Composition for forming wafer edge protective film, method for forming wafer edge protective film, and method for forming a pattern

Abstract

The present invention provides a wafer edge protective film forming composition that exhibits excellent dry etching resistance and excellent uniform coating properties even on wafer edges where coating is difficult. [Solution] A wafer edge protective film forming composition for forming a wafer edge (1E) protective film on the peripheral edge 1a of a substrate 1 comprises a polymer represented by formula (1) and a solvent. TIFF2026069843000031.tif74140 W is -SO2-, -C(=O)-, or -O-.

Description

Technical Field

[0001] The present invention relates to a composition for forming a wafer edge protective film for forming a wafer edge protective film at a peripheral edge of a substrate, a method for forming a wafer edge protective film using the composition for forming a wafer edge protective film, and a method for forming a pattern using the protective film.

Background Art

[0002] In the manufacturing process of semiconductor devices, for example, a resist coating process of applying a resist chemical solution onto a substrate such as a semiconductor substrate to form a resist upper layer film, an exposure process of exposing the resist film to a predetermined pattern, a development process of developing the exposed resist upper layer film, etc. are sequentially performed to form a resist pattern on the substrate. Then, an etching process is applied to the substrate using the resist pattern as a mask, and a predetermined pattern is formed on the substrate.

[0003] In such substrate processing, when etching a substrate to be processed using a resist upper layer film pattern as a mask, if there is a substrate peripheral edge (wafer edge) where the substrate is exposed, the exposed portion of the substrate is etched to generate particles, which causes a problem of affecting the yield reduction in semiconductor manufacturing.

[0004] As shown in FIG. 1, usually, the wafer edge (peripheral edge) 1E gradually slopes from the surface of the wafer 1 (the edge surface 1b on the front side and the edge surface 1e on the back side), and has a shape that is cut off. The chamfered portions of the wafer edge 1E are referred to as bevels 1c and 1d, and the vertical portion is referred to as an apex (also called an a-pex) 1a. The wafer edge 1E has a shape as shown in FIG. 1(A) called a round type, and a shape as shown in FIG. 1(B) is called a blet type.

[0005] In order to suppress particle generation from the wafer edge, a technique of forming a resist film only on the wafer edge is known. For example, as disclosed in Patent Document 1, there is a method of applying a photoresist solution to the wafer edge while rotating the wafer.

[0006] Furthermore, in recent years, there has been research into forming coated films using coating materials that contain inorganic metals in the resist (upper resist film) and the under resist film. Since the adhesion of metal to unintended areas of the semiconductor substrate during the semiconductor device manufacturing process strongly affects the electrical properties of the semiconductor device, such adhesion is strictly controlled.

[0007] However, when forming a coating film containing metal as described above, there is a concern that the chemical solution supplied to the surface of the substrate may spread to the wafer edge and the peripheral edge of the back surface, forming a coating film on these unintended areas, thus contaminating them with metal. There is also a concern that particles generated when etching the metal-containing film may adhere to the wafer edge, contaminating these areas with metal. Furthermore, if the contaminated parts of the substrate come into contact with substrate processing equipment such as exposure equipment and etching equipment, or substrate transport mechanisms, substrates transported and processed after that substrate may also become contaminated with metal, meaning that cross-contamination may occur. For this reason, as disclosed in Patent Documents 2 and 3, methods for forming a protective film to protect the wafer edge and the peripheral edge of the back surface from metal-containing materials have been reported.

[0008] As described above, the wafer edge protective film formation method is useful in the fine patterning process of semiconductor manufacturing, such as suppressing etching damage to the wafer edge and suppressing metal contamination of the wafer edge during metal-containing material processing.

[0009] On the other hand, in the manufacturing of semiconductor devices in recent years, the process of forming patterns with ultra-high aspect ratios on the substrate has increased due to the 3D nature of device structures. While negative-type photoresist solutions have generally been used for conventional wafer edge protection films, the manufacturing of advanced devices is seeing an acceleration in the complexity and length of etching processes, and it is anticipated that wafer edge protection films will require improved etching resistance.

[0010] A masking composition has been proposed to prevent metal contamination on the edges of substrates during the manufacturing of electronic devices (Patent Document 4). However, this material has insufficient dry etching resistance, and there is a need for wafer edge protective films with higher dry etching resistance. [Prior art documents] [Patent Documents]

[0011] [Patent Document 1] Japanese Patent Publication No. 2014-110386 [Patent Document 2] Japanese Patent Publication No. 2014-045171 [Patent Document 3] Japanese Patent Publication No. 2018-124354 [Patent Document 4] Special Publication No. 2020-514509 [Overview of the project] [Problems that the invention aims to solve]

[0012] The present invention has been made in view of the above circumstances, and aims to provide a wafer edge protective film formation composition that can provide a wafer edge protective film that can exhibit better dry etching resistance than conventional wafer edge protective films and can exhibit excellent uniform coating even on wafer edges that are difficult to coat, as well as a wafer edge protective film formation method and pattern formation method using the composition. [Means for solving the problem]

[0013] To solve the above problems, the present invention provides a wafer edge protective film forming composition for forming a wafer edge protective film on the peripheral edge of a substrate, A polymer (A) represented by the following general formula (1), Solvent and The present invention provides a composition for forming a wafer edge protective film, characterized by containing the following: [Chemical formula] (In the formula, W is -SO2-, -C(=O)- or -O-, and R1, R2, R3, R4 and R5 are each independently a halogen atom, a monovalent organic group having 1 to 3 carbon atoms, or a hydroxy group, and a, b, c, d and e are each independently an integer from 0 to 4.)

[0014] For such a composition for forming a wafer edge protective film, since the polymer (A) has a trifunctional structure and repeating units of the polymer, it has high film density and can form a wafer edge protective film excellent in dry etching resistance, even on a wafer edge portion that is difficult to coat, with excellent uniform coating properties. Also, the wafer edge protective film formed in this way can reliably protect the wafer edge even when forming a pattern with a high aspect ratio on a substrate to be processed.

[0015] Moreover, it is preferable that the weight average molecular weight of the polymer (A) is 1,000 to 30,000.

[0016] For the polymer (A) within such a range of weight average molecular weight, it does not impair the solubility in the solvent and can suppress outgassing during baking.

[0017] Also, it is preferable that the content of the polymer (A) in the composition for forming a wafer edge protective film is 10% by mass or more.

[0018] By using such a composition for forming a wafer edge protective film, it is surely possible to form a thick film of the edge protective film even on a wafer edge portion that is difficult to coat, and it is possible to provide an edge protective film having a film thickness sufficient to withstand the dry etching process of the substrate to be processed.

[0019] Also, the composition for forming a wafer edge protective film further comprises a crosslinking agent, a surfactant, an acid generator, and Plasticizer It is preferable that it contains one or more of them.

[0020] By using the composition for forming an edge protection film containing the above additives, various physical properties required when forming a wafer edge protection film, such as defect suppression characteristics, dry etching resistance, and substrate adhesion, can be adjusted within an appropriate range.

[0021] Moreover, it is preferable that the solvent is a mixture of a high-boiling solvent having a boiling point of 180 °C or higher and a low-boiling solvent having a boiling point of less than 180 °C.

[0022] By including such a high-boiling solvent having such a boiling point, there is no risk that the volatilization during baking (heat treatment) will be too fast due to the boiling point being too low, so sufficient thermal fluidity can be obtained during film formation, and even in the difficult-to-coat wafer edge portion, a wafer edge protection film having excellent uniform coating properties can be formed.

[0023] Further, in the present invention, there is provided a method for forming a wafer edge protection film for forming a wafer edge protection film on a peripheral edge portion of a substrate, (i) A step of coating a peripheral edge portion of the substrate with the composition for forming a wafer edge protection film according to the present invention to obtain a coating film; (ii) A step of curing the coating film by heat or light irradiation to form the wafer edge protection film on the peripheral edge portion of the substrate. A method for forming a wafer edge protection film characterized by including the above steps is provided.

[0024] According to such a method for forming a wafer edge protection film, since a composition containing the polymer (A) which is a material for forming a wafer edge protection film containing the above general formula (1) having a repeating unit of a polymer in a trifunctional structure is used, it has excellent dry etching resistance, and even in a difficult-to-coat wafer edge portion, it is possible to exhibit excellent uniform coating properties, and also when forming a pattern having a high aspect ratio on a workpiece substrate, it is possible to form a wafer edge protection film capable of protecting the wafer edge.

[0025] Furthermore, in step (i), the wafer edge protective film forming composition is coated not only on the front edge surface of the peripheral edge of the substrate, but also on the back edge surface of the peripheral edge of the substrate. In step (ii) above, it is preferable to also form the wafer edge protective film on the edge surface on the back side of the substrate.

[0026] By forming a wafer edge protective film on the back edge surface of the peripheral edge of the substrate using the wafer edge protective film forming composition of the present invention, it is possible to avoid the risk of metal contamination in these areas, that is, metal contamination caused by the chemical solution supplied to the surface of the substrate during the formation of a coating film containing metal seeping into the peripheral edge on the back side, resulting in the formation of a coating film on these unintended peripheral edges on the back side.

[0027] Furthermore, it is preferable that the coating in step (i) be performed using a rotary coating method, and that the wafer edge protective film is not formed anywhere other than the peripheral edge of the substrate.

[0028] By applying the wafer edge protective film formation composition of the present invention by a rotary coating method, and forming a wafer edge protective film only on the peripheral edges, including the edge surfaces on both the front and back sides, it is possible to significantly contribute to improving the productivity of semiconductor manufacturing processes by reducing chemical consumption and shortening manufacturing time.

[0029] Furthermore, in step (ii) above, it is preferable to cure the coating film by heat treatment at a temperature of 100°C to 800°C for 10 to 7,200 seconds.

[0030] By thermal curing, a dense cured film can be formed, improving the resistance to dry etching.

[0031] Furthermore, the present invention provides a method for forming a wafer edge protective film on the peripheral edge of a workpiece substrate on which a patterned film is formed, and for forming a pattern on the workpiece substrate, (I-1) A step of applying the wafer edge protective film forming composition of the present invention to the peripheral edge of a workpiece substrate on which a film having a pattern has been formed to obtain a coating film, (I-2) A step of curing the coating film by heat treatment or light irradiation to form a wafer edge protective film on the peripheral edge of the substrate, (I-3) A step of forming a pattern on the substrate to be processed by dry etching using the film having the pattern as a mask, (I-4) A step of removing the wafer edge protective film, The present invention provides a pattern forming method characterized by including the following:

[0032] The above pattern formation method makes it possible to reliably suppress particle generation from the wafer edge when dry etching the substrate to be processed.

[0033] Furthermore, in step (I-1), the wafer edge protective film forming composition is applied not only to the front edge surface of the peripheral edge of the substrate, but also to the back edge surface of the peripheral edge of the substrate. In step (I-2) above, it is preferable to also form the wafer edge protective film on the edge surface on the back side of the substrate.

[0034] By forming a wafer edge protective film up to the edge surface on the back side of the peripheral edge using the protective film-forming composition of the present invention, it becomes possible to avoid the risk of metal contamination in these areas, that is, metal contamination caused by the chemical solution supplied to the surface of the substrate during the formation of a coating film containing metal seeping into the peripheral edges on the back side, resulting in the formation of a coating film on these unintended peripheral edges on the back side (for example, the edge surface on the back side).

[0035] Furthermore, the present invention provides a method for forming a wafer edge protective film on the peripheral edge of a substrate to be processed, and for forming a pattern on the substrate to be processed, (II-1) A step of applying the wafer edge protective film forming composition of the present invention to the peripheral edge of the substrate to be processed to obtain a coating film, (II-2) A step of curing the coating film by heat treatment or light irradiation to form a wafer edge protective film on the peripheral edge of the substrate to be processed, (II-3) A step of forming a resist upper layer film pattern on the substrate to be processed, and using the resist upper layer film pattern as a mask, forming a pattern on the substrate to be processed by dry etching, (II-4) A step of removing the wafer edge protective film, The present invention provides a pattern forming method characterized by including the following:

[0036] The above pattern formation method makes it possible to suppress particle generation from the wafer edge when dry etching the substrate to be processed. Furthermore, when forming the resist upper layer film, the chemical solution supplied to the surface of the substrate may spread to the peripheral edges of the back surface, and the coating film may form on these unintended peripheral edges of the back surface (for example, the edge surface on the back side), thus avoiding the risk of contamination of these areas.

[0037] Furthermore, in step (II-1), the wafer edge protective film forming composition is applied not only to the front edge surface of the peripheral edge of the substrate, but also to the back edge surface of the peripheral edge of the substrate. In step (II-2) described above, it is preferable to also form the wafer edge protective film on the edge surface on the back side of the substrate.

[0038] By forming a wafer edge protective film up to the edge surface on the back side of the peripheral edge using the wafer edge protective film forming composition of the present invention, it is possible to avoid the risk of metal contamination in these areas, that is, when forming a coating film containing metal, the chemical solution supplied to the surface of the substrate flows to the peripheral edge on the back side, and the coating film is formed on these unintended peripheral edges on the back side (for example, the edge surface on the back side). [Effects of the Invention]

[0039] As described above, the wafer edge protective film forming composition of the present invention has high film density because the polymer (A) has a trifunctional structure and repeating polymer units. Therefore, it has better dry etching resistance than conventional wafer edge protective films and can provide a wafer edge protective film that exhibits excellent uniform coating even on wafer edges, which are difficult to coat. In particular, even in dry etching processes that form high aspect ratio fine patterns, such as those found in 3D-NAND memory with increasing stacking, it is possible to protect the wafer edge from etchants until the etching of the substrate is completed, and particle generation from the wafer edge due to etching can be reduced. Therefore, it is extremely useful in fine patterning processes in semiconductor manufacturing processes.

[0040] Furthermore, the wafer edge protective film formation method of the present invention provides a wafer edge protective film that has superior dry etching resistance compared to conventional wafer edge protective films, and exhibits excellent uniform coating even on wafer edges that are difficult to coat. In addition, by forming the wafer edge protective film on the surface of the back side of the peripheral edge, it is possible to avoid the risk of metal contamination in these areas, that is, metal contamination caused by the chemical solution supplied to the surface of the substrate during the formation of a coating film containing metal seeping into the peripheral edges of the back side, resulting in the formation of a coating film on these unintended back peripheral edges.

[0041] Furthermore, the pattern formation method of the present invention makes it possible to suppress particle generation from the wafer edge when dry etching the substrate to be processed. In addition, when forming the resist upper layer film, the chemical solution supplied to the surface of the substrate may spread to the peripheral edges of the back surface, and the coating film may be formed on these unintended peripheral edges of the back surface (for example, the edge surface on the back side), thus avoiding the risk of contamination of these areas. [Brief explanation of the drawing]

[0042] [Figure 1] These are diagrams illustrating some examples of wafer edges. [Figure 2] This is another diagram illustrating the wafer edge. [Figure 3] This is an explanatory diagram of an example of the wafer edge protection film formation method of the present invention (protection of the peripheral edge on the surface side). [Figure 4] This is an explanatory diagram of another example of the wafer edge protection film formation method of the present invention (protection of the peripheral edge on the front side and the peripheral edge on the back side). [Figure 5] This is an explanatory diagram of yet another example of the wafer edge protection film formation method of the present invention (protection of the peripheral edge on the front side and the peripheral edge on the back side). [Figure 6] This is an explanatory diagram illustrating an example of the pattern formation method of the present invention. [Figure 7] This is an explanatory diagram illustrating another example of the pattern formation method of the present invention. [Figure 8] This is an explanatory diagram of the area for evaluating the thickness of the wafer edge protective film. [Figure 9] This is an explanatory diagram of a method for evaluating the amount of surface metal impurities at the peripheral edge of a wafer. [Modes for carrying out the invention]

[0043] As described above, wafer edge protective films are used in the fine patterning process of semiconductor manufacturing to prevent particle generation from the wafer edge during etching. However, in recent semiconductor device manufacturing, with the increasing 3D nature of device structures, there has been a growing need for processes that form patterns with ultra-high aspect ratios on the substrate to be processed. This has created a demand for wafer edge protective films that can withstand the increased complexity and duration of the etching process.

[0044] The inventors of the present invention have diligently studied the above-mentioned problems and have been searching for a wafer edge protective film formation method that offers excellent dry etching resistance and coverage to the wafer edge. As a result, they have found that a wafer edge protective film formation method using a wafer edge protective film formation composition containing a polymer with a trifunctional structure and repeating units is extremely effective, leading to the completion of the present invention.

[0045] In other words, the present invention is a wafer edge protective film forming composition for forming a wafer edge protective film on the peripheral edge of a substrate, A polymer (A) represented by the following general formula (1), Solvent and This is a wafer edge protective film formation composition characterized by containing [a specific ingredient]. [ka] (In the formula, W is -SO2-, -C(=O)-, or -O-; R1, R2, R3, R4, and R5 are each independently a halogen atom, a monovalent organic group having 1 to 3 carbon atoms, or a hydroxyl group; and a, b, c, d, and e are each independently an integer from 0 to 4.)

[0046] The present invention will be described in detail below, but the present invention is not limited to these descriptions.

[0047] <Composition for forming wafer edge protective film> The wafer edge protective film forming composition of the present invention contains a polymer (A) represented by the following general formula (1) and a solvent. [ka] (In the formula, W is -SO2-, -C(=O)-, or -O-; R1, R2, R3, R4, and R5 are each independently a halogen atom, a monovalent organic group having 1 to 3 carbon atoms, or a hydroxyl group; and a, b, c, d, and e are each independently an integer from 0 to 4.)

[0048] The details of the polymer (A) and solvent contained in the wafer edge protective film forming composition according to the present invention will be described below.

[0049] [(A) Polymer] Because the polymer (A) is represented by the general formula (1), that is, because it contains the repeating unit represented by the general formula (1), it has a trifunctional structure with repeating polymer units, thus enabling the formation of a wafer edge protection film with high film density and excellent dry etching resistance. Such a wafer edge protection film can protect the wafer edge even when a pattern with a high aspect ratio is formed on the substrate to be processed.

[0050] In the above general formula (1), R1, R2, R3, R4, and R5 are each independently a halogen atom, a monovalent organic group having 1 to 3 carbon atoms, or a hydroxyl group, and a, b, c, d, and e are each independently integers from 0 to 4. From the viewpoint of dry etching resistance, it is preferable that a, b, c, d, and e are each 0.

[0051] In the above general formula (1), when R1, R2, R3, R4, and R5 are monovalent organic groups having 1 to 3 carbon atoms, examples include methyl groups, ethyl groups, propyl groups, etc.

[0052] The weight-average molecular weight of the polymer (A) is preferably 1,000 to 30,000, and more preferably 2,000 to 15,000.

[0053] A polymer (A) within this molecular weight range ensures solubility in solvents and suppresses sublimation during baking. In other words, it suppresses outgassing. Furthermore, the composition for forming wafer edge protective films exhibits good thermal fluidity, and when incorporated into materials, it provides a wafer edge protective film-forming composition with superior wafer edge coverage and defect suppression properties.

[0054] The wafer edge protective film forming composition of the present invention preferably contains the polymer (A) in an amount of 10% by mass or more, more preferably 15% by mass or more, and even more preferably 20% by mass or more.

[0055] Even in a dry etching process that forms fine patterns with an ultra-high aspect ratio on a substrate, a thick wafer edge protective film is necessary to protect the wafer edge from the etchant until the etching of the substrate is complete. A wafer edge protective film formation composition containing the polymer (A) in the above-described content makes it possible to form a thick wafer edge protective film according to the required characteristics.

[0056] [Method for producing polymer (A)] One means of obtaining the polymer (A) contained in the wafer edge protective film forming composition of the present invention is synthesis by a substitution reaction between phenols and aryl halides using a base catalyst as shown below. The phenols and aryl halides used in the synthesis can be used individually or in combination of two or more types. These can be appropriately selected and combined according to the required properties. In the following formula, W, R1, R2, R3, R4, R5, a, b, c, d, and e are the same as described above, and X is a halogen atom.

[0057] [ka]

[0058] Examples of base catalysts used in this process include inorganic base compounds such as sodium bicarbonate, sodium carbonate, potassium carbonate, calcium carbonate, cesium carbonate, sodium hydroxide, potassium hydroxide, sodium hydride, and potassium phosphate, as well as organic amine compounds such as triethylamine, pyridine, and N-methylmorpholine. One of these may be used alone, or two or more may be used in combination. The amount of these catalysts used is preferably in the range of 0.1 to 20 moles, more preferably 0.2 to 10 moles, per mole of hydroxyl groups of the raw material phenols.

[0059] The solvent used in this process is not particularly limited as long as it is inert to the above reaction. Examples include ether-based solvents such as diethyl ether, tetrahydrofuran, and dioxane; aromatic solvents such as benzene, toluene, and xylene; acetonitrile, dimethyl sulfoxide, N,N-dimethylformamide, N-methylpyrrolidone, and water. One of these can be used alone or in mixture. These solvents can be used in an amount of 0 to 2000 parts by mass per 100 parts by mass of the reaction raw materials. The reaction temperature is preferably from -50°C to the boiling point of the solvent, and more preferably from room temperature to 150°C. The reaction time is appropriately selected from 0.1 to 100 hours. In this specification, the solvent and the boiling point of the solvent refer to the boiling point at standard atmospheric pressure (1 atm = 10¹³.25 hPa).

[0060] Reaction methods include, for example, charging phenols and aryl halides together in a solvent; charging phenols and aryl halides individually or mixed, or dispersing or dissolving them individually or as a mixture, dropwise; and dispersing or dissolving either phenols or aryl halides in a solvent, then dropping the other dispersed or dissolved in the solvent. When charging multiple phenols and aryl halides, they may be mixed and reacted beforehand, or they may be reacted sequentially individually. When using a base catalyst, examples include charging phenols and aryl halides together in a single charge, or dispersing or dissolving the base catalyst beforehand before adding phenols and aryl halides dropwise.

[0061] The resulting reaction solution can also be recovered by diluting it with an organic solvent to remove unreacted raw materials, catalysts, etc., present in the system, followed by liquid-liquid washing.

[0062] The organic solvent used for liquid-liquid washing is not particularly limited as long as it can dissolve the above-mentioned phenols and aryl halides and separates into two layers when mixed with water. Examples include hydrocarbons such as hexane, heptane, benzene, toluene, and xylene; esters such as ethyl acetate, n-butyl acetate, and propylene glycol methyl ether acetate; ketones such as methyl ethyl ketone, methyl amyl ketone, cyclohexanone, and methyl isobutyl ketone; ethers such as diethyl ether, diisopropyl ether, methyl tert-butyl ether, ethylcyclopentyl methyl ether, and tetrahydrofuran; chlorinated solvents such as methylene chloride, chloroform, dichloroethane, and trichloroethylene; and mixtures thereof. The washing water used in this process can be what is commonly called deionized water or ultrapure water. One or more washes are sufficient, but washing more than 10 times does not necessarily guarantee the desired washing effect, so 1 to 5 washes are preferred.

[0063] During liquid-liquid washing, washing with a basic aqueous solution may be performed to remove unreacted raw materials or acidic components from the system. Examples of basics include alkali metal hydroxides, alkali metal carbonates, alkaline earth metal hydroxides, alkaline earth metal carbonates, ammonia, and organic ammonium compounds.

[0064] Furthermore, during liquid-liquid washing, washing with an acidic aqueous solution may be performed to remove unreacted raw materials, metal impurities, or basic components from the system. Examples of acids include inorganic acids such as hydrochloric acid, hydrobromic acid, sulfuric acid, nitric acid, phosphoric acid, and heteropoly acids, as well as organic acids such as oxalic acid, fumaric acid, maleic acid, trifluoroacetic acid, methanesulfonic acid, benzenesulfonic acid, p-toluenesulfonic acid, and trifluoromethanesulfonic acid.

[0065] The above-mentioned washing with a basic aqueous solution and liquid-liquid washing with an acidic aqueous solution may be performed individually or in combination. From the viewpoint of removing metal impurities, it is preferable to perform the liquid-liquid washing in the order of basic aqueous solution followed by acidic aqueous solution.

[0066] After the liquid-liquid washing with the above-mentioned basic aqueous solution and / or acidic aqueous solution, the mixture may be washed again with neutral water. As neutral water, deionized water or ultrapure water as described above may be used. One or more washes are sufficient, but fewer washes may not remove the basic or acidic components. Washing more than 10 times does not necessarily guarantee the desired effect, so 1 to 5 washes are preferable.

[0067] Furthermore, the reaction product after the liquid-liquid separation can be recovered as a powder by concentrating the solvent to dryness or crystallizing it under reduced pressure or atmospheric pressure. However, to improve the handling when preparing the composition for forming the wafer edge protective film, it is also possible to keep it in a solution of an appropriate concentration. The concentration at this time is preferably 0.1 to 50% by mass, and more preferably 0.5 to 30% by mass. At such a concentration, the viscosity does not tend to become high, thus preventing impairment of handling, and it is also economical because the amount of solvent does not become excessive.

[0068] The solvent used in this case is not particularly limited as long as it can dissolve the compound, but specific examples include ketones such as cyclohexanone and methyl-2-amyl ketone; alcohols such as 3-methoxybutanol, 3-methyl-3-methoxybutanol, 1-methoxy-2-propanol, and 1-ethoxy-2-propanol; ethers such as propylene glycol monomethyl ether, ethylene glycol monomethyl ether, propylene glycol monoethyl ether, ethylene glycol monoethyl ether, propylene glycol dimethyl ether, and diethylene glycol dimethyl ether; and esters such as propylene glycol monomethyl ether acetate, propylene glycol monoethyl ether acetate, ethyl lactate, ethyl pyruvate, butyl acetate, methyl 3-methoxypropionate, ethyl 3-ethoxypropionate, tert-butyl acetate, tert-butyl propionate, and propylene glycol monotert-butyl ether acetate. These can be used individually or in mixtures of two or more types.

[0069] The above reaction allows for the combination of phenols and aryl halides according to the required performance. Specifically, substituents that contribute to solvent solubility, etching resistance, and thermal fluidity can be introduced to meet desired performance requirements. A wafer edge protective film formation composition using these compounds as raw materials for polymer (A) can achieve a high level of both etching resistance and thermal fluidity.

[0070] [(B) Solvent] The solvent (organic solvent) that can be used in the above-mentioned wafer edge protective film forming composition is not particularly limited as long as it can dissolve the polymer (A), and it is preferable that it can also dissolve the crosslinking agent, surfactant, acid generator, and plasticizer described later.

[0071] Specifically, as a solvent, for example, solvents described in paragraphs

[0091] to

[0092] of Japanese Patent Publication No. 2007-199653 can be added. More specifically, propylene glycol monomethyl ether acetate, propylene glycol monomethyl ether, propylene glycol monoethyl ether, propylene glycol monopropyl ether, 2-heptanone, cyclopentanone, cyclohexanone, and γ-butyrolactone, or a mixture containing one or more of these, are preferably used.

[0072] The amount of solvent added should preferably be adjusted according to the desired thickness of the wafer edge protective film, but it is usually in the range of 100 to 50,000 parts by mass per 100 parts by mass of the polymer (A).

[0073] Furthermore, the above-mentioned wafer edge protective film forming composition may contain a high-boiling-point solvent having a boiling point of 180°C or higher at standard atmospheric pressure. In this case, the solvent included in the composition may be a mixture of one or more solvents having a boiling point of less than 180°C (hereinafter also referred to as "low-boiling-point solvents") and one or more solvents having a boiling point of 180°C or higher (hereinafter also referred to as "high-boiling-point solvents").

[0074] Examples of low-boiling point solvents include propylene glycol monomethyl ether acetate, propylene glycol monomethyl ether, propylene glycol monoethyl ether, propylene glycol monopropyl ether, 2-heptanone, cyclopentanone, and cyclohexanone.

[0075] As for the high-boiling point solvent, there are no particular restrictions on hydrocarbons, alcohols, ketones, esters, ethers, and chlorinated solvents, as long as they can dissolve each component of the wafer edge protective film forming composition of the present invention. Specific examples include 1-octanol, 2-ethylhexanol, 1-nonanol, 1-decanol, 1-undecanol, ethylene glycol, 1,2-propylene glycol, 1,3-butylene glycol, 2,4-pentanediol, 2-methyl-2,4-pentanediol, 2,5-hexanediol, 2,4-heptanediol, 2-ethyl-1,3-Hexanediol, diethylene glycol, dipropylene glycol, triethylene glycol, tripropylene glycol, glycerin, n-nonyl acetate, monohexyl ether, ethylene glycol mono-2-ethylhexyl ether, ethylene glycol monophenyl ether, ethylene glycol monobenzyl ether, diethylene glycol monoethyl ether, diethylene glycol monoisopropyl ether, diethylene glycol mono-n-butyl ether, diethylene glycol monoisobutyl ether, diethylene glycol monohexyl ether, diethylene glycol monophenyl ether, diethylene glycol monobenzyl ether, diethylene glycol diethyl ether, diethylene glycol dibutyl ether, diethylene glycol butyl methyl ether, triethylene glycol dimethyl ether, triethylene glycol monomethyl ether, triethylene glycol-n-butyl ether, triethylene glycol Dibutyl methyl ether, tetraethylene glycol dimethyl ether, dipropylene glycol monomethyl ether, dipropylene glycol mono-n-propyl ether, dipropylene glycol mono-n-butyl ether, tripropylene glycol dimethyl ether, tripropylene glycol monomethyl ether, tripropylene glycol mono-n-propyl ether, tripropylene glycol mono-n-butyl ether, ethylene glycol monoethyl ether acetate, ethylene glycol monobutyl ether acetate, diethylene glycol monomethyl ether acetate, diethylene glycol monoethyl ether acetate, diethylene glycol monobutyl ether acetate, triacetin, propylene glycol diacetate, dipropylene glycol methyl-n-propyl ether, dipropylene glycol methyl ether acetate, 1,4-butanediol diacetate, 1,3-butylene glycol diacetate, 1,Examples include 6-hexanediol diacetate, triethylene glycol diacetate, γ-butyrolactone, methyl benzoate, ethyl benzoate, propyl benzoate, butyl benzoate, dihexyl malonate, diethyl succinate, dipropyl succinate, dibutyl succinate, dihexyl succinate, dimethyl adipate, diethyl adipate, and dibutyl adipate, and these may be used individually or in combination of two or more.

[0076] The high-boiling-point solvent can be appropriately selected from the above-mentioned options, for example, according to the temperature at which the wafer edge protective film formation composition is heat-treated. The boiling point of the high-boiling-point solvent is preferably 180°C to 300°C, and more preferably 200°C to 300°C. With such a boiling point, there is no risk of excessive volatilization during baking (heat treatment) due to a boiling point that is too low, so sufficient thermal fluidity can be obtained during film formation, and it is believed that a wafer edge protective film with excellent uniform coating properties can be formed even on wafer edges, which are difficult to coat. Furthermore, with such a boiling point, there is no risk of the solvent remaining in the film without volatilizing after baking due to a boiling point that is too high, so there is no risk of adverse effects on film properties such as etching resistance.

[0077] Furthermore, when using a high-boiling point solvent, the amount blended is preferably 1 to 200 parts by mass, and more preferably 1 to 100 parts by mass, per 100 parts by mass of the polymer (A). Such a blending amount is preferable because it avoids the risk of the blending amount being too small to provide sufficient thermal fluidity during baking, or the blending amount being too large, which may remain in the film and lead to deterioration of film properties such as etching resistance.

[0078] The wafer edge protective film forming composition of the present invention further comprises the polymer (A) and solvent (B) described above, as well as an optional component: Crosslinking agent, Surfactants, Acid generator, and plasticizer It may contain one or more of the following. These optional components are described below.

[0079] [(C) Crosslinking agent] Furthermore, a crosslinking agent may be added to the above wafer edge protective film forming composition to enhance curability and improve dry etching resistance. The crosslinking agent is not particularly limited, and various known types of crosslinking agents can be widely used. Examples include melamine-based crosslinking agents, glycoluryl-based crosslinking agents, benzoguanamine-based crosslinking agents, urea-based crosslinking agents, β-hydroxyalkylamide-based crosslinking agents, isocyanurate-based crosslinking agents, aziridine-based crosslinking agents, oxazoline-based crosslinking agents, epoxy-based crosslinking agents, and phenol-based crosslinking agents (e.g., methylol or alkoxymethyl type crosslinking agents of polynuclear phenols). When a crosslinking agent is added, the amount added is preferably 5 to 100 parts by mass, more preferably 10 to 50 parts by mass, per 100 parts by mass of the polymer (A).

[0080] Examples of melamine-based crosslinking agents include hexamethoxymethylated melamine, hexasubtoxicmethylated melamine, their alkoxy and / or hydroxy-substituted derivatives, and their partial self-condensates. Examples of glycoluryl-based crosslinking agents include tetramethoxymethylated glycoluryl, tetrabutoxymethylated glycoluryl, their alkoxy and / or hydroxy-substituted derivatives, and their partial self-condensates. Examples of benzoguanamine-based crosslinking agents include tetramethoxymethylated benzoguanamine, tetrabutoxymethylated benzoguanamine, their alkoxy and / or hydroxy-substituted derivatives, and their partial self-condensates. Examples of urea-based crosslinking agents include dimethoxymethylated dimethoxyethyleneurea, its alkoxy and / or hydroxy-substituted derivatives, and their partial self-condensates. Examples of β-hydroxyalkylamide-based crosslinking agents include N,N,N',N'-tetra(2-hydroxyethyl)adipamide. Examples of isocyanurate-based crosslinking agents include triglycidyl isocyanurate and triallyl isocyanurate. Examples of aziridine-based crosslinking agents include 4,4'-bis(ethyleneiminocarbonylamino)diphenylmethane and 2,2-bishydroxymethylbutanol-tris[3-(1-aziridinyl)propionate]. Examples of oxazoline-based crosslinking agents include 2,2'-isopropylidenebis(4-benzyl-2-oxazoline), 2,2'-isopropylidenebis(4-phenyl-2-oxazoline), 2,2'-isopropylidenebis(4-phenyl-2-oxazoline), 2,2'-methylenebis-4,5-diphenyl-2-oxazoline, 2,2'-methylenebis-4-phenyl-2-oxazoline, 2,2'-methylenebis-4-tertbutyl-2-oxazoline, 2,2'-bis(2-oxazoline), 1,3-phenylenebis(2-oxazoline), 1,4-phenylenebis(2-oxazoline), and 2-isopropenyloxazoline copolymers.Examples of epoxy crosslinking agents include diglycidyl ether, ethylene glycol diglycidyl ether, 1,4-butanediol diglycidyl ether, 1,4-cyclohexanedimethanol diglycidyl ether, poly(glycidyl methacrylate), trimethylolethane triglycidyl ether, trimethylolpropane triglycidyl ether, and pentaerythritol tetraglycidyl ether.

[0081] Examples of polynuclear phenolic crosslinking agents include the compound represented by the following general formula (C-2).

[0082] [ka] (In the formula, Q is a single bond or a q-valent hydrocarbon group with 1 to 20 carbon atoms. R3 is a hydrogen atom or a methyl group. q is an integer from 1 to 5. Note that the definitions of the symbols in the formula apply only to this formula.)

[0083] In the above general formula (C-2), Q is a single bond or a q-valent hydrocarbon group having 1 to 20 carbon atoms. Q is an integer from 1 to 5, and is more preferably 2 or 3. When Q is a q-valent hydrocarbon group having 1 to 20 carbon atoms, Q is a q-valent hydrocarbon group obtained by removing q hydrogen atoms from a hydrocarbon having 1 to 20 carbon atoms. More specifically, examples of hydrocarbons having 1 to 20 carbon atoms in this case include methane, ethane, propane, butane, isobutane, pentane, cyclopentane, hexane, cyclohexane, methylpentane, methylcyclohexane, dimethylcyclohexane, trimethylcyclohexane, benzene, toluene, xylene, ethylbenzene, ethylisopropylbenzene, diisopropylbenzene, methylnaphthalene, ethylnaphthalene, and eicosane.

[0084] In the above general formula (C-2), R3 is a hydrogen atom or a methyl group, preferably a methyl group.

[0085] By including the compound represented by the above general formula (C-2) as a crosslinking agent, the crosslinking reactivity of the hydroxyl groups contained in the polymer (A) is increased, making it possible to improve the density of the film. This makes it possible to further improve the heat resistance properties of the wafer edge protective film formation composition.

[0086] Examples of compounds represented by the above general formula (C-2) include, but are not limited to, the following compounds. In the formula below, R3 is the same as above. When q=3 and R3=methyl group is satisfied, it is preferable from the viewpoint of curability, improved film thickness uniformity, and reduction of sublimation, and in particular, hexamethoxymethylated triphenolmethane, triphenolethane, 1,1,1-tris(4-hydroxyphenyl)ethane, or tris(4-hydroxyphenyl)-1-ethyl-4-isopropylbenzene are preferred.

[0087] [ka]

[0088] [ka]

[0089] The crosslinking agent can be used alone or in combination of two or more types. The crosslinking agent content is preferably 5% to 100% by mass, and more preferably 10% to 50% by mass, relative to 100% by mass of the polymer (A). If the amount added is 5% by mass or more, the crosslinking reaction with polymer (A) is promoted, and a dense film with excellent curability is formed, so a wafer edge protective film with good heat resistance, dry etching resistance, and film thickness uniformity can be formed. On the other hand, if the amount added is 100% by mass or less, the generation of sublimation products due to the slowing of the crosslinking reaction between polymer (A) and crosslinking agent (C) can be suppressed, and the generation of sublimation products and deterioration of film thickness uniformity can be reduced.

[0090] [(D) Surfactants] A surfactant (D) may be added to the above wafer edge protective film forming composition to improve the coatability in spin coating. As the surfactant, for example, those described in

[0142] to

[0147] of Japanese Patent Application Publication No. 2009-269953 can be used. When adding a surfactant, the amount to be added is preferably 0.001 to 20 parts by mass, more preferably 0.01 to 10 parts by mass, per 100 parts by mass of the polymer (A).

[0091] [(E) Acid Generator] (E) an acid generator may be added to the above wafer edge protective film forming composition to further promote the curing reaction. Acid generators include those that generate acid by thermal decomposition and those that generate acid by light irradiation, and either type can be added. Specifically, materials described in paragraphs

[0061] to

[0085] of Japanese Patent Application Publication No. 2007-199653 can be added, but are not limited to these.

[0092] The above-mentioned acid generating agent may be used alone or in combination of two or more types. When adding an acid generating agent, the amount added is preferably 0.05 to 50 parts by mass, more preferably 0.1 to 10 parts by mass, per 100 parts by mass of the polymer (A).

[0093] [(F) Plasticizer] Furthermore, to further improve film formation on the wafer edge, a plasticizer (G) may be added to the above-mentioned wafer edge protective film formation composition. The plasticizer is not particularly limited, and various known types of plasticizers can be widely used. Examples include low molecular weight compounds such as phthalates, adipicates, phosphates, trimelliticates, and citrates, as well as polymers such as polyethers, polyesters, and polyacetal polymers described in Japanese Patent Application Publication No. 2013-253227. When a plasticizer is added, the amount added is preferably 5 to 500 parts by mass, more preferably 10 to 200 parts by mass, per 100 parts by mass of the polymer (A).

[0094] [Other additives] Furthermore, in addition to the above optional components, additives may be added to the above wafer edge protective film forming composition to further improve film formation on the wafer edge. The above additive is not particularly limited as long as it contributes to improving thermal fluidity and imparts film formation on the wafer edge, but for example, a liquid additive having a polyethylene glycol or polypropylene glycol structure, or a pyrolytic polymer having a weight loss rate of 40% by mass or more between 30°C and 250°C and a weight-average molecular weight of 300 to 200,000 is preferably used. This pyrolytic polymer preferably contains repeating units having an acetal structure represented by the following general formulas (DP1) and (DP1a).

[0095] [ka] (In the formula, R6 is a hydrogen atom or a saturated or unsaturated monovalent organic group having 1 to 30 carbon atoms, which may be substituted. Y is a saturated or unsaturated divalent organic group having 2 to 30 carbon atoms. Note that the definitions of the symbols in the formula apply only to this formula.)

[0096] [ka] (In the formula, R 6a Y is an alkyl group having 1 to 4 carbon atoms. a (where n is a saturated or unsaturated divalent hydrocarbon group having 4 to 10 carbon atoms, and may have an ether bond. n represents the average number of repeating units, ranging from 3 to 500.)

[0097] As described above, the wafer edge protective film forming composition according to the present invention has a trifunctional structure in which polymer (A) has repeating polymer units, resulting in a wafer edge protective film with high film density and excellent dry etching resistance. This film can be formed with excellent uniform coating properties even on wafer edges, which are difficult to coat. Furthermore, the wafer edge protective film formed in this manner can reliably protect the wafer edge even when a pattern with a high aspect ratio is formed on the substrate to be processed.

[0098] <Method for forming a wafer edge protective film> In the wafer edge protective film formation method of the present invention, a wafer edge protective film is generally formed on the peripheral edge of the substrate by applying the wafer edge protective film formation composition according to the present invention to the peripheral edge of the substrate.

[0099] Specifically, the present invention relates to a wafer edge protection film formation method for forming a wafer edge protection film on the peripheral edge of a substrate, (i) A step of coating the peripheral edge of the substrate with the wafer edge protective film forming composition according to the present invention to obtain a coating film, (ii) A step of curing the coating film by heat or light irradiation to form the wafer edge protective film on the peripheral edge of the substrate, The present invention provides a method for forming a wafer edge protective film, characterized by including the following:

[0100] In this wafer edge protection film formation method, since the wafer edge protection film formation composition according to the present invention is used, a wafer edge protection film that can withstand the complexity and length of the etching process can be formed with a low defect rate.

[0101] The above-mentioned substrate is not particularly limited and can be any substrate such as Si, α-Si, p-Si, SiO2, SiN, SiON, W, TiN, and Al, or a substrate on which the workpiece layer has been deposited. The workpiece layer can be any low-k film and its stopper film such as Si, SiO2, SiON, SiN, p-Si, α-Si, W, W-Si, Al, Cu, and Al-Si, or an alloy thereof such as Hf, Zr, Cr, Ge, Ag, Au, In, Ga, As, Pd, Fe, Ta, Co, Mn, Mo, Ru, or an alloy thereof, amorphous carbon, an organic resist underlayer, a silicon-containing resist interlayer, or an inorganic hard mask. It can typically be formed to a thickness of 50-10,000 nm, particularly 100-5,000 nm. When depositing the workpiece layer, the substrate and the workpiece layer are made of different materials.

[0102] Here, as shown in Figure 2, the peripheral edge 1E of the substrate 1 is preferably within 15 mm, more preferably within 10 mm, and particularly preferably within 5 mm, from the apex 1a, which is the peripheral edge of the substrate 1. In this specification, the peripheral edge (wafer edge) 1E of the substrate refers to the area including the front edge surface 1b, bevel 1c, and apex 1a, as shown in Figure 1. Furthermore, the peripheral edge (wafer edge) 1E of the substrate may also include the back edge surface (back edge surface) 1e and bevel 1d. In this case, the portion including the front edge surface 1b and bevel 1c is also referred to as the front peripheral edge, and the portion including the back edge surface 1e and bevel 1d is also referred to as the back peripheral edge.

[0103] A wafer edge protective film formation method using the wafer edge protective film formation composition of the present invention can be used, for example, to form a wafer edge protective film on the peripheral edge on the surface side of a substrate by applying the wafer edge protective film formation composition of the present invention to the peripheral edge on the surface side of a substrate.

[0104] As shown in Figure 3(A), in step (i), a wafer (substrate) 1 is first placed on a rotatable spin chuck 2. The method for applying the wafer edge protective film forming composition of the present invention to the substrate 1 is not particularly limited, but suitable coating means such as a rotary coating method (spin coating method) in which the coating liquid is continuously discharged onto the substrate 1 which is rotating at a constant speed, or a spray method in which the coating liquid is sprayed onto the surface of the substrate 1 can be used. In this embodiment, a rotary coating method is used as a means for applying the wafer edge protective film forming composition to the edge surface 1b on the surface side of the peripheral edge of the wafer 1. Specifically, as shown in Figure 3(B), the wafer edge protective film forming composition 4 is coated (applied) to the edge surface 1b on the surface side of the peripheral edge 1E of the wafer 1 while the spin chuck 2 is rotated at a rotation speed corresponding to the viscosity of the wafer edge protective film forming composition 4 and the desired coating film thickness, thereby obtaining a coating film 4'. For example, as shown in Figure 3(B), the wafer edge protective film forming composition 4 is discharged from the tip of a supply nozzle 3 for supplying the wafer edge protective film forming composition 4 from above onto the edge surface 1b on the surface side of the peripheral edge 1E of the wafer 1, which rotates around a vertical axis in a horizontal plane. Then, in step (ii), the coating 4' is cured by heat or light irradiation to form a wafer edge protective film 4A on the edge surface 1b on the surface side of the peripheral edge 1E, as shown in Figure 3(C).

[0105] The wafer edge protection film formation method of the present invention may be a method of forming a wafer edge protection film on the peripheral edge (wafer edge) of a substrate on which a resist upper layer film pattern has been formed on the substrate to be processed, or a method of forming a wafer edge protection film on the substrate to be processed, then applying a resist upper layer film, and forming a resist upper layer film pattern by exposure or the like. Alternatively, a method of forming a resist upper layer film pattern using a multilayer resist method, such as a three-layer resist process, may be used, in which a wafer edge protection film is formed on the substrate to be processed, then a resist underlayer film, an inorganic hard mask, etc., is formed, and then a resist upper layer film is formed on top of them. Since the resist upper layer film on which the pattern has been formed is used as a mask to process the substrate to be processed, it is preferable if the wafer edge protection film can be formed on the wafer edge with a wafer edge protection film forming composition before dry etching is started, as this can suppress the generation of particles from the wafer edge.

[0106] Furthermore, when applying the wafer edge protective film forming composition of the present invention to the peripheral edge of a substrate, the coating may be dried after application by rotating a spin chuck at, for example, 10 to 4000 rpm.

[0107] Furthermore, the wafer edge protection film formation method of the present invention can also form a wafer edge protection film on the front and back edge surfaces (front and back peripheral edges) of the peripheral edge of a substrate by applying a wafer edge protection film formation composition to the front and back edge surfaces of the peripheral edge of the substrate.

[0108] In this example, as shown in Figure 4(A), in step (i), a wafer (substrate) 1 is first placed on a rotatable spin chuck 2. The method for applying the wafer edge protective film forming composition of the present invention to the substrate is not particularly limited, but suitable coating means such as a rotary coating method (spin coating method) in which the coating liquid of the wafer edge protective film forming composition is continuously discharged onto the substrate 1 which is rotating at a constant speed, or a spray method in which the coating liquid is sprayed onto the substrate surface can be used. In this embodiment, a rotary coating method is used as a means for applying the wafer edge protective film forming composition 4 to the front edge surface 1b and the back edge surface 1e of the peripheral edge end 1E of the wafer 1. Specifically, as shown in Figure 4(B), the wafer edge protective film forming composition 4 is coated (applied) to the front edge surface 1b and the back edge surface 1e of the peripheral edge end 1E of the wafer 1 while the spin chuck 2 is rotated at a rotation speed corresponding to the viscosity of the wafer edge protective film forming composition 4 and the desired coating film thickness, thereby obtaining a coating film 4'. More specifically, as shown in Figure 4(B), the wafer edge protective film forming composition 4 is discharged from the tip of a supply nozzle 3 for supplying the wafer edge protective film forming composition 4 from above onto the front edge surface 1b and the back edge surface 1e of the peripheral edge 1E of the wafer 1, which rotates around a vertical axis in a horizontal plane. Then, in step (ii), the coating 4' is cured by heat or light irradiation, and as shown in Figure 4(C), a wafer edge protective film 4A is formed on the front edge surface 1b and the back edge surface 1e of the peripheral edge 1E.

[0109] Furthermore, when applying the wafer edge protective film forming composition to the front and back edges of the peripheral edge of the substrate, the composition may be supplied to the front and back peripheral edges from separate supply nozzles. For example, in the embodiment shown in Figure 5, as shown in Figure 5(A), the wafer 1 is placed on the spin chuck 2, and then, as shown in Figure 5(B), the wafer edge protective film forming composition 4 is discharged from the tips of the upper supply nozzle 3A and lower supply nozzle 3B for supplying the wafer edge protective film forming composition 4 from above and below, respectively, onto the front edge surface 1b and the back edge surface 1e of the peripheral edge 1E of the rotating wafer 1, thereby forming a wafer edge protective film 4A on the front and back peripheral edges 1E, as shown in Figure 5(C). In addition, after application, the coating film 4' may be dried by rotating the spin chuck 2 at, for example, 10 to 4000 rpm.

[0110] The lower limit of the average thickness of the wafer edge protective film described above is preferably 100 nm for the portion covering the front edge surface, and more preferably 200 nm for the portion covering the bevel, and more preferably 200 nm for the portion covering the apex, and more preferably 200 nm for the portion covering the apex, and more preferably 300 nm for the portion covering the back edge surface, and more preferably 1 nm for the portion covering the back edge surface, and more preferably 5 nm for the portion covering the back edge surface.

[0111] The upper limit of the average thickness of the wafer edge protective film described above is preferably 5,000 nm for the portion covering the front edge surface, and more preferably 4,000 nm for the portion covering the bevel, preferably 5,000 nm for the portion covering the apex, and more preferably 6,000 nm for the portion covering the apex, and preferably 1,000 nm for the portion covering the back edge surface, and more preferably 500 nm for the portion covering the back edge surface.

[0112] The thickness of the wafer edge protection film can be appropriately selected according to the purpose of edge protection, but within the above range, it is possible to provide a wafer edge protection film formation method that can withstand the increasing complexity and length of etching processes, such as the pattern formation process with an ultra-high aspect ratio.

[0113] The wafer edge protection film formation method of the present invention preferably forms the wafer edge protection film only on the peripheral edge of the substrate (including the edge surface on the front side and the edge surface on the back side). This contributes to the rationalization of the semiconductor manufacturing process by reducing the amount of chemical solution consumed for the wafer edge protection film formation composition and simplifying the protective film formation process and the protective film removal process.

[0114] In the wafer edge protection film formation method of the present invention, in step (ii), the coating film of the wafer edge protection film forming composition applied to the peripheral edge of the substrate is cured by heat or light irradiation. In particular, a heat curing method is more preferred from the viewpoint of dry etching resistance.

[0115] When heat-curing a coating applied to the peripheral edge of a substrate, it is preferable to cure the coating by heat-treating it at a temperature of 100°C to 800°C, preferably 150°C to 600°C, for a period of 10 to 7,200 seconds, preferably 10 to 600 seconds, thereby forming a wafer edge protective film. From the viewpoint of reducing sublimation of the wafer edge protective film forming composition, it is more preferable to heat-treat at a temperature of 100°C to 450°C, and from the viewpoint of productivity, it is more preferable to heat-treat for a period of 10 to 300 seconds.

[0116] If the heat treatment is performed within the above temperature range, a wafer edge protective film with excellent dry etching resistance can be formed. Furthermore, when applying a coating material such as a photoresist to a workpiece substrate on which the wafer edge protective film has been formed, problems such as mixing of the wafer edge protective film and the resist film, or peeling of the protective film due to edge cut rinsing such as PGMEA, do not occur, which is preferable.

[0117] When curing a wafer edge protective film formation composition applied to the peripheral edge of a substrate by light irradiation, the light used for curing is not particularly limited and can be, for example, light or radiation with wavelengths in the range of high-energy ionizing radiation, near-ultraviolet light, far-ultraviolet light, visible light, infrared light, etc. Suitable radiations include, for example, microwaves, EUV, LEDs, semiconductor laser light, or laser light used in microfabrication of optical semiconductors, such as 248 nm KrF excimer laser light or 193 nm ArF excimer laser light.

[0118] These lights may be monochromatic or mixed light with multiple different wavelengths. The wavelength of the light may be, for example, 150 to 800 nm, preferably 150 to 600 nm, and more preferably 150 to 400 nm. The irradiation amount (irradiation energy) is not particularly limited and may be, for example, 1 to 10,000 mW, preferably 5 to 5,000 mW, and more preferably 10 to 1,000 mW. The irradiation time is also not particularly limited and may be, for example, 5 seconds to 60 minutes, preferably 10 seconds to 30 minutes, and more preferably 30 seconds to 10 minutes.

[0119] Furthermore, a combination of heat treatment and light irradiation may also be used.

[0120] Coating the peripheral edges (wafer edges) is more difficult to achieve a uniform film compared to coating the wafer surface, and therefore, wafer edge protective film formation compositions require excellent film-forming properties. On the other hand, with the wafer edge protective film formation method of the present invention, since the peripheral edges of the substrate to be processed are protected using a wafer edge protective film formation composition containing the polymer (A) represented by the general formula (1) above, it is possible to repair the roughness of the film that occurs during coating by thermal fluid, and a wafer edge protective film formation method with excellent uniform coating properties can be provided.

[0121] <Pattern Formation Method> Furthermore, in the present invention, as a pattern formation method of the first embodiment, a wafer edge protective film is formed on the peripheral edge of a workpiece substrate on which a film having a pattern is formed, and a pattern is formed on the workpiece substrate, (I-1) A step of applying the wafer edge protective film forming composition according to the present invention to the peripheral edge of a workpiece substrate on which a film having a pattern has been formed to obtain a coating film, (I-2) A step of curing the coating film by heat treatment or light irradiation to form a wafer edge protective film on the peripheral edge of the substrate, (I-3) A step of forming a pattern on the substrate to be processed by dry etching using the film having the pattern as a mask, (I-4) A step of removing the wafer edge protective film, The present invention provides a pattern forming method characterized by including the following:

[0122] An example of a first embodiment of the pattern formation method of the present invention will be specifically described with reference to Figure 6. First, in step (I-1), a workpiece substrate 1 on which a patterned film 5 is formed is placed on a spin chuck 2 (Figure 6(A)), and the above-mentioned wafer edge protection film forming composition 4 of the present invention is applied to the peripheral edge 1E of the workpiece substrate 1 from a supply nozzle 3 to obtain a coating film 4' (Figure 6(B)). Next, in step (I-2), the coating film 4' is cured by heat treatment or light irradiation to form a wafer edge protection film 4A on the peripheral edge 1E of the workpiece substrate 1 (Figure 6(C)). Next, in step (I-3), a pattern 1A is formed on the workpiece substrate 1 by dry etching using the patterned film 5 as a mask (Figure 6(D)). Then, in step (I-4), the patterned film 5 is removed (Figure 6(E)), followed by the removal of the wafer edge protection film 4A (Figure 6(G)). This allows a pattern 1A to be formed on the workpiece substrate 1.

[0123] If the wafer edge is damaged by dry etching, particles generated from the wafer edge may scatter toward the center of the wafer, potentially causing pattern bridging or disconnection. On the other hand, with the pattern formation method of the present invention, the peripheral portion 1E of the substrate to be processed 1 (wafer edge; including the peripheral edge on the front side and the peripheral edge on the back side) is protected by the wafer edge protective film 4A. Therefore, the generation of defects from the wafer edge 1E during the dry etching process can be suppressed, and it is possible to form a pattern on the substrate to be processed 1 with high precision and low defects.

[0124] The patterned film formed on the substrate to be processed is not particularly limited, but examples include a resist upper layer film, a silicon-containing resist interlayer film, an inorganic hard mask interlayer film, and a resist lower layer film. Since the substrate to be processed is carried out using the patterned film as a mask, if a wafer edge protective film can be formed on the wafer edge with a wafer edge protective film forming composition before dry etching is started, particle generation from the wafer edge can be suppressed, so the patterned film is preferably a resist upper layer film.

[0125] The pattern formation method of the present invention is suitably used in multilayer resist processes such as, for example, a silicon-containing two-layer resist process, a three-layer resist process using a resist underlayer film and a silicon-containing resist interlayer film, or a four-layer resist process using a resist underlayer film, an inorganic hard mask interlayer film and an organic thin film, or a silicon-free two-layer resist process. Therefore, a silicon-containing resist interlayer film, an inorganic hard mask interlayer film, an organic thin film, a resist underlayer film, etc., may be formed between the resist upper layer film on which the pattern is formed and the substrate to be processed, and a resist underlayer film, etc., may be formed between the silicon-containing resist interlayer film or inorganic hard mask interlayer film on which the pattern is formed and the substrate to be processed.

[0126] When forming a resist underlayer, the resist underlayer can be formed using methods such as coating-type organic underlayer materials, CVD, or ALD. Examples of coating-type organic underlayer film materials include those listed in Japanese Patent Publication No. 2012-1687, 2012-77295, 2004-264710, 2005-043471, 2005-250434, 2007-293294, 2008-65303, 2004-205685, 2007-171895, 2009-14816, 2007-199653, 2008-274250, 2010-122656, and 2012-214720. Examples of resins and compositions shown in Japanese Patent Publication No. 2014-29435, International Publication No. WO2012 / 077640, International Publication No. WO2010 / 147155, International Publication No. WO2012 / 176767, Japanese Patent Publication No. 2005-128509, Japanese Patent Publication No. 2006-259249, Japanese Patent Publication No. 2006-259482, Japanese Patent Publication No. 2006-293298, Japanese Patent Publication No. 2007-316282, Japanese Patent Publication No. 2012-145897, Japanese Patent Publication No. 2017-119671, Japanese Patent Publication No. 2019-44022, etc., can be cited. The resist underlayer material may also contain metal atoms such as Sn, In, Ga, Ge, Al, Ce, La, Cs, Zr, Hf, Ti, Bi, Sb, and Zn.

[0127] When forming an inorganic hard mask interlayer, a silicon oxide film, silicon nitride film, or silicon oxynitride film (SiON film) is formed by methods such as CVD or ALD. Methods for forming nitride films are described in Japanese Patent Application Publication No. 2002-334869 and WO2004 / 066377. The thickness of the inorganic hard mask interlayer is preferably 5 to 3,000 nm, more preferably 10 to 2,000 nm, and among these, the SiON film, which has a high effect as an anti-reflective film, is most preferably used for ArF exposure applications.

[0128] As the silicon-containing resist interlayer, a polysilsesquioxane-based resist interlayer can be suitably used. A polysilsesquioxane-based resist interlayer can easily be given an anti-reflective effect in excimer exposure, which suppresses reflected light during pattern exposure of the resist upper layer and has the advantage of excellent resolution. In particular for 193nm exposure, if a material containing many aromatic groups is used as the resist underlayer, the k value becomes high and substrate reflection increases, but by suppressing reflection with the resist interlayer, substrate reflection can be reduced to 0.5% or less. As a resist interlayer with an anti-reflective effect, anthracene is preferably used for 248nm and 157nm exposure, and polysilsesquioxane, which has phenyl groups or absorbent groups having silicon-silicon bonds pendanted to it and is crosslinked with acid or heat, is preferably used for 193nm exposure.

[0129] In the pattern formation method described above, the resist upper layer film can be either positive or negative, and the same photoresist composition as commonly used can be used. Furthermore, the photoresist composition may contain metal atoms such as Sn, In, Ga, Ge, Al, Ce, La, Cs, Zr, Hf, Ti, Bi, Sb, and Zn. When forming the resist upper layer film using the above photoresist composition, the method may be spin coating or deposition by CVD or ALD.

[0130] When forming a photoresist composition by spin coating, pre-baking is performed after resist coating, preferably at a temperature of 60-180°C for 10-300 seconds. Subsequently, exposure is performed according to a conventional method, followed by post-exposure baking (PEB) and development to obtain the resist pattern. The thickness of the resist upper layer film is not particularly limited, but is preferably 10-500 nm, and especially preferably 20-400 nm.

[0131] When a photoresist composition is formed by vapor deposition by CVD or ALD, the resist composition is an EUV-sensitive metal oxide film, and the metal is selected from Sn, Zr, Hf, Ti, Bi, Sb, etc., with Sn being preferred due to its excellent EUV photosensitivity. The metal oxide-containing film may be a photosensitive organometallic oxide film such as an organotin oxide (e.g., haloalkylSn, alkoxyalkylSn, or amidealkylSn). Some specific examples of suitable precursors include trimethyltin chloride, dimethyltin dichloride, methyltin trichloride, tris(dimethylamino)methyltin(IV), and (dimethylamino)trimethyltin(IV).

[0132] The metal oxide film may be deposited by PECVD or PEALD using, for example, a Lam Vector® tool, and in the ALD example, the Sn oxide precursor is separated from the O precursor / plasma. The deposition temperature is preferably in the range of 50°C to 600°C. The deposition pressure is preferably between 100 and 6000 mTorr. The flow rate of the metal oxide-containing film precursor liquid (e.g., organotin oxide precursor) may be 0.01 to 10 cm, and the gas flow rate (CO2, CO, Ar, N2) may be 100 to 10000 sccm. The plasma power may be 200 to 1000 W per 300 mm wafer station using a high-frequency plasma (e.g., 13.56 MHz, 27.1 MHz, or higher frequency). The deposition thickness is preferably 100 to 2000 Å.

[0133] Examples of exposure light include high-energy rays with wavelengths of 300 nm or less, specifically excimer lasers of 248 nm, 193 nm, or 157 nm, soft X-rays of 3 to 20 nm, electron beams, and X-rays.

[0134] Regarding the method for removing the wafer edge protective film from the wafer edge of the substrate after pattern formation, removal by dry etching is preferred. When removing the wafer edge protective film by dry etching, since the wafer edge protective film is composed of an organic film, it can be removed by etching using an oxygen-based or hydrogen-based gas.

[0135] For example, if the substrate contains Si, SiO2, SiN, SiON, or a silica-based low-dielectric constant insulating film, it will be resistant to etching using oxygen-based or hydrogen-based gases, allowing the wafer edge protective film to be removed without damaging the wafer edge of the substrate being processed.

[0136] If the wafer edge is damaged by dry etching, particles generated from the wafer edge may scatter toward the center of the wafer, potentially causing pattern bridging or disconnections. However, with the pattern formation method of the present invention, the peripheral edges (including, for example, the edge surfaces on the front and back sides) are protected by a wafer edge protective film. This suppresses the generation of defects from the wafer edge during the dry etching process, enabling the formation of patterns on the workpiece with high precision and low defects. Furthermore, it is possible to suppress the risk of metal contamination of the wafer edge by particles generated when etching a film containing metal atoms and adhering to the wafer edge.

[0137] In addition, the present invention provides a pattern formation method for the second embodiment, which involves forming a wafer edge protective film on the peripheral edge of a substrate to be processed, and forming a pattern on the substrate to be processed, (II-1) A step of applying the wafer edge protective film forming composition of the present invention to the peripheral edge of the substrate to be processed to obtain a coating film, (II-2) A step of curing the coating film by heat treatment or light irradiation to form a wafer edge protective film on the peripheral edge of the substrate to be processed, (II-3) A step of forming a resist upper layer film pattern on the substrate to be processed, and using the resist upper layer film pattern as a mask, forming a pattern on the substrate to be processed by dry etching, (II-4) A step of removing the wafer edge protective film, The present invention provides a pattern forming method characterized by including the following:

[0138] An example of a pattern formation method according to a second embodiment of the present invention will be specifically described with reference to Figure 7. First, in step (II-1), the above-described wafer edge protective film forming composition 4 of the present invention is applied from the supply nozzle 3 to the peripheral edge 1E of the workpiece substrate 1 placed on the spin chuck 2 to obtain a coating film 4' (Figure 7(A)). Note that a workpiece layer 6 such as a silicon-containing resist interlayer, an inorganic hard mask interlayer, an organic thin film, or a resist underlayer may be formed on the workpiece substrate 1 (Figure 7(A)). Next, in step (II-2), the coating film 4' of the wafer edge protective film forming composition 4 is cured by heat treatment or light irradiation to form a wafer edge protective film 4A on the peripheral edge 1E (Figure 7(B)). Next, in step (II-3), a resist upper layer film 7 is formed on the workpiece layer 6 (Figure 7(C)), and exposure or the like is performed to form a resist upper layer film pattern 7A (Figure 7(D)). Next, using the resist upper layer pattern 7A as a mask, pattern 6A is formed on the workpiece layer 6 by dry etching (Figure 7(E)), and then, using pattern 6A as a mask, pattern 1A is formed on the workpiece substrate 1 by dry etching (Figure 7(F)). Then, in step (II-4), the workpiece layer 6 having pattern 6A is removed (Figure 7(G)), followed by the removal of the wafer edge protective film 4A (Figure 7(H)).

[0139] The above pattern formation method makes it possible to suppress particle generation from the wafer edge when dry etching the substrate to be processed. Furthermore, when forming the resist upper layer film, the chemical solution supplied to the surface of the substrate flows to the peripheral edges of the back surface, and the risk of contamination of these unintended areas due to the formation of a coating film on these back surface edges can be avoided.

[0140] When forming a resist upper layer film using the above photoresist composition, a spin coating method is preferred. When forming a photoresist composition by the spin coating method, pre-baking is performed after resist coating, preferably at 60 to 180°C for 10 to 300 seconds. Thereafter, exposure is performed according to a conventional method, followed by post-exposure baking (PEB) and development to obtain a resist upper layer film pattern. The thickness of the resist upper layer film is not particularly limited, but can be, for example, 10 to 500 nm, and particularly preferably 20 to 400 nm.

[0141] In the pattern formation method described above, the resist upper layer film can be either positive or negative, and the same photoresist compositions and metal atom-containing photoresist compositions commonly used can be used.

[0142] When the resist upper layer film used in the pattern formation method described above is a composition containing metal atoms, the pattern formation method using the wafer edge protection film forming composition of the present invention is particularly effective in suppressing contamination of the wafer edges on both the front and back sides. For this reason, it is preferable that the resist upper layer film be formed from a composition containing metal atoms.

[0143] If the above photoresist composition contains metal atoms, the metal atoms are preferably Sn, In, Ga, Ge, Al, Ce, La, Cs, Zr, Hf, Ti, Bi, Sb, or Zn, and are particularly preferably Sn, Zr, Hf, or Ti.

[0144] Examples of exposure light include high-energy rays with wavelengths of 300 nm or less, specifically excimer lasers of 248 nm, 193 nm, or 157 nm, soft X-rays of 3 to 20 nm, electron beams, and X-rays. Among these, extreme ultraviolet light with wavelengths of 3 to 15 nm is preferred.

[0145] In the pattern formation method described above, a silicon-containing resist interlayer, an inorganic hard mask interlayer, an organic thin film, a resist underlayer, etc., may be formed between the substrate to be processed and the resist upper layer film.

[0146] The above pattern formation method may include the steps of applying the wafer edge protection formation composition of the present invention to the peripheral edge of a substrate to be processed, a substrate on which a resist underlayer film is formed, a substrate on which a resist underlayer film and a silicon-containing resist interlayer film or inorganic hard mask are formed, a substrate on which a resist underlayer film, an inorganic hard mask and an organic thin film are formed, or a substrate on which a silicon-containing resist interlayer film or inorganic hard mask is formed to obtain a coating film, curing the coating film to form a wafer edge protection film, and then applying a resist top layer film.

[0147] The pattern formation method of the present invention is suitably used in multilayer resist processes such as a silicon-containing two-layer resist process, a three-layer resist process using a resist underlayer film and a silicon-containing resist interlayer film, a four-layer resist process using a resist underlayer film, an inorganic hard mask interlayer film and an organic thin film, and a silicon-free two-layer resist process.

[0148] Regarding the method for removing the wafer edge protective film of the present invention from the wafer edge of the substrate after pattern formation on the substrate, removal by dry etching is preferred. When removing by dry etching, since the wafer edge protective film is composed of an organic film, it can be removed by etching using an oxygen-based or hydrogen-based gas.

[0149] For example, if the substrate is a Si, SiO2, SiN, SiON, or silica-based low-dielectric-constant insulating film, it will be resistant to etching using oxygen-based or hydrogen-based gases, allowing the wafer edge protective film to be removed without damaging the wafer edge of the substrate being processed.

[0150] When a wafer edge is damaged by dry etching, particles generated from the wafer edge can scatter toward the center of the wafer, potentially causing pattern bridging or disconnections. However, with the pattern formation method of the present invention, the peripheral edges of the substrate to be processed (including, for example, the edge surfaces on the front and back sides) are protected by a wafer edge protective film with excellent dry etching resistance. This suppresses the generation of defects from the wafer edge during the dry etching process, enabling the formation of patterns on the substrate with high precision and low defects. Furthermore, when the resist upper layer film used in the pattern formation method is a composition containing metal atoms, the pattern formation method using the wafer edge protective film forming composition of the present invention is particularly effective in suppressing contamination of the wafer edges on both the front and back sides. [Examples]

[0151] The present invention will be specifically described below with reference to examples and comparative examples, but the present invention is not limited to these descriptions. The molecular weight and dispersion were measured by the following method. The weight-average molecular weight (Mw) and dispersion (Mw / Mn) in polystyrene terms were determined by gel permeation chromatography (GPC) using tetrahydrofuran as the eluent.

[0152] [Example of combination] In the following synthesis examples, one of the phenols (a-1) to (a-2) and one of the difluoro compounds (aryl halides) (b-1) to (b-3) shown below were used. Furthermore, the comparative synthesis starting materials (r-1) to (r-3) shown below were used for the comparative compounds (R-1) to (R-2).

[0153] The phenols used are (a-1) and (a-2) shown below.

[0154] [ka]

[0155] The difluoro compounds used are (b-1) to (b-3) below.

[0156] [ka]

[0157] The synthetic raw materials used for comparative examples, (r-1) to (r-3), are shown below. [ka]

[0158] [Synthesis Example 1] Synthesis of Polymer (A-1) 8.8 g of phenol (a-1), 11.4 g of difluoro compound (b-1), and 12.4 g of potassium carbonate were added to 80 g of N-methylpyrrolidone, and the reaction was carried out under a nitrogen atmosphere at an internal temperature of 150°C for 15 hours. After cooling to room temperature, 50 ml of methyl isobutyl ketone, 50 ml of tetrahydrofuran, and 100 ml of pure water were added to the reaction solution and homogenized, and the separated aqueous layer was removed. The organic layer was then washed twice with 100 ml of 3% nitric acid aqueous solution and five times with 100 ml of pure water, and the organic layer was dried under reduced pressure. 30 g of THF was added to the residue to make a homogeneous solution, and crystallization was performed with 150 g of methanol. The precipitated crystals were separated by filtration and washed twice with 30 g of methanol to recover the crystals. Polymer (A-1) was obtained by vacuum drying the recovered crystals at 70°C.

[0159] The weight-average molecular weight (Mw) and dispersion (Mw / Mn) were determined using GPC, and the following results were obtained. (A-1): Mw=22230, Mw / Mn=6.91

[0160] [ka]

[0161] [Synthesis Example 2] Synthesis of Polymer (A-2) 8.8 g of phenols (a-1), 9.8 g of difluoro compound (b-2), and 12.4 g of potassium carbonate were added to 80 g of N-methylpyrrolidone, and the reaction was carried out under a nitrogen atmosphere at an internal temperature of 150°C for 15 hours. After cooling to room temperature, 50 ml of methyl isobutyl ketone, 50 ml of tetrahydrofuran, and 100 ml of pure water were added to the reaction solution and homogenized, and the separated aqueous layer was removed. The organic layer was then washed twice with 100 ml of 3% nitric acid aqueous solution and five times with 100 ml of pure water, and the organic layer was dried under reduced pressure. 30 g of THF was added to the residue to make a homogeneous solution, and crystallization was performed with 150 g of methanol. The precipitated crystals were separated by filtration, washed twice with 30 g of methanol, and the crystals were recovered. Polymer (A-2) was obtained by vacuum drying the recovered crystals at 70°C.

[0162] The weight-average molecular weight (Mw) and dispersion (Mw / Mn) were determined using GPC, and the following results were obtained. (A-2): Mw=18990, Mw / Mn=5.83

[0163] [ka]

[0164] [Synthesis Example 3] Synthesis of Polymer (A-3) 9.2 g of phenols (a-2), 9.3 g of difluoro compound (b-3), and 12.4 g of potassium carbonate were added to 80 g of N-methylpyrrolidone, and the reaction was carried out under a nitrogen atmosphere at an internal temperature of 150°C for 15 hours. After cooling to room temperature, 50 ml of methyl isobutyl ketone, 50 ml of tetrahydrofuran, and 100 ml of pure water were added to the reaction solution and homogenized, and the separated aqueous layer was removed. The organic layer was then washed twice with 100 ml of 3% nitric acid aqueous solution and five times with 100 ml of pure water, and the organic layer was dried under reduced pressure. 30 g of THF was added to the residue to make a homogeneous solution, and crystallization was performed with 150 g of methanol. The precipitated crystals were separated by filtration, washed twice with 30 g of methanol, and the crystals were recovered. Polymer (A-3) was obtained by vacuum drying of the recovered crystals at 70°C.

[0165] The weight-average molecular weight (Mw) and dispersion (Mw / Mn) were determined using GPC, and the following results were obtained. (A-3): Mw=9980, Mw / Mn=3.39

[0166] [ka]

[0167] [Comparative Synthesis Example 1] Synthesis of comparative polymer (R-1) 45.6 g of comparative synthetic raw material (r-1), 57.4 g of comparative synthetic raw material (r-2), 55.3 g of dried potassium carbonate, 400 mL of DMA (dimethylacetamide), and 50 mL of toluene were charged into a 2 L volume four-neck round-bottom flask equipped with a condenser, nitrogen sweep, Dean-Stark trap (filled with toluene), and overhead mechanical stirrer. This mixture was mixed at room temperature for 10 minutes. The reaction mixture was heated on a heated mantle at 150 °C for 9.5 hours. The reaction mixture was then cooled to below 50 °C and filtered through filter paper. The filtered solution (pH 9-10) was neutralized to pH 7-6 with 10% HCl and then poured into a 5 L flask with deionized water (3200 mL). A precipitate formed. This mixture was mixed for 30 minutes and then allowed to settle overnight. Water was decanted (3400 mL), and 1 L of THF was added to the viscous solid. After mixing, the mixture was transferred to a beaker and heated on a hot plate to reduce its volume to 1 liter. This solution was added to 12 liters of hexane and mixed for 1 hour, after which the polymer was precipitated by allowing the solid matter to settle. The solution was filtered through filter paper and washed with hexane. The polymer was dried in a vacuum furnace at 80°C for two days to obtain 85 g of comparative polymer (R-1).

[0168] The weight-average molecular weight (Mw) and dispersion (Mw / Mn) were determined using GPC, and the following results were obtained. (R-1): Mw=9769, Mw / Mn=2.23

[0169] [ka]

[0170] [Comparative Synthesis Example 2] Synthesis of comparative polymer (R-2) 22.8 g of comparative synthesis raw material (r-1), 21.8 g of comparative synthesis raw material (r-3), 27.6 g of potassium carbonate, 200 mL of dimethylacetamide, and 27.5 mL of toluene were charged into a 500 mL four-neck round-bottom flask equipped with a stirrer, condenser, thermowatch, Dean-Stark trap filled with toluene, and nitrogen purge. The solution was mixed at room temperature for 10 minutes, and then the temperature was set to 150 °C. Since reflux begins at 147 °C, the solution was maintained under reflux for 90 minutes. The solution was then cooled to below 70 °C, filtered to remove salts, and the filtrate was neutralized with a small amount of 10% HCl. The solution was added to 1600 mL of deionized water to precipitate, mixed for 1 hour, and then allowed the solids to settle. The aqueous layer was poured out, and then 500 mL of tetrahydrofuran was added. The solution was mixed for 30 minutes, transferred to a beaker, and then reduced to 600 mL on a hot plate. The polymer was precipitated by placing it in 3 liters of hexane, filtered, washed, dried, and then left overnight in a vacuum furnace to obtain 37 g of comparative polymer (R-2).

[0171] The weight-average molecular weight (Mw) and dispersion (Mw / Mn) were determined using GPC, and the following results were obtained. (R-2): Mw=15125, Mw / Mn=2.10

[0172] [ka]

[0173] [(C) Crosslinking agent] The following are the (C) crosslinking agents used in the wafer edge protective film formation composition.

[0174] [ka]

[0175] [High boiling point solvents] The high-boiling point solvent (diethylene glycol monobenzyl ether: boiling point 302°C) used in the wafer edge protective film formation composition is shown below.

[0176] [ka]

[0177] [(E) Thermal acid generator] The (E) thermal acid generator used in the wafer edge protective film formation composition is shown below.

[0178] [ka]

[0179] [Preparation of EPF-1 composition for wafer edge protective film formation] As polymer (A), polymer (A-1) was dissolved in cyclohexanone (CyHO) as the main solvent containing 0.5% by mass of surfactant FC-4430 (manufactured by Sumitomo 3M Co., Ltd.) in the proportions shown in Table 1, and a wafer edge protective film forming composition (EPF-1) was prepared by filtering through a 0.02 μm membrane filter.

[0180] [Preparation of wafer edge protective film formation compositions EPF-2 to 6 and comparative examples EPF-1 to 3] Except for the types and contents of each component shown in Table 1, each composition was prepared in the same manner as the preparation of the wafer edge protective film formation composition EPF-1. In Table 1, "-" indicates that the corresponding component was not used.

[0181] [Table 1]

[0182] [Examples 1-1 to 6, Comparative Examples 1-1 to 3: Evaluation of wafer edge protective film thickness] Each of the above-mentioned wafer edge protective film formation compositions (EPF-1 to 6 and Comparative Examples EPF-1 to 3) was applied by rotation to the peripheral edge (wafer edge) of a silicon wafer, forming a coating film on the wafer edge. The coating film was then baked for 60 seconds at the temperatures shown in Table 2 to cure the coating film formed on the wafer edge. Thus, each wafer edge protective film was formed.

[0183] The film thickness of each wafer edge protective film formed on the wafer edge was evaluated by cross-sectional observation using a Hitachi, Ltd. electron microscope (S-4700). As shown in Figure 8, the evaluation was performed on the thickness 4s of the portion covering the surface of the wafer edge (1.5 mm from apex 1a toward the wafer center) and the thickness 4a of the portion covering apex 1a.

[0184] [Table 2]

[0185] As shown in Table 2, the wafer edge protective film formation method using the wafer edge protective film formation compositions (EPF-1 to EPF-6) of the present invention can effectively cover the wafer from the edge surface to the apex.

[0186] [Examples 2-1 to 6, Comparative Examples 2-1 to 3: Etching resistance evaluation] Each of the wafer edge protective film formation compositions (EPF-1 to 6 and Comparative Examples EPF-1 to 3) prepared above was applied to the surface of a silicon substrate to obtain a coating film. Each coating film was baked in air at the temperatures shown in Table 3 for 60 seconds to form a 1200 nm protective film. The thickness of the formed protective film was measured as film thickness A. Next, etching was performed for 1 minute using CF4 gas and O2 gas under the following conditions using the Telius etching apparatus manufactured by Tokyo Electron, and the thickness of the protective film after etching was measured as film thickness B. The film thickness etched per minute (film thickness B - film thickness A) was calculated as the etching resistance. In the case of CF4 gas etching, a film thickness difference of less than 75 nm between film thickness B and film thickness A was classified as "A" (excellent), a difference of 75 nm or more and less than 80 nm was classified as "B" (good), and a difference of 80 nm or more was classified as "C" (poor). In the case of O2 gas etching, a difference in film thickness between film thickness B and film thickness A was classified as "A" (excellent), between 110 nm and 120 nm as "B" (good), and between 120 nm and 120 nm as "C" (poor). The results are shown in Table 3.

[0187] Dry etching conditions with CF4 gas Chamber pressure: 100mT RF Power (Top): 500W RF Power (Lower): 400W CF4 gas flow rate: 300 sccm Time: 60sec

[0188] Dry etching conditions using O2 gas Chamber pressure: 15mT RF Power (Top): 300W RF Power (Bottom): 50W O2 gas flow rate: 30 sccm N2 gas flow rate: 270 sccm Time: 60sec

[0189] [Table 3]

[0190] As shown in Table 3, the wafer edge protective film forming compositions (EPF-1 to EPF6) of the present invention were found to have excellent dry etching resistance to CF4 gas and O2 gas. The polymer (A) represented by general formula (1) has a trifunctional structure and repeating polymer units, resulting in high film density, which is thought to contribute to the high dry etching resistance.

[0191] On the other hand, wafer edge protective film formation compositions that do not have a trifunctional structure like that of general formula (1) (comparative EPF-1 to 3) showed insufficient dry etching resistance. When comparing EPF-1, which has the same diphenylsulfone structure, with comparative EPF-1, or when comparing EPF-2, which has the same benzophenone structure, with comparative EPF-2, EPF-1 and EPF-2, which have the trifunctional structure shown by general formula (1), showed superior dry etching resistance. Therefore, it is inferred that the trifunctional structure shown by general formula (1) contributes to the formation of a dense cured film.

[0192] As described above, the wafer edge protective film formation compositions (EPF-1 to EPF-6) used in the wafer edge protective film formation method of the present invention have been found to have excellent dry etching resistance to CF4 gas and O2 gas. Therefore, the wafer edge protective film formation method using these compositions is expected to function as a wafer edge protective film that can protect the wafer edge from etchants until the etching of the substrate is completed, even in dry etching processes that form high aspect ratio fine patterns, such as those found in 3D-NAND memory, where high stacking is progressing.

[0193] [Examples 3-1 to 3, Comparative Examples 3-1 to 3: Surface metal impurity content at the wafer periphery] The amount of metal impurities introduced to the wafer periphery by the metal-containing resist upper layer film was evaluated. The metal-containing compounds (M-1) to (M-3) used in the evaluation were synthesized as follows.

[0194] [Synthesis of metal-containing compounds (M-1)] 340 g of titanium tetrabutoxide was dissolved in 500 g of 1-butanol. A mixed solution of 27 g of deionized water and 500 g of 1-butanol was added dropwise to this solution over 2 hours at room temperature while stirring. 1,200 g of propylene glycol monomethyl ether acetate (PGMEA) was added to the resulting solution, and the mixture was heated at 50°C under reduced pressure until no more 1-butanol distilled off, yielding 1,000 g of a PGMEA solution of the titanium-containing compound (metal-containing compound (M-1)). The polystyrene-based molecular weight was measured to be Mw = 1,050.

[0195] [Synthesis of metal-containing compounds (M-2)] 480 g of an 80% by mass 1-butanol solution of zirconium tetraisopropoxide was dissolved in 400 g of 1-butanol. A mixed solution of 27 g of deionized water and 500 g of 1-butanol was added dropwise to this solution over 2 hours at room temperature while stirring. 90 g of 1,3-butanediol was added to the resulting solution and stirred at room temperature for 30 minutes. This solution was concentrated under reduced pressure at 30°C, then heated to 60°C, and continued under reduced pressure until no more distillate was observed. Once no distillate was observed, 1,200 g of PGMEA was added and heated at 40°C under reduced pressure until no more 1-butanol distilled, yielding 1,000 g of a PGMEA solution of the zirconium-containing compound (metal-containing compound (M-2)). The polystyrene-equivalent molecular weight was measured to be Mw = 1,400.

[0196] [Synthesis of metal-containing compounds (M-3)] 480 g of an 80% by mass 1-butanol solution of hafnium tetraisopropoxide was dissolved in 400 g of 1-butanol. A mixture of 27 g of deionized water and 500 g of 1-butanol was added dropwise to this solution over 2 hours at room temperature while stirring. 90 g of 1,3-butanediol was added to the resulting solution and stirred at room temperature for 30 minutes. This solution was concentrated under reduced pressure at 30°C, then heated to 60°C, and continued under reduced pressure until no more distillate was observed. Once no distillate was observed, 1,200 g of PGMEA was added and heated at 40°C under reduced pressure until no more 1-butanol distilled, yielding 1,000 g of a PGMEA solution of the hafnium-containing compound (metal-containing compound (M-3)). The polystyrene-equivalent molecular weight was measured to be Mw = 1,500.

[0197] [Preparation of compositions for forming metal-containing resist upper layers] Each of the metal-containing compounds (M-1) to (M-3) obtained in the above synthesis example was dissolved in a solvent containing 100 ppm of 3M's fluorine-based surfactant FC-4430, according to the composition shown in Table 4. Each of the resulting solutions was filtered through a 0.2 μm filter to prepare the metal-containing resist upper layer film formation compositions MR-1 to MR-3.

[0198] The compositions listed in Table 4 below are as follows: Acid generator: PAG-1, 2 (see structural formula below) Basic compound: Base-1 (see structural formula below)

[0199] [ka]

[0200] [ka]

[0201] [Table 4]

[0202] As shown in Figure 9, the wafer edge protection film formation compositions (EPF-1 to 6, comparative examples EPF-1 to 3) 4 prepared above were applied from the supply nozzle 3 to the peripheral edges on the front and back sides (peripheral edge 1E) of the silicon substrate 1 to obtain a coating film 4' (Figure 9(A)). Next, the coating film 4' was baked in air at 350°C for 60 seconds to cure it and form a wafer edge protection film 4A (Figure 9(B)). Subsequently, each of the metal-containing resist upper layer film formation compositions (MR-1 to 3 above) 8 was applied to the surface of the silicon substrate from the resist supply nozzle 9 to obtain a coating film 8' (Figure 9(C)). Next, the coating film 8' was pre-baked on a hot plate at 170°C for 60 seconds to form a 35 nm metal-containing resist upper layer film 8A (Figure 9(D)). Next, the metal-containing resist upper layer film 8A was removed using a developer (butyl acetate) (Figure 9(E)), and then the wafer edge protective film 4A formed on the peripheral edges of the front and back sides (peripheral edge 1E) of the silicon substrate 1 was removed by dry etching using O2 gas (Figure 9(F)). The peripheral edges of the front and back sides (peripheral edge 1E) of the silicon substrate 1 were treated with a mixture of hydrofluoric acid and hydrogen peroxide, the solution was recovered and evaluated using an Expert VPD-ICP-MS manufactured by IAS. The amount of metal atom impurities was 1.0 × 10⁻⁶ E⁻¹. +10 (atoms / cm 2 If the result is less than or equal to 1.0 × 10E, it is classified as "A" (good), 1.0 × 10E +10 (atoms / cm 2 If the result exceeded the specified value, it was evaluated as "B" (poor). The results are shown in Table 5.

[0203] Furthermore, the number of defects in the wafer edge after etching as described above was evaluated using VisEdge manufactured by KLA-Tencor. A wafer edge 1E with fewer than 30 defects was classified as "A" (excellent), 30 to less than 100 defects as "B" (good), and 100 or more defects as "C" (poor). The results are shown in Table 5.

[0204] [Table 5]

[0205] As shown in Table 5, by forming the wafer edge protective film-forming compositions (EPF-1 to 6) of the present invention as wafer edge protective films on the peripheral edges of the substrate, including the peripheral edges on the front and back sides, sufficient etching resistance was obtained. As a result, the amount of metal adhering to the silicon substrate when applying the metal-containing resist upper layer film-forming compositions was significantly less than when using comparative examples EPF-1 to 3.

[0206] As described above, by using the wafer edge protective film formation compositions (EPF-1 to 6) of the present invention, the amount of metal adhering to the silicon substrate during coating can be reduced, making it possible to form a wafer edge protective film with excellent defect suppression properties.

[0207] From the above, the wafer edge protective film formation method using the wafer edge protective film formation composition of the present invention provides a wafer edge protective film that has superior dry etching resistance compared to conventional wafer edge protective films, and also has excellent film formation properties even on wafer edges where coating is difficult. Furthermore, by forming the wafer edge protective film on the peripheral edge of the back side, it is possible to avoid the risk of metal contamination of these areas, which occurs when forming a coating film containing metal, due to the chemical solution supplied to the surface of the substrate flowing to the peripheral edge of the back side and forming a coating film on these unintended back peripheral edges.Therefore, these can be suitably used for forming fine resist patterns in the lithography process of various electronic devices such as semiconductor devices and liquid crystal devices, which are expected to become increasingly miniaturized in the future.

[0208] This specification includes the following embodiments: [1] A wafer edge protective film forming composition for forming a wafer edge protective film on the peripheral edge of a substrate, characterized in that it comprises a polymer (A) represented by the following general formula (1) and a solvent. [ka] (In the formula, W is -SO2-, -C(=O)-, or -O-; R1, R2, R3, R4, and R5 are each independently a halogen atom, a monovalent organic group having 1 to 3 carbon atoms, or a hydroxyl group; and a, b, c, d, and e are each independently an integer from 0 to 4.) [2] The wafer edge protective film forming composition according to [1], characterized in that the weight-average molecular weight of the polymer (A) is 1,000 to 30,000. [3] The wafer edge protective film forming composition according to [1] or [2], characterized in that the polymer (A) content is 10% by mass or more. [4] The wafer edge protective film forming composition according to any one of [1] to [3], further comprising one or more of a crosslinking agent, a surfactant, an acid generator, and a plasticizer. [5] A wafer edge protective film forming composition according to any one of [1] to [4], characterized in that the solvent is a mixture of a high-boiling-point solvent having a boiling point of 180°C or higher and a low-boiling-point solvent having a boiling point of less than 180°C. [6] A method for forming a wafer edge protective film on the peripheral edge of a substrate, (i) A step of obtaining a coating film by coating the peripheral edge of the substrate with any one of the wafer edge protective film forming compositions described in [1] to [5], (ii) A step of curing the coating film by heat or light irradiation to form the wafer edge protective film on the peripheral edge of the substrate, A method for forming a wafer edge protective film, characterized by including the following: [7] The wafer edge protective film forming method according to [6], characterized in that, in step (i), the wafer edge protective film forming composition is coated not only on the front edge surface of the peripheral edge of the substrate but also on the back edge surface of the peripheral edge of the substrate, and in step (ii), the wafer edge protective film is also formed on the back edge surface of the substrate. [8] The coating in the step (i) is performed by a spin coating method, and the wafer edge protective film is not formed except for the peripheral edge portion of the substrate. The method for forming a wafer edge protective film according to claim [6] or [7]. [9] In the step (ii), the coating film is cured by heat treatment at a temperature of 100 °C or higher and 800 °C or lower for 10 seconds to 7,200 seconds. The method for forming a wafer edge protective film according to any one of [6] to [8].

[10] A method for forming a pattern on a processed substrate having a film with a pattern, comprising forming a wafer edge protective film on the peripheral edge portion of the processed substrate and forming a pattern on the processed substrate. (I-1) A step of applying the composition for forming a wafer edge protective film according to any one of [1] to [5] to the peripheral edge portion of the processed substrate having a film with a pattern to obtain a coating film. (I-2) A step of curing the coating film by heat treatment or light irradiation to form a wafer edge protective film on the peripheral edge portion of the substrate. (I-3) A step of forming a pattern on the processed substrate by dry etching using the film with a pattern as a mask. (I―4) A step of removing the wafer edge protective film. The pattern forming method characterized by including the above steps.

[11] A method for forming a pattern on a processed substrate having a film with a pattern, comprising forming a wafer edge protective film on the peripheral edge portion of the processed substrate and forming a pattern on the processed substrate. (II-1) A step of applying the composition for forming a wafer edge protective film according to any one of [1] to [5] to the peripheral edge portion of the processed substrate to obtain a coating film. (II-2) A step of curing the coating film by heat treatment or light irradiation to form a wafer edge protective film on the peripheral edge portion of the processed substrate. (II-3) A step of forming a resist upper layer film pattern on the processed substrate and forming a pattern on the processed substrate by dry etching using the resist upper layer film pattern as a mask. (II―4) A step of removing the wafer edge protective film. The pattern forming method characterized by including the above steps.

[12] The pattern forming method according to

[10] , characterized in that, in step (I-1), the wafer edge protective film forming composition is applied not only to the front edge surface of the peripheral edge of the substrate but also to the back edge surface of the peripheral edge of the substrate, and in step (I-2), the wafer edge protective film is also formed on the back edge surface of the substrate.

[13] The pattern forming method according to

[11] , characterized in that, in step (II-1), the wafer edge protective film forming composition is applied not only to the front edge surface of the peripheral edge of the substrate but also to the back edge surface of the peripheral edge of the substrate, and in step (II-2), the wafer edge protective film is also formed on the back edge surface of the substrate.

[0209] It should be noted that the present invention is not limited to the embodiments described above. The embodiments described above are illustrative, and any configuration that is substantially identical to the technical idea described in the claims of the present invention and achieves similar effects is included within the technical scope of the present invention. [Explanation of symbols]

[0210] 1...Wafer (substrate, substrate to be processed), 1a...Apex (peripheral edge), 1b...Front edge surface, 1c and 1d...Bevel, 1e...Back edge surface, 1A...Pattern, 1E...Peripheral edge (wafer edge), 2...Spin chuck, 3...Supply nozzle, 3A...Upper supply nozzle, 3B...Lower supply nozzle, 4...Composition for forming wafer edge protective film, 4'...Coating film, 4A...Wafer edge protective film, 4a...Thickness of the portion covering the apex, 4s...Thickness of the portion covering the wafer edge surface, 5...Film having a pattern, 6...Layer to be processed, 6A...Pattern, 7...Resist upper layer film, 7A...Resist upper layer film pattern, 8...Composition for forming metal-containing resist upper layer film, 8'...Coating film, 8A...Metal-containing resist upper layer film, 9...Resist supply nozzle.

Claims

1. A wafer edge protective film forming composition for forming a wafer edge protective film on the peripheral edge of a substrate, A polymer (A) represented by the following general formula (1), Solvent and A composition for forming a wafer edge protective film, characterized by containing the following: 【Chemistry 1】 (In the formula, W is -SO) ２ -, -C (=O)- or -O-, R １ , R ２ , R ３ , R ４ and R ５ Each of these is independently a halogen atom, a monovalent organic group having 1 to 3 carbon atoms, or a hydroxyl group, and each of a, b, c, d, and e is independently an integer from 0 to 4.

2. The wafer edge protective film forming composition according to claim 1, characterized in that the weight-average molecular weight of the polymer (A) is 1,000 to 30,000.

3. The wafer edge protective film forming composition according to claim 1, characterized in that the polymer (A) content is 10% by mass or more.

4. The wafer edge protective film forming composition further comprises: Crosslinking agent, Surfactants, Acid generator, and plasticizer The wafer edge protective film forming composition according to claim 1, characterized in that it contains one or more of the following.

5. The wafer edge protective film forming composition according to claim 1, characterized in that the solvent is a mixture of a high-boiling-point solvent having a boiling point of 180°C or higher and a low-boiling-point solvent having a boiling point of less than 180°C.

6. A method for forming a wafer edge protective film on the peripheral edge of a substrate, (i) A step of obtaining a coating film by coating the peripheral edge of the substrate with the wafer edge protective film forming composition according to any one of claims 1 to 5, (ii) A step of curing the coating film by heat or light irradiation to form the wafer edge protective film on the peripheral edge of the substrate, A method for forming a wafer edge protective film, characterized by including the following:

7. In step (i) above, the wafer edge protective film forming composition is coated not only on the front edge surface of the peripheral edge of the substrate, but also on the back edge surface of the peripheral edge of the substrate. The wafer edge protective film forming method according to claim 6, characterized in that in step (ii) above, the wafer edge protective film is also formed on the edge surface on the back side of the substrate.

8. The wafer edge protective film formation method according to claim 6, characterized in that the coating in step (i) is performed using a rotary coating method, and the wafer edge protective film is not formed on any part of the substrate other than the peripheral edge.

9. The wafer edge protective film forming method according to claim 6, characterized in that in step (ii) above, the coating film is cured by heat treatment at a temperature of 100°C to 800°C for 10 to 7,200 seconds.

10. A method for forming a wafer edge protective film on the peripheral edge of a workpiece substrate on which a film having a pattern has been formed, and for forming a pattern on the workpiece substrate, (I-1) A step of applying the wafer edge protective film forming composition according to any one of claims 1 to 5 to the peripheral edge of a workpiece substrate on which a film having a pattern has been formed to obtain a coating film, (I-2) A step of curing the coating film by heat treatment or light irradiation to form a wafer edge protective film on the peripheral edge of the substrate, (I-3) A step of forming a pattern on the substrate to be processed by dry etching using the film having the pattern as a mask, (I-4) A step of removing the wafer edge protective film, A pattern forming method characterized by including the following.

11. A method for forming a wafer edge protective film on the peripheral edge of a substrate to be processed, and for forming a pattern on the substrate to be processed, (II-1) A step of applying the wafer edge protective film forming composition according to any one of claims 1 to 5 to the peripheral edge of the substrate to be processed to obtain a coating film, (II-2) A step of curing the coating film by heat treatment or light irradiation to form a wafer edge protective film on the peripheral edge of the substrate to be processed, (II-3) A step of forming a resist upper layer film pattern on the substrate to be processed, and using the resist upper layer film pattern as a mask, forming a pattern on the substrate to be processed by dry etching, (II-4) A step of removing the wafer edge protective film, A pattern forming method characterized by including the following.

12. In step (I-1) above, the wafer edge protective film forming composition is applied not only to the front edge surface of the peripheral edge of the substrate, but also to the back edge surface of the peripheral edge of the substrate. The pattern forming method according to claim 10, characterized in that in step (I-2), the wafer edge protective film is also formed on the edge surface on the back side of the substrate.

13. In step (II-1) above, the wafer edge protective film forming composition is applied not only to the front edge surface of the peripheral edge of the substrate, but also to the back edge surface of the peripheral edge of the substrate. The pattern forming method according to claim 11, characterized in that in step (II-2), the wafer edge protective film is also formed on the edge surface on the back side of the substrate.

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