post-corrosion cleaning step uses pure water for cleaning at a temperature of 30° C.–40° C. for a cleaning time of 40 to 45 seconds.

6. The method for silicon wafer surface treatment and thin film deposition defect repair according to claim 1, characterized in that: Two pure water rinses are included after the alkaline etching step: First level rinsing: pure water, temperature 30℃, time 40S; Second level rinsing: pure water, temperature 40℃, time 40S.

7. The method for silicon wafer surface treatment and thin film deposition defect repair according to claim 1, characterized in that: The pre-LPCVD cleaning includes a chemical cleaning step to remove particles and metal residues.

8. The method for silicon wafer surface treatment and thin film deposition defect repair according to claim 1, wherein: The LPCVD deposition is low-pressure chemical vapor deposition, which forms a polysilicon film on the surface of the silicon wafer.

9. The method for silicon wafer surface treatment and thin film deposition defect repair according to claim 1, characterized in that: The LP contamination is a defect caused by environmental particles being wrapped by polysilicon during the LPCVD process.

10. An alkaline etching device for realizing a method for silicon wafer surface treatment and thin film deposition defect repair, characterized in that: Includes a three-tank corrosion system: Among them, the first tank is a constant temperature potassium hydroxide corrosion tank, and the second and third tanks are pure water rinsing tanks; Temperature control module: control the temperature of the first tank at 80-95°C, the temperature of the second tank at 20-40°C, and the temperature of the third tank at 30-50°C; Timing module: controls the processing time of silicon wafers in each slot to 30 to 60 seconds.

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