Method for manufacturing semiconductor substrate

Abstract

In one embodiment, provided is a method for manufacturing a semiconductor substrate, the method including a paddle cleaning step that is highly effective in removing an adhesive for wafer processing. In one embodiment, the present disclosure relates to a method for manufacturing a semiconductor substrate including the following Step 1. Step 1: paddle-cleaning a wafer having a surface to which an adhesive for wafer processing adheres, using a chemical solution satisfying the following requirement. Requirement: When 600 seconds have elapsed after 1 μL of the chemical solution is dropped onto a surface of a wafer obtained by uniformly forming, over the entire surface thereof, a 30-μm-thick film of the same adhesive for wafer processing as the adhesive for wafer processing adhering to the wafer cleaned in Step 1, and then heat-treating the wafer at 80°C for 5 minutes and at 250°C for 5 minutes, the diameter of a region into which the chemical solution has permeated and diffused is 5 mm or more.

Description

Semiconductor substrate manufacturing method

[0001] This disclosure relates to a method for manufacturing a semiconductor substrate and a wafer cleaning method using paddle cleaning.

[0002] In recent years, semiconductor devices have become highly integrated, and 3D integrated circuit (3DIC) technology has attracted attention. 3DIC technology is a technique for stacking wafers in multiple layers while connecting them with through-silicon vias (TSVs), etc. When stacking wafers in multiple layers, it is necessary to thin the back surface (the side without circuits) of the wafer where the circuits are formed by polishing, and then to process the back surface by forming electrodes. Before thinning, the wafer is bonded (temporarily bonded, temporarily fixed) to a fixing member (support) with adhesive, and after processing such as polishing and electrode formation, the wafer is separated from the fixing member. Often, adhesive remains on the wafer after it has been separated from the fixing member, which can cause problems in subsequent processes. Therefore, a cleaning process is performed to remove the adhesive remaining on the wafer.

[0003] Various compositions have been developed to remove such adhesive residues. For example, Japanese Patent Publication No. 2003-45842 (Patent Document 1) proposes a method for removing photoresist from a substrate surface, characterized by sequentially performing the following steps: supplying acetic acid to the substrate surface to form a liquid acetic acid film with a thickness of 10 μm to 300 μm on the substrate surface; introducing a gas containing ozone into a layered space formed between the substrate surface and a plate-like member provided adjacent to the substrate surface; dissolving ozone at a high concentration in the liquid acetic acid film to decompose the photoresist with ozone; and supplying acetic acid again to the substrate surface to dissolve and remove the decomposed photoresist.

[0004] In one aspect, the present disclosure relates to a method for manufacturing a semiconductor substrate, comprising the following step 1. Step 1: A step of performing paddle cleaning on a wafer having an adhesive for wafer processing adhered to a surface thereof with a chemical solution that satisfies the following requirement: Requirement: After 600 seconds have elapsed since 1 μL of the chemical solution was dropped onto the surface of a wafer obtained by uniformly forming a film of the same wafer processing adhesive as the wafer processing adhesive adhered to the wafer to be cleaned in step 1 over the entire surface with a thickness of 30 μm, and then performing a heat treatment at 80° C. for 5 minutes and a heat treatment at 250° C. for 5 minutes, the diameter of the region where the chemical solution has permeated and diffused is 5 mm or more.

[0005] In one aspect, the present disclosure is a cleaning method for removing an adhesive for wafer processing from a wafer having the adhesive for wafer processing adhered to the surface thereof, and relates to a wafer cleaning method comprising a step of performing paddle cleaning on a wafer having the adhesive for wafer processing adhered to the surface thereof with a chemical solution that satisfies the following requirement: Requirement: After 600 seconds have elapsed since 1 μL of the chemical solution was dropped onto the surface of a wafer obtained by uniformly forming a film of the adhesive for wafer processing over the entire surface of the wafer with a thickness of 30 μm, and then performing a heat treatment at 80° C. for 5 minutes and a heat treatment at 250° C. for 5 minutes, the diameter of the region where the chemical solution has permeated and diffused is 5 mm or more.

[0006] FIG. 1 is a flowchart showing each step in an embodiment of the method for manufacturing a semiconductor substrate of the present disclosure. FIG. 2 is a schematic diagram for explaining each step in an embodiment of the method for manufacturing a semiconductor substrate of the present disclosure.

[0007] In the manufacturing process of three-dimensional integrated circuits (3DICs), processing such as electrode formation after polishing wafers that have been temporarily bonded (temporarily fixed) to a fixed member (support) with adhesive is sometimes carried out at high temperatures of 150°C or higher. When the adhesive is heated, it tends to deteriorate (harden), making it difficult to remove. The chemicals used to clean the adhesive need to have excellent removal properties (cleaning properties) for temporary fixing adhesives (wafer processing adhesives) used during such wafer processing. Adhesive removal is carried out by penetrating and diffusing a chemical solution (e.g., a cleaning agent) into the wafer processing adhesive, but conventional chemical solutions have insufficient penetration and diffusion properties, and adhesive residue tends to be left on the wafer (especially at the wafer edges). Furthermore, as shown in Patent Document 1, in the cleaning process of semiconductor wafers, the amount of chemical solution used for cleaning can be reduced by using a cleaning method that forms a liquid film called a paddle on the semiconductor wafer. However, when the material to be cleaned is one that does not easily allow chemical solutions to penetrate and diffuse, such as wafer processing adhesive, it has been difficult to completely clean and remove the wafer processing adhesive present at the edges of the semiconductor wafer.

[0008] Therefore, this disclosure provides a method for manufacturing a semiconductor substrate and a cleaning method that include a paddle cleaning step which is excellent in removing adhesives used for wafer processing.

[0009] According to this disclosure, a method for manufacturing a semiconductor substrate and a method for cleaning it can be provided, which include a paddle cleaning step that is excellent in removing adhesives used for wafer processing.

[0010] This disclosure is based on the finding that wafer processing adhesive can be efficiently removed by paddle cleaning wafers to which the adhesive has adhered using a specific chemical solution.

[0011] This disclosure relates in one embodiment to a method for manufacturing a semiconductor substrate (hereinafter also referred to as "the semiconductor substrate manufacturing method of this disclosure"), which includes the following step 1. Step 1: A step in which a wafer with wafer processing adhesive attached to its surface (hereinafter also referred to as "the object to be cleaned") is paddle-cleaned with a chemical solution that satisfies the following requirements: The same wafer processing adhesive attached to the wafer to be cleaned in step 1 is uniformly deposited on the entire surface with a thickness of 30 μm, and the diameter of the area in which the chemical solution has penetrated and diffused after 600 seconds have elapsed since dropping 1 μL of the chemical solution onto the wafer surface obtained by heat treatment at 80°C for 5 minutes and heat treatment at 250°C for 5 minutes is 5 mm or more. In this disclosure, "diameter of the area in which the chemical solution has penetrated and diffused" means the diameter of the area (circular) if the area in which the chemical solution has penetrated and diffused is circular, and the diameter of the smallest inclusion circle, which is the smallest circle that completely encloses the area if the area in which the chemical solution has penetrated and diffused is not circular.

[0012] According to this disclosure, in one or more embodiments, a method for manufacturing a semiconductor substrate is provided that includes a paddle cleaning step that is excellent in removing wafer processing adhesives. As a result, high-quality semiconductor substrates can be obtained with a high yield.

[0013] While the detailed mechanism of action for the effects of this disclosure is unclear, it is presumed to be as follows: In paddle cleaning, if the penetration and diffusion of the chemical solution into the wafer processing adhesive is low, the cleaning performance may decrease, and this is a particularly significant problem at the wafer edges where the chemical solution is difficult to spread. However, by using a chemical solution with high penetration and diffusion properties as described in this disclosure, high cleaning performance can be achieved, and it is believed that even the wafer edges can be effectively cleaned. However, this disclosure does not have to be interpreted as being limited to this mechanism.

[0014] <Object to be cleaned> The object to be cleaned is a wafer to which wafer processing adhesive is attached. In one or more embodiments, the wafer is a semiconductor substrate. Examples of semiconductor substrates include silicon wafers, germanium wafers, gallium-arsenide wafers, gallium-phosphorus wafers, and gallium-arsenide-aluminum wafers. In one or more embodiments, the wafer is a substrate having pads and / or lands which are areas for bonding and mounting. Examples of materials for the pads and lands include metals such as gold, copper, and aluminum. Examples of wafer processing adhesives (hereinafter also simply referred to as "adhesive") include those that can bond the wafer to a fixing member, have durability that can withstand polishing and processing steps, and allow the wafer to be easily separated from the fixing member in the separation step. Examples of adhesives include at least one selected from acrylic adhesives, urethane adhesives, silicone adhesives, novolac adhesives, and polyimide adhesives. In one or more embodiments, the wafer processing adhesive attached to the wafer refers to the cured adhesive, and includes the adhesive after the separation process described later, and the adhesive cured by heat treatment. Examples of wafers to which adhesive is attached include, in one or more embodiments, wafers that have been separated from a fixing member after being bonded (temporarily fixed) to the fixing member with adhesive. In one or more embodiments, wafers that have been bonded (temporarily fixed) to the fixing member with adhesive have undergone heat treatment. The temperature of the heat treatment can be, for example, 200°C or higher. In one or more embodiments, the heat treatment can be the heat treatment in the processing process described later. In one or more embodiments, wafers separated from the fixing member are substrates having metal pads to which adhesive is attached. Examples of wafers to which adhesive is attached include substrates to which adhesive used in the manufacturing process of three-dimensional integrated circuits (3DICs) is attached. In one or more embodiments, wafers to which adhesive is attached have undergone heat treatment at a temperature of 200°C or higher. In one or more embodiments, the heat treatment can be the heat treatment in the processing process described later.

[0015] In one or more embodiments, the semiconductor substrate manufacturing method of this disclosure may further include a step of preparing a wafer (work to be cleaned) with a wafer processing adhesive attached to its surface before step 1 (hereinafter also referred to as the "preparation step"). In one or more embodiments, the preparation step includes the following steps: bonding step (1), polishing step (2), processing step (3), and separation step (4). Each step will be described with reference to Figures 1 and 2. Figure 1 is a flowchart showing each step in one embodiment of the semiconductor substrate manufacturing method of this disclosure. Figure 2 is a schematic diagram illustrating each step in one embodiment of the semiconductor substrate manufacturing method of this disclosure.

[0016] <Step (1): Bonding Step> Step (1) is a step (bonding step) in which the wafer 3 is bonded to the fixing member 1 with adhesive 2 (step S1). Step (1) includes, in one or more embodiments, a step (1-1) in which adhesive is applied to the surface of the wafer or the fixing member to form an adhesive layer, and a step (1-2) in which the wafer and the fixing member are bonded together via the adhesive layer and then heat-treated to join them.

[0017] Examples of wafers used in step (1) include silicon wafers and glass wafers with a diameter of 100 to 500 mm and a thickness of 50 to 2,000 μm. In one or more embodiments, the wafer used in step (1) is a substrate having metal pads.

[0018] The fixing member used in step (1) is not particularly limited, but examples include a silicon wafer or glass plate with a diameter of 100 to 500 mm and a thickness of 50 to 20,000 μm.

[0019] The adhesive used in step (1) is not particularly limited as long as it can bond the wafer to the fixing member, has sufficient durability to withstand the polishing and processing steps, and allows the wafer to be easily separated from the fixing member in the separation step. For example, a wafer processing adhesive used in the manufacturing process of 3DICs can be used. Examples of wafer processing adhesives include at least one adhesive (adhesive composition) selected from acrylic adhesives, urethane adhesives, silicone adhesives, polyimide adhesives, and novolac adhesives. Specifically, an adhesive composition described in Japanese Patent Application Publication No. 2021-161196 can be used. In one or more embodiments, the adhesive composition used in step (1) includes at least one adhesive component selected from acrylic adhesives, urethane adhesives, silicone adhesives, polyimide adhesives, and novolac adhesives, and may further include a platinum group metal catalyst, a release agent component, a solvent, etc. The viscosity of the adhesive composition used in step (1) can be adjusted by appropriately changing the concentration of the contained components, etc., depending on the application method, film thickness, etc.

[0020] In step (1-1), the method of applying the adhesive (adhesive composition) is not particularly limited, but examples include the spin coating method. The film thickness of the adhesive (adhesive composition) coating layer (adhesive layer) is, for example, 5 to 500 μm. In one or more embodiments, step (1-1) includes bonding the surface of the wafer having a metal pad to the fixing member with the adhesive.

[0021] In step (1-2), the heat treatment temperature is, for example, 80°C or higher, and is preferably 300°C or lower from the viewpoint of suppressing excessive hardening of the adhesive. The heat treatment time is, for example, 30 seconds or more, and is preferably 10 minutes or less from the viewpoint of suppressing deterioration of the adhesive layer and other components. Heating can be carried out using, for example, a hot plate or an oven. The thickness of the adhesive layer after heat treatment is, for example, 5 μm to 100 μm.

[0022] <Step (2): Polishing Step> Step (2) is a step (polishing step) in which the surface (back surface) 3a of the wafer 3 opposite to the surface that adheres to the fixing member 1 is polished (step S2). Examples of polishing methods include mechanical polishing with abrasive grains and chemical mechanical polishing. In step (2), the thickness of the wafer after polishing (thinned wafer) is preferably 200 μm or less, for example, 50 μm to 200 μm.

[0023] <Step (3): Processing Step> Step (3) is a process (processing step) for processing the polished surface (back surface of the thinned wafer) 3a of the wafer 3 (step S3). In one or more embodiments, step (3) may include an electrode formation step, a metal wiring formation step, a protective film formation step, etc. Examples of conventionally known processing steps include metal sputtering for electrode formation, wet etching, resist coating, pattern formation, resist stripping, dry etching, metal plating formation, silicon etching for silicon through-silicon (TSV) formation, and oxide film formation on the silicon surface. In step (3), the processing is carried out at a high temperature of 150°C or higher in one or more embodiments. When forming electrodes such as TSVs, for example, a heat treatment at 250°C to 350°C may be performed.

[0024] <Step (4): Separation Step> Step (4) is a step (separation step) in which the processed wafer 3 and the fixed member 1 are separated (step S4). Examples of separation methods include solvent peeling, laser peeling, and mechanical peeling.

[0025] [Step 1: Paddle Cleaning Step] Step 1 in the semiconductor substrate manufacturing method of the present disclosure is a step (paddle cleaning step) in which a wafer on which wafer processing adhesive is attached to the surface is paddle cleaned with a chemical solution that satisfies the following requirements (hereinafter also referred to as "the chemical solution of the present disclosure"). Requirements: When 600 seconds have elapsed since dropping 1 μL of the chemical solution onto the wafer surface on which the wafer processing adhesive is attached, the diameter of the area in which the chemical solution has penetrated and diffused is 5 mm or more. The above requirements can be as follows, as described in the examples. Requirements: The same wafer processing adhesive attached to the wafer to be cleaned in Step 1 is uniformly deposited on the entire surface with a thickness of 30 μm, and the wafer is obtained by heat treatment at 80°C for 5 minutes and at 250°C for 5 minutes. When 600 seconds have elapsed since dropping 1 μL of the chemical solution onto the surface of the wafer, the diameter of the area in which the chemical solution has penetrated and diffused is 5 mm or more.

[0026] In this disclosure, "paddle" refers to a liquid film of a chemical solution with a thickness of 1 μm to 5000 μm that is held on the wafer surface of the object to be cleaned. In one or more embodiments, the paddle can be formed by supplying the chemical solution while the wafer is rotating at a low speed or stopped, utilizing the surface tension of the chemical solution. In this disclosure, "paddle cleaning" is a cleaning method in one or more embodiments that involves forming or holding paddles of chemical solution on the wafer surface of the object to be cleaned while the wafer is rotating at a low speed or stopped. In one or more embodiments, the wafer surface of the object to be cleaned includes the surface on which the wafer processing adhesive is attached to the object to be cleaned, and the wafer processing adhesive attached to the wafer that is the object to be cleaned. The rotation speed of the wafer in paddle cleaning is preferably 0 rpm or more, and preferably 30 rpm or less. Before and / or after paddle cleaning, the wafer that is the object to be cleaned may be rotated while the chemical solution of this disclosure is supplied to the wafer surface for cleaning (spin cleaning). Step 1 includes, in one or more embodiments, spin cleaning the wafer before paddle cleaning. The rotation speed of the wafer in spin cleaning is preferably 50 rpm or more, more preferably 100 rpm or more, preferably 1000 rpm or less, and more preferably 800 rpm or less. The cleaning time for spin cleaning is preferably 10 seconds or more, more preferably 20 seconds or more, more preferably 30 seconds or more, even more preferably 1 minute or more, preferably 10 minutes or less, more preferably 8 minutes or less, and even more preferably 6 minutes or less. The temperature of the chemical solution used for spin cleaning can be, for example, 15°C to 80°C. Therefore, in one or more embodiments, step 1 includes forming or holding paddles of the chemical solution on the surface of a wafer to which wafer processing adhesive has been applied, while the wafer is rotating at a low speed or stopped rotating. Step 1, in one or more embodiments, includes, while rotating a wafer on which a wafer processing adhesive is attached to its surface, supplying the chemical solution of the present disclosure to the wafer surface to which the wafer processing adhesive is attached for cleaning (spin cleaning), and forming or holding paddles of the chemical solution of the present disclosure on the wafer surface while the wafer is rotating at a low speed or stopped after spin cleaning.In one or more embodiments, the thickness of the paddle is preferably 1 μm or more, more preferably 5 μm or more, even more preferably 10 μm or more, and even more preferably 100 μm or more, and preferably 20,000 μm or less, more preferably 10,000 μm or less, even more preferably 5,000 μm or less, and even more preferably 500 μm or less, from the viewpoint of cleaning performance and reduction of chemical consumption.

[0027] Step 1 is a step (Step S5) in which, in one or more embodiments, adhesive residue 2a remaining on the separated wafer 3 is removed by paddle cleaning with the chemical solution of the present disclosure, as shown in Figures 1 and 2. Here, the separated wafer is, in one or more embodiments, a wafer to which adhesive has been attached (the object to be cleaned as described above), for example, a substrate to which adhesive has been attached to a metal pad. Therefore, the chemical solution of the present disclosure can be used in one or more embodiments to remove adhesive remaining on a wafer after separating a wafer bonded to a fixing member with adhesive from the fixing member by paddle cleaning. The chemical solution of the present disclosure is, in one or more embodiments, a cleaning agent composition or adhesive remover for removing adhesive remaining on a wafer after separating a wafer bonded to a fixing member with adhesive from the fixing member by paddle cleaning.

[0028] The temperature of the chemical solution used in step 1 (washing temperature) is preferably 50°C or higher, more preferably 60°C or higher, and even more preferably 70°C or higher, from the viewpoint of improving the removal of the wafer processing adhesive. From the viewpoint of suppressing the volatilization and deterioration of the chemical solution components, it is preferably 100°C or lower, more preferably 90°C or lower, and even more preferably 80°C or lower. The washing time in step 1 is preferably 2 minutes or more, more preferably 3 minutes or more, and even more preferably 4 minutes or more, from the viewpoint of improving the removal of the wafer processing adhesive. From the viewpoint of productivity, it is preferably 60 minutes or less, more preferably 40 minutes or less, and even more preferably 20 minutes or less.

[0029] <Chemical Solution Used in Step 1> The chemical solution used in Step 1 is a chemical solution that satisfies the following requirements. Requirements: When 600 seconds have elapsed since dropping 1 μL of the chemical solution onto the wafer surface to which the wafer processing adhesive is attached, the diameter of the area to which the chemical solution has permeated and diffused is 5 mm or more. From the viewpoint of improving the removeability of the wafer processing adhesive, the diameter of the permeated and diffused area is 5 mm or more, preferably 7 mm or more, and more preferably 10 mm or more. The diameter is determined by the following method in one or more embodiments. If the area to which the chemical solution has permeated and diffused is circular, the diameter is the diameter of the circle. If the area to which the chemical solution has permeated and diffused is not circular, the diameter is the diameter of the smallest inclusion circle, which is the smallest circle that completely encloses the area.

[0030] (Flash point of the chemical solution) In one or more embodiments of the present disclosure, the flash point of the chemical solution is preferably 90°C or higher, more preferably 100°C or higher, and even more preferably 110°C or higher, from the viewpoint of safety. In one or more embodiments of step 1, from the viewpoint of safety, it is preferable to wash the paddle at a temperature of 10°C or lower than the flash point of the chemical solution.

[0031] (Aprotic polar solvent in the chemical solution) In one or more embodiments of the present disclosure, the chemical solution contains an aprotic polar solvent from the viewpoint of improving the removeability of the wafer processing adhesive, and in one or more embodiments, consists of an aprotic polar solvent. The aprotic polar solvent may be one type or a combination of two or more types. From a similar viewpoint, the aprotic polar solvent is preferably a nitrogen-containing aprotic polar solvent, for example, an imidazolidinone-based solvent or a pyrrolidone-based solvent. For example, an imidazolidinone-based solvent is 1,3-dimethyl-2-imidazolidinone (DMI). For example, a pyrrolidone-based solvent is N-methyl-2-pyrrolidone (NMP). The aprotic polar solvent preferably contains one or more selected from imidazolidinone-based solvents and pyrrolidone-based solvents, more preferably contains both imidazolidinone-based and pyrrolidone-based solvents, even more preferably a combination of imidazolidinone-based and pyrrolidone-based solvents, and even more preferably a combination of 1,3-dimethyl-2-imidazolidinone (DMI) and N-methyl-2-pyrrolidone (NMP).

[0032] From the viewpoint of cleaning properties, the content of the aprotic polar solvent in the chemical solution of this disclosure is preferably 30% by mass or more, more preferably 50% by mass or more, even more preferably 70% by mass or more, even more preferably more than 70% by mass, and even more preferably 80% by mass or more. From the viewpoint of cleaning properties and safety, it is preferably 100% by mass or less, more preferably 99.5% by mass or less, and even more preferably 99% by mass or less. More specifically, the content of the aprotic polar solvent in the chemical solution of this disclosure is preferably 30% by mass or more and 100% by mass or less, more preferably 50% by mass or more and 99.5% by mass or less, even more preferably 70% by mass or more and 99% by mass or less, even more preferably more than 70% by mass and 99% by mass or less, and even more preferably 80% by mass or more and 99% by mass or less. When there is a combination of two or more aprotic polar solvents, the content of the aprotic polar solvent refers to their total content. The preferred content of the nitrogen-containing aprotic polar solvent in the drug solution of this disclosure may, in one or more embodiments, be the same as the preferred content of the aprotic polar solvent in the drug solution of this disclosure described above. When the aprotic polar solvent includes an imidazolidinone-based solvent and a pyrrolidone-based solvent, the content of the imidazolidinone-based solvent in the drug solution of this disclosure is preferably 30% by mass or more, more preferably 50% by mass or more, even more preferably 70% by mass or more, and from the viewpoint of cleanliness and safety, preferably 95% by mass or less, more preferably 90% by mass or less, and even more preferably 85% by mass or less. More specifically, the content of the imidazolidinone-based solvent in the drug solution of this disclosure is preferably 30% by mass or more and 95% by mass or less, more preferably 50% by mass or more and 90% by mass or less, and even more preferably 70% by mass or more and 85% by mass or less. When the imidazolidinone solvent is a combination of two or more types, the imidazolidinone solvent content refers to the total content of those solvents. When the aprotic polar solvent includes an imidazolidinone solvent and a pyrrolidone solvent, the pyrrolidone solvent content in the chemical solution of this disclosure is preferably 5% by mass or more, more preferably 10% by mass or more, and even more preferably 15% by mass or more, from the viewpoint of cleaning properties, and preferably 70% by mass or less, more preferably 50% by mass or less, and even more preferably 30% by mass or less, from the viewpoint of safety.More specifically, the content of the pyrrolidone-based solvent in the drug solution of this disclosure is preferably 5% by mass or more and 70% by mass or less, more preferably 10% by mass or more and 50% by mass or less, and even more preferably 15% by mass or more and 30% by mass or less. When the pyrrolidone-based solvent is a combination of two or more types, the content of the pyrrolidone-based solvent refers to their total content. When the aprotic polar solvent includes an imidazolidinone-based solvent and a pyrrolidone-based solvent, the total content of the imidazolidinone-based solvent and the pyrrolidone-based solvent in the drug solution of this disclosure is preferably 50% by mass or more, more preferably 60% by mass or more, and even more preferably 70% by mass or more, from the viewpoint of cleaning properties, and preferably 100% by mass or less, more preferably 95% by mass or less, and even more preferably 90% by mass or less, from the viewpoint of cleaning properties and safety. More specifically, the total content of imidazolidinone-based solvent and pyrrolidone-based solvent in the chemical solution of this disclosure is preferably 50% by mass or more and 100% by mass or less, more preferably 60% by mass or more and 95% by mass or less, and even more preferably 70% by mass or more and 90% by mass or less. When the aprotic polar solvent contains both imidazolidinone-based solvent and pyrrolidone-based solvent, the mass ratio of imidazolidinone-based solvent to pyrrolidone-based solvent (imidazolidinone-based solvent / pyrrolidone-based solvent) is preferably 1 or more, more preferably 2 or more, even more preferably 3 or more, and from the viewpoint of cleanliness and safety, preferably 20 or less, more preferably 15 or less, and even more preferably 10 or less. More specifically, the mass ratio (imidazolidinone-based solvent / pyrrolidone-based solvent) in the chemical solution of this disclosure is preferably 1 or more and 20 or less, more preferably 2 or more and 15 or less, and even more preferably 3 or more and 10 or less.

[0033] In this disclosure, "content of each component in the chemical solution" may mean the content of each component at the time of cleaning, that is, at the time when the chemical solution is first used for cleaning. In one or more embodiments, the content of each component in the chemical solution of this disclosure may be considered as the amount of each component blended in the chemical solution of this disclosure.

[0034] (Water in the chemical solution) In one or more embodiments of the chemical solution of this disclosure, the chemical solution may contain no water or have a water content of 5% by mass or less. Examples of water in one or more embodiments include ion-exchanged water, RO water, distilled water, pure water, ultrapure water, etc. If the chemical solution of this disclosure contains water, the water content in the chemical solution of this disclosure may be the remainder after excluding the aprotic polar solvent and optional components described later. Specifically, from the viewpoint of cleaning properties and stability, the water content in the chemical solution of this disclosure is preferably 5% by mass or less, more preferably 3% by mass or less, even more preferably 1% by mass or less, and even more preferably 0% by mass (i.e., none).

[0035] (Other components in the chemical solution) In one or more embodiments of the chemical solution of this disclosure, other components may be further included as needed, in addition to the aprotic polar solvent. Examples of other components include components that can be used in ordinary cleaning agents, such as solvents other than aprotic polar solvents, alkaline agents, surfactants, chelating agents, thickeners, dispersants, rust inhibitors, metal corrosion inhibitors, polymer compounds, solubilizers, antioxidants, preservatives, defoamers, antibacterial agents, etc.

[0036] In one or more embodiments, the chemical solutions of the present disclosure may be substantially free of nitrile compounds. For example, the content of nitrile compounds in the chemical solutions of the present disclosure is preferably less than 50% by mass, more preferably 10% by mass or less, even more preferably 1% by mass or less, and even more preferably 0% by mass (i.e., none). In one or more embodiments, the chemical solutions of the present disclosure may be substantially free of organic amines. For example, the content of organic amines in the chemical solutions of the present disclosure is preferably less than 0.1% by mass, more preferably 0.01% by mass or less, and even more preferably 0% by mass (i.e., none).

[0037] (Method for Manufacturing the Drug Solution) The drug solution of this disclosure can be manufactured in one or more embodiments by compounding the aprotic polar solvent and optionally the above-mentioned optional components (water, other components) in a known manner. For example, the drug solution of this disclosure may consist of at least the aprotic polar solvent. Accordingly, in one embodiment, this disclosure relates to a method for manufacturing the drug solution, which includes the step of compounding at least the aprotic polar solvent. In this disclosure, "compounding" includes mixing the aprotic polar solvent and optionally the above-mentioned optional components (water, other components) simultaneously or in any order. In the method for manufacturing the drug solution of this disclosure, the preferred amount of each component may be the same as the preferred content of each component of the drug solution of this disclosure described above.

[0038] Step 1 is, in one or more other embodiments, a step of removing the adhesive remaining on the separated wafer by paddle washing with the chemical solution of the present disclosure. That is, in one or more embodiments, the method for manufacturing a semiconductor substrate is a method for manufacturing a semiconductor substrate that includes (1) a step of bonding a wafer to a fixing member with an adhesive, (2) a step of polishing the side of the wafer opposite to the side bonded to the fixing member, (3) a step of processing the polished side of the wafer, (4) a step of separating the processed wafer from the fixing member, and (5) a step of removing the adhesive remaining on the separated wafer by paddle washing with the chemical solution of the present disclosure.

[0039] [Step 2: Removal of chemical solution] In one or more embodiments, the semiconductor substrate manufacturing method of the present disclosure may further include the following Step 2. Step 2: Step of removing the chemical solution used in Step 1 from the wafer.

[0040] Step 2 is, in one or more embodiments, a step of removing the chemical solution paddle formed in Step 1 from the wafer. In one or more embodiments, a method for removing the chemical solution from the wafer in Step 2 is to wash the wafer after Step 1 with water or rinse it with a rinsing agent to remove the chemical solution paddle from the wafer. The wafer after rinsing may be dried. Therefore, in one or more embodiments, Step 2 includes washing the wafer after Step 1 with water or rinsing it with a rinsing agent and drying it. Examples of rinsing agents include at least one rinsing agent selected from methanol, ethanol, isopropyl alcohol, and propylene glycol monomethyl ether. Examples of rinsing times include 10 seconds to 5 minutes. Examples of drying methods include spin drying. Examples of drying times include 10 seconds to 5 minutes. Examples of drying temperatures include 15°C to 50°C.

[0041] [Wafer Cleaning Method] This disclosure relates to a wafer cleaning method (hereinafter also referred to as "the cleaning method of this disclosure") that, in one embodiment, removes a wafer processing adhesive from a wafer (object to be cleaned) on which the wafer processing adhesive is attached to the surface, and includes a step of paddle cleaning the wafer on which the wafer processing adhesive is attached to the surface with a chemical solution that satisfies the following requirements (paddle cleaning step). Requirements: When 600 seconds have elapsed since dropping 1 μL of the chemical solution onto the wafer surface on which the wafer processing adhesive is attached, the diameter of the area in which the chemical solution has penetrated and diffused is 5 mm or more. The diameter is a value determined by the following method in one or more embodiments. If the area in which the chemical solution has penetrated and diffused is circular, the diameter is the diameter of the circle; if the area in which the chemical solution has penetrated and diffused is not circular, the diameter is the diameter of the smallest inclusion circle, which is the smallest circle that completely encloses the area. The above requirements can be as follows, as described in the examples. Requirements: The wafer processing adhesive is uniformly deposited on the entire surface of the wafer with a thickness of 30 μm, and after heat treatment at 80°C for 5 minutes and 250°C for 5 minutes, 1 μL of the chemical solution is dropped onto the wafer surface, and after 600 seconds, the diameter of the area where the chemical solution has penetrated and diffused is 5 mm or more. In one or more embodiments of the cleaning method of this disclosure, the paddle cleaning step is a step of removing the wafer processing adhesive remaining on the wafer by paddle cleaning using the chemical solution of this disclosure after separating the wafer bonded to the fixing member with the wafer processing adhesive from the fixing member. According to the cleaning method of this disclosure, the wafer processing adhesive can be removed efficiently.

[0042] In one or more embodiments, the cleaning method of the paddle cleaning step in the cleaning method of the present disclosure may be the same as the cleaning method of step 1 in the above-described method for manufacturing a semiconductor substrate of the present disclosure. In one or more embodiments of the cleaning method of the present disclosure, a wafer bonded to a fixing member with an adhesive has preferably undergone a heat treatment at a temperature of 230°C or higher, more preferably 270°C or higher. Examples of the heat treatment at a temperature of 230°C or higher include a heat treatment for bonding a device such as a semiconductor chip and a substrate on which another circuit is formed to a substrate on which a circuit is formed using solder or metal fine particles. In one or more embodiments, the heat treatment step is performed after the processing step of step (3) and before step (4). In one or more embodiments, examples of the object to be cleaned in the cleaning method of the present disclosure include a wafer that has undergone steps (1) to (4) in the method for manufacturing a semiconductor substrate of the present disclosure.

[0043] In one or more embodiments, the cleaning method of the present disclosure may further include a step of rinsing the wafer after the paddle cleaning step with at least one rinsing agent selected from methanol, ethanol, isopropyl alcohol, and propylene glycol monomethyl ether, followed by drying.

[0044] In one or more embodiments, the paddle cleaning step in the cleaning method of the present disclosure is a step (removal step) of removing the adhesive remaining on the wafer with an adhesive remover after separating the wafer bonded to the fixing member with the adhesive from the fixing member. Examples of the adhesive remover in the removal step include the chemical solution of the present disclosure described above. Examples of the removal method in the removal step include the paddle cleaning described above. That is, in one or more embodiments, the cleaning method of the present disclosure is an adhesive removal method including the step of removing the adhesive remaining on the wafer by paddle cleaning using the adhesive remover of the present disclosure after separating the wafer bonded to the fixing member with the adhesive from the fixing member.

[0045] This disclosure further relates to one or more embodiments described below. <1> A method for manufacturing a semiconductor substrate, comprising the following step 1: Step 1: A step of paddle cleaning a wafer on which a wafer processing adhesive is attached to the surface with a chemical solution that satisfies the following requirements: The same wafer processing adhesive attached to the wafer to be cleaned in step 1 is uniformly deposited on the entire surface with a thickness of 30 μm, and 1 μL of the chemical solution is dropped onto the wafer surface obtained by heating at 80°C for 5 minutes and at 250°C for 5 minutes, and after 600 seconds, the diameter of the area where the chemical solution has penetrated and diffused is 5 mm or more. <2> The method for manufacturing a semiconductor substrate according to <1>, further comprising the following step 2: Step 2: A step of removing the chemical solution used in step 1 from the wafer. <3> The method for manufacturing a semiconductor substrate according to <1> or <2>, wherein the chemical solution used in step 1 contains an aprotic polar solvent. <4> The method for manufacturing a semiconductor substrate according to <3>, wherein the aprotic polar solvent is a nitrogen-containing aprotic polar solvent. <5> The method for producing a semiconductor substrate according to <3> or <4>, wherein the aprotic polar solvent comprises one or more selected from imidazolidinone-based solvents and pyrrolidone-based solvents. <6> The method for producing a semiconductor substrate according to <3> or <4>, wherein the aprotic polar solvent comprises imidazolidinone-based solvents and pyrrolidone-based solvents. <7> The method for producing a semiconductor substrate according to any one of <3> to <6>, wherein the aprotic polar solvent comprises 1,3-dimethyl-2-imidazolidinone (DMI) and N-methyl-2-pyrrolidone (NMP). <8> A method for manufacturing a semiconductor substrate according to any one of <3> to <7>, wherein the content of the aprotic polar solvent in the chemical solution used in step 1 is 30% by mass or more, or 50% by mass or more, or 70% by mass or more, or more than 70% by mass or 80% by mass or more, and is 100% by mass or less, or 99.5% by mass or less, or 99% by mass or less. <9> A method for manufacturing a semiconductor substrate according to any one of <4> to <8>, wherein the content of the nitrogen-containing aprotic polar solvent in the chemical solution used in step 1 is 30% by mass or more, or 50% by mass or more, or 70% by mass or more, or more than 70% by mass or 80% by mass or more, and is 100% by mass or less, or 99.5% by mass or less, or 99% by mass or less.<10> The method for manufacturing a semiconductor substrate according to <5>, <6>, or <7>, wherein the content of the imidazolidinone-based solvent in the chemical solution used in step 1 is 30% by mass or more, or 50% by mass or more, or 70% by mass or more, and 95% by mass or less, or 90% by mass or less, or 85% by mass or less. <11> The method for manufacturing a semiconductor substrate according to <5>, <6>, <7>, or <10>, wherein the content of the pyrrolidone-based solvent in the chemical solution used in step 1 is 5% by mass or more, or 10% by mass or more, or 15% by mass or more, and 70% by mass or less, or 50% by mass or less, or 30% by mass or less. <12> The method for manufacturing a semiconductor substrate according to <5>, <6>, <7>, <10>, or <11>, wherein the mass ratio of the imidazolidinone solvent to the pyrrolidone solvent in the chemical solution used in step 1 (imidazolidinone solvent / pyrrolidone solvent) is 1 or more, or 2 or more, or 3 or more, and is 20 or less, or 15 or less, or 10 or less. <13> The method for manufacturing a semiconductor substrate according to any one of <1> to <12>, wherein the water content in the chemical solution used in step 1 is 5% by mass or less, or 3% by mass or less, or 1% by mass or less, or 0% by mass. <14> The method for manufacturing a semiconductor substrate according to any one of <1> to <13>, wherein the flash point of the chemical solution used in step 1 is 90°C or higher, or 100°C or higher, or 110°C or higher. <15> The method for manufacturing a semiconductor substrate according to <14>, wherein step 1 includes paddle cleaning at a temperature 10°C or lower than the flash point of the chemical solution. <16> The method for manufacturing a semiconductor substrate according to any one of <1> to <15>, wherein the wafer processing adhesive is at least one selected from acrylic adhesives, urethane adhesives, silicone adhesives, novolac adhesives, and polyimide adhesives. <17> The method for manufacturing a semiconductor substrate according to any one of <1> to <16>, wherein the wafer is at least one selected from silicon wafers, germanium wafers, gallium-arsenide wafers, gallium-phosphorus wafers, and gallium-arsenide-aluminum wafers. <18> The method for manufacturing a semiconductor substrate according to any one of <1> to <17>, wherein step 1 includes spin cleaning the wafer before paddle cleaning.<19> The method for manufacturing a semiconductor substrate according to <18>, wherein the rotation speed of the wafer in the spin cleaning is 50 rpm or more, or 100 rpm or more, and 1000 rpm or less, or 800 rpm or less. <20> The method for manufacturing a semiconductor substrate according to any one of <1> to <19>, wherein the rotation speed of the wafer in the paddle cleaning of step 1 is 0 rpm or more, or 30 rpm or less. <21> The method for manufacturing a semiconductor substrate according to any one of <1> to <20>, further comprising a step of preparing a wafer with wafer processing adhesive attached to its surface before step 1. <22> A cleaning method for removing a wafer processing adhesive attached to the surface of a wafer, comprising a step of paddle cleaning the wafer with wafer processing adhesive attached to its surface using a chemical solution that satisfies the following requirements. Requirements: The wafer processing adhesive is uniformly deposited on the entire surface of the wafer with a thickness of 30 μm, and after 600 seconds have elapsed since dropping 1 μL of the chemical solution onto the wafer surface obtained by heating at 80°C for 5 minutes and 250°C for 5 minutes, the diameter of the area where the chemical solution has penetrated and diffused is 5 mm or more. <23> The cleaning method according to <22>, wherein the wafer processing adhesive is at least one selected from acrylic adhesives, urethane adhesives, silicone adhesives, novolac adhesives, and polyimide adhesives. <24> The cleaning method according to <22> or <23>, wherein the wafer is at least one selected from silicon wafers, germanium wafers, gallium-arsenide wafers, gallium-phosphorus wafers, and gallium-arsenide-aluminum wafers. <25> The cleaning method according to any one of <22> to <24>, wherein the step includes spin cleaning the wafer before paddle cleaning. <26> The cleaning method according to <25>, wherein the rotation speed of the wafer in the spin cleaning is 50 rpm or more, or 100 rpm or more, and 1000 rpm or less, or 800 rpm or less. <27> The cleaning method according to any one of <22> to <26>, wherein the rotation speed of the wafer in the paddle cleaning of step 1 is 0 rpm or more, or 30 rpm or less. <28> A method for manufacturing a semiconductor substrate, comprising the following step 1.Step 1: A step of paddle cleaning a silicon wafer having an adhesive for wafer processing, which is a polyimide-based adhesive, attached to the surface thereof with a chemical solution that satisfies the following requirements and contains an imidazolidinone-based solvent and a pyrrolidone-based solvent Requirements: The same wafer processing adhesive as the wafer processing adhesive attached to the wafer to be cleaned in Step 1 is uniformly formed into a film with a thickness of 30 μm over the entire surface, and after heat treatment at 80°C for 5 minutes and heat treatment at 250°C for 5 minutes, when 1 μL of the chemical solution is dropped onto the obtained wafer surface and 600 seconds have elapsed, the diameter of the region where the chemical solution has permeated and diffused is 5 mm or more.

[0046] Hereinafter, the present disclosure will be specifically described with reference to examples, but the present disclosure is not limited in any way by these examples.

[0047] 1. Preparation of chemical solutions (cleaning agent compositions) of Examples 1 to 3 and Comparative Examples 1 to 2 The components shown in Tables 1 to 2 were blended in the blending amounts (mass%, effective content) described in Tables 1 to 2, and the mixture was stirred and mixed to prepare the chemical solutions of Examples 1 to 3 and Comparative Examples 1 to 2.

[0048] The following materials were used for preparing the chemical solutions of Examples 1 to 3 and Comparative Examples 1 to 2. 1,3-dimethyl-2-imidazolidinone (DMI) [manufactured by Tokyo Chemical Industry Co., Ltd.] N-methyl-2-pyrrolidone (NMP) [manufactured by Fujifilm Wako Pure Chemical Corporation] Butyl diglycol (BDG) [manufactured by Nippon Emulsifier Co., Ltd.] Benzonitrile [manufactured by Fujifilm Wako Pure Chemical Corporation] Monoethanolamine (MEA) [manufactured by Nippon Shokubai Co., Ltd.] Tetrapropylammonium hydroxide (TPAH) [Tokyo Chemical Industry Co., Ltd.] Water [pure water with a conductivity of 1 μS / cm or less produced by a pure water apparatus G-10DSTSET manufactured by Organo Corporation]

[0049] 2. Evaluation of chemical solutions of Examples 1 to 3 and Comparative Examples 1 to 2 The following evaluations were performed on the prepared chemical solutions of Examples 1 to 3 and Comparative Examples 1 to 2.

[0050] [Evaluation Substrate] After a polyimide adhesive having a thickness of 30 μm was uniformly formed into a film on the entire surface of the wafer, a heat treatment at 80°C for 5 minutes and a heat treatment at 250°C for 5 minutes were performed to produce an evaluation substrate. A silicon wafer was used as the wafer.

[0051] [Penetration and Diffusion] 1 μL of the chemical solution was dropped onto the adhesive surface of the evaluation substrate. The adhesive surface was visually observed, and after standing for 10 minutes, the diameter of the area where the chemical solution had penetrated and diffused was measured. The penetration and diffusion properties were determined according to the following evaluation criteria. A larger diameter indicates better penetration and diffusion properties. The results are shown in Tables 1 and 2. The diameter is determined by the following method. If the area where the chemical solution penetrated and diffused is circular, the diameter of that area (circular) is used as the diameter. If the area where the chemical solution penetrated and diffused is not circular, the diameter of the smallest inclusion circle, which is the smallest circle that completely encloses that area, is used as the diameter. <Evaluation Criteria> A: Penetration and diffusion of 10 mm or more in diameter B: Penetration and diffusion of 7 mm or more in diameter but less than 10 mm C: Penetration and diffusion of 5 mm or more in diameter but less than 7 mm D: Penetration and diffusion of less than 5 mm in diameter

[0052] [Cleaning Performance (Adhesive Removal)] The cleaning performance (adhesive removal) of each chemical solution was evaluated as follows. The evaluation of cleaning performance 1 below was performed on the chemical solutions of Example 1 and Comparative Example 1. The evaluation of cleaning performance 2 below was performed on the chemical solutions of Examples 1 to 3 and Comparative Examples 1 to 2.

[0053] Cleaning Performance 1: Evaluation using a spin processor (Example 1 and Comparative Example 1) 20 L of each chemical solution was heated to 50°C using a spin processor. Using the heated chemical solution, the adhesive on the surface of the evaluation substrate was subjected to a 30-second flowing spin cleaning (rotation speed: 70 rpm). Then, the spin was stopped, a liquid film (paddle) of the chemical solution was formed on the adhesive on the surface of the evaluation substrate, and paddle cleaning was performed by letting it stand for 6 minutes. After that, the spin was restarted (rotation speed: 100 rpm), and a 1-minute flowing rinse was performed using isopropyl alcohol (IPA, manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.), followed by spin drying (1 minute, 25°C). The presence or absence of adhesive residue was determined by visual observation. The amount of adhesive dissolved per unit volume (unit: g) of chemical solution (mg) was calculated as follows: A 2 cm square adhesive film was dropped into 5 g of chemical solution at 25°C, and manually stirred at 1 minute, 2 minutes, and 2.5 minutes. After 3 minutes, the dissolution state of the adhesive film was visually observed. If it was completely dissolved, the next adhesive film was added. If it was not completely dissolved, the process was terminated. This operation was repeated to determine the amount of adhesive dissolved per unit volume of chemical solution. The results are shown in Table 1.

[0054] Cleanability 2: Manual Evaluation (Examples 1-3 and Comparative Examples 1-2) A chemical solution heated to 50°C was used to manually rinse the adhesive on the surface of the evaluation substrate for 30 seconds. A liquid film (paddle) of the chemical solution was then formed on the adhesive on the surface of the evaluation substrate, and paddle cleaning was performed by letting it stand for 6 minutes. After that, the paddle on the surface of the evaluation substrate was removed by tilting the substrate, and then a rinse was performed using isopropyl alcohol (IPA, manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) for 1 minute. After drying with an air blower (1 minute), the presence or absence of adhesive residue was determined by visual inspection. The results are shown in Table 2.

[0055]

[0056]

[0057] As shown in Table 1, the chemical solution used in Example 1 had good penetration and diffusion properties, with a diameter of 10 mm or more in the area where the chemical solution penetrated and diffused. On the other hand, the chemical solution used in Comparative Example 1 had poor penetration and diffusion properties, with a diameter of less than 3 mm in the area where the chemical solution penetrated and diffused. Furthermore, Example 1, in which paddle cleaning was performed using a chemical solution with good penetration and diffusion properties, showed superior adhesive residue removal compared to Comparative Example 1, in which paddle cleaning was performed using a chemical solution that had better adhesive dissolution but poor penetration and diffusion properties. As shown in Table 2, the chemical solutions used in Examples 1 to 3 showed better penetration and diffusion properties and superior adhesive residue removal compared to Comparative Examples 1 and 2. The flash points of the chemical solutions used in Examples 1 to 3 were 90°C or higher.

[0058] According to this disclosure, a method for manufacturing a semiconductor substrate is provided, which includes a paddle cleaning step that offers excellent removal of adhesives used for wafer processing. Furthermore, the semiconductor substrate manufacturing method according to this disclosure can improve the productivity of semiconductor substrates.

[0059] 1. Fixing member 2. Adhesive for wafer processing 2a. Residue of the adhesive for wafer processing 3. Wafer 3a. Polished and processed surface of the wafer

Claims

1. A method for manufacturing a semiconductor substrate, comprising the following step 1: Step 1: A step in which a wafer with wafer processing adhesive attached to its surface is paddle-cleaned with a chemical solution that satisfies the following requirements: The same wafer processing adhesive attached to the wafer to be cleaned in step 1 is uniformly deposited on the entire surface with a thickness of 30 μm, and after 600 seconds have elapsed since dropping 1 μL of the chemical solution onto the wafer surface obtained by heating at 80°C for 5 minutes and at 250°C for 5 minutes, the diameter of the area where the chemical solution has penetrated and diffused is 5 mm or more.

2. A method for manufacturing a semiconductor substrate according to claim 1, further comprising step 2 below: Step 2: A step of removing the chemical solution used in step 1 from the wafer.

3. The method for manufacturing a semiconductor substrate according to claim 1 or 2, wherein the chemical solution used in step 1 contains an aprotic polar solvent.

4. The method for manufacturing a semiconductor substrate according to claim 3, wherein the aprotic polar solvent is a nitrogen-containing aprotic polar solvent.

5. The method for producing a semiconductor substrate according to claim 3 or 4, wherein the aprotic polar solvent comprises one or more selected from imidazolidinone-based solvents and pyrrolidone-based solvents.

6. The method for producing a semiconductor substrate according to claim 3 or 4, wherein the aprotic polar solvent includes an imidazolidinone-based solvent and a pyrrolidone-based solvent.

7. A method for manufacturing a semiconductor substrate according to any one of claims 3 to 6, wherein the content of the aprotic polar solvent in the chemical solution used in step 1 is more than 70% by mass.

8. The method for manufacturing a semiconductor substrate according to any one of claims 4 to 7, wherein the content of the nitrogen-containing aprotic polar solvent in the chemical solution used in step 1 is 70% by mass or more.

9. The method for manufacturing a semiconductor substrate according to claim 5 or 6, wherein the content of the imidazolidinone-based solvent in the chemical solution used in step 1 is 30% by mass or more and 95% by mass or less.

10. The method for manufacturing a semiconductor substrate according to claim 5 or 6, wherein the content of the pyrrolidone-based solvent in the chemical solution used in step 1 is 5% by mass or more and 70% by mass or less.

11. The method for manufacturing a semiconductor substrate according to claim 5, 6, 9, or 10, wherein the mass ratio of the imidazolidinone solvent to the pyrrolidone solvent in the chemical solution used in step 1 (imidazolidinone solvent / pyrrolidone solvent) is 1 or more and 20 or less.

12. The method for manufacturing a semiconductor substrate according to any one of claims 1 to 11, wherein the water content in the chemical solution used in step 1 is 5% by mass or less.

13. A method for manufacturing a semiconductor substrate according to any one of claims 1 to 12, wherein the flash point of the chemical solution used in step 1 is 90°C or higher.

14. The method for manufacturing a semiconductor substrate according to claim 13, wherein step 1 includes cleaning a paddle at a temperature 10°C or lower than the flash point of the chemical solution.

15. The method for manufacturing a semiconductor substrate according to any one of claims 1 to 14, wherein the wafer processing adhesive is a polyimide-based adhesive.

16. The method for manufacturing a semiconductor substrate according to any one of claims 1 to 15, wherein the wafer is a silicon wafer.

17. A method for manufacturing a semiconductor substrate according to any one of claims 1 to 16, wherein step 1 includes spin-cleaning the wafer before paddle cleaning.

18. The method for manufacturing a semiconductor substrate according to any one of claims 1 to 17, wherein the rotation speed of the wafer in the paddle cleaning of step 1 is 30 rpm or less.

19. A method for manufacturing a semiconductor substrate according to any one of claims 1 to 18, further comprising the step of preparing a wafer with a wafer processing adhesive attached to its surface before step 1.

20. A wafer cleaning method for removing a wafer processing adhesive from a wafer on which the adhesive has adhered to the surface, comprising the step of paddle cleaning the wafer on which the wafer processing adhesive has adhered to the surface with a chemical solution that satisfies the following requirements: The wafer processing adhesive is uniformly formed on the entire surface of the wafer with a thickness of 30 μm, and the diameter of the area in which the chemical solution has penetrated and diffused after 600 seconds have elapsed since dropping 1 μL of the chemical solution onto the wafer surface obtained by heating at 80°C for 5 minutes and at 250°C for 5 minutes is 5 mm or more.

21. The wafer cleaning method according to claim 20, wherein the wafer processing adhesive is a polyimide-based adhesive.

22. The wafer cleaning method according to claim 20 or 21, wherein the wafer is a silicon wafer.

23. The wafer cleaning method according to any one of claims 20 to 22, wherein the step comprises spin-cleaning the wafer before paddle cleaning.

24. The wafer cleaning method according to any one of claims 20 to 23, wherein the rotation speed of the wafer in the paddle cleaning is 30 rpm or less.

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