A method for cleaning a substrate and a system for cleaning a substrate

Abstract

An embodiment of the present disclosure provides a method for cleaning a substrate, the method comprising: exposing the substrate to a cleaning agent to remove impurities located on the surface of the substrate; exposing the substrate to a liquid desiccant chemical to remove the cleaning agent located on the surface of the substrate; solidifying the liquid desiccant chemical remaining on the surface of the substrate to obtain a solid desiccant chemical; and sublimating and removing the solid desiccant chemical. By solidifying the liquid desiccant chemical and then removing it by sublimation, the solidified desiccant chemical can eliminate the gas / liquid interface, making the surface tension close to zero, eliminating capillary force during the subsequent sublimation removal process, reducing the damage to the substrate structure caused by the capillary force, and achieving a non-destructive cleaning effect. At the same time, since the influence of the capillary force is eliminated, the residue of cleaning agent and impurities on the substrate surface can be greatly reduced.

Description

Technical Field

[0001] The present disclosure relates to the field of semiconductor technology, and in particular to a method for cleaning a substrate and a system for cleaning the substrate. Background Art

[0002] The manufacturing of semiconductor wafer substrates requires multiple processes, including deposition, planarization, photolithography, and etching. Each of these steps requires critical wet cleaning to ensure the smooth progress of subsequent processes. However, substrate cleaning often presents problems such as poor cleanliness, residual detergent, and structural damage, which can significantly reduce yield and waste production capacity. With the increasing integration of devices, optimizing substrate cleaning methods has become a pressing technical challenge. Summary of the Invention

[0003] An embodiment of the present disclosure provides a method for cleaning a substrate, the method comprising: exposing the substrate to a cleaning agent to remove impurities located on the surface of the substrate; exposing the substrate to a liquid desiccant chemical to remove the cleaning agent located on the surface of the substrate; solidifying the liquid desiccant chemical remaining on the surface of the substrate to obtain a solid desiccant chemical; and sublimating and removing the solid desiccant chemical.

[0004] In some embodiments, curing the liquid desiccant chemical remaining on the surface of the substrate to obtain a solid desiccant chemical includes: controlling temperature and / or pressure so that the liquid desiccant chemical remaining on the surface of the substrate solidifies into a solid desiccant chemical.

[0005] In some embodiments, sublimating and removing the solid dehumidifying chemical includes: controlling temperature and / or pressure to sublime the solid dehumidifying chemical into a gaseous dehumidifying chemical, and discharging the gaseous dehumidifying chemical.

[0006] In some embodiments, after removing the gaseous dehumidifying chemical, the method further comprises: exposing the substrate to an inert gas to bring the substrate environment to atmospheric pressure, wherein the inert gas is swept from the center of the substrate toward the edge.

[0007] In some embodiments, the surface of the substrate includes a void structure having an aspect ratio greater than or equal to 8.

[0008] In some embodiments, after removing the solid dehumidification chemical, the method further comprises: exposing the substrate to a cleaning gas for plasma ashing, wherein the cleaning gas comprises H 2 N 2 gas.

[0009] In some embodiments, the method includes: the purity of the H2N2 gas is at least 98%.

[0010] In some embodiments, the method includes: the liquid drying chemistry having a density value less than a density value of the solid drying chemistry.

[0011] In some embodiments, the method includes: the saturated vapor pressure of the liquid desiccant chemical at room temperature is greater than 4.0 KPa; the miscibility of the liquid desiccant chemical and the cleaning agent is greater than 70%; and the evaporation rate of the liquid desiccant chemical is greater than 1.

[0012] In some embodiments, the liquid desiccant chemical comprises acetone or isopropyl alcohol.

[0013] In some embodiments, exposing the substrate to a liquid desiccant chemical to remove the cleaning agent located on the surface of the substrate includes: controlling the substrate to rotate at a first speed, spraying the liquid desiccant chemical on the surface of the substrate to dissolve the cleaning agent remaining on the surface of the substrate in the liquid desiccant chemical; controlling the substrate to rotate at a second speed to remove a portion of the liquid desiccant chemical located on the surface of the substrate, wherein the second speed is less than the first speed.

[0014] In some embodiments, exposing the substrate to a cleaning agent includes: controlling the substrate to rotate at a third speed to spray a first cleaning agent on the surface of the substrate; and controlling the substrate to rotate at a fourth speed to spray a second cleaning agent on the surface of the substrate to remove the first cleaning agent on the surface of the substrate.

[0015] In some embodiments, solidifying the liquid desiccant chemical remaining on the surface of the substrate to obtain a solid desiccant chemical includes: controlling the substrate to rotate at a fifth speed, controlling the temperature and / or pressure of the chamber so that the temperature in the chamber is lower than the freezing point of the liquid desiccant chemical under the chamber pressure, so that the liquid desiccant chemical remaining on the substrate solidifies to obtain a solid desiccant chemical; removing the solid desiccant chemical includes: controlling the substrate to rotate at a sixth speed, controlling the temperature and / or pressure of the chamber so that the temperature in the chamber is higher than the sublimation point of the solid desiccant chemical under the chamber pressure, so that the solid desiccant chemical sublimates to obtain a gaseous desiccant chemical; wherein the first speed, the third speed, and the fourth speed are greater than the sixth speed, and the sixth speed is greater than the second speed and the fifth speed.

[0016] In some embodiments, curing the liquid desiccant chemical remaining on the surface of the substrate to obtain a solid desiccant chemical includes: controlling the fifth speed of the substrate to 5 to 50 rpm, controlling the temperature of the chamber to -120 to -40 degrees Celsius, and controlling the pressure of the chamber to 0.1 to 100 mTorr; removing the solid desiccant chemical includes: controlling the fifth speed of the substrate to 100 to 1000 rpm and the temperature of the chamber to 20 to 50 degrees Celsius.

[0017] An embodiment of the present disclosure also provides a system for cleaning a substrate, the system comprising: a chamber for receiving and processing a substrate; a wafer stage for supporting and clamping the substrate in the chamber; a nozzle for at least providing a liquid desiccant chemical to the surface of the substrate; a vacuum pump for controlling the air pressure in the chamber; a temperature controller for controlling the temperature of the substrate and / or the chamber; an atmosphere control system for exhausting gas from the chamber or introducing gas into the chamber; a controller that communicates with the vacuum pump, the temperature controller and the atmosphere control system and is configured to solidify the liquid desiccant chemical to obtain a solid desiccant chemical and remove the solid desiccant chemical.

[0018] In some embodiments, the controller is configured to solidify the liquid desiccant chemical agent to obtain a solid desiccant chemical agent, including: controlling the temperature and / or pressure of the chamber so that the temperature in the chamber is lower than the freezing point of the liquid desiccant chemical agent under the pressure of the chamber, so that the liquid desiccant chemical agent solidifies to obtain a solid desiccant chemical agent.

[0019] In some embodiments, the controller is configured to remove the solid desiccant chemical, including: controlling the temperature and / or pressure of the chamber so that the temperature in the chamber is higher than the sublimation point of the solid desiccant chemical at the pressure of the chamber, so that the solid desiccant chemical sublimates to obtain a gaseous desiccant chemical, and removing the gaseous desiccant chemical.

[0020] In some embodiments, the system includes: the controller also communicates with the wafer stage and the nozzle, and the controller is further configured to: control the wafer stage to rotate at a first speed, control the nozzle to provide liquid desiccant chemical to the surface of the substrate; control the wafer stage to rotate at a second speed, wherein the second speed is less than the first speed.

[0021] An embodiment of the present disclosure provides a method for cleaning a substrate, the method comprising: exposing the substrate to a cleaning agent to remove impurities located on the surface of the substrate; exposing the substrate to a liquid desiccant chemical to remove the cleaning agent located on the surface of the substrate; solidifying the liquid desiccant chemical remaining on the surface of the substrate to obtain a solid desiccant chemical; and sublimating and removing the solid desiccant chemical. The present disclosure provides a method for removing the liquid desiccant chemical by solidifying it and then sublimating it. The solidified desiccant chemical can eliminate the gas / liquid interface, making the surface tension close to zero, eliminating capillary force during the subsequent sublimation removal process, reducing the damage to the substrate structure caused by the capillary force, and achieving a non-destructive cleaning effect. At the same time, since the influence of the capillary force is eliminated, the residue of cleaning agent and impurities on the substrate surface can be greatly reduced.

[0022] Additional aspects and advantages of the present disclosure will be given in part in the following description and in part will be obvious from the following description, or will be learned through practice of the present disclosure. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to more clearly illustrate the embodiments of the present disclosure or the technical solutions in the traditional technology, the following briefly introduces the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments of the present disclosure. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0024] Figure 1 A flowchart of a substrate cleaning method provided in one embodiment of the present disclosure;

[0025] Figure 2 A schematic diagram illustrating the principle of a substrate cleaning method according to an embodiment of the present disclosure;

[0026] Figure 3a-3b A schematic diagram of each step in a substrate cleaning process according to an embodiment of the present disclosure;

[0027] Figure 4 is a schematic diagram of a system for cleaning a substrate according to an embodiment of the present disclosure; DETAILED DESCRIPTION

[0028] Exemplary embodiments of the present disclosure will be described in more detail below with reference to the accompanying drawings. Although exemplary embodiments of the present disclosure are shown in the accompanying drawings, it should be understood that the present disclosure can be implemented in various forms and should not be limited by the specific embodiments described herein. Instead, these embodiments are provided to enable a more thorough understanding of the present disclosure and to fully convey the scope of the present disclosure to those skilled in the art.

[0029] In the drawings, the sizes of layers, regions, elements and their relative sizes may be exaggerated for clarity. Like reference numerals denote like elements throughout.

[0030] It should be understood that when an element or layer is referred to as being "on, adjacent to, connected to, or coupled to" another element or layer, it may be directly on, adjacent to, connected to, or coupled to the other element or layer, or there may be intervening elements or layers. In contrast, when an element is referred to as being "directly on, directly adjacent to, directly connected to, or directly coupled to" another element or layer, there may be no intervening elements or layers. It should be understood that although the terms first, second, third, etc. may be used to describe various elements, components, regions, layers, and / or parts, these elements, components, regions, layers, and / or parts should not be limited by these terms. These terms are merely used to distinguish one element, component, region, layer, or part from another element, component, region, layer, or part. Therefore, without departing from the teachings of the present disclosure, the first element, component, region, layer, or part discussed below may be represented as a second element, component, region, layer, or part. However, when the second element, component, region, layer, or part is discussed, it does not necessarily mean that the first element, component, region, layer, or part exists in the present disclosure.

[0031] Spatially relative terms such as "under," "beneath," "below," "under," "above," "above," etc., may be used herein for convenience of description to describe the relationship of one element or feature shown in the figures to other elements or features. It should be understood that in addition to the orientations shown in the figures, the spatially relative terms are intended to include different orientations of the device in use and operation. For example, if the device in the drawings is flipped, then the elements or features described as "under the other elements" or "under it" or "under it" will be oriented as "on" the other elements or features. Thus, the exemplary terms "under" and "under" may include both upper and lower orientations. The device may be oriented otherwise (rotated 90 degrees or in other orientations) and the spatial descriptors used herein are interpreted accordingly.

[0032] The purpose of the terms used herein is only to describe specific embodiments and is not intended to limit the present disclosure. When used herein, the singular forms "a", "an", and "the" are intended to include the plural forms, unless the context clearly indicates otherwise. It should also be understood that the terms "comprising" and / or "comprising", when used in this specification, determine the presence of the features, integers, steps, operations, elements and / or parts, but do not exclude the presence or addition of one or more other features, integers, steps, operations, elements, parts and / or groups. When used herein, the term "and / or" includes any and all combinations of the relevant listed items.

[0033] The present disclosure provides a method for cleaning a substrate. Figure 1 , the method comprising:

[0034] Step 101: exposing the substrate to a cleaning agent to remove impurities on the surface of the substrate;

[0035] Step 102: exposing the substrate to a liquid desiccant chemical to remove the cleaning agent on the surface of the substrate;

[0036] Step 103: solidifying the liquid desiccant chemical remaining on the surface of the substrate to obtain a solid desiccant chemical;

[0037] Step 104: Sublime and remove the solid dehumidifying chemical.

[0038] As attached Figure 2 As shown in the figure, due to the limitations of the polishing process or device design, the surface of the substrate is often not smooth, but rather has some fine structures, such as high aspect ratio structures (e.g., pillars), gaps, etc. As a result, after cleaning, the detergent may remain in some tiny gaps on the substrate surface or between adjacent high aspect ratio structures, and generate capillary forces with the adjacent structures. The capillary forces will damage the substrate surface structure during the subsequent drying process, and will also prevent the removal of residual detergent (e.g., Figure 2 (as shown in Figure a).

[0039] Combine Figure 2 As shown in Figure b), the method of the present invention, which solidifies the liquid desiccant and then removes it by sublimation, eliminates the air / liquid interface, reducing surface tension to near zero. This eliminates capillary forces during the subsequent sublimation removal process, minimizing damage to the substrate structure and achieving non-destructive cleaning. Furthermore, by eliminating the effects of capillary forces, the residue of cleaning agents and impurities on the substrate surface is significantly reduced.

[0040] The following is combined with Figure 3a-3b The substrate cleaning method provided in the embodiment of the present invention is described in detail.

[0041] First, as attached Figure 3a As shown in FIG. a), a substrate 201 to be cleaned is provided, and the surface of the substrate may contain some impurities. The impurities may be dirt, foreign matter, water vapor, or sacrificial materials or mask materials from the previous process, such as dry etching residues.

[0042] In some embodiments, the surface of the substrate includes a void structure, wherein the void structure has an aspect ratio greater than or equal to 8. In actual operation, the substrate may be a wafer, and the void structure may correspond to an isolation region (e.g., a shallow trench isolation (STI) region) or a high aspect ratio feature (e.g., a feature used in forming capacitors, transistors, and other electrical components). The void structure may be a high aspect ratio (HAR) void structure, and the HAR may have an aspect ratio of 15:1, 30:1, or greater. In some embodiments, the void structure further includes a structure with a half pitch less than 19 nm.

[0043] Next, execute step 101, as shown in the attached Figure 3a As shown in Figures b) and c), the substrate is exposed to a cleaning agent to remove impurities 201 on the substrate surface. In some embodiments, the cleaning agent is miscible with the impurities. In actual operation, the cleaning agent may include, but is not limited to, deionized water (DI water), aqueous ammonium hydroxide, aqueous hydrochloric acid, and aqueous hydrogen peroxide.

[0044] In some embodiments, exposing the substrate to the cleaning agent may include: controlling the substrate to rotate at a third speed to spray a first cleaning agent on the surface of the substrate; and controlling the substrate to rotate at a fourth speed to spray a second cleaning agent on the surface of the substrate to remove the first cleaning agent on the surface of the substrate. In this manner, a primary cleaning is performed using the first cleaning agent to remove most impurities soluble in the first cleaning agent, followed by a secondary cleaning using the second cleaning agent to remove impurities soluble in both the first cleaning agent and the second cleaning agent. Multiple cleaning cycles ensure effective impurity removal and improve cleanliness.

[0045] Specifically, such as Figure 3a As shown in FIG. 2( b), the substrate is controlled to rotate at a third speed 204, and a first cleaning agent 203 is sprayed on the surface of the substrate. In actual operation, the third speed is 500 to 1200 rpm (revolutions per minute). The first cleaning agent can be a wet chemical agent to remove impurities on the surface of the substrate.

[0046] Then, if Figure 3a As shown in FIG. 3 c), the substrate is controlled to rotate at a fourth speed 206, and a second cleaning agent 205 is sprayed on the surface of the substrate to remove the first cleaning agent 203 on the substrate surface. In actual operation, the third speed is 500 to 1200 rpm (revolutions per minute), and the second cleaning agent can be deionized water.

[0047] Next, execute step 102, as shown in the attached Figure 3aAs shown in Figures d) and e), the substrate is exposed to a liquid desiccant chemical 207 to remove the cleaning agent on the surface of the substrate.

[0048] In some embodiments, the method includes: the saturated vapor pressure of the liquid desiccant chemical at room temperature is greater than 4.0 kPa; the miscibility of the liquid desiccant chemical with the cleaning agent is greater than 70%; and the evaporation rate of the liquid desiccant chemical is greater than 1. In practice, the cleaning agent and the desiccant chemical can be deionized water and acetone, respectively. This facilitates mixing of the liquid desiccant chemical and the cleaning agent and accelerates the evaporation rate, making it easier for the liquid desiccant chemical to replace the cleaning agent, thereby improving cleaning efficiency.

[0049] In some embodiments, the liquid desiccant chemical comprises acetone or isopropyl alcohol. Acetone and isopropyl alcohol have low surface tension, which can reduce the risk of structural deformation or collapse of the substrate surface during the evaporation process.

[0050] In some embodiments, exposing the substrate to a liquid desiccant chemical to remove the cleaning agent located on the surface of the substrate includes: controlling the substrate to rotate at a first speed, spraying the liquid desiccant chemical onto the surface of the substrate to dissolve the cleaning agent remaining on the surface of the substrate in the liquid desiccant chemical; and controlling the substrate to rotate at a second speed to remove a portion of the liquid desiccant chemical located on the surface of the substrate, wherein the second speed is less than the first speed. By rotating the substrate at a high speed to replace the cleaning agent with the liquid desiccant chemical, and then rotating the substrate at a low speed, only a portion of the liquid desiccant chemical puddles remain on the surface of the substrate, reducing the amount of sample required for subsequent freeze drying and improving cleaning efficiency.

[0051] Specifically, such as Figure 3a As shown in FIG. d), the substrate is controlled to rotate at a first speed 208, and the liquid desiccant chemical 207 is sprayed onto the surface of the substrate to dissolve the cleaning agent remaining on the surface of the substrate in the liquid desiccant chemical. In actual operation, the first speed is 500 to 1200 rpm (revolutions per minute), the cleaning agent can be deionized water, and the desiccant chemical can be acetone.

[0052] Next, if Figure 3a As shown in FIG. 5( e) , the substrate is controlled to rotate at a second speed 210 to remove a portion of the liquid desiccant on the surface of the substrate. The second speed is less than the first speed. This results in the liquid desiccant 209 remaining on the surface of the substrate. In actual operation, the second speed is 5 to 50 rpm (revolutions per minute). The desiccant may be acetone.

[0053] Then, execute step 103, as shown in the attached Figure 3b As shown in Figures f) and g), the liquid desiccant chemical 209 remaining on the surface of the substrate is solidified to obtain a solid desiccant chemical 211. In practice, the liquid desiccant chemical can be solidified through a physical reaction or a chemical reaction. In some embodiments, the liquid desiccant chemical is exposed to a reactive gas, wherein the liquid desiccant chemical includes acetic acid and the reactive gas includes ammonia. For example, the acetic acid reacts with ammonia to form a volatile solid ammonium salt.

[0054] In some embodiments, solidifying the liquid desiccant chemical 209 remaining on the surface of the substrate to obtain the solid desiccant chemical 211 includes controlling temperature and / or pressure to solidify the liquid desiccant chemical remaining on the surface of the substrate into the solid desiccant chemical. By controlling temperature and / or pressure and solidifying the liquid desiccant chemical through a physical reaction, the process is environmentally friendly and avoids the introduction of intermediate products that contaminate the substrate.

[0055] In some embodiments, solidifying the liquid desiccant chemical 209 remaining on the surface of the substrate to obtain a solid desiccant chemical 211 includes: controlling the substrate to rotate at a fifth speed 212, controlling the temperature and / or pressure of the chamber so that the temperature in the chamber is below the freezing point of the liquid desiccant chemical at the chamber pressure, so that the liquid desiccant chemical remaining on the substrate solidifies to obtain the solid desiccant chemical. In actual operation, the fifth speed of the substrate is controlled to be 5 to 50 rpm (revolutions per minute), the temperature of the chamber is controlled to be -120 to -40 degrees Celsius, and the pressure of the chamber is controlled to be 0.1 to 100 mtorr (mitorr). Excessively high chamber pressure or temperature is not conducive to the solidification of the liquid desiccant chemical, while excessively low temperature and pressure impose higher process requirements and increase energy consumption. In other embodiments, the chamber or wafer stage can be pre-cooled, and then the liquid desiccant chemical can be rapidly cooled to -30 degrees Celsius when the substrate is placed on the wafer stage to freeze the desiccant chemical. Because desiccant chemicals are volatile, rapid cooling can prevent capillary forces from affecting the substrate during the desiccant chemical volatilization process. In practice, the desiccant chemical freezing time does not exceed 30 seconds, and the chamber pressure reduction time does not exceed 20 seconds. In other embodiments, rapid cooling can be provided by contacting the substrate with liquid nitrogen.

[0056] In some embodiments, the method further includes: the density of the liquid desiccant chemical is less than the density of the solid desiccant chemical, so that during the curing process, the structure of the substrate surface is not damaged due to the increase in volume of the desiccant chemical during phase change.

[0057] Finally, execute step 104, as shown in the attached Figure 3bAs shown in Figures h) and i), the solid dehumidifying chemical 211 is sublimated and removed. It should be noted that the sublimation refers to converting the solid dehumidifying chemical into a gas. It includes utilizing a chemical reaction to decompose the solid dehumidifying chemical into one or more gases. In actual operation, if the solid dehumidifying chemical is an ammonium salt, for example, the solid dehumidifying chemical can be decomposed by heating the ammonium salt crystals. In other embodiments, before sublimating and removing the solid dehumidifying chemical, it also includes: mechanically removing part of the solid dehumidifying chemical. In actual operation, part of the solid dehumidifying chemical can be removed by external force or vibration. Specifically, it can be directly grabbed by a robotic arm or directly blown by an air gun. In this way, cleaning efficiency can be improved and energy consumption can be reduced.

[0058] In some embodiments, sublimating and removing the solid desiccant chemical 211 includes controlling temperature and / or pressure to sublime the solid desiccant chemical into a gaseous desiccant chemical, and then discharging the gaseous desiccant chemical. By controlling temperature and / or pressure and utilizing a physical reaction to sublimate the solid desiccant chemical, the process is environmentally friendly and avoids the introduction of intermediate products that contaminate the substrate.

[0059] In some embodiments, as shown in the attached Figure 3b As shown in Figures h) and i), removing the solid desiccant chemical 211 includes: controlling the substrate to rotate at a sixth speed 213, and controlling the temperature and / or pressure of the chamber so that the temperature in the chamber is higher than the sublimation point of the solid desiccant chemical at the chamber pressure, so that the solid desiccant chemical sublimates to produce a gaseous desiccant chemical. In actual operation, the sixth speed of the substrate is controlled to be 100 to 1000 rpm (revolutions per minute), and the temperature of the chamber is 20 to 50 degrees Celsius. A chamber temperature that is too low is not conducive to the sublimation of the solid desiccant chemical, while a temperature that is too high will increase energy consumption.

[0060] Specifically, as attached Figure 3b As shown in Figures h) and i), the solid desiccant chemical can be directly heated into a gaseous desiccant chemical by the heating unit 214 located in the wafer stage at the bottom of the substrate and the heating lamp (not shown in the figure) above the substrate, without melting into a liquid desiccant chemical. Then, the temperature of the chamber is increased for secondary drying, while the pressure of the chamber is maintained at a low pressure, sublimating into a gaseous desiccant chemical, and directly removing the sublimated gaseous desiccant chemical. In other embodiments, the temperature of the secondary drying is higher than the temperature of the triple point of the desiccant chemical, and multiple dryings can ensure that the solid desiccant chemical is completely removed. For example, the gaseous desiccant chemical can be removed by a dry vacuum pump. In actual operation, the atmosphere of the chamber is an inert gas such as nitrogen, argon, and helium to prevent the substrate from being contaminated, and to make the heat distribution of the chamber uniform, thereby improving the heat transfer rate.

[0061] In some embodiments, as shown in the attached Figure 3b As shown in Figure j), after removing the gaseous desiccant chemical agent, the method further includes: exposing the substrate to an inert gas so that the substrate environment reaches atmospheric pressure, and the inert gas is purged along the center toward the edge of the substrate. In actual operation, the chamber pressure is restored to atmospheric pressure by discharging an inert gas into the chamber, and the inert gas is purged on the substrate surface from the center to the edge of the substrate to ensure that no dry chemicals remain. The inert gas can be nitrogen or argon, helium or other rare gases. When the inert gas causes the chamber to reach atmospheric pressure, the substrate can be cleaned again, and the desiccant chemical agent remaining on the surface of the substrate can be removed by direct purging. The center-to-edge purging method can also improve the cleaning efficiency. On the other hand, the inert gas is not easy to react with the substrate or other substances in the chamber environment, and will not cause secondary pollution.

[0062] In some embodiments, the first speed 208, the third speed 204, and the fourth speed 206 are greater than the sixth speed 213, and the sixth speed 213 is greater than the second speed 210 and the fifth speed 212. For example, the first speed, the third speed, and the fourth speed are 500 to 1200 rpm (revolutions per minute), the sixth speed is 100 to 1000 rpm (revolutions per minute), and the second speed and the fifth speed are 5 to 50 rpm (revolutions per minute). A relatively fast rotation speed can improve cleaning efficiency, while a relatively slow rotation speed can ensure that the structure of the substrate surface is not damaged during the cleaning process.

[0063] In some embodiments, after removing the solid desiccant chemical, the method further includes exposing the substrate to a plasma ashing process with a cleaning gas comprising H2N2 gas. H2N2 gas is used as a cleaning gas, and hydrogen can be decarbonized from the H2N2 into shorter chains, making it more volatile. Hydrogen reacts with carbon, hydrogen, and oxygen (C, H, and O) in the residual desiccant chemical to form volatile substances. The complete removal of the desiccant chemical after the ashing process increases substrate cleanliness and is beneficial to semiconductor device performance. The H2N2 gas contains 96% N2, similar to the role of N2 in promoting the ashing process. In actual operation, the parameters of the ashing process include an ashing chamber temperature of 220 to 280 degrees Celsius, an RF power of 2000 to 5000 W, an ashing chamber pressure of 50 to 1500 mtorr, and an ashing time of 5 to 300 seconds.

[0064] In some embodiments, the purity of the H2N2 gas is at least 98%. After ashing with pure H2N2, no additional oxide layer is formed on the substrate surface, and no intermediate products are formed, thereby improving substrate cleanliness. In actual operation, the flow rate of the H2N2 gas is 5000 to 15000 seem (standard milliliters per minute).

[0065] The present disclosure also provides a system for cleaning a substrate, as shown in the attached Figure 4 As shown, the system includes: a chamber 501 for receiving and processing a substrate 201; a wafer stage 503 for supporting and clamping the substrate 201 in the chamber; a nozzle 505 for at least providing a liquid desiccant chemical to the surface of the substrate; a vacuum pump 507 for controlling the gas pressure in the chamber; a temperature controller 509 for controlling the temperature of the substrate and / or the chamber; an atmosphere control system 511 for exhausting gas from the chamber or supplying gas into the chamber; a controller 513 in communication with the vacuum pump 507, the temperature controller 509 and the atmosphere control system 511, and configured to solidify the liquid desiccant chemical to obtain a solid desiccant chemical and remove the solid desiccant chemical. In actual operation, the vacuum pump can use a variety of different devices to reduce the gas pressure in the chamber, for example, a dry vacuum pump, a mechanical pump, a cryogenic pump and / or a turbomolecular pump. The atmosphere control system can be such as nitrogen, argon, helium and other inert gases, supplied to the chamber at a controlled flow rate to maintain the pressure in the chamber, or the substrate can be directly purged with an inert gas. In actual operation, the temperature controller can include a refrigerator system having one or more refrigerators or thermoelectric units, and the cooling and / or heating of the substrate can be completed by a refrigerator system having one or more refrigerators or thermoelectric units. In actual operation, the controller can be an electronic device having various integrated circuits, logic, memory and / or software for receiving instructions, issuing instructions, controlling operations, etc. The controller 513 can be connected to one or more sensors for monitoring operating parameters (such as temperature, pressure, etc.) in the chamber 501. A temperature controller 509 can be set as needed to control the temperature of the substrate and / or the chamber, an atmosphere control system can be set as needed to exhaust the gas in the chamber or to feed gas into the chamber, and a vacuum pump can be set as needed to control the air pressure in the chamber.

[0066] In some embodiments, the controller is configured to solidify the liquid desiccant chemical agent to obtain a solid desiccant chemical agent, including: controlling the temperature and / or pressure of the chamber so that the temperature in the chamber is lower than the freezing point of the liquid desiccant chemical agent under the pressure of the chamber, so that the liquid desiccant chemical agent solidifies to obtain a solid desiccant chemical agent.

[0067] In some embodiments, the controller is configured to remove the solid desiccant chemical, including: controlling the temperature and / or pressure of the chamber so that the temperature in the chamber is higher than the sublimation point of the solid desiccant chemical at the pressure of the chamber, so that the solid desiccant chemical sublimates to obtain a gaseous desiccant chemical, and removing the gaseous desiccant chemical.

[0068] In this way, by solidifying the liquid desiccant chemical and then removing it by sublimation, the solidified desiccant chemical can eliminate the gas / liquid interface, making the surface tension close to zero, eliminating the capillary force in the subsequent sublimation removal process, reducing the damage of the capillary force to the substrate structure, and achieving a non-destructive cleaning effect.

[0069] In some embodiments, as shown in the attached Figure 4 As shown, the system includes: the controller is further in communication with the wafer stage 503 and the nozzle 505, and the controller is further configured to: control the wafer stage to rotate at a first speed, control the nozzle to supply liquid desiccant to the surface of the substrate; and control the wafer stage to rotate at a second speed, wherein the second speed is less than the first speed. By rotating the wafer stage at high speed, the cleaning agent is replaced with the liquid desiccant, and then the substrate is rotated at a low speed, so that only a small puddle of liquid desiccant remains on the substrate surface, reducing the amount of sample required for subsequent freeze drying and improving cleaning efficiency.

[0070] In summary, the present disclosure utilizes a method for solidifying a liquid desiccant chemical and then removing it by sublimation. The solidified desiccant chemical eliminates the air / liquid interface, reducing surface tension to near zero. This eliminates capillary forces during the subsequent sublimation removal process, minimizing damage to the substrate structure and achieving non-destructive cleaning. Furthermore, by eliminating the effects of capillary forces, the amount of cleaning agent and impurities remaining on the substrate surface can be significantly reduced.

[0071] It should be noted that the various technical features in the technical solutions described in the embodiments can be arbitrarily combined without conflict. Those skilled in the art can change the order of the steps of the above-mentioned formation method without departing from the scope of protection of the present disclosure.

[0072] The above description is merely a preferred embodiment of the present disclosure and is not intended to limit the scope of protection of the present disclosure. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present disclosure shall be included in the scope of protection of the present disclosure.

Claims

1. A method for cleaning a substrate, characterized in that: include: Removing impurities on the surface of the substrate by exposing the substrate to a cleaning agent, comprising: controlling the substrate to rotate at a third speed to spray a first cleaning agent on the surface of the substrate; controlling the substrate to rotate at a fourth speed to spray a second cleaning agent on the surface of the substrate to remove the first cleaning agent on the surface of the substrate; Removing the cleaning agent on the surface of the substrate by exposing the substrate to a liquid desiccant chemical, comprising: controlling the substrate to rotate at a first speed, spraying the liquid desiccant chemical on the surface of the substrate to dissolve the cleaning agent remaining on the surface of the substrate in the liquid desiccant chemical; controlling the substrate to rotate at a second speed to remove a portion of the liquid desiccant chemical on the surface of the substrate, wherein the second speed is less than the first speed; Solidifying the liquid desiccant chemical remaining on the surface of the substrate to obtain a solid desiccant chemical, comprising: controlling the substrate to rotate at a fifth speed, controlling the temperature and / or pressure of the chamber so that the temperature in the chamber is lower than the freezing point of the liquid desiccant chemical at the chamber pressure, so that the liquid desiccant chemical remaining on the substrate solidifies to obtain a solid desiccant chemical; removing the solid desiccant chemical, comprising: controlling the substrate to rotate at a sixth speed, controlling the temperature and / or pressure of the chamber so that the temperature in the chamber is higher than the sublimation point of the solid desiccant chemical at the chamber pressure, so that the solid desiccant chemical sublimates to obtain a gaseous desiccant chemical; wherein the first speed, the third speed, and the fourth speed are greater than the sixth speed, and the sixth speed is greater than the second speed and the fifth speed; The solid dehumidifying chemical is sublimed and removed.

2. The cleaning method according to claim 1, wherein Subliming and removing the solid dehumidifying chemical, comprising: The temperature and / or pressure of the chamber is controlled to allow the solid desiccant chemical to sublime into a gaseous desiccant chemical, and the gaseous desiccant chemical is discharged.

3. The cleaning method according to claim 2, wherein: After the gaseous dehumidification chemical is extracted, the method further comprises: The substrate is exposed to an inert gas to bring the substrate environment to atmospheric pressure, and the inert gas is swept from the center of the substrate toward the edge.

4. The cleaning method according to claim 1, wherein: The surface of the substrate includes a void structure having an aspect ratio greater than or equal to 8.

5. The cleaning method according to claim 1, wherein: After removing the solid dehumidification chemical, the method further comprises: The substrate is exposed to a cleaning gas for plasma ashing, wherein the cleaning gas includes H2N2 gas.

6. The cleaning method according to claim 5, characterized in that include: The purity of the H2N2 gas is at least 98%.

7. The cleaning method according to claim 1, wherein: include: The density of the liquid dehumidifying chemical agent is smaller than the density of the solid dehumidifying chemical agent.

8. The cleaning method according to claim 1, wherein: include: The saturated vapor pressure of the liquid dehumidifying chemical agent at room temperature is greater than 4.0 KPa; the miscibility of the liquid dehumidifying chemical agent and the cleaning agent is greater than 70%; and the evaporation rate of the liquid dehumidifying chemical agent is greater than 1.

9. The cleaning method according to claim 1, wherein: The liquid dehumidifying chemical comprises acetone or isopropyl alcohol.

10. The cleaning method according to claim 1, wherein: Solidifying the liquid desiccant chemical remaining on the surface of the substrate to obtain a solid desiccant chemical, comprising: controlling a fifth speed of the substrate to be 5 to 50 rpm, controlling a temperature of the chamber to be -120 to -40 degrees Celsius, and controlling a pressure of the chamber to be 0.1 to 100 mTorr; Removing the solid dehumidifying chemical includes: controlling the fifth speed of the substrate to be 100 to 1000 rpm; and controlling the temperature of the chamber to be 20 to 50 degrees Celsius.

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