Cleaning method for quartz substrate after grinding of aluminum oxide

Abstract

The invention provides a cleaning method for a quartz substrate after aluminum oxide grinding, and belongs to the technical field of semiconductor device cleaning. The method comprises the following steps: immersing a quartz substrate after grinding aluminum oxide in an alkaline solution containing an alkaline cleaning agent, and carrying out ultrasonic-assisted cleaning on the quartz substrate to realize first-time separation treatment on aluminum oxide particles; carrying out ultrapure water spraying treatment on the quartz substrate; soaking the quartz substrate in ultrapure water, and performing secondary separation treatment on the aluminum oxide particles on the surface of the quartz substrate by adopting a bubbling gas treatment process; ultrapure water used for soaking the quartz substrate is discharged for third-time separation treatment; soaking the quartz substrate in a hydrofluoric acid solution, and performing ultrasonic-assisted cleaning on the quartz substrate; and carrying out secondary ultrapure water spraying, secondary bubbling gas treatment and secondary ultrapure water discharging on the quartz substrate so as to remove the hydrofluoric acid solution on the quartz substrate. And efficient and low-loss cleaning of the quartz substrate after aluminum oxide grinding can be achieved.

Description

Technical Field

[0001] The present application belongs to the technical field of semiconductor device cleaning, and specifically relates to a method for cleaning a quartz substrate after alumina grinding. Background Art

[0002] As one of the key materials in the manufacturing process of semiconductor devices, the surface quality of quartz substrate is directly related to the performance and reliability of the final product. In order to achieve high-specification and high-precision technical indicators, quartz substrates need to undergo a series of precision processing techniques, such as grinding and polishing. During these processing processes, especially after grinding with high-mesh alumina, a large amount of alumina particles will inevitably remain on the surface of the quartz substrate.

[0003] If these residual aluminum oxide particles are not cleaned promptly and effectively, they may become new sources of surface defects in subsequent processing steps, affecting the quality of the quartz substrate and thus reducing product yield.

[0004] Currently, the cleaning process in the semiconductor industry is mainly focused on cleaning wafers after cerium oxide polishing, which is achieved by using chemical reagents combined with ultrasonic waves or brushes. However, the existing technology has certain limitations for cleaning quartz substrates after aluminum oxide grinding, especially the lack of effective solutions specifically for such situations. Traditional cleaning methods cannot fully adapt to the characteristics of aluminum oxide particles, resulting in poor cleaning effects, or the use of contact cleaning tools (such as brushes) increases the risk of secondary contamination. Summary of the invention

[0005] In order to solve at least one of the technical problems existing in the background technology, the present application provides a method for cleaning a quartz substrate after alumina grinding, which can effectively remove alumina particles in different particle size ranges and reduce physical contact with the surface of the quartz substrate, avoiding the introduction of new pollutants, and achieving efficient and low-loss cleaning of the quartz substrate after alumina grinding.

[0006] The technical solution adopted in this application is:

[0007] The present application embodiment provides a method for cleaning a quartz substrate after alumina grinding, comprising:

[0008] Immersing the alumina-ground quartz substrate in an alkaline solution containing an alkaline cleaning agent to precipitate alumina particles on the surface of the quartz substrate, and performing ultrasonic-assisted cleaning on the quartz substrate to achieve a first detachment treatment of the alumina particles;

[0009] The quartz substrate is subjected to an ultrapure water spray treatment to clean the residual alkaline solution on the surface of the quartz substrate;

[0010] The quartz substrate is immersed in ultrapure water, and the aluminum oxide particles on the surface of the quartz substrate are subjected to a second detachment treatment by a bubbling gas treatment process;

[0011] The ultrapure water used to soak the quartz substrate is discharged, and the aluminum oxide particles on the surface of the quartz substrate are subjected to a third detachment treatment by the pulling force generated by the flow of water;

[0012] Immersing the quartz substrate in a hydrofluoric acid solution and performing ultrasonic-assisted cleaning on the quartz substrate to achieve a fourth detachment treatment of the aluminum oxide particles and a detachment treatment of the oxide layer on the surface of the quartz substrate;

[0013] The quartz substrate is subjected to secondary ultrapure water spraying, secondary bubbling gas treatment and secondary ultrapure water discharge to remove the hydrofluoric acid solution on the quartz substrate.

[0014] According to the cleaning method for a quartz substrate after alumina grinding provided in an embodiment of the present application, the quartz substrate after alumina grinding is first immersed in an alkaline solution containing an alkaline cleaning agent of a specific concentration and composition, the alkaline environment is used to loosen the alumina particles, and ultrasonic vibration is used to accelerate the particles to detach from the surface of the quartz substrate. The alkaline solution can react chemically with the alumina to form a precipitate, thereby weakening its adhesion to the quartz substrate. The shock wave formed during the ultrasonic vibration can effectively promote the shedding of the alumina particles; after the first step of cleaning, the quartz substrate is sprayed with ultrapure water to remove the alkaline solution remaining on the surface. The ultrapure water has extremely high purity and will not introduce new impurities. The high-pressure spray can effectively rinse away the residual alkaline solution to prevent it from reacting adversely with chemicals in subsequent processes, and at the same time avoid the alkaline solution from causing damage to the equipment or operators; then the quartz substrate is immersed in ultrapure water, and gas is introduced for bubbling treatment. The micro shock waves generated by the bursting of bubbles are used to further remove the alumina particles on the surface of the quartz substrate. The bubbling gas is a non-contact cleaning method that avoids physical friction. The micro shock waves generated when the bubbles burst can penetrate into the tiny bumps and depressions of the quartz substrate, effectively remove the smaller aluminum oxide particles and reduce surface defects. Then, the ultrapure water used to soak the quartz substrate is discharged, and the pulling force generated by the rapid flow of water can further clean the aluminum oxide particles on the surface of the quartz substrate. The pulling force of the water flow can help take away the aluminum oxide particles that have been loosened but not completely detached. The quartz substrate is immersed in a hydrofluoric acid solution of a certain concentration and ultrasonic cleaning is applied to remove the remaining aluminum oxide particles and the oxide layer on the surface of the quartz substrate. Hydrofluoric acid is highly corrosive and can react with silicon dioxide to dissolve the oxide layer on the surface and corrode the tiny aluminum oxide particles. Ultrasonic vibration further enhances the cleaning effect to ensure that the surface cleanliness meets high specifications. Finally, the quartz substrate is sprayed with ultrapure water for the second time, treated with nitrogen bubbling for the second time, and discharged with ultrapure water for the second time to completely remove the hydrofluoric acid solution on the quartz substrate, and further dried. The secondary cleaning is to ensure that there is no residual hydrofluoric acid or other chemicals to avoid negative impact on subsequent processes or product performance. In summary, the cleaning method for a quartz substrate after alumina grinding provided in the embodiment of the present application can effectively remove alumina particles within different particle size ranges, reduce physical contact with the surface of the quartz substrate, avoid the introduction of new pollutants, and achieve efficient and low-loss cleaning of the quartz substrate after alumina grinding.

[0015] According to one embodiment of the present application, the quartz substrate after the aluminum oxide is ground is immersed in an alkaline solution including an alkaline cleaning agent to precipitate the aluminum oxide particles on the surface of the quartz substrate, specifically:

[0016] Mixing the alkaline cleaning agent with ultrapure water, wherein the mixing ratio of the alkaline cleaning agent to the ultrapure water is 1:3;

[0017] The alkaline solution is heated to 30° C. to 60° C., and the soaking time is 3 minutes to 10 minutes.

[0018] According to one embodiment of the present application, the ultrasonic-assisted cleaning of the quartz substrate to achieve the first separation treatment of the aluminum oxide particles is specifically:

[0019] The ultrasonic frequency range is controlled to be 40kHz to 80kHz, and the ultrasonic-assisted cleaning time is 5 minutes to 10 minutes.

[0020] According to an embodiment of the present application, the quartz substrate is subjected to an ultrapure water spray treatment to clean the residual alkaline solution on the surface of the quartz substrate, specifically:

[0021] The spraying pressure of the ultrapure water is controlled to be in the range of 0.3Mpa to 1Mpa, and the spraying time is in the range of 10 seconds to 60 seconds.

[0022] According to an embodiment of the present application, the quartz substrate is immersed in ultrapure water, and a bubbling gas treatment process is used to perform a second separation treatment on the aluminum oxide particles on the surface of the quartz substrate, specifically:

[0023] Nitrogen is introduced into the ultrapure water for bubbling, the nitrogen pressure ranges from 0.4 MPa to 0.8 MPa, and the bubbling time is from 20 seconds to 60 seconds.

[0024] According to an embodiment of the present application, the ultrapure water used to soak the quartz substrate is discharged, and the aluminum oxide particles on the surface of the quartz substrate are subjected to a third separation treatment by the pulling force generated by the flow of water, specifically:

[0025] The ultrapure water is drained for 10 to 60 seconds.

[0026] According to an embodiment of the present application, immersing the quartz substrate in a hydrofluoric acid solution is specifically:

[0027] The concentration of the hydrofluoric acid solution ranges from 0.1 wt % to 1 wt %, and the temperature of the hydrofluoric acid solution ranges from 16° C. to 22° C.

[0028] According to an embodiment of the present application, the quartz substrate is immersed in a hydrofluoric acid solution and ultrasonic-assisted cleaning is performed on the quartz substrate, specifically:

[0029] The ultrasonic frequency range is controlled to be 100kHz to 130kHz, and the ultrasonic-assisted cleaning time is 5 minutes to 15 minutes.

[0030] According to one embodiment of the present application, the method further includes:

[0031] Drying the cleaned quartz substrate;

[0032] The quartz substrate is placed in a dark room, and a light intensity of 200,000 lux is used to irradiate the surface of the quartz substrate. When there is no aluminum oxide particle with a size of not less than 5 μm on the surface of the quartz substrate, the cleaning is qualified.

[0033] According to one embodiment of the present application, the alkaline cleaning agent includes an inorganic base, a nonionic surfactant and a chelating agent, and the pH value is 13-9. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] The drawings described herein are used to provide a further understanding of the present application and constitute a part of the present application. The illustrative embodiments of the present application and their descriptions are used to explain the present application and do not constitute an improper limitation on the present application. In the drawings:

[0035] Figure 1 A schematic flow chart of a method for cleaning a quartz substrate after alumina grinding provided in an embodiment of the present application. DETAILED DESCRIPTION

[0036] In order to more clearly illustrate the overall concept of the present application, a detailed description is given below in an illustrative manner in conjunction with the accompanying drawings.

[0037] In the following description, many specific details are set forth to facilitate a full understanding of the present application. However, the present application may also be implemented in other ways different from those described herein. Therefore, the protection scope of the present application is not limited by the specific embodiments disclosed below. It should be noted that the embodiments of the present application and the features in each embodiment may be combined with each other without conflict.

[0038] In the present application, unless otherwise clearly specified and limited, a first feature "above" or "below" a second feature may be that the first and second features are in direct contact, or the first and second features are in indirect contact through an intermediate medium. In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present application. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in an appropriate manner in any one or more embodiments or examples.

[0039] like Figure 1As shown, the embodiment of the present application provides a method for cleaning a quartz substrate after alumina grinding, comprising:

[0040] Step 100: immerse the quartz substrate after alumina grinding in an alkaline solution including an alkaline cleaning agent to precipitate the alumina particles on the surface of the quartz substrate, and perform ultrasonic assisted cleaning on the quartz substrate to achieve a first detachment treatment of the alumina particles.

[0041] Step 200 : performing ultrapure water spraying treatment on the quartz substrate to clean the residual alkaline solution on the surface of the quartz substrate.

[0042] Step 300: Immerse the quartz substrate in ultrapure water, and use a bubbling gas treatment process to perform a second detachment treatment on the aluminum oxide particles on the surface of the quartz substrate.

[0043] Step 400: drain the ultrapure water used to soak the quartz substrate, and perform a third detachment treatment on the aluminum oxide particles on the surface of the quartz substrate by the tension generated by the flow of water.

[0044] Step 500: immerse the quartz substrate in a hydrofluoric acid solution and perform ultrasonic-assisted cleaning on the quartz substrate to achieve a fourth detachment treatment of the aluminum oxide particles and a detachment treatment of the oxide layer on the surface of the quartz substrate.

[0045] Step 600 , performing a second ultrapure water spraying, a second bubbling gas treatment and a second ultrapure water discharge on the quartz substrate to remove the hydrofluoric acid solution on the quartz substrate.

[0046] In step 100, alkaline substances (such as sodium hydroxide, potassium hydroxide, etc.) in the alkaline solution react chemically with aluminum oxide to form a precipitate, which weakens its adhesion to the quartz substrate. The shock waves generated by ultrasonic vibration can accelerate the detachment of aluminum oxide particles from the surface of the quartz substrate. The first detachment treatment can initially remove aluminum oxide particles with a particle size range of 20 μm to 80 μm.

[0047] In step 200, ultrapure water, also known as high-purity water or deionized water, refers to water that has been subjected to multiple purification processes and contains almost no impurities. Ultrapure water has extremely high purity and does not introduce new impurities. High-pressure spraying can effectively wash away residual alkaline solution to ensure the smooth progress of subsequent steps. In addition, it can also prevent the residual alkaline solution from causing damage to equipment or operators.

[0048] In step 300, the bubbling gas treatment process is a technique for generating a large number of tiny bubbles by introducing gas (usually an inert gas such as nitrogen, argon, etc.) into a liquid. These bubbles will burst during the rising process, forming tiny shock waves and turbulence, thereby cleaning or treating the surface of the object immersed in the liquid. This non-contact cleaning avoids the damage that may be caused by physical friction and reduces the risk of secondary contamination.

[0049] In step 400, as a third separation process, the aluminum oxide particles that are loose but not completely separated are further removed. The drainage speed is usually relatively fast, and fast drainage can generate a large water flow pulling force in a short time to help take away the loose aluminum oxide particles.

[0050] In step 500, hydrofluoric acid reacts with silicon dioxide to dissolve the oxide layer on the surface, while also effectively corroding the fine aluminum oxide particles. Ultrasonic vibration further enhances the cleaning effect, ensuring that the surface cleanliness meets high specifications.

[0051] In addition, other acidic solutions (such as nitric acid and hydrochloric acid) can also be used for cleaning.

[0052] In step 600, the second spraying is performed by spraying with ultrapure water again to ensure that the hydrofluoric acid residue is completely removed.

[0053] Secondary bubbling is to perform bubbling gas treatment again to ensure that there are no residual particles on the surface.

[0054] Secondary drainage is to quickly drain and rinse again to ensure that there is no hydrofluoric acid residue and aluminum oxide particles remaining on the surface.

[0055] According to the cleaning method for a quartz substrate after alumina grinding provided in an embodiment of the present application, the quartz substrate after alumina grinding is first immersed in an alkaline solution containing an alkaline cleaning agent of a specific concentration and composition, the alkaline environment is used to loosen the alumina particles, and ultrasonic vibration is used to accelerate the particles to detach from the surface of the quartz substrate. The alkaline solution can react chemically with the alumina to form a precipitate, thereby weakening its adhesion to the quartz substrate. The shock wave formed during the ultrasonic vibration can effectively promote the shedding of the alumina particles; after the first step of cleaning, the quartz substrate is sprayed with ultrapure water to remove the alkaline solution remaining on the surface. The ultrapure water has extremely high purity and will not introduce new impurities. The high-pressure spray can effectively rinse away the residual alkaline solution to prevent it from reacting adversely with chemicals in subsequent processes, and at the same time avoid the alkaline solution from causing damage to the equipment or operators; then the quartz substrate is immersed in ultrapure water, and gas is introduced for bubbling treatment. The micro shock waves generated by the bursting of bubbles are used to further remove the alumina particles on the surface of the quartz substrate. The bubbling gas is a non-contact cleaning method that avoids physical friction. The micro shock waves generated when the bubbles burst can penetrate into the tiny bumps and depressions of the quartz substrate, effectively remove the smaller aluminum oxide particles and reduce surface defects. Then, the ultrapure water used to soak the quartz substrate is discharged, and the pulling force generated by the rapid flow of water can further clean the aluminum oxide particles on the surface of the quartz substrate. The pulling force of the water flow can help take away the aluminum oxide particles that have been loosened but not completely detached. The quartz substrate is immersed in a hydrofluoric acid solution of a certain concentration and ultrasonic cleaning is applied to remove the remaining aluminum oxide particles and the oxide layer on the surface of the quartz substrate. Hydrofluoric acid is highly corrosive and can react with silicon dioxide to dissolve the oxide layer on the surface and corrode the tiny aluminum oxide particles. Ultrasonic vibration further enhances the cleaning effect to ensure that the surface cleanliness meets high specifications. Finally, the quartz substrate is sprayed with ultrapure water for the second time, treated with nitrogen bubbling for the second time, and discharged with ultrapure water for the second time to completely remove the hydrofluoric acid solution on the quartz substrate, and further dried. The secondary cleaning is to ensure that there is no residual hydrofluoric acid or other chemicals to avoid negative impact on subsequent processes or product performance. In summary, the cleaning method for a quartz substrate after alumina grinding provided in the embodiment of the present application can effectively remove alumina particles within different particle size ranges, reduce physical contact with the surface of the quartz substrate, avoid the introduction of new pollutants, and achieve efficient and low-loss cleaning of the quartz substrate after alumina grinding.

[0056] In some embodiments of the present application, the quartz substrate after aluminum oxide grinding is immersed in an alkaline solution including an alkaline cleaning agent to precipitate aluminum oxide particles on the surface of the quartz substrate, specifically:

[0057] Mix the alkaline cleaning agent with ultrapure water, the mixing ratio of the alkaline cleaning agent to the ultrapure water is 1:3;

[0058] Heat the alkaline solution to 30°C to 60°C and soak for 3 to 10 minutes.

[0059] Specifically, an appropriate dilution ratio can ensure that the concentration of the alkaline solution is moderate, which can effectively remove the aluminum oxide particles without causing excessive corrosion or damage to the quartz substrate. Heating can accelerate the rate of chemical reactions and promote the reaction between aluminum oxide particles and alkaline substances. 30°C is the lowest temperature, which ensures that the chemical reaction can be carried out effectively, while avoiding the problem of too slow a reaction rate due to too low a temperature. 60°C is the highest temperature, which prevents excessive temperature from causing damage to the quartz substrate or cleaning equipment, especially avoiding the impact of thermal stress on the quartz substrate. In a specific embodiment of the present application, the temperature of the alkaline solution is set to 40°C, which is a relatively mild temperature that can effectively accelerate the chemical reaction without causing damage to the quartz substrate or cleaning equipment. In actual operation, the temperature of the alkaline solution can be precisely controlled by a constant temperature control system to ensure that it always remains within the set range.

[0060] The choice of soaking time depends on the particle size of the aluminum oxide particles and the surface characteristics of the quartz substrate. In a specific embodiment of the present application, the soaking time is set to 5 minutes, which can remove most of the residual aluminum oxide particles with a particle size range of 20 μm-80 μm.

[0061] In some embodiments of the present application, the quartz substrate is subjected to ultrasonic assisted cleaning to achieve a first detachment treatment of the aluminum oxide particles, specifically:

[0062] The ultrasonic frequency range is controlled to be 40kHz to 80kHz, and the ultrasonic-assisted cleaning time is 5 minutes to 10 minutes.

[0063] Specifically, ultrasound can cause vibrations in the cleaning liquid, which can accelerate the flow of the cleaning liquid and ensure that the cleaning liquid is evenly distributed across the entire surface of the quartz substrate, especially in tiny bumps and gaps. This helps to remove aluminum oxide particles more thoroughly. Ultrasonic waves can also promote the chemical reaction between the alkaline solution and the aluminum oxide particles, accelerating the dissolution or loosening of the aluminum oxide particles. At the same time, ultrasound can also prevent the sediment in the cleaning liquid from redepositing on the substrate surface, ensuring the continuity of the cleaning effect.

[0064] After ultrasonic assisted cleaning, the alumina particles will gradually loosen and fall off from the surface of the quartz substrate and enter the solution. At this point, most of the larger alumina particles (20μm-80μm) have been effectively removed, laying a good foundation for the subsequent cleaning steps. Since ultrasonic assisted cleaning is a non-contact cleaning method, it avoids secondary contamination that may be caused by physical friction and ensures the purity of the quartz substrate surface.

[0065] The frequency range of 40kHz to 80kHz can achieve a good balance between alumina particles of different particle sizes, which can remove large particles and effectively deal with fine particles. The cleaning time of 5 minutes to 10 minutes can be flexibly adjusted according to the specific situation to ensure the cleaning effect while avoiding damage to the quartz substrate.

[0066] In some embodiments of the present application, the quartz substrate is subjected to an ultrapure water spray treatment to clean the residual alkaline solution on the surface of the quartz substrate, specifically:

[0067] The spraying pressure range of ultrapure water is controlled to be 0.3Mpa to 1Mpa, and the spraying time is 10 seconds to 60 seconds.

[0068] Specifically, higher spray pressures can generate stronger water flow impacts, which can more effectively wash away residual alkaline solutions and loose particles on the surface of the quartz substrate. This is critical to ensure that there is no residual alkali in subsequent processes, as residual alkali may react adversely with subsequent chemicals and affect product quality. If the spray pressure is too high, it may cause physical damage to the surface of the quartz substrate, especially if there are tiny cracks or defects on the surface of the quartz substrate. Therefore, it is very important to choose the appropriate spray pressure to ensure the cleaning effect while avoiding damage to the substrate.

[0069] For more sensitive quartz substrates or preliminary cleaning, a lower spray pressure (such as 0.3Mpa) can be selected to avoid damage to the substrate surface. For situations where the surface is heavily contaminated or requires more thorough cleaning, a higher spray pressure (such as 1Mpa) can be selected to ensure the cleaning effect. In actual operation, the spray pressure can be flexibly adjusted according to the specific situation, and the best cleaning effect can be verified through experiments.

[0070] The spraying time of 10 to 60 seconds can be flexibly adjusted according to the specific situation to ensure the cleaning effect while reducing potential damage to the substrate. In a specific embodiment of the present application, the spraying time is set to 30 seconds.

[0071] In some embodiments of the present application, the quartz substrate is immersed in ultrapure water, and the aluminum oxide particles on the surface of the quartz substrate are subjected to a second detachment treatment using a bubbling gas treatment process, specifically:

[0072] Nitrogen gas was introduced into ultrapure water for bubbling, the nitrogen pressure range was 0.4 MPa to 0.8 MPa, and the bubbling time was 20 seconds to 60 seconds.

[0073] Nitrogen is an inert gas with very stable chemical properties. It hardly reacts with other substances at room temperature and pressure. This means that nitrogen will not react adversely with ultrapure water, alkaline solutions, hydrofluoric acid solutions or other cleaning chemicals, nor will it cause any chemical damage to the surface of the quartz substrate. The high purity of nitrogen ensures that it will not carry any impurities or contaminants into the cleaning system, avoiding the risk of secondary contamination.

[0074] Nitrogen can effectively replace dissolved oxygen in water and reduce the presence of oxygen. Oxygen in water may cause the formation of a tiny oxide layer on the surface of the quartz substrate, especially at high temperatures or in the presence of chemical reagents, which will affect the quality of the quartz substrate. By introducing nitrogen, the dissolution of oxygen can be reduced to prevent oxidation and corrosion of the surface of the quartz substrate. The bubbles formed by nitrogen in water are moderate in size and can generate sufficient shock waves and turbulence during the rising process, effectively destroying the adhesion between the alumina particles and the surface of the quartz substrate. At the same time, the low solubility of nitrogen ensures that the bubbles can burst in a shorter time, producing a stronger impact effect.

[0075] The low solubility of nitrogen also means that it can be more evenly distributed in the cleaning solution, ensuring that the entire surface of the quartz substrate is evenly impacted by bubbles, improving the uniformity of the cleaning effect.

[0076] Specifically, during the nitrogen bubbling process, the gas forms a large number of tiny bubbles in ultrapure water. These bubbles contact the surface of the quartz substrate during the rising process and burst when approaching the liquid surface, generating tiny shock waves and turbulence. These shock waves can effectively destroy the adhesion between the aluminum oxide particles and the surface of the quartz substrate, causing the particles to fall off the substrate. The micro shock waves generated by the bubble burst can penetrate into the tiny concave and convex parts of the quartz substrate, effectively removing the tiny particles hidden in these areas, and ensuring that the cleaning effect is more thorough. During the bubbling process, the rise and burst of the bubbles can stir the cleaning liquid, prevent the particles that have been detached from from being redeposited on the surface of the quartz substrate, and ensure the continuity of the cleaning effect. In a specific embodiment of the present application, the bubbling duration is set to 40 seconds.

[0077] In some embodiments of the present application, the ultrapure water used to soak the quartz substrate is discharged, and the aluminum oxide particles on the surface of the quartz substrate are subjected to a third detachment treatment by the pulling force generated by the flow of water, specifically:

[0078] The drain time for ultrapure water is 10 to 60 seconds.

[0079] Specifically, for a quartz substrate that is being initially cleaned or has light surface contamination, a shorter drainage time (eg, 10 seconds) may be selected to ensure a cleaning effect while reducing potential damage to the substrate.

[0080] For surfaces that are heavily contaminated or require more thorough cleaning, a longer drain time (such as 60 seconds) can be selected to ensure a more thorough cleaning effect.

[0081] In actual operation, the optimal drainage time can be verified by experiments to ensure that the best cleaning effect is achieved without affecting the quality of the substrate. In a specific embodiment of the present application, the drainage time is set to 20 seconds.

[0082] In some embodiments of the present application, the quartz substrate is immersed in a hydrofluoric acid solution, specifically:

[0083] The concentration of the hydrofluoric acid solution ranges from 0.1 wt % to 1 wt %, and the temperature of the hydrofluoric acid solution ranges from 16° C. to 22° C.

[0084] Specifically, for more sensitive quartz substrates or preliminary cleaning, a lower hydrofluoric acid concentration (such as 0.1wt%) can be selected to reduce potential damage to the substrate surface. For situations where the surface is heavily contaminated or requires more thorough cleaning, a higher hydrofluoric acid concentration (such as 1wt%) can be selected to ensure the cleaning effect.

[0085] In actual operation, the optimal hydrofluoric acid concentration can be verified through experiments to ensure that the best cleaning effect is achieved without affecting the quality of the substrate.

[0086] The oxide layer is a thin layer formed on the surface of the quartz substrate due to exposure to air or high temperature treatment. Hydrofluoric acid can quickly dissolve these oxide layers and restore the original surface state of the quartz substrate, providing a good foundation for subsequent processing. After the first few cleaning steps, there may still be a small amount of fine aluminum oxide particles (particle size range of 1μm-20μm) attached to the surface of the quartz substrate. Hydrofluoric acid can further loosen and dissolve these particles to ensure a cleaner surface. The temperature range of 16℃ to 22℃ can accelerate the reaction rate while avoiding damage to the substrate.

[0087] In some embodiments of the present application, the quartz substrate is immersed in a hydrofluoric acid solution, and the quartz substrate is subjected to ultrasonic assisted cleaning, specifically:

[0088] The ultrasonic frequency range is controlled to be 100kHz to 130kHz, and the ultrasonic-assisted cleaning time is 5 minutes to 15 minutes.

[0089] Specifically, ultrasound can promote the chemical reaction between the hydrofluoric acid solution and the alumina particles, accelerating the dissolution or loosening of the alumina particles. Ultrasonic waves can also promote the flow of the hydrofluoric acid solution, preventing the detached particles from re-depositing on the surface of the quartz substrate, ensuring the continuity of the cleaning effect.

[0090] In some embodiments of the present application, the method further comprises:

[0091] Drying the cleaned quartz substrate;

[0092] Place the quartz substrate in a dark room and irradiate the surface of the quartz substrate with a light intensity of 200,000 lux. When there are no aluminum oxide particles less than 5μm on the surface of the quartz substrate, the cleaning is qualified.

[0093] Specifically, the drying process is to remove the residual moisture on the surface of the quartz substrate to ensure that it is completely dry. If there is residual moisture on the surface of the quartz substrate, it may cause water stains, bubbles or other adverse effects in subsequent processes, affecting product quality.

[0094] Drying methods may include the following:

[0095] Natural drying: Place the cleaned quartz substrate in a clean, dust-free environment and let it air dry naturally. Natural drying is suitable for situations where the drying speed is not required, but it is necessary to ensure that the humidity in the environment is low to prevent moisture from being re-adsorbed onto the substrate surface.

[0096] Nitrogen drying: Use high-purity nitrogen (such as 99.999%) to dry the surface of the quartz substrate. Nitrogen drying can quickly remove moisture from the surface, and the inert properties of nitrogen can prevent oxygen or contaminants in the air from reattaching to the substrate surface. Nitrogen drying is a commonly used drying method in the semiconductor industry to ensure the purity of the substrate surface.

[0097] Hot air drying: In some cases, filtered hot air can be used to dry the quartz substrate. Hot air drying can accelerate the evaporation of water, but it is necessary to control the temperature to avoid excessive temperature causing thermal stress damage to the quartz substrate. Generally, the temperature of hot air drying should be controlled below 60°C to ensure the safety of the substrate.

[0098] The drying time depends on the drying method used. Natural drying may take a long time (such as 30 minutes to 1 hour), while nitrogen drying or hot air drying can be completed in a few minutes. The specific time should be adjusted according to the actual situation to ensure that the substrate surface is completely dry.

[0099] The purpose of optical inspection is to check whether there are aluminum oxide particles or other contaminants on the surface of the quartz substrate to ensure that the surface cleanliness of the substrate after cleaning meets high specifications. Through high-brightness light, tiny particles on the surface of the substrate can be clearly observed to ensure that they meet quality standards.

[0100] Optical inspection conditions:

[0101] Darkroom environment: Light inspection should be carried out in a darkroom to ensure that the background light is as weak as possible, so that tiny particles on the surface of the substrate can be observed. The darkroom environment can reduce the interference of external light and improve the accuracy of detection.

[0102] Light intensity: Use a high-brightness light source of 200,000 lux to illuminate the surface of the quartz substrate. 200,000 lux is a very high light intensity that can clearly show the tiny particles on the surface of the substrate. This light intensity is enough to illuminate every detail on the surface of the substrate to ensure that no particles are missed.

[0103] Light source type: Commonly used light sources include LED lamps, fluorescent lamps or halogen lamps, etc. LED lamps are the most commonly used light source in optical inspection due to their high brightness, low heat and long life.

[0104] Inspection standard: When there are no aluminum oxide particles less than 5μm on the surface of the quartz substrate, the cleaning is qualified. This means that any particles greater than or equal to 5μm will be considered unqualified and must be re-cleaned or processed. 5μm is a common particle size standard that is suitable for most high-precision applications such as semiconductor manufacturing, optical devices, etc.

[0105] In order to detect particles more accurately, equipment such as microscopes or particle counters can be used. Microscopes can magnify the surface of the substrate to help operators observe tiny particles more clearly; particle counters can automatically scan the surface of the substrate, count the number and size of particles, and provide more objective detection results.

[0106] The testing process may include the following:

[0107] Prepare a darkroom: Make sure the light in the darkroom is as dim as possible and avoid interference from external light.

[0108] Place the quartz substrate: Place the dried quartz substrate on the test bench, making sure the surface of the substrate is flat and avoid tilting or bending.

[0109] Illumination light source: Use a high-brightness light source of 200,000 lux to illuminate the surface of the quartz substrate from different angles to ensure that the entire surface is fully illuminated.

[0110] Observe particles: Carefully observe the surface of the substrate and look for any particles larger than or equal to 5μm. You can use a microscope or a particle counter to assist in observation.

[0111] Record results: If any unacceptable particles are found, record their location and size and decide if re-cleaning or treatment is required.

[0112] Qualification judgment: When there are no aluminum oxide particles less than 5μm on the surface of the quartz substrate, the cleaning is qualified and can enter the subsequent process.

[0113] The quartz substrate that has been cleaned and qualified should be packaged immediately to avoid being exposed to the air again. Antistatic bags or vacuum packaging can be used to ensure that the substrate is not contaminated during transportation and storage.

[0114] In addition, the quartz substrate that has been cleaned properly can directly enter the subsequent processing steps, such as coating, photolithography, etching, etc. Ensure the cleanliness and smoothness of the substrate surface, and provide a high-quality foundation for subsequent processes.

[0115] In some embodiments of the present application, the alkaline cleaning agent includes an inorganic base, a nonionic surfactant and a chelating agent, and the pH value is 13-9.

[0116] Common inorganic alkalis include sodium hydroxide (NaOH), potassium hydroxide (KOH), sodium carbonate (Na2CO3), etc. These inorganic alkalis can provide a strong alkaline environment to promote the chemical reaction between the aluminum oxide particles and the surface of the quartz substrate. Inorganic alkalis are the main components for adjusting the pH value of the cleaning agent to ensure that the cleaning solution has sufficient alkalinity to accelerate the dissolution of aluminum oxide particles. The higher the pH value, the stronger the alkalinity and the stronger the dissolving ability.

[0117] Common nonionic surfactants include polyethylene glycol (PEG), fatty alcohol polyoxyethylene ether (AEO), etc. These surfactants are uncharged and can form micelles in water to reduce the surface tension of the solution. Nonionic surfactants can significantly reduce the surface tension of the cleaning solution, making it easier for the cleaning solution to wet the surface of the quartz substrate, especially the tiny bumps and gaps. This helps the cleaning solution to be more evenly distributed on the substrate surface and improve the cleaning effect. Nonionic surfactants can disperse the loosened alumina particles during the cleaning process to prevent them from redepositing on the surface of the quartz substrate. In addition, surfactants can also peel off oil or other organic pollutants from the substrate surface and suspend them in the cleaning solution through emulsification, further improving the cleaning effect. Some nonionic surfactants can increase the foam stability of the cleaning solution, prolong the existence time of bubbles, and enhance the effect of ultrasonic cleaning. The shock wave generated when the bubbles burst can more effectively destroy the adhesion between the alumina particles and the substrate surface.

[0118] Common chelating agents include ethylenediaminetetraacetic acid (EDTA), citric acid, gluconic acid, etc. These chelating agents can form stable complexes with metal ions to prevent adverse reactions between metal ions and the surface of the quartz substrate. Chelating agents can form stable complexes with metal ions such as calcium, magnesium, and iron in water to prevent these ions from reacting with the surface of the quartz substrate, causing secondary pollution or surface damage. For example, calcium ions and magnesium ions may form insoluble precipitates with the surface of the quartz substrate at high temperatures, affecting the cleaning effect. Chelating agents can effectively prevent this from happening. Chelating agents can work synergistically with other cleaning ingredients (such as inorganic bases and surfactants) to enhance the overall cleaning effect. For example, chelating agents can prevent metal ions from interfering with the reaction of inorganic bases with alumina particles, ensuring that the alumina particles can be dissolved more thoroughly. When using hard water (containing higher concentrations of calcium and magnesium ions) as a cleaning water source, chelating agents can effectively prevent the influence of metal ions in hard water on the cleaning effect and ensure the stability and effectiveness of the cleaning solution.

[0119] For surfaces with heavy contamination or where more thorough cleaning is required, a higher pH value (such as pH 13) can be selected to ensure effective cleaning.

[0120] For more sensitive quartz substrates or preliminary cleaning, a lower pH value (such as pH 9) can be selected to reduce potential damage to the substrate surface.

[0121] Anything not described in this application can be achieved by adopting or drawing on existing technologies.

[0122] The various embodiments in this specification are described in a progressive manner, and the same or similar parts between the various embodiments can be referenced to each other, and each embodiment focuses on the differences from other embodiments.

[0123] The above is only the embodiment of the present application and is not intended to limit the present application. For those skilled in the art, the present application may have various changes and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application should be included in the protection scope of the present application.

Claims

1. A method for cleaning a quartz substrate after alumina grinding, characterized in that: include: Immersing the alumina-ground quartz substrate in an alkaline solution containing an alkaline cleaning agent to precipitate alumina particles on the surface of the quartz substrate, and performing ultrasonic-assisted cleaning on the quartz substrate to achieve a first detachment treatment of the alumina particles; The quartz substrate is subjected to an ultrapure water spray treatment to clean the residual alkaline solution on the surface of the quartz substrate; The quartz substrate is immersed in ultrapure water, and the aluminum oxide particles on the surface of the quartz substrate are subjected to a second detachment treatment by a bubbling gas treatment process; The ultrapure water used to soak the quartz substrate is discharged, and the aluminum oxide particles on the surface of the quartz substrate are subjected to a third detachment treatment by the pulling force generated by the flow of water; Immersing the quartz substrate in a hydrofluoric acid solution and performing ultrasonic-assisted cleaning on the quartz substrate to achieve a fourth detachment treatment of the aluminum oxide particles and a detachment treatment of the oxide layer on the surface of the quartz substrate; The quartz substrate is subjected to secondary ultrapure water spraying, secondary bubbling gas treatment and secondary ultrapure water discharge to remove the hydrofluoric acid solution on the quartz substrate.

2. The method for cleaning a quartz substrate after alumina grinding according to claim 1, characterized in that: The quartz substrate after the aluminum oxide is ground is immersed in an alkaline solution including an alkaline cleaning agent to precipitate the aluminum oxide particles on the surface of the quartz substrate, specifically: Mixing the alkaline cleaning agent with ultrapure water, wherein the mixing ratio of the alkaline cleaning agent to the ultrapure water is 1:3; The alkaline solution is heated to 30° C. to 60° C., and the soaking time is 3 minutes to 10 minutes.

3. The cleaning method for a quartz substrate after alumina grinding according to claim 2, characterized in that: The ultrasonic-assisted cleaning of the quartz substrate to achieve the first separation treatment of the aluminum oxide particles is specifically: The ultrasonic frequency range is controlled to be 40kHz to 80kHz, and the ultrasonic-assisted cleaning time is 5 minutes to 10 minutes.

4. The method for cleaning a quartz substrate after alumina grinding according to claim 1, characterized in that: The ultrapure water spraying treatment is performed on the quartz substrate to clean the residual alkaline solution on the surface of the quartz substrate, specifically: The spraying pressure of the ultrapure water is controlled to be in the range of 0.3Mpa to 1Mpa, and the spraying time is in the range of 10 seconds to 60 seconds.

5. The method for cleaning a quartz substrate after alumina grinding according to claim 1, characterized in that: The quartz substrate is immersed in ultrapure water, and the aluminum oxide particles on the surface of the quartz substrate are subjected to a second separation treatment using a bubbling gas treatment process, specifically: Nitrogen is introduced into the ultrapure water for bubbling, the nitrogen pressure ranges from 0.4 MPa to 0.8 MPa, and the bubbling time is from 20 seconds to 60 seconds.

6. The method for cleaning a quartz substrate after alumina grinding according to claim 1, characterized in that: The ultrapure water used to soak the quartz substrate is discharged, and the aluminum oxide particles on the surface of the quartz substrate are subjected to a third separation treatment by the pulling force generated by the flow of water, specifically: The ultrapure water is drained for 10 to 60 seconds.

7. The method for cleaning a quartz substrate after alumina grinding according to claim 1, characterized in that: The quartz substrate is immersed in a hydrofluoric acid solution, specifically: The concentration of the hydrofluoric acid solution ranges from 0.1 wt % to 1 wt %, and the temperature of the hydrofluoric acid solution ranges from 16° C. to 22° C.

8. The method for cleaning a quartz substrate after alumina grinding according to claim 7, characterized in that: The quartz substrate is immersed in a hydrofluoric acid solution and ultrasonic-assisted cleaning is performed on the quartz substrate, specifically: The ultrasonic frequency range is controlled to be 100kHz to 130kHz, and the ultrasonic-assisted cleaning time is 5 minutes to 15 minutes.

9. The method for cleaning a quartz substrate after alumina grinding according to any one of claims 1 to 8, characterized in that: The method also includes: Drying the cleaned quartz substrate; The quartz substrate is placed in a dark room, and a light intensity of 200,000 lux is used to irradiate the surface of the quartz substrate. When there is no aluminum oxide particle with a size of not less than 5 μm on the surface of the quartz substrate, the cleaning is qualified.

10. The method for cleaning a quartz substrate after alumina grinding according to any one of claims 1 to 8, characterized in that: The alkaline cleaning agent comprises an inorganic base, a nonionic surfactant and a chelating agent, and the pH value is 13-9.

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