JP7751760B2 - Cleaning composition for wafer processing - Google Patents

Description

This disclosure relates to a cleaning composition for wafer processing, a cleaning method and a semiconductor substrate manufacturing method using the same, and an adhesive remover.

In recent years, the high integration of semiconductor devices has progressed dramatically, and three-dimensional integrated circuit (3DIC) technology has attracted attention. 3DIC technology is a technology for stacking wafers in multiple layers while connecting them using through-silicon vias (TSVs) and other methods. When stacking wafers in multiple layers, it is necessary to thin the backside of the wafer on which the circuits are formed (the side on which the circuits are not formed) by polishing, and then form electrodes on the backside.
Before thinning, the wafer is bonded (temporarily bonded or temporarily fixed) to a fixing member (support) with an adhesive, and after undergoing processing such as polishing and electrode formation, the wafer is separated from the fixing member. After the wafer is separated from the fixing member, adhesive often remains, which can cause problems in subsequent processes. Therefore, a cleaning process is performed to remove any adhesive remaining on the wafer.

A variety of compositions have been developed to remove such adhesive residues.
For example, Patent Document 1 proposes a cleaning agent for semiconductor substrates capable of removing particles and carbon defects present on the substrate surface, which contains 0.05 to 50% by weight of an organic acid having at least one carboxy group, 0.01 to 30% by weight of a specific complexing agent, and 0.05 to 50% by weight of a specific organic solvent.
Patent Document 2 proposes a residue-stripping liquid composition as a cleaning agent for removing resist residues and metal residues derived from wiring materials, the residue-stripping liquid composition containing ammonium fluoride, methanesulfonic acid, a compound having a specific carbon-carbon triple bond, a specific water-soluble organic solvent, and water in specific amounts.
Patent Document 3 proposes an adhesive treatment liquid that can remove adhesives, which contains a liquid having a Hansen solubility parameter value of 25 or less and an alkaline compound, wherein the liquid having a Hansen solubility parameter value of 25 or less contains a mixed solvent of a lower alcohol and an organic solvent other than the lower alcohol, and the concentration of the alkaline compound is 0.05% by weight to 20% by weight.
Patent Document 4 discloses a rework solvent containing at least an amine-based solvent and a specific glycol ether-based solvent as a rework solvent for cleaning an adhesive layer attached to a peeled semiconductor circuit-forming substrate or a support substrate.
Patent Document 5 proposes a composition containing an alcohol, an aprotic polar solvent, an azole compound, an alkanolamine, and water as a composition for semiconductor devices that has excellent residue removal properties.
Patent Document 6 proposes a cleaning composition containing (i) an alkanolamine, (ii) an ether alcohol solvent or an aromatic-containing alcohol, and (iii) a corrosion inhibitor as a composition for removing photoresist from a substrate.
Patent Document 7 proposes a polymer cleaning composition that can remove adhesive polymers remaining on the circuit surface of a wafer during a semiconductor manufacturing process without corroding the metal, and that contains a fluorinated alkyl compound, a polar protic solvent, and an amine compound, where the amine compound contains an acyclic secondary amine compound or an acyclic amine compound.
Patent Document 8 proposes an alkaline cleaner for removing oils, grease, resins, particles, etc. adhering to electronic components, etc., which comprises an alkaline component and a hydrophilic organic solvent and has an electric conductivity of 0.1 to 3.0 mS/cm at 30°C.

JP 2012-186480 A WO2010/016350 Japanese Patent Application Laid-Open No. 2023-105258 WO2016/021646 WO2022/163350 Special Publication No. 2022-549372 Japanese Patent Application Laid-Open No. 2021-158352 Japanese Patent Application Laid-Open No. 2006-63201

In the manufacturing process of three-dimensional integrated circuits (3DICs), processing such as electrode formation after polishing a wafer bonded (temporarily bonded or temporarily fixed) to a fixing member (support) with an adhesive may be performed at high temperatures of 150° C. or higher, and if the adhesive is altered by heating, it tends to become difficult to remove. A cleaning composition is required to have excellent removability (cleaning ability) for the temporary fixing adhesive (wafer processing adhesive) used in such wafer processing.
However, the compositions proposed in Patent Documents 1 to 3 do not have sufficient removability for wafer processing adhesives. In addition, Patent Document 4 proposes a rework agent containing monoethanolamine and 1-methyl-2-pyrrolidone (NMP) in its examples, but in recent years, the use of NMP and other compounds in cleaning compositions has been restricted due to environmental concerns.

The present disclosure therefore provides a wafer processing cleaning composition that is excellent at removing adhesives used in wafer processing, a cleaning method and semiconductor substrate manufacturing method using the same, and an adhesive remover.

In one aspect, the present disclosure relates to a cleaning composition for removing residual wafer processing adhesive from wafers, the cleaning composition comprising a nitrogen-containing aprotic polar solvent (component A) having 2 to 10 carbon atoms and an organic amine (component B), wherein component A is a nitrile compound, and the mixed solvent consisting of components A and B has a Hansen solubility parameter value of 20.0 to 26.0.

In one aspect, the present disclosure relates to a wafer cleaning method for removing a wafer processing adhesive from a wafer to which the adhesive has adhered, the wafer cleaning method including a cleaning step of cleaning the wafer to which the wafer processing adhesive has adhered using a wafer processing detergent composition of the present disclosure.

In one aspect, the present disclosure relates to a method for manufacturing a semiconductor substrate, including the steps of: (1) bonding a wafer to a fixing member with an adhesive; (2) polishing the surface of the wafer opposite the surface bonded to the fixing member; (3) processing the polished surface of the wafer; (4) separating the processed wafer from the fixing member; and (5) removing any adhesive remaining on the separated wafer with a cleaning agent, wherein the cleaning agent is a cleaning agent composition containing a nitrogen-containing aprotic polar solvent having 2 to 10 carbon atoms (component A) and an organic amine (component B), where component A is a nitrile compound, and the mixed solvent consisting of component A and component B has a Hansen solubility parameter value of 20.0 to 26.0.

In one aspect, the present disclosure relates to an adhesive remover for removing wafer processing adhesive remaining on a wafer, the adhesive remover comprising a nitrogen-containing aprotic polar solvent (component A) having 2 to 10 carbon atoms and an organic amine (component B), wherein component A is a nitrile compound, and the mixed solvent consisting of components A and B has a Hansen solubility parameter value of 20.0 to 26.0.

This disclosure provides a wafer processing cleaning composition that is excellent at removing adhesives used in wafer processing, a cleaning method and semiconductor substrate manufacturing method using the same, and an adhesive remover.

FIG. 1 is a flowchart showing the steps in one embodiment of a method for manufacturing a semiconductor substrate according to the present disclosure. FIG. 2 is a schematic diagram for explaining each step in one embodiment of the method for manufacturing a semiconductor substrate according to the present disclosure.

This disclosure is based on the discovery that wafer processing adhesives (hereinafter simply referred to as "adhesives") can be efficiently removed by using a cleaning composition containing a nitrile compound (component A), which is an aprotic polar solvent having from 2 to 10 carbon atoms, and an organic amine (component B), in which the Hansen solubility parameter value of the mixed solvent consisting of components A and B is within a specified range.

In one aspect, the present disclosure relates to a cleaning composition for removing wafer processing adhesive remaining on a wafer, the cleaning composition for wafer processing (hereinafter also referred to as the "cleaning composition of the present disclosure") comprising a nitrogen-containing aprotic polar solvent (component A) having from 2 to 10 carbon atoms and an organic amine (component B), wherein component A is a nitrile compound, and the mixed solvent consisting of components A and B has a Hansen solubility parameter value of from 20.0 to 26.0.

In one or more embodiments, the present disclosure provides a cleaning composition that is excellent at removing adhesives used in wafer processing. Furthermore, by using the cleaning composition of the present disclosure, high-quality semiconductor substrates can be obtained with a high yield.

Although the details of the mechanism of action by which the effects of the present disclosure are manifested are still unclear, it is presumed as follows.
In the cleaning composition of the present disclosure, the nitrile compound (component A), an aprotic polar solvent having from 2 to 10 carbon atoms, penetrates into the adhesive remaining on the wafer and swells it, thereby generating stress on the adhesive surface and promoting peeling of the adhesive. Furthermore, while a predetermined amount of organic amine (component B) alone has difficulty penetrating into the adhesive, the cleaning composition of the present disclosure combines the organic amine (component B) with the nitrile compound (component A), an aprotic polar solvent having from 2 to 10 carbon atoms, and adjusts the Hansen solubility parameter of the mixed solvent consisting of components A and B to 20.0 to 26.0. This promotes penetration of the cleaning composition into the adhesive, and the stress generated by dissolution or swelling of the adhesive is thought to facilitate peeling of the adhesive from the substrate.
However, the present disclosure need not be construed as being limited to this mechanism.

In one or more embodiments, the cleaning composition of the present disclosure is used to remove an adhesive from a wafer to which the adhesive has adhered. That is, in one or more embodiments, the cleaning composition of the present disclosure is an adhesive remover for removing a wafer processing adhesive remaining on a wafer (hereinafter also referred to as the "adhesive remover of the present disclosure"). In one or more embodiments, the adhesive remover of the present disclosure contains a nitrogen-containing aprotic polar solvent having from 2 to 10 carbon atoms (component A) and an organic amine (component B), wherein component A is a nitrile compound, and the mixed solvent consisting of component A and component B has a Hansen solubility parameter value of from 20.0 to 26.0.
In one or more embodiments, the cleaning composition or adhesive remover of the present disclosure can be used to remove adhesive remaining on a wafer after the wafer, which has been adhesively bonded to a fixing member, is separated from the fixing member.
Examples of the wafer include semiconductor substrates, such as silicon wafers, germanium wafers, gallium-arsenide wafers, gallium-phosphorus wafers, and gallium-arsenide-aluminum wafers. In one or more embodiments, the wafer may be a substrate having pads and/or lands that are used for bonding and mounting.
Examples of adhesives for wafer processing include those that can bond a wafer to a fixing member, have durability sufficient to withstand the polishing and processing steps, and allow the wafer to be easily separated from the fixing member in the separation step, such as at least one adhesive selected from acrylic adhesives, urethane adhesives, silicone adhesives, novolac adhesives, and polyimide adhesives.

[Nitrogen-containing aprotic polar solvent having 2 to 10 carbon atoms (component A)]
The nitrogen-containing aprotic polar solvent having 2 to 10 carbon atoms (hereinafter also referred to as "Component A") contained in the cleaning composition of the present disclosure may be one type or a combination of two or more types.

From the same viewpoint, and from the viewpoint of improving the removability of the wafer processing adhesive, the number of carbon atoms in component A is from 2 to 10, preferably from 2 to 9, and more preferably from 2 to 8.

From the viewpoint of improving the removability of the wafer processing adhesive, the Hansen solubility parameter value of component A is preferably 26.0 or less, preferably 25.5 or less, more preferably 25.0 or less, and even more preferably 24.5 or less, and from the same viewpoint, it is preferably 20.0 or more, more preferably 20.5 or more, and even more preferably 21.0 or more.
Here, in the present disclosure, the Hansen solubility parameter (hereinafter also referred to as "HSP") is a value used to predict the solubility of a substance, which was announced by Charles M. Hansen in 1967, and is a parameter based on the idea that "two substances with similar intermolecular interactions are likely to dissolve in each other." The HSP is composed of the following three parameters (unit: MPa ^0.5 ):
δd: Energy due to intermolecular dispersion forces δp: Energy due to intermolecular dipole interactions δh: Energy due to intermolecular hydrogen bonds Detailed explanations are given in the March 2010 issue of Chemical Industry (Chemical Industry Co., Ltd.), and the Hansen solubility parameters of various substances can be obtained using the computer software "HSPiP: Hansen Solubility Parameters in Practice." HSP can also be determined by the method described in the Examples.

Component A is a nitrile compound, such as at least one selected from benzonitrile, phenylacetonitrile, and acetonitrile, from the viewpoint of improving the removability of the wafer processing adhesive.

From the viewpoint of penetration of the cleaning composition into the wafer processing adhesive, the content of component A in the cleaning composition of the present disclosure is preferably 50.0% by mass or more, more preferably 60.0% by mass or more, and even more preferably 70.0% by mass or more. From the same viewpoint, the content is preferably 99.9% by mass or less, more preferably 95.0% by mass or less, and even more preferably 90.0% by mass or less. More specifically, the content of component A in the cleaning composition of the present disclosure is preferably 50.0% by mass or more and 99.9% by mass or less, more preferably 60.0% by mass or more and 95.0% by mass or less, and even more preferably 70.0% by mass or more and 90.0% by mass or less. When component A is a combination of two or more types, the content of component A refers to the total content of those components.

In the present disclosure, the "content of each component in the detergent composition" refers to the content of each component at the time of cleaning, i.e., at the time when the detergent composition is first used for cleaning.
In one or more embodiments, the content of each component in the cleaning composition of the present disclosure can be considered to be the blending amount of each component in the cleaning composition of the present disclosure.

(Component B: organic amine)
The organic amine (hereinafter also referred to as "component B") contained in the cleaning composition of the present disclosure may be one type or a combination of two or more types.
From the viewpoint of improving the removability of the wafer processing adhesive, examples of component B include compounds represented by the following formula (I).
In the above formula (I), ^R1 represents a linear alkanol group having from 2 to 4 carbon atoms, ^R2 represents a linear alkanol group having from 2 to 4 carbon atoms, a methyl group, or a hydrogen atom, and ^R3 represents a methyl group or a hydrogen atom.
In the above formula (I), ^R1 is preferably a linear alkanol group having 2 or 3 carbon atoms from the viewpoint of improving the removability of the wafer processing adhesive. From the same viewpoint, ^R2 is preferably a hydrogen atom. From the same viewpoint, ^R3 is preferably a hydrogen atom.

In one or more embodiments, component B may be an organic amine such that the Hansen solubility parameter (HSP) of the mixed solvent consisting of components A and B is in the range of 20.0 to 26.0, and the Hansen solubility parameter value of component B is not particularly limited.

From the viewpoint of improving the removability of the wafer processing adhesive, component B is preferably an alkanolamine (amino alcohol). Examples of alkanolamines include at least one selected from N-methylmonoethanolamine, N-ethylmonoethanolamine, diethanolamine, N-dimethylmonoethanolamine, N-methyldiethanolamine, N-diethylmonoethanolamine, N-ethyldiethanolamine, N-(β-aminoethyl)ethanolamine, N-(β-aminoethyl)diethanolamine, monoethanolamine, and 2-(methylamino)ethanol. Of these, at least one selected from monoethanolamine, N-methyldiethanolamine, and 2-(methylamino)ethanolamine is preferred, at least one selected from monoethanolamine and 2-(methylamino)ethanolamine is more preferred, and monoethanolamine is even more preferred.

From the viewpoint of improving the removability of wafer processing adhesives, the content of component B in the cleaning composition of the present disclosure is preferably 0.1% by mass or more, more preferably 5.0% by mass or more, and even more preferably 10.0% by mass or more. From the same viewpoint, it is preferably 50.0% by mass or less, more preferably 40.0% by mass or less, and even more preferably 30.0% by mass or less. More specifically, the content of component B in the cleaning composition of the present disclosure is preferably 0.1% by mass or more and 50.0% by mass or less, more preferably 5.0% by mass or more and 40.0% by mass or less, and even more preferably 10.0% by mass or more and 30.0% by mass or less. When component B is a combination of two or more types, the content of component B refers to the total content of those components.

The mass ratio B/A of component B to component A (content of component B/content of component A) in the cleaning composition of the present disclosure is preferably 0.001 or more, more preferably 0.01 or more, and even more preferably 0.1 or more, from the viewpoint of improving the removability of wafer processing adhesives. From the same viewpoint, it is preferably 1 or less, more preferably 0.7 or less, and even more preferably 0.5 or less. More specifically, the mass ratio B/A is preferably 0.001 or more and 1 or less, more preferably 0.01 or more and 0.7 or less, and even more preferably 0.1 or more and 0.5 or less.

From the viewpoint of improving the removability of wafer processing adhesives, the total content of components A and B in the cleaning composition of the present disclosure is preferably 50.1% by mass or more, more preferably 65% by mass or more, even more preferably 80% by mass or more, still more preferably 95% by mass or more, and even more preferably 98% by mass or more. From the viewpoint of improving the removability of wafer processing adhesives, the total content of components A and B in the cleaning composition of the present disclosure may be 100% by mass.

(Hansen solubility parameter values for mixed solvents)
The solubility parameter value (HSP) of the mixed solvent consisting of component A and component B is 20.0 or more, preferably 20.5 or more, more preferably 21.0 or more, from the viewpoint of improving the removability of the wafer processing adhesive, and from the same viewpoint, is 26.0 or less, preferably 25.5 or less, more preferably 25.0 or less, and even more preferably 24.5 or less. More specifically, the solubility parameter value of the mixed solvent consisting of component A and component B is 20.0 or more and 26.0 or less, preferably 20.5 or more and 25.5 or less, and even more preferably 21.0 or more and 24.5 or less. The HSP of the mixed solvent can be determined by the method described in the examples.

[Water (component C)]
In one or more embodiments, the cleaning composition of the present disclosure may be water-free or contain 5 mass% or less of water. In one or more embodiments, examples of water (hereinafter also referred to as "component C") include ion-exchanged water, RO water, distilled water, pure water, and ultrapure water.
When the cleaning composition of the present disclosure contains water (component C), the content of component C in the cleaning composition of the present disclosure can be the remainder excluding components A, B, and the optional components described below. Specifically, from the viewpoint of improving adhesive removability, the content of component C in the cleaning composition of the present 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., no component is contained).

[Other ingredients]
The cleaning composition of the present disclosure may further contain water (component C) or other components as needed, in addition to the components A and B. Examples of other components include components that can be used in ordinary cleaning agents, such as solvents other than component A, alkaline agents other than component B, surfactants, chelating agents, thickeners, dispersants, rust inhibitors, metal corrosion inhibitors, polymeric compounds, solubilizing agents, antioxidants, preservatives, antifoaming agents, and antibacterial agents.
It is preferable that optional components other than these components A and B (component C and other components) do not significantly affect the Hansen solubility parameter value of the mixed solvent consisting of components A and B.

In one or more embodiments, the cleaning composition of the present disclosure may be substantially free of an organic acid having at least one carboxyl group. For example, the content of the organic acid having at least one carboxyl group in the cleaning composition of the present disclosure is preferably less than 0.05% by mass, more preferably 0.01% by mass or less, and even more preferably 0% by mass (i.e., no organic acid is contained).
In one or more embodiments, the cleaning composition of the present disclosure may be substantially free of ammonium fluoride. For example, the content of ammonium fluoride in the cleaning composition of the present disclosure is preferably less than 0.005% by mass, more preferably 0.001% by mass or less, and even more preferably 0% by mass (i.e., no ammonium fluoride is contained).
In one or more embodiments, the cleaning composition of the present disclosure may be substantially free of methanesulfonic acid. For example, the content of methanesulfonic acid in the cleaning composition of the present disclosure is more preferably 0% by mass (i.e., no methanesulfonic acid is contained).
In one or more embodiments, the cleaning composition of the present disclosure may be substantially free of hydroxides, carbonates, or metal alkoxides of alkali metals or alkaline earth metals. For example, the content of hydroxides, carbonates, or metal alkoxides of alkali metals or alkaline earth metals in the cleaning composition of the present disclosure is preferably less than 0.001% by mass, and more preferably 0% by mass (i.e., no alkali metals or alkaline earth metals are contained).
In one or more embodiments, the cleaning composition of the present disclosure may be substantially free of an azole compound. For example, the content of the azole compound in the cleaning composition of the present disclosure is preferably less than 0.1% by mass, and more preferably 0% by mass (i.e., no azole compound is contained).
In one or more embodiments, the cleaning composition of the present disclosure may be substantially free of a fluorinated alkyl compound. For example, the content of a fluorinated alkyl compound in the cleaning composition of the present disclosure is preferably less than 0.1% by mass, and more preferably 0% by mass (i.e., no fluorinated alkyl compound is contained).

[Method of producing the cleaning composition]
In one or more embodiments, the cleaning composition of the present disclosure can be produced by blending Components A to B and, if necessary, the optional components described above (Component C and other components) using a known method. For example, the cleaning composition of the present disclosure can be produced by blending at least Components A to B. Thus, in one aspect, the present disclosure relates to a method for producing a cleaning composition, the method including a step of blending at least Components A to B. In the present disclosure, "blending" includes mixing Components A to B and, if necessary, the optional components described above (Component C and other components) simultaneously or in any order. In the method for producing a cleaning composition of the present disclosure, the preferred amount of each component to be blended can be the same as the preferred content of each component in the cleaning composition of the present disclosure described above.

[Item to be cleaned]
An example of the object to be cleaned is a wafer having a wafer processing adhesive attached thereto. In one or more embodiments, the wafer may be a semiconductor substrate. Examples of the semiconductor substrate include a silicon wafer, a germanium wafer, a gallium-arsenide wafer, a gallium-phosphorus wafer, and a gallium-arsenide-aluminum wafer. In one or more embodiments, the wafer may be a substrate having pads and/or lands that are used for bonding and mounting. Examples of materials for the pads and lands include metals such as gold, copper, and aluminum.
In one or more embodiments, the wafer with adhesive attached thereto may be a wafer obtained after a wafer adhesively bonded to a fixing member is separated from the fixing member. In one or more embodiments, the wafer separated from the fixing member is a substrate having metal pads to which an adhesive is attached. Accordingly, in one aspect, the present disclosure relates to the use of a cleaning composition of the present disclosure as a cleaning agent for removing adhesive remaining on a wafer adhesively bonded to a fixing member after separation from the fixing member. In another aspect, the present disclosure relates to the use of an adhesive remover of the present disclosure as a remover for removing adhesive remaining on a wafer adhesively bonded to a fixing member after separation from the fixing member. In one or more embodiments, the wafer adhesively fixed to a fixing member has undergone heat treatment. The heat treatment temperature may be, for example, 200°C or higher. In one or more embodiments, the heat treatment may be the heat treatment in the processing step described below.
In one or more embodiments, wafers having adhesives attached thereto include substrates having adhesives attached thereto used in the manufacturing process of three-dimensional integrated circuits (3DIC). Accordingly, in one aspect, the present disclosure relates to the use of the cleaning composition of the present disclosure as a cleaning agent for removing adhesives used in the manufacturing process of three-dimensional integrated circuits. In another aspect, the present disclosure relates to the use of the adhesive remover of the present disclosure as a remover for removing adhesives used in the manufacturing process of three-dimensional integrated circuits.
In one or more embodiments, the wafer to which the adhesive is attached has undergone a heat treatment at a temperature of 200° C. or higher. In one or more embodiments, the heat treatment may be a heat treatment in a processing step described below.

[Method of manufacturing semiconductor substrate]
In one aspect, the present disclosure relates to a method for producing a semiconductor substrate, the method including: (1) bonding a wafer to a fixing member with an adhesive; (2) polishing the surface of the wafer opposite the surface bonded to the fixing member; (3) processing the polished surface of the wafer; (4) separating the processed wafer from the fixing member; and (5) removing any adhesive remaining on the separated wafer with a cleaning agent, wherein the cleaning agent is a cleaning agent composition containing a nitrogen-containing aprotic polar solvent having from 2 to 10 carbon atoms (component A) and an organic amine (component B), and the mixed solvent consisting of component A and component B has a Hansen solubility parameter of from 20.0 to 26.0 (hereinafter also referred to as the "semiconductor substrate production method of the present disclosure"). In one or more embodiments, the cleaning agent used in step (5) is the cleaning agent composition of the present disclosure described above.

The method for manufacturing a semiconductor substrate according to the present disclosure will be described using Figures 1 and 2. Figure 1 is a flowchart illustrating each step in one embodiment of the method for manufacturing a semiconductor substrate according to the present disclosure. Figure 2 is a schematic diagram illustrating each step in one embodiment of the method for manufacturing a semiconductor substrate according to the present disclosure.

<Process (1): Adhesion process>
Step (1) is a step (adhesion step) of adhering a wafer 3 to a fixing member 1 with an adhesive 2 (step S1). In one or more embodiments, step (1) includes a step (1-1) of applying an adhesive to the surface of the wafer or the fixing member to form an adhesive layer, and a step (1-2) of bonding the wafer and the fixing member together via the adhesive layer and performing a heat treatment to bond them.

The wafer used in step (1) may be, for example, a silicon wafer or glass wafer having 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.

The fixing member used in step (1) is not particularly limited, but examples include substrates such as silicon wafers and glass plates with a diameter of 100 to 500 mm and a thickness of 50 to 20,000 μm.

The adhesive used in step (1) is not particularly limited as long as it can bond the wafer to the fixing member, has durability sufficient to withstand the polishing and processing steps, and can easily separate the wafer from the fixing member in the separation step. For example, a wafer processing adhesive used in the manufacturing process of 3DIC 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, the adhesive composition described in JP 2021-161196 A can be used.
In one or more embodiments, the adhesive composition used in step (1) includes, as an adhesive component, at least one adhesive selected from an acrylic adhesive, a urethane adhesive, a silicone adhesive, a polyimide adhesive, and a novolac adhesive, and may further include a platinum group metal catalyst, a release agent component, a solvent, and the like.
The viscosity of the adhesive composition used in step (1) can be adjusted by appropriately changing the concentration of the components contained therein depending on the application method, film thickness, etc.

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

In the step (1-2), the temperature for the heat treatment is, for example, 80° C. or higher, and is preferably 300° C. or lower in order to prevent the adhesive from being excessively hardened.
The heat treatment time may be, 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 members.
Heating can be carried out using, for example, a hot plate, an oven, or the like.
The thickness of the adhesive layer after the heat treatment is, for example, 5 μm or more and 100 μm or less.

<Step (2): Polishing step>
The process (2) is a polishing process (polishing process) for polishing the surface (rear surface) 3a of the wafer 3 opposite to the surface bonded to the fixing member 1 (step S2).
Examples of the polishing method include mechanical polishing using abrasive grains and chemical mechanical polishing.
In step (2), the thickness of the polished wafer (thinned wafer) is preferably 200 μm or less, for example, 50 μm to 200 μm.

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

<Step (4): Separation step>
Step (4) is a step (separation step) of separating the processed wafer 3 from the fixing member 1 (step S4).
Examples of the separation method include solvent peeling, laser peeling, and mechanical peeling.

<Step (5): Cleaning step>
Step (5) is a step (cleaning step) of removing the adhesive (adhesive residue) 2a remaining on the separated wafer 3 with a cleaning agent (step S5). In one or more embodiments, the separated wafer is a wafer with an adhesive attached thereto (the object to be cleaned described above), for example, a substrate with an adhesive attached to a metal pad.
In one or more embodiments, the cleaning agent used in step (5) may be the cleaning agent composition of the present disclosure described above.

Examples of cleaning methods (methods for removing adhesives) in the cleaning step include immersion cleaning and spray cleaning. Accordingly, in one or more embodiments, the cleaning step is a step of immersing a wafer (object to be cleaned) having an adhesive attached thereto in the cleaning composition of the present disclosure (immersion cleaning step). From the viewpoint of improving the removability of the wafer processing adhesive, the immersion cleaning step is preferably a step of immersing a wafer (object to be cleaned) having an adhesive attached thereto in the cleaning composition at a temperature of 50°C or higher and 100°C or lower.
The temperature of the cleaning agent used in the cleaning step (cleaning temperature) or the immersion temperature in the immersion cleaning step 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 removability of the wafer processing adhesive. From the viewpoint of suppressing volatilization and deterioration of the cleaning agent components, it is preferably 100°C or lower, more preferably 90°C or lower, and even more preferably 80°C or lower. The cleaning time in the cleaning step or the immersion time in the immersion cleaning step is preferably 5 minutes or longer, more preferably 10 minutes or longer, and even more preferably 15 minutes or longer, from the viewpoint of improving the removability of the wafer processing adhesive. From the viewpoint of productivity, it is preferably 60 minutes or shorter, more preferably 40 minutes or shorter, and even more preferably 20 minutes or shorter. In the cleaning step or the immersion cleaning step, ultrasonic vibrations are preferably applied to the cleaning composition of the present disclosure, from the viewpoint of easily exerting the detergency of the cleaning composition of the present disclosure. For example, ultrasonic vibrations are preferably applied at 25 to 50 kHz, and more preferably at 35 to 45 kHz, from the viewpoint of suppressing damage to the wafer.

In one or more embodiments, the wafer after the cleaning step may be washed with water or rinsed with a rinse agent, and then dried. Examples of rinse agents include at least one rinse agent selected from methanol, ethanol, isopropyl alcohol, and propylene glycol monomethyl ether.

In one or more other embodiments, step (5) is a step of removing the adhesive remaining on the separated wafer with an adhesive remover. In one or more embodiments, the adhesive remover used in step (5) may be the adhesive remover of the present disclosure described above.
That is, in one or more embodiments, the method for manufacturing a semiconductor substrate of the present disclosure is a method for manufacturing a semiconductor substrate that includes the steps of: (1) bonding a wafer to a fixing member with an adhesive; (2) polishing the surface of the wafer opposite to the surface bonded to the fixing member; (3) processing the polished surface of the wafer; (4) separating the processed wafer from the fixing member; and (5) removing adhesive remaining on the separated wafer with the adhesive remover of the present disclosure.

[Wafer cleaning method]
In one aspect, the present disclosure relates to a wafer cleaning method (hereinafter also referred to as the "cleaning method of the present disclosure") for removing a wafer processing adhesive from a wafer (object to be cleaned) to which the adhesive has adhered, the method comprising a cleaning step of cleaning the wafer to which the adhesive has adhered using a cleaning composition for wafer processing of the present disclosure. In one or more embodiments, the cleaning step is a step of removing the wafer processing adhesive remaining on the wafer using the cleaning composition of the present disclosure after separating the wafer bonded to a fixing member with the adhesive from the fixing member. The cleaning method of the present disclosure allows for efficient removal of the wafer processing adhesive.

In one or more embodiments, the cleaning method (adhesive removal method) in the cleaning step of the cleaning method of the present disclosure may be the same as the cleaning method (adhesive removal method) in step (5) in the semiconductor substrate manufacturing method of the present disclosure described above. From the viewpoint of improving the removability of the wafer processing adhesive, in one or more embodiments, the cleaning step in the cleaning method of the present disclosure is preferably a step (immersion cleaning step) of immersing a wafer (object to be cleaned) having the adhesive adhered thereto in the cleaning composition at a temperature of 50° C. or higher and 100° C. or lower. In one or more embodiments, the immersion conditions in the immersion cleaning step (immersion temperature, immersion time, ultrasonic vibration, etc.) may be the immersion conditions in the immersion cleaning step (5) in the semiconductor substrate manufacturing method of the present disclosure described above (immersion temperature, immersion time, ultrasonic vibration, etc.).
In one or more embodiments of the cleaning method of the present disclosure, the wafer bonded to the fixing member with an adhesive has undergone a heat treatment at a temperature of preferably 230° C. or higher, more preferably 270° C. or higher. Heat treatment at a temperature of 230° C. or higher includes, for example, 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 may be performed after the processing step of step (3) and before step (4).
In one or more embodiments, the object to be cleaned in the cleaning method of the present disclosure may be a wafer that has undergone steps (1) to (4) in the semiconductor substrate manufacturing method of the present disclosure.

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

In one or more embodiments, the 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 from the fixing member, the adhesive remover being the adhesive remover of the present disclosure described above.
That is, in one or more embodiments, the cleaning method of the present disclosure is an adhesive removal method that includes a step of removing the adhesive remaining on the wafer with the adhesive remover of the present disclosure after separating the wafer, which is adhesively bonded to a fixing member, from the fixing member.

[kit]
In one aspect, the present disclosure relates to a kit for use in either the cleaning method of the present disclosure or the semiconductor substrate manufacturing method of the present disclosure (hereinafter also referred to as the "kit of the present disclosure"). In one or more embodiments, the kit of the present disclosure is a kit for producing the cleaning composition of the present disclosure. The kit of the present disclosure allows for the production of a cleaning composition that is excellent in removing adhesives used in wafer processing.
An embodiment of the cleaning agent composition of the present disclosure may be a so-called one-component type in which component A and component B are mixed and provided on the market, or may be a two-component type in which components are mixed when used.
Therefore, in one or more embodiments, the kit of the present disclosure may include a kit including a solution containing component A and component B. The solution may contain the above-mentioned optional components (component C, other components) as needed. The solution may be diluted with water (component C) or an organic solvent as needed before use.
In one or more embodiments, the kit of the present disclosure may be a kit (two-liquid cleaning composition) that includes a solution containing component A (first liquid) and a solution containing component B (second liquid) in a mutually unmixed state, and the first liquid and the second liquid are mixed at the time of use. After the first liquid and the second liquid are mixed, they may be diluted with component C (water) or an organic solvent as needed. Each of the first liquid and the second liquid may contain the above-mentioned optional components as needed.

The present disclosure will be explained in detail below using examples, but the present disclosure is not limited to these examples in any way.

1. Preparation of Cleaning Compositions of Examples 1 to 8 and Comparative Examples 1 to 6 The components shown in Table 1 were blended in the amounts (% by mass, active ingredient) shown in Table 1 and mixed by stirring to prepare the cleaning compositions of Examples 1 to 8 and Comparative Examples 1 to 6.

The following materials were used to prepare the cleaning compositions of Examples 1 to 8 and Comparative Examples 1 to 6.
(Nitrogen-containing aprotic polar solvent)
Benzonitrile [Fujifilm Wako Pure Chemical Industries, Ltd.]
<δd=18.8, δp=12.0, δh=3.3>
Phenylacetonitrile [Tokyo Chemical Industry Co., Ltd.]
<δd=19.5, δp=12.3, δh=3.8>
Acetonitrile [Fujifilm Wako Pure Chemical Industries, Ltd.]
<δd=15.3, δp=18.0, δh=6.1>
1-methyl-2-pyrrolidone [manufactured by Mitsubishi Chemical Corporation]
<δd=18.0, δp=12.3, δh=7.2>
(Aprotic Solvent)
Dimethyl sulfoxide [Fujifilm Wako Pure Chemical Industries, Ltd.]
<δd=18.4, δp=16.4, δh=10.2>
γ-Butyrolactone [Fujifilm Wako Pure Chemical Industries, Ltd.]
<δd=18.0, δp=16.6, δh=7.4>
(organic amine)
Monoethanolamine [Nippon Shokubai Co., Ltd.]
<δd=17.0, δp=15.5, δh=21.0>
2-(methylamino)ethanol [amino alcohol MMA, manufactured by Nippon Nyukazai Co., Ltd.]
<δd=16.8, δp=8.7, δh=16.4>
N-methyldiethanolamine [Amino alcohol MDA, manufactured by Nippon Nyukazai Co., Ltd.]
<δd=16.8, δp=8.3, δh=17.6>

[Hansen Solubility Parameter Value]
The Hansen solubility parameter (HSP) values of mixed solvents consisting of nitrogen-containing aprotic polar solvents and organic amines are shown in Table 1. The HSP values were calculated using the following formula.
In formula (1), δd, δp, and δh are parameters specific to the compound, where δd represents the energy due to intermolecular dispersion forces, δp represents the energy due to intermolecular dipole interactions, and δh represents the energy due to intermolecular hydrogen bonds.
In the case of a mixed solvent of two or more types, each parameter value (δd, δp, δh) can be calculated as a weighted average shown in formula (2), and the δd, δp, and δh of the mixed solvent calculated by formula (2) were applied to formula (1) to calculate the HSP value of the mixed solvent.
In formula (2), φ1 and φ2 are the volume fractions of the respective compounds.

2. Evaluation of the Cleaning Compositions of Examples 1 to 8 and Comparative Examples 1 to 6 The prepared cleaning compositions of Examples 1 to 8 and Comparative Examples 1 to 6 were evaluated as follows.

[Evaluation of cleaning ability (adhesive removability)]
(Test piece)
A Si substrate (wafer) having an adhesive (adhesive layer) was cut into a 2 cm square and used as a test piece.
The adhesive used was a polyimide adhesive.
The adhesive layer was formed by uniformly applying the adhesive to the entire surface of the Si substrate (wafer), subjecting it to a heat treatment at 80° C. for 5 minutes, and then further subjecting it to a heat treatment at 250° C. for 5 minutes. The thickness of the adhesive layer after the heat treatment was 30 μm.
(Cleaning test)
50 mL of each of the cleaning compositions of Examples 1 to 8 and Comparative Examples 1 to 6 was added to a 100 mL beaker and heated to 50° C. Then, the test pieces were immersed in the cleaning composition at 50° C. for 15 minutes. Then, the test pieces were removed from the cleaning composition and rinsed with a rinse agent (isopropyl alcohol, IPA, manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) at room temperature for 30 seconds, and then dried with air.
(Evaluation of cleaning ability)
The test pieces after cleaning and drying were visually inspected for the presence or absence of adhesive residue, and then the surface of the test pieces after the cleaning test was subjected to X-ray photoelectron spectroscopy (ESCA) (PHI Quantera SXM, manufactured by ULVAC-PHI, Inc.) to calculate the carbon/silicon ratio (C 1s/Si 2p), which was expressed as a relative value, with the carbon/silicon ratio of a Si substrate (mirror wafer) with no adhesive applied being set at 100. The results are shown in Table 1. The smaller the value, the better the cleaning ability can be evaluated.
In addition, in Comparative Examples 3 and 6, adhesive residue was visually confirmed on the Si substrate (wafer), so residue evaluation by ESCA was not performed, and therefore these are indicated as "x" in Table 1.

[Evaluation of damage to Al substrate]
(Test piece)
In order to evaluate the damage to an Al electrode that can be formed on a Si substrate, a pure Al substrate of 20 mm x 50 mm (thickness 0.8 mm) was used as a test piece.
(Damage assessment)
The weight of each pure Al substrate was precisely measured using a precision balance, and the substrate was immersed in 50 mL of each of the cleaning compositions of Examples 1 to 8 and Comparative Examples 1 to 6 at 50°C for 15 minutes, as shown in the cleaning test above. The test piece was then removed from the cleaning composition, rinsed with a rinse agent (IPA) at room temperature for 30 seconds, and then air-dried. The weight of the dried Al substrate was precisely measured using a precision balance, and the amount of Al substrate etching was calculated from the difference in weight between the substrate before and after immersion in the cleaning composition, and evaluated based on the following evaluation criteria. As a result, the damage to the Al substrates of Examples 1 to 8 and Comparative Examples 1 to 6 was rated A for all of them.
(Evaluation criteria)
A: Weight difference is less than 0.1 mg (Good: Almost no damage is visible)
B: Weight difference is 0.1 mg or more but less than 0.5 mg C: Weight difference is 0.5 mg or more (Fail: Damage is observed)

As shown in Table 1, the cleaning compositions of Examples 1 to 8 were superior to those of Comparative Examples 1 to 6 in removing adhesive residue. Furthermore, as mentioned above, the cleaning compositions of Examples 1 to 8 showed almost no damage to the Al substrate, suggesting that they can suppress damage to the Al electrode.

The present disclosure provides a cleaning composition that is excellent at removing adhesives used in wafer processing. Furthermore, use of the cleaning composition of the present disclosure can improve the productivity of semiconductor substrates.

1 Fixing member 2 Wafer processing adhesive 2a Residue of wafer processing adhesive 3 Wafer 3a Polished/processed surface of wafer

Claims (12)

A cleaning composition for removing a wafer processing adhesive remaining on a wafer, comprising:
The composition contains a nitrogen-containing aprotic polar solvent (component A) having 2 to 10 carbon atoms and an organic amine (component B),
Component A is a nitrile compound,
A cleaning agent composition for wafer processing, wherein the mixed solvent consisting of component A and component B has a Hansen solubility parameter value of 20.0 or more and 26.0 or less. The wafer processing cleaning composition according to claim 1, wherein the content of component A is 50.0% by mass or more and 99.9% by mass or less. 3. The cleaning composition for wafer processing according to claim 1, wherein component B comprises a compound represented by the following formula (I):
In the above formula (I), ^R1 represents a linear alkanol group having from 2 to 4 carbon atoms, ^R2 represents a linear alkanol group having from 2 to 4 carbon atoms, a methyl group, or a hydrogen atom, and ^R3 represents a methyl group or a hydrogen atom. The wafer processing cleaning composition according to claim 1 or 2, wherein component B is at least one selected from monoethanolamine and 2-(methylamino)ethanol. The cleaning composition for wafer processing according to claim 1 or 2, wherein the content of component B is 0.1% by mass or more and 50.0% by mass or less. The cleaning composition for wafer processing according to claim 1 or 2, wherein the mass ratio B/A of component B to component A is 0.001 or more and 1 or less. The wafer processing cleaning composition according to claim 1 or 2, wherein the wafer processing cleaning composition does not contain water or contains 5% by mass or less of water. 1. A cleaning method for removing a wafer processing adhesive from a wafer to which the adhesive has adhered, comprising:
A wafer cleaning method comprising a cleaning step of cleaning a wafer having an adhesive for wafer processing adhered thereto with the cleaning composition for wafer processing according to claim 1 or 2. The wafer cleaning method according to claim 8, wherein the cleaning step is a step of immersing the wafer to which the adhesive has adhered in the cleaning composition at a temperature of 50°C or higher and 100°C or lower. (1) a step of bonding a wafer to a fixing member with an adhesive;
(2) polishing the backside of the wafer from the adhesive surface to the fixing member;
(3) processing the polished surface of the wafer;
(4) separating the processed wafer from the fixing member;
(5) removing any adhesive remaining on the separated wafers with a cleaning agent;
A method for manufacturing a semiconductor substrate, comprising:
the cleaning agent is a cleaning agent composition containing a nitrogen-containing aprotic polar solvent (component A) having from 2 to 10 carbon atoms and an organic amine (component B), wherein component A is a nitrile compound, and the mixed solvent consisting of components A and B has a Hansen solubility parameter value of from 20.0 to 26.0. The method for producing a semiconductor substrate according to claim 10, wherein the content of component A in the cleaning composition is 50.0% by mass or more and 99.9% by mass or less. An adhesive remover for removing a wafer processing adhesive remaining on a wafer, comprising:
The composition contains a nitrogen-containing aprotic polar solvent (component A) having 2 to 10 carbon atoms and an organic amine (component B),
Component A is a nitrile compound,
An adhesive remover, wherein the mixed solvent consisting of component A and component B has a Hansen solubility parameter value of 20.0 or more and 26.0 or less.