Substrate treatment method and substrate treatment device

Abstract

A substrate treatment method comprising: (A) a step for preparing a substrate on which a coating film of a chemically amplified resist is formed and which has been subjected to an exposure treatment and a heating treatment after the exposure treatment; (B) a step for subjecting the substrate to first development for removing, depending on whether the chemically amplified resist is of a positive type or a negative type, either an unexposed portion or an exposure portion formed by the exposure treatment in the coating film, thereby forming a pattern of the chemically amplified resist; (C) a step, after step (B), for subjecting the substrate to a treatment for changing the properties of the chemically amplified resist in the pattern; and (D) a step, after step (C), for subjecting the substrate to second development for removing the chemically amplified resist from the surface of the pattern using a development material different from that for the first development.

Description

Substrate processing method and substrate processing apparatus

[0001] The present disclosure relates to a substrate processing method and a substrate processing apparatus.

[0002] US Pat. No. 6,299,499 discloses a technique for reducing shot noise in extreme ultraviolet (EUV) lithography and patterning of photosensitized chemically amplified resist (PS-CAR).

[0003] Japanese Patent Application Laid-Open No. 2019-109540

[0004] The technology according to the present disclosure improves the roughness of the pattern surface while suppressing deterioration in exposure dose sensitivity when forming at least a chemically amplified resist (CAR) pattern.

[0005] One aspect of the present disclosure is a substrate processing method including: (A) preparing a substrate on which a chemically amplified resist film has been formed and which has been subjected to an exposure process and a post-exposure heat treatment; (B) performing a first development process on the substrate to remove either an exposed portion or an unexposed portion of the film by the exposure process to form a pattern of the chemically amplified resist; (C) after the process (B), performing a process on the substrate to change properties of the chemically amplified resist in the pattern; and (D) after the process (C), performing a second development process on the substrate using a developer material different from that used in the first development process to modify the shape of the pattern.

[0006] According to the present disclosure, it is possible to improve the roughness of the pattern surface while suppressing deterioration in exposure dose sensitivity at least when forming a CAR pattern.

[0007] 1. FIG. 1 is an explanatory diagram showing an outline of the internal configuration of a wafer processing apparatus as a substrate processing apparatus according to the present embodiment. FIG. 2 is a diagram showing an outline of the internal configuration of the front side of a wet processing section. FIG. 3 is a diagram showing an outline of the internal configuration of the back side of a wet processing section. FIG. 4 is a diagram showing a schematic cross section of the wafer processing apparatus at a transfer block portion of FIG. 1. FIG. 5 is a flowchart showing main steps of processing sequence example 1. FIG. 6 is a diagram showing the state on a wafer when processing sequence example 1 is being executed. FIG. 7 is a graph showing the power spectral density of the surface roughness of formed patterns in test example 1 and comparative example 1. FIG. 8 is a graph showing the relationship between the pattern exposure dose and the dimensions of convex portions of formed patterns in test examples 1 and 2 and comparative example 1. FIG. 9 is a graph showing the relationship between the dimensions and surface roughness when the dimensions of FIG. 8 are obtained in test examples 1 and 2 and comparative example 1. FIG. 10 is a flowchart showing main steps of processing sequence example 2. FIG. 11 is a diagram showing the state on a wafer when processing sequence example 2 is being executed. FIG. 11 is a graph showing the power spectral density of the surface roughness of formed patterns in test example 3 and comparative example 2. FIG. 12 is a graph showing the relationship between the dimensions of convex portions of formed patterns and surface roughness in test examples 4 and 5 and comparative example 3. 1 is a graph showing the relationship between the irradiation intensity during ultraviolet irradiation processing and the surface roughness of the photo-amplified resist pattern when processing is performed up to the ultraviolet irradiation processing of processing sequence example 2. FIG. 2 is a flowchart showing the main steps of processing sequence example 3. FIG. 3 is a diagram showing the state on the wafer when processing sequence example 3 is being performed. FIG. 4 is a flowchart showing the main steps of processing sequence example 4.

[0008] The configuration of the substrate processing apparatus according to this embodiment will be described below with reference to the drawings. In this specification, elements having substantially the same functional configuration are designated by the same reference numerals, and redundant description will be omitted.

[0009] <Wafer Processing Apparatus> Fig. 1 is an explanatory diagram showing an outline of the internal configuration of a wafer processing apparatus as a substrate processing apparatus according to this embodiment. Figs. 2 and 3 are diagrams showing an outline of the internal configuration of the front and rear sides, respectively, of a wet processing section described below. Fig. 4 is a diagram showing a schematic cross section of the wafer processing apparatus of Fig. 1 at a transfer block portion described below.

[0010] The wafer processing apparatus 1 in FIG. 1 forms a pattern of chemically amplified resist on a wafer (semiconductor wafer (hereinafter referred to as "wafer") W as a substrate; specifically, forms a pattern of chemically amplified resist for EUV (Extreme Ultra-Violet) light. In chemically amplified resist, acid generated by pattern exposure serves as a catalyst to induce a reaction for forming the resist pattern. Note that the chemically amplified resist (CAR) in this disclosure differs from photosensitized chemically amplified resist in that it does not contain a photosensitizer. The wafer processing apparatus 1 includes, for example, a wet (liquid phase) processing section 2, a dry (vapor phase) processing section 3, and an intermediary transport section 4.

[0011] 1 to 3, the wet processing section 2 includes a cassette station 10, a processing station 11, and an interface station 12, and is connected to an exposure apparatus E. The exposure apparatus E subjects the wafer W to an exposure process, specifically, an exposure process using, for example, EUV light. In the wet processing section 2, the cassette station 10, the processing station 11, and the interface station 12 are integrally connected.

[0012] In the following description, the direction in which the wet processing section 2 and the exposure device E are connected is referred to as the width direction, and the direction perpendicular to the connection direction, i.e., the width direction, in a top view is referred to as the depth direction.

[0013] The cassette station 10 of the wet processing unit 2 is used to load and unload cassettes C, which are containers configured to hold a plurality of wafers W. The cassette station 10 is provided with a cassette mounting table 20, for example, at one end in the width direction (the negative side in the Y direction in FIG. 1 , etc.). A plurality of, for example, four mounting plates 21 are provided on the cassette mounting table 20. The mounting plates 21 are arranged in a row in the depth direction (the X direction in FIG. 1 ). The cassettes C can be placed on these mounting plates 21 when they are loaded and unloaded from the outside of the wet processing unit 2.

[0014] The cassette station 10 is also provided with a transfer module 23 for transferring wafers W, for example, on the other widthwise side (the positive side in the Y direction in FIG. 1 ). The transfer module 23 has a transfer arm 23a configured to be movable in the depth direction (the X direction in FIG. 1 ). The transfer arm 23a of the transfer module 23 is also configured to be movable in the vertical direction and around the vertical axis. The transfer module 23 can transfer wafers W between the cassettes C on each mounting plate 21 and a transfer module 51 of a transfer tower 50, which will be described later.

[0015] The processing station 11 includes a plurality of processing modules for performing predetermined processing such as development processing on the wafer W.

[0016] The processing station 11 is divided into a plurality of blocks (two in the illustrated example) each equipped with various modules. The processing block BL1 is located on the interface station 12 side, and the transfer block BL2 is located on the cassette station 10 side.

[0017] The processing block BL1 has, for example, a first block G1 on the front side (negative side in the X direction in FIG. 1) and a second block G2 on the back side (positive side in the X direction in FIG. 1).

[0018] 2, the first block G1 includes a plurality of liquid processing modules, such as a first developing module 30, a second developing module 31, a third developing module 32, a fourth developing module 33, and a resist coating module 34, arranged in this order from bottom to top. The first to fourth developing modules 30 to 33 are all wet developing units that wet develop the wafer W. The resist coating module 34 is a resist coating unit that applies a chemically amplified resist to the wafer W to form a chemically amplified resist coating, i.e., a chemically amplified resist film.

[0019] The first developing module 30 performs a first development on the wafer W on which a chemically amplified resist film has been formed, using a strong-polarity developer as a strong-polarity developing material. The first development removes either the exposed or unexposed portions of the chemically amplified resist film resulting from the exposure process (hereinafter sometimes referred to as a pattern exposure process) performed by the exposure apparatus E that transfers the mask pattern, thereby forming a chemically amplified resist pattern. The removal of either the exposed or unexposed portions of the chemically amplified resist film in the first development varies depending on the type of developing material. In the case of the strong-polarity developing material (developer) used by the first developing module 30, the exposed portions of the chemically amplified resist film resulting from the exposure process are removed in the first development. In other words, the first development by the first developing module 30 is positive.

[0020] The strong polarity developer used by the first developing module 30 for the positive first development is, for example, a solution of an alkaline material. Examples of the alkaline material include inorganic alkalis such as sodium hydroxide, potassium hydroxide, sodium carbonate, sodium silicate, sodium metasilicate, and aqueous ammonia; primary amines such as ethylamine and n-propylamine; secondary amines such as diethylamine and di-n-butylamine; tertiary amines such as triethylamine and methyldiethylamine; alcohol amines such as dimethylethanolamine and triethanolamine; tetraalkylammonium hydroxides such as tetramethylammonium hydroxide, tetraethylammonium hydroxide, tetrapropylammonium hydroxide, tetrabutylammonium hydroxide, tetrapentylammonium hydroxide, tetrahexylammonium hydroxide, tetraoctylammonium hydroxide, ethyltrimethylammonium hydroxide, butyltrimethylammonium hydroxide, methylamylammonium hydroxide, and dibutyldipentylammonium hydroxide; quaternary ammonium salts such as trimethylphenylammonium hydroxide, trimethylbenzylammonium hydroxide, triethylbenzylammonium hydroxide, and dimethylbis(2-hydroxyethyl)ammonium hydroxide; and cyclic amines such as pyrrole and piheridine. The solvent for the alkaline material solution is, for example, water. In this case, an appropriate amount of alcohols such as isopropyl alcohol or a nonionic surfactant may be added. Incidentally, alcohol (e.g., methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, ethane-1,2-diol, propane-1,2,3-triol, etc.) may be used as the solvent for the alkaline material solution. The strongly polar developer may also be an aqueous solution of an acidic material. The acidic material here is an organic sulfonic acid, an organic carboxylic acid (acetic acid, citric acid, etc.), an inorganic acid, or a combination thereof. Preferably, an aqueous solution of an alkaline material, i.e., an alkaline aqueous solution, is used as the strongly polar developer. The alkaline aqueous solution as the strongly polar developer has, for example, an alkali concentration of 0.1 to 20% by mass and a pH of 10.0 to 15.0.Furthermore, as a developer with a strong polarity, an aqueous solution of tetramethylammonium hydroxide (TMAH) is particularly preferable, and the aqueous solution of tetramethylammonium hydroxide (TMAH) preferably has a TMAH concentration of 2.38% by mass.

[0021] The second developing module 31 performs a second development using a weakly polar developer as a weakly polar developer material on the wafer W on which a chemically amplified resist pattern has been formed by the first positive development performed by the first developing module 30. The second development corrects the shape of the pattern after a process for changing the properties of the chemically amplified resist in the pattern, which will be described later. Specifically, the second development removes the chemically amplified resist on the surface of the pattern after a process for changing the properties of the chemically amplified resist in the pattern.

[0022] The weakly polar developer used by the second developing module 31 for the second development is, for example, deionized water (DIW). Alternatively, the weakly polar developer may be the developer used by the first developing module 30 for the first development diluted with deionized water or an alcohol-based solvent. Examples of the alcohol-based solvent include alcohols such as methyl alcohol, ethyl alcohol, n-propyl alcohol, isopropyl alcohol, n-butyl alcohol, sec-butyl alcohol, 4-methyl-2-pentanol, tert-butyl alcohol, isobutyl alcohol, n-hexyl alcohol, n-heptyl alcohol, n-octyl alcohol, and n-decanol; glycol-based solvents such as ethylene glycol, diethylene glycol, and triethylene glycol; and glycol ether-based solvents such as ethylene glycol monomethyl ether, propylene glycol monomethyl ether, ethylene glycol monoethyl ether, propylene glycol monoethyl ether, diethylene glycol monomethyl ether, triethylene glycol monoethyl ether, and methoxymethylbutanol.

[0023] The third developing module 32 performs a first development using a predetermined developer on the wafer W on which the chemically amplified resist film has been formed. The first development by the third developing module 32 differs from the first development by the first developing module 30 in that the unexposed portions of the chemically amplified resist film resulting from the pattern exposure process are removed, forming a pattern of the chemically amplified resist. In other words, the first development by the third developing module 32 is negative.

[0024] The predetermined developer used by the third developing module 32 for the first negative development is, for example, an organic solvent or a mixture of organic solvents. Examples of the organic solvent include polar solvents such as ketone-based solvents, ester-based solvents, alcohol-based solvents, amide-based solvents, and ether-based solvents, as well as hydrocarbon-based solvents. In this disclosure, a ketone-based solvent refers to a solvent having a ketone group in its molecule, an ester-based solvent refers to a solvent having an ester group in its molecule, an alcohol-based solvent refers to a solvent having an alcoholic hydroxyl group in its molecule, an amide-based solvent refers to a solvent having an amide group in its molecule, and an ether-based solvent refers to a solvent having an ether bond in its molecule. Among these, there are solvents that have multiple types of functional groups in one molecule, and in such cases, the term applies to any solvent type containing the functional groups possessed by the solvent. For example, diethylene glycol monomethyl ether is considered to fall into both the alcohol-based solvent and the ether-based solvent categories. Furthermore, a hydrocarbon-based solvent refers to a hydrocarbon solvent without a substituent. The predetermined developer used by the third developing module 32 for the negative first development is preferably a developer containing at least one solvent selected from ketone-based solvents, ester-based solvents, alcohol-based solvents, and ether-based solvents. In particular, from the viewpoint of suppressing swelling of the resist film, it is preferable to use an ester-based solvent having 7 or more carbon atoms (preferably 7 to 14, more preferably 7 to 12, and even more preferably 7 to 10) and 2 or less heteroatoms. The heteroatoms of the ester-based solvents are atoms other than carbon atoms and hydrogen atoms, such as oxygen atoms, nitrogen atoms, and sulfur atoms. The number of heteroatoms is preferably 2 or less. Preferred examples of ester-based solvents having 7 or more carbon atoms and 2 or less heteroatoms include amyl acetate, isoamyl acetate, 2-methylbutyl acetate, 1-methylbutyl acetate, hexyl acetate, pentyl propionate, hexyl propionate, heptyl propionate, butyl butanoate, and isobutyl isobutanoate. It is particularly preferable to use isoamyl acetate or isobutyl isobutanoate.The predetermined developer used by the third developing module 32 for the first negative development may be a mixed solvent of an ester solvent and a hydrocarbon solvent, or a mixed solvent of a ketone solvent and a hydrocarbon solvent, instead of the ester solvent having seven or more carbon atoms and two or less heteroatoms. This is also effective in suppressing swelling of the resist film. When using a combination of an ester solvent and a hydrocarbon solvent, it is preferable to use isoamyl acetate as the ester solvent, and from the viewpoint of adjusting the solubility of the resist film, it is preferable to use a saturated hydrocarbon solvent (e.g., octane, nonane, decane, dodecane, undecane, hexadecane, etc.) as the hydrocarbon solvent. Examples of ketone solvents include 1-octanone, 2-octanone, 1-nonanone, 2-nonanone, acetone, 2-heptanone (methyl amyl ketone), 4-heptanone, 1-hexanone, 2-hexanone, diisobutyl ketone, 2,5-dimethyl-4-hexanone, diisobutyl ketone, cyclohexanone, methylcyclohexanone, phenylacetone, methyl ethyl ketone, methyl isobutyl ketone, acetylacetone, acetonylacetone, ionone, diacetonyl alcohol, acetylcarbinol, acetophenone, methyl naphthyl ketone, isophorone, and propylene carbonate. It is particularly preferable to use diisobutyl ketone and 2,5-dimethyl-4-hexanone. Examples of ester-based solvents include methyl acetate, butyl acetate, ethyl acetate, isopropyl acetate, pentyl acetate, isoamyl acetate, amyl acetate, propylene glycol monomethyl ether acetate, ethylene glycol monoethyl ether acetate, diethylene glycol monobutyl ether acetate, diethylene glycol monoethyl ether acetate, ethyl-3-ethoxypropionate, 3-methoxybutyl acetate, 3-methyl-3-methoxybutyl acetate, methyl formate, ethyl formate, butyl formate, propyl formate, ethyl lactate, butyl lactate, propyl lactate, butyl butyrate, and methyl 2-hydroxyisobutyrate.Examples of alcohol-based solvents include alcohols such as methyl alcohol, ethyl alcohol, n-propyl alcohol, isopropyl alcohol, n-butyl alcohol, sec-butyl alcohol, 4-methyl-2-pentanol, tert-butyl alcohol, isobutyl alcohol, n-hexyl alcohol, n-heptyl alcohol, n-octyl alcohol, and n-decanol, glycol-based solvents such as ethylene glycol, diethylene glycol, and triethylene glycol, and glycol ether-based solvents such as ethylene glycol monomethyl ether, propylene glycol monomethyl ether, ethylene glycol monoethyl ether, propylene glycol monoethyl ether, diethylene glycol monomethyl ether, triethylene glycol monoethyl ether, and methoxymethylbutanol. Examples of ether-based solvents include, in addition to the above glycol ether-based solvents, anisole, dioxane, and tetrahydrofuran. Examples of amide solvents that can be used include N-methyl-2-pyrrolidone, N,N-dimethylacetamide, N,N-dimethylformamide, hexamethylphosphoric triamide, and 1,3-dimethyl-2-imidazolidinone. Examples of hydrocarbon solvents include aromatic hydrocarbon solvents such as toluene and xylene, and aliphatic hydrocarbon solvents such as pentane, hexane, octane, decane, and undecane. The aliphatic hydrocarbon solvent may be a mixture of compounds having the same carbon number but different structures. For example, when decane is used as the aliphatic hydrocarbon solvent, the aliphatic hydrocarbon solvent may contain compounds having the same carbon number but different structures, such as 2-methylnonane, 2,2-dimethyloctane, 4-ethyloctane, and isooctane. The compounds having the same carbon number but different structures may be contained alone or in combination, as described above. The predetermined developer used by the third developing module 32 for the first negative development may be a mixture of the above organic solvent with a solvent other than those mentioned above or water.However, to fully achieve the effects of the developer of the present disclosure, the water content of the developer as a whole, other than the organic solvent, or water, is preferably less than 10% by mass, and more preferably, the developer contains substantially no other solvents or water. The concentration of the organic solvent (total concentration when multiple organic solvents are mixed) in the predetermined developer used by the third developing module 32 for the first development of the negative tone is preferably 50% by mass or more, more preferably 50 to 100% by mass, even more preferably 85 to 100% by mass, even more preferably 90 to 100% by mass, and particularly preferably 95 to 100% by mass. Most preferably, the developer consists essentially of the organic solvent. Note that the term "consisting essentially of the organic solvent" includes the case where the developer contains trace amounts of surfactants, antioxidants, stabilizers, antifoaming agents, and the like. The predetermined developer used by the third developing module 32 for the first development of the negative tone may also be a solution of an acidic material using the organic solvent as a solvent. In this case, the acidic material is an organic acid, an inorganic acid, or a combination thereof, and the organic acid is, for example, an organic carboxylic acid such as acetic acid or citric acid.

[0025] The fourth developing module 33 performs the second development using a predetermined developer on the wafer W on which the chemically amplified resist pattern has been formed by the negative first development performed by the third developing module 32 .

[0026] The predetermined developer used by the fourth developing module 33 for the second development has a higher polarity than the developer used for the negative first development by the third developing module 32. When the developer for the negative first development is an organic solvent, the predetermined developer contains at least one organic solvent selected from, for example, a ketone solvent, an ester solvent, an alcohol solvent, and an ether solvent, and more specifically, is, for example, butyl acetate.

[0027] The predetermined developer used by the fourth developing module 33 for the second development may be water (pure water).

[0028] For example, four of each of the first to fourth developing modules 30 to 33 and resist coating modules 34 are arranged in the width direction (Y direction in the drawing). Note that the number and arrangement of the first to fourth developing modules 30 to 33 and resist coating modules 34 can be selected arbitrarily.

[0029] In these first to fourth developing modules 30 to 33 and resist coating module 34, a predetermined processing liquid is applied onto the wafer W by, for example, spin coating. In the spin coating method, for example, the processing liquid is discharged onto the wafer W from a discharge nozzle, and the wafer W is rotated to spread the processing liquid over the surface of the wafer W. In each of the first to fourth developing modules 30 to 33, a liquid film (puddle) of the corresponding developer is formed to develop the wafer W. Note that the first to fourth developing modules 30 to 33 may be equipped with a rinse nozzle in addition to the discharge nozzle that discharges the developer. For example, in the first developing module 30, after forming a liquid film of the developer on the wafer W by spin coating, a first development stop process is performed on the wafer W using pure water as a rinse liquid discharged from a rinse nozzle. Specifically, the first development stop process is a process of removing the developer from the wafer W using a rinse liquid. A surfactant may be added to the pure water used as the rinse liquid. In the first developing module 30, the process of stopping the first development may include a step of removing the developer with pure water as a rinse liquid and then spinning and drying the wafer W. Note that, when pure water is used as a weakly polar developer in the second developing module 31, the rinse nozzle may be omitted, and after a liquid film of the developer is formed on the wafer W by a spin coating method, the wafer W may be spun and dried without removing the developer with a rinse liquid.

[0030] 3, the second block G2 has a plurality of heat treatment modules 40 and ultraviolet irradiation modules 45 arranged in the vertical direction (up and down direction in the figure) and width direction (Y direction in the figure). The number and arrangement of the heat treatment modules 40 and ultraviolet irradiation modules 45 can also be selected arbitrarily.

[0031] For example, at least some of the heat treatment modules 40 are formed by connecting a heating section for heating the wafer W with a cooling section for cooling the wafer W. In the heat treatment module 40, the heating section has a hot plate 41, as shown in FIG. 1 , and the cooling section has a cooling plate 42. The hot plate 41 is configured to receive the wafer W and has a heating means such as a resistance heater installed therein. The cooling plate 42 is configured to receive the wafer W and has a cooling means such as a cooling refrigerant flow path installed therein. The ultraviolet irradiation module 45 performs an ultraviolet irradiation process on the wafer W. The ultraviolet irradiation process is a process of irradiating the entire upper surface of the wafer W, i.e., the entire surface, with ultraviolet rays. Specifically, the ultraviolet irradiation process is a process of irradiating the entire surface of the wafer W with ultraviolet rays in an inert gas atmosphere without a mask. Note that the "entire surface of the wafer W" includes at least the entire device formation region of the wafer W.

[0032] 1, the processing block BL1 is provided with a transport path R1 extending in the width direction between the first block G1 and the second block G2. In the processing block BL1, first to fourth developing modules 30 to 33 and a resist coating module 34 are arranged in a line along the transport path R1 extending in the width direction. A transport module R2 that transports wafers W is arranged along the transport path R1.

[0033] The transfer module R2 has a transfer arm R2a that is movable, for example, in the width direction (Y direction in FIG. 1), the vertical direction, and the direction around the vertical axis. The transfer module R2 moves the transfer arm R2a holding the wafer W within the wafer transfer region D, and can transfer the wafer W to predetermined devices in the surrounding first block G1, second block G2, transfer tower 50 (described later), and transfer tower 60. A plurality of transfer modules R2 are arranged vertically, for example, as shown in FIG. 3, and can transfer the wafer W to predetermined modules of approximately the same height in each of the first block G1, second block G2, and transfer towers 50 and 60.

[0034] Further, the transfer path R1 is provided with a shuttle transfer module R3 that transfers the wafer W linearly between the transfer tower 50 and the transfer tower 60.

[0035] The shuttle transfer module R3 can move the supported wafer W linearly in the Y direction and transfer the wafer W between the devices in the transfer tower 50 and the transfer tower 60, which are at approximately the same height.

[0036] 1, the transfer block BL2 has a transfer tower 50 provided at the center in the depth direction (X direction in the figure). Specifically, the transfer tower 50 is provided at a position in the transfer block BL2 adjacent to the transport path R1 of the processing block BL1 in the width direction (Y direction in the figure). As shown in FIG. 3, the transfer tower 50 has a plurality of transfer modules 51 arranged vertically one on top of the other.

[0037] 1, the interface station 12 is provided between the processing station 11 and the exposure apparatus E, and serves to transfer wafers W therebetween. A transfer tower 60 is provided in the interface station 12 at a position adjacent to the transfer path R1 of the processing block BL1 in the width direction (the Y direction in the figure). As shown in FIG. 3, the transfer tower 60 has a plurality of transfer modules 61 arranged vertically one on top of the other.

[0038] As shown in FIG. 1, the interface station 12 is also provided with a transport module R4.

[0039] The transfer module R4 is provided at a position adjacent to the transfer tower 60 in the width direction (Y direction in the figure), and has a transfer arm R4a that is movable, for example, in the depth direction (X direction in FIG. 1), the vertical direction, and the direction around the vertical axis. The transfer module R4 holds a wafer W on the transfer arm R4a and can transfer the wafer W between the multiple transfer modules 61 of the transfer tower 60 and the exposure apparatus E.

[0040] 1, the transfer block BL2 of the processing station 11 has a transfer tower 52 at its rear end (the positive side in the X direction in the figure). As shown in Fig. 4, the transfer tower 52 has a transfer module 53. In the transfer tower 52, a plurality of transfer modules 53 may be provided so as to be stacked in the vertical direction (the up-and-down direction in Fig. 4).

[0041] 1, the transfer block BL2 is further provided with a transfer module R5. The transfer module R5 is provided between the transfer tower 50 and the transfer tower 52 and has a transfer arm R5a that is movable, for example, in the vertical direction and in a direction around the vertical axis. The transfer module R5 holds a wafer W on the transfer arm R5a and can transfer the wafer W between the multiple transfer modules 51 of the transfer tower 50 and the multiple transfer modules 53 of the transfer tower 52.

[0042] 1, the dry processing section 3 includes a load lock station 100 and a processing station 101. In the dry processing section 3, the load lock station 100 and the processing station 101 are integrally connected. In this example, the direction in which the load lock station 100 and the processing station 101 are connected is perpendicular to the direction in which the wet processing section 2 and the exposure apparatus E are connected in a top view.

[0043] The load lock station 100 is provided with a load lock module 110 configured so that the internal atmosphere can be switched between a reduced pressure atmosphere and an atmospheric pressure atmosphere.

[0044] The processing station 101 includes, for example, a vacuum transfer chamber 120 and first to fourth dry developing modules 121 to 124 .

[0045] The vacuum transfer chamber 120 is made of a sealable housing, and its interior is kept under reduced pressure (vacuum state). The vacuum transfer chamber 120 is formed, for example, in a substantially polygonal shape (pentagonal in the illustrated example) when viewed from above.

[0046] The first to fourth dry developing modules 121 to 124 are all dry developing units that dry develop the wafer W. While the wet type is a method that uses a liquid, the dry type is a method that uses a gas, specifically, a method that uses a gas under reduced pressure.

[0047] The first dry developing module 121 performs a first positive development by dry processing on the wafer W on which the chemically amplified resist is formed. The developing material used by the first dry developing module 121 is, for example, a vaporized product of the developing solution exemplified by the first developing module 30.

[0048] The second dry developing module 122 performs a second dry development on the wafer W on which a chemically amplified resist pattern has been formed by the first positive development performed by the first developing module 30. The developing material used by the second dry developing module 122 is, for example, a vaporized product of the developer exemplified by the second developing module 31.

[0049] The third dry developing module 123 performs a negative first development by dry processing on the wafer W on which the chemically amplified resist is formed. The developing material used by the third dry developing module 123 is, for example, a vaporized product of the developing solution exemplified by the third developing module 32.

[0050] The fourth dry developing module 124 performs a second dry development on the wafer W on which the chemically amplified resist has been formed by the negative first development performed by the first developing module 30. The developing material used by the fourth dry developing module 124 is, for example, a vaporized product of the developing solution exemplified by the fourth developing module 33.

[0051] For example, one each of the first to fourth dry developing modules 121 to 124 is provided.

[0052] In the processing station 101, the first to fourth dry developing modules 121 to 124 and the load lock station 100 are arranged, for example, surrounding the periphery of the vacuum transfer chamber 120 when viewed from above, i.e., aligned around a vertical axis passing through the center of the vacuum transfer chamber 120.

[0053] The processing station 101 may include a thermal processing module (not shown) that heats the wafer W, i.e., subjects the wafer W to a thermal process.

[0054] A transfer module 125 for transferring a wafer W is provided inside the vacuum transfer chamber 120. The transfer module 125 has a transfer arm 125a that is movable, for example, around a vertical axis. The transfer module 125 holds the wafer W on the transfer arm 125a and can transfer the wafer W between the first to fourth dry developing modules 121 to 124 and the load lock module 110, for example.

[0055] The intermediary transfer unit 4 transfers the wafers W between the wet treatment unit 2 and the dry treatment unit 3, specifically, transfers the wafers W wafer by wafer, that is, one wafer at a time.

[0056] The relay transfer unit 4 is provided with a transfer path 130, and transfers wafers W between the wet treatment unit 2 and the dry treatment unit 3 via the transfer path 130. The transfer path 130 of the relay transfer unit 4 constitutes a transfer route that extends in the depth direction (X direction in the drawing) including the transfer tower 50 of the transfer block BL2 and the like.

[0057] In this embodiment, the relay transport unit 4 is connected to a portion of the wet processing unit 2 that is farther away from the exposure device E than the processing block BL1, and more specifically, is connected to the transfer block BL2. More specifically, the transport path 130 of the relay transport unit 4 is connected to the transfer block BL2.

[0058] A transfer module 131 for transferring a wafer W is disposed on the transfer path 130. The transfer module 131 has a transfer arm 131a that is movable, for example, in the vertical direction and in a direction around the vertical axis. The transfer module 131 holds the wafer W on the transfer arm 131a and can transfer the wafer W between the multiple transfer modules 53 of the transfer tower 52, the cooling module 54, and the load lock module 110.

[0059] As shown in FIG. 1 , the wafer processing apparatus 1 includes at least one controller 5. The controller 5 processes computer-executable instructions that cause the wafer processing apparatus 1 to perform the various processes described in this disclosure. The controller 5 may be configured to control each element of the wafer processing apparatus 1 to perform the various processes described herein. In one embodiment, part or all of the controller 5 may be included in the wafer processing apparatus 1. The controller 5 may include a processor, a storage unit, and a communication interface. The controller 5 may be implemented, for example, by a computer. The processor may be configured to read from the storage unit a program that provides logic or routines that enable the various control operations and execute the read program to perform the various control operations. This program may be stored in the storage unit in advance or may be acquired via a medium when needed. The acquired program is stored in the storage unit and read from the storage unit by the processor for execution. The medium may be various computer-readable storage media or a communication line connected to the communication interface. The storage medium may be a temporary medium or a non-temporary medium H. The processor may be a central processing unit (CPU) or one or more circuits. The storage unit may include a RAM (Random Access Memory), a ROM (Read Only Memory), a HDD (Hard Disk Drive), a SSD (Solid State Drive), or a combination thereof. The communication interface may communicate with the wafer processing apparatus 1 via a communication line such as a LAN (Local Area Network).

[0060] <Processing Sequence Example 1> Next, a description will be given of an example of a processing sequence executed by the wafer processing apparatus 1. Fig. 5 is a flowchart showing main steps of processing sequence example 1. Fig. 6 is a diagram showing the state on the wafer W when processing sequence example 1 is being executed.

[0061] First, a wafer W is loaded into the wafer processing apparatus 1 (step S1). Specifically, for example, the wafer W is first removed from the cassette C on the cassette mounting table 20 by the transfer module 23 of the wet processing section 2 and transferred to the transfer module 51 of the transfer tower 50 of the transfer block BL2.

[0062] Next, the wafer W is subjected to a resist coating process, and a chemically amplified resist film is formed on the wafer W (step S2). Specifically, for example, the wafer W is transferred by the transfer module R2 to the resist coating module 34 in the processing block BL1. Then, in the resist coating module 34, a chemically amplified resist is applied to the surface of the wafer W by a spin coating method, and a chemically amplified resist film is formed so as to cover the surface of the wafer W. The thickness of the formed chemically amplified resist film is, for example, 3 nm to 100 nm, and preferably 20 nm to 50 nm, in the case of EUV light.

[0063] Next, a pre-applied bake (PAB) process is performed on the wafer W (step S3). Specifically, the wafer W is transferred to the heat treatment module 40 for the PAB process, and the heat treatment is performed on the wafer W. Thereafter, the wafer W is transferred to the transfer module 61 of the transfer tower 60 of the interface station 12.

[0064] Next, the wafer W is subjected to an exposure process (step S4). Specifically, for example, the wafer W is transferred to the exposure apparatus E by the transfer module R4, and the wafer W is subjected to a pattern exposure process using EUV light. As a result, a predetermined pattern formed on the mask is transferred to the chemically amplified resist film on the wafer W by the EUV light. In the exposed portion of the chemically amplified resist film, a photoacid generator (PAG) in the resist is photodecomposed to generate acid. After the pattern exposure process, the wafer W is transferred to the transfer module 61 of the transfer tower 60 by the transfer module R4.

[0065] Next, the wafer W is subjected to a post-exposure heat treatment (PEB treatment) (step S5). Specifically, for example, the wafer W is transferred by the transfer module R2 to a heat treatment module 40 for the PEB treatment, and the wafer W is subjected to a heat treatment using a heating plate 41. This provides energy that activates a reaction catalyzed by the acid generated in the pattern exposure treatment, and the resin in the exposed portion of the chemically amplified resist changes from non-polar to polar due to the acid-catalyzed reaction, making it soluble in a polar developer.

[0066] The target temperature, i.e., the set temperature, of the wafer W during the PEB treatment in step S5 is preferably 60° C. to 170° C., and more preferably 80° C. to 130° C. The lower the temperature of the wafer W during the PEB treatment, the smaller the surface roughness of the resist pattern obtained by process sequence example 1 tends to be, but the exposure dose sensitivity tends to be degraded. Therefore, the temperature is optimized so as to achieve the desired results.

[0067] The above steps S1 to S5 are an example of a process for preparing a wafer W on which a chemically amplified resist film is formed and which has been subjected to exposure processing and PEB processing.

[0068] Next, the wafer W is subjected to a first positive development using a developer with a strong polarity (step S6). Specifically, for example, the wafer W is transferred to the first developing module 30 by the transfer module R2. Then, in the first developing module 30, a liquid film of the developer with a strong polarity is formed on the wafer W, and the exposed portions of the chemically amplified resist film are selectively removed by the developer. Next, in the first developing module 30, a process for stopping the first development is performed on the wafer W using pure water as a rinse liquid, and the developer with a strong polarity is removed from the wafer W. This process may be omitted. Thereafter, the wafer W is rotated and dried. In step S6, as shown in FIG. 6A, the exposed portions F1 of the exposed portions F1 and unexposed portions F2 of the chemically amplified resist film are selectively removed, and the unexposed portions F2 remain on the wafer W as protrusions P11, thereby forming a chemically amplified resist pattern P1. Furthermore, the dimension (CD: Critical Dimension) of the convex portion P11 constituting the pattern P1 formed at this time is a first dimension L1 that is larger than the target dimension Lt.

[0069] Next, the wafer W is subjected to an additional PEB process (step S7) as a process for changing the characteristics of the pattern of the chemically amplified resist. Specifically, for example, the wafer W is transferred by the transfer module R2 to a heat treatment module 40 for the additional PEB process, and the wafer W is subjected to a heat treatment using a heating plate 41.

[0070] The target temperature, i.e., set temperature, of the wafer W for the additional PEB processing is higher than that for the PEB processing in step S5, preferably 80°C to 300°C, and more preferably 120°C to 170°C, which is around the glass transition point of the chemically amplified resist.

[0071] The purpose of the additional PEB treatment in step S7 is to impart appropriate fluidity to the chemically amplified resist pattern P1 by heat, thereby smoothing the surface of the pattern P1 (specifically, the convex portions P11 of the chemically amplified resist constituting the pattern P1), i.e., to smooth the surface. However, by imparting fluidity, as shown in FIG. 6B , the dimension La of the convex portions P11 constituting the pattern P1 becomes larger than the first dimension L1, i.e., the convex portions P11 become thicker. Furthermore, the additional PEB treatment promotes a change in the constituent resin of the chemically amplified resist on the wafer W from non-polar to polar. In other words, the additional PEB treatment is a treatment that increases the solubility of the chemically amplified resist on the wafer W in a polar developer.

[0072] Next, the wafer W is subjected to a second development using a weakly polar developer (step S8). Specifically, for example, the wafer W is transferred to the second developing module 31 by the transfer module R2. Then, in the second developing module 31, a liquid film of the weakly polar developer is formed on the wafer W. As a result, of the chemically amplified resist on the wafer W, whose constituent resin has changed from non-polar to polar as described above, that located on the surface of the chemically amplified resist pattern P1 on the wafer W is removed by the weakly polar developer. Thereafter, the wafer W is rotated and dried.

[0073] By this step S8, while suppressing deterioration of the roughness of the surface of the pattern P1, as shown in FIG. 6(C), the convex portion P11 constituting the pattern P1 can be reduced to a second dimension L2 that is smaller than the aforementioned first dimension L1 and approximately equal to the target dimension Lt.

[0074] Then, the wafer W is unloaded from the wafer processing apparatus 1 (step S9). Specifically, the wafer W is returned to the cassette C in the reverse order of step S1.

[0075] This completes the processing sequence.

[0076] <Major Effects of Process Sequence Example 1> In process sequence example 1, a positive first development is performed on the wafer W to form a chemically amplified resist pattern P1. Thereafter, an additional PEB process is performed on the wafer W as a process to change the properties of the chemically amplified resist in the pattern. Thereafter, a second development is performed on the wafer W using a developer different from that used in the first development (specifically, a developer with a weaker polarity than the developer used in the positive first development). Here, process sequence example 1 will be compared with a conventional process sequence in which the additional development and second development are omitted from process sequence example 1.

[0077] Generally, to reduce the dimensions of the convex portions of a chemically amplified resist pattern obtained by positive development for pattern formation (corresponding to the first positive development in Process Sequence Example 1), it is necessary to increase the exposure dose during the pattern exposure process in the exposure apparatus E (hereinafter referred to as the pattern exposure dose). However, in the case of the conventional process sequence described above, the pattern exposure dose, i.e., the exposure dose sensitivity required to achieve the target dimensions of the chemically amplified resist pattern by positive development, can be reduced by, for example, lengthening the PEB process time or increasing the amount of quencher in the resist. However, this method worsens the surface roughness of the pattern. Furthermore, in the conventional process sequence, shortening the PEB process time to improve the roughness worsens the exposure dose sensitivity. In other words, in the conventional process sequence, improving either the exposure dose sensitivity or the pattern surface roughness worsens the other.

[0078] In contrast, in the example of the processing sequence 1, the dimension of the chemically amplified resist pattern P1 formed by the first development, which is the development for pattern formation, may be a first dimension L1 larger than the target dimension Lt. Therefore, the pattern exposure dose may be small. Furthermore, an additional PEB process, which is performed on the wafer W after the first development and serves to change the characteristics of the chemically amplified resist in the pattern, improves the surface roughness of the positive chemically amplified resist pattern P1. Furthermore, although the additional PEB process increases the dimension of the convex portion P11 constituting the chemically amplified resist pattern P1 beyond the first dimension larger than the target dimension Lt, the second development can reduce the dimension of the convex portion P11 to a second dimension L2 substantially equal to the target dimension Lt. Furthermore, the developer for the second development is different from the developer for the first positive development. Specifically, the developer for the first positive development is a developer with a strong polarity, while the developer for the second development is a developer with a weak polarity. Therefore, the chemically amplified resist on the wafer W, which has become more soluble in a polar developer by the additional PEB treatment, is not excessively removed by the second development, thereby suppressing deterioration of the pattern surface roughness. Therefore, according to the example 1 of the process sequence, even with a small pattern exposure dose, the pattern P1 of the chemically amplified resist that is finally formed can be reduced to the target dimension Lt, and the roughness of the pattern surface can be reduced. That is, according to the example 1 of the process sequence, when positive-tone development is performed on the chemically amplified resist, it is possible to improve both the surface roughness of the pattern P1 while suppressing deterioration in exposure dose sensitivity. Furthermore, in this example, the additional PEB treatment can improve both the exposure dose sensitivity and the surface roughness of the pattern P1. Furthermore, as described above, the chemically amplified resist on the wafer W, which has become more soluble in a polar developer by the additional PEB treatment, is not excessively removed by the second development, thereby suppressing poor resolution.

[0079] Furthermore, according to processing sequence example 1, there is no need to adopt processing or processing conditions that result in a deterioration in resolution (for example, development using a developer with a stronger development power than a general developer, or prolonged heating in a PEB process before pattern formation, etc.), so that deterioration in resolution can be suppressed.

[0080] Furthermore, according to the processing sequence example 1, even if residues are generated between the convex portions P11 constituting the chemically amplified resist pattern P1 formed by the first positive development, i.e., in the unexposed portions, after the first development, depending on the resist type, the residues can be removed by the second development as a result of the additional PEB treatment, thereby achieving low defectivity.

[0081] FIG. 7 is a graph showing the power spectral density of the surface roughness (specifically, line width roughness (LWR)) of the formed patterns in Test Example 1 and Comparative Example 1. FIG. 8 is a graph showing the relationship between the pattern exposure dose and the dimension (CD) of the convex portion of the formed pattern in Test Examples 1 and 2 and Comparative Example 1. FIG. 9 is a graph showing the relationship between the dimension and the surface roughness (specifically, unbiased line width roughness (LWR)) when the dimension (CD) shown in FIG. 8 was obtained in Test Examples 1 and 2 and Comparative Example 1. In Test Example 1, processing was performed up to the additional PEB processing of Processing Sequence Example 1. In Test Example 2, processing was performed up to the end of Processing Sequence Example 1. In Comparative Example 1, processing was performed according to the conventional processing sequence described above. In both Test Example 2 and Comparative Example 1, a line-and-space pattern was formed, and the thickness of the chemically amplified resist film was set to 50 nm. In Test Examples 1 and 2 and Comparative Example 1, the temperature of the wafer W during PEB processing was 110° C., and the heating time was 60 seconds. A TMAH aqueous solution, which is a developing material with strong polarity, was used in the first development in Test Examples 1 and 2 and the development in Comparative Example 1. Furthermore, in the additional PEB treatment in Test Examples 1 and 2, the temperature of the wafer W was 130° C. and the heating time was 60 seconds. Furthermore, in the second development in Test Example 2, water, which is a developing material with weak polarity, was used.

[0082] FIG. 7 shows the results of Test Example 1, which was processed under conditions that resulted in a line width of 22 nm after the first development, and Comparative Example 1, which was processed under conditions that ultimately resulted in a line width of 22 nm according to the conventional processing sequence described above. As is clear from FIG. 7 , Test Example 1 had a lower surface roughness power spectral density in almost all spatial frequency bands compared to Comparative Example 1. That is, by performing processing up to the additional PEB treatment of Processing Sequence Example 1, surface roughness can be reduced regardless of the spatial appearance interval compared to the conventional processing sequence described above. In particular, Test Example 1 had a lower surface roughness power spectral density in the low spatial frequency band, which is difficult to improve with the conventional processing sequence. That is, by performing processing up to the additional PEB treatment of Processing Sequence Example 1, surface roughness with a short appearance interval, which is difficult to improve with the conventional processing sequence described above, can be improved. Furthermore, although not shown, according to tests conducted by the inventors, Test Example 2, which was processed under conditions that resulted in a line width of 22 nm, had a surface roughness power spectral density similar to that of Test Example 1 shown in FIG. 7 .

[0083] As is clear from Fig. 8, in Test Example 2, a chemically amplified resist pattern having a similar dimension (CD) can be obtained with a smaller exposure dose than in Comparative Example 1. Also, as is clear from Fig. 9, in Test Example 2, when the dimension (CD) of the chemically amplified resist pattern is similar to that of Comparative Example 11, the surface roughness of the pattern is smaller than in Comparative Example 1. Therefore, according to Processing Sequence Example 1, the surface roughness and exposure dose sensitivity of the chemically amplified resist pattern can be improved when positive development is performed.

[0084] As is clear from FIGS. 8 and 9, the additional PEB treatment can improve the surface roughness, although it increases the dimension (CD).

[0085] <Processing Sequence Example 2> Fig. 10 is a flowchart showing the main steps of Processing Sequence Example 2. Fig. 11 is a diagram showing the state on the wafer W when Processing Sequence Example 2 is being executed. In Processing Sequence Example 2, as shown in Fig. 10, first, steps up to step S6 in Processing Sequence Example 1 are performed. As a result, a chemically amplified resist pattern P1 is formed on the wafer W, as shown in Fig. 10(A). Furthermore, the dimension (CD) of the convex portion P11 constituting the pattern P1 formed at this time is a first dimension L1 that is larger than the target dimension Lt.

[0086] Next, as a process for changing the characteristics of the pattern of the chemically amplified resist, the wafer W is subjected to an ultraviolet irradiation process (step S11) instead of the additional PEB process in the process sequence example 1. Specifically, the wafer W is transferred by the transfer module R2 to the ultraviolet irradiation module 45, and the entire surface of the wafer W is irradiated with ultraviolet rays.

[0087] The purpose of the UV treatment in step S11 is to decompose the constituent resins, PAGs, and quenchers in the chemically amplified resist on the wafer W with UV light, thereby lowering the molecular weight of the resist and thereby reducing distortion in the chemically amplified resist pattern P1 (specifically, the convex portions P11 of the chemically amplified resist constituting the pattern P1) and smoothing the pattern surface, i.e., smoothing the surface. However, as the molecular weight is lowered, the chemically amplified resist pattern P1 becomes soft and reflows, and as shown in FIG. 11B, the dimension La' of the convex portions P11 constituting the pattern P1 becomes larger than the first dimension L1, i.e., the convex portions P11 become thicker. Furthermore, the height of the convex portions P11 decreases. Furthermore, the UV irradiation treatment decomposes the PAGs and quenchers in the chemically amplified resist on the wafer W, converting them from non-polar to polar, and as a result, the chemically amplified resist on the wafer W also changes from non-polar to polar. That is, the ultraviolet irradiation process is a process that increases the solubility of the chemically amplified resist on the wafer W in a polar developer, similar to the additional PEB process.

[0088] The wavelength of the ultraviolet light used in the ultraviolet irradiation process in step S11 may be any wavelength that decomposes the constituent resins, PAG, and quencher, for example, 170 nm or more and 400 nm or less. If the wavelength is 190 nm or less, direct decomposition of the constituent resins will result in decomposition of the methacrylic resin and crosslinking of the polyhydroxystyrene resin. Therefore, ultraviolet light with a short wavelength of 190 nm or less can be used to adjust the polarity of the resist. In practice, a light source such as a lamp or LED must be compatible with the ultraviolet light used in the ultraviolet irradiation process. A mercury lamp capable of emitting ultraviolet light with a wavelength of 170 nm to 400 nm is desirable as the light source for the ultraviolet irradiation process. Furthermore, because the light intensity during the ultraviolet irradiation process is directly related to the dimensions of the pattern P1, it is preferable to use a light source with an LED that allows for easy light intensity control. Specifically, it is preferable to use a light source with an LED that can irradiate ultraviolet light with wavelengths of 280 nm and 365 nm to 395 nm.

[0089] Subsequently, the wafer W is subjected to a second development using a developer with a weak polarity (step S8). Specifically, as described above.

[0090] By this step S8, while suppressing deterioration of the roughness of the surface of the pattern P1, as shown in FIG. 11(C), the convex portion P11 constituting the pattern P1 can be reduced to a second dimension L2 that is smaller than the aforementioned first dimension L1 and approximately equal to the target dimension Lt.

[0091] Then, the wafer W is unloaded from the wafer processing apparatus 1 (step S9).

[0092] <Major Effects of Processing Sequence Example 2> According to processing sequence example 2, when performing positive development on a chemically amplified resist, it is possible to improve the surface roughness of pattern P1 while suppressing deterioration in exposure sensitivity, and to suppress the occurrence of poor resolution, for the same reasons as in processing sequence example 1. Furthermore, according to processing sequence example 2, it is possible to suppress deterioration in resolution, for the same reasons as in processing sequence example 1.

[0093] Furthermore, according to the processing sequence example 2, even if residues are generated between the convex portions P11 constituting the chemically amplified resist pattern P1 formed by the positive first development, i.e., in the unexposed portions, after the first development, the PAG and quencher in the residues are decomposed by the ultraviolet irradiation process, and the solubility of the residues in a polar developer increases. Therefore, the residues can be removed by the second development, thereby reducing defects on the wafer W.

[0094] FIG. 12 is a graph showing the power spectral density of the surface roughness (specifically, line width roughness (LWR)) of the formed patterns in Test Example 3 and Comparative Example 2. FIG. 13 is a graph showing the relationship between the dimension (CD) of the convex portions of the formed patterns and the surface roughness (specifically, unbiased line width roughness (uLWR)) in Test Examples 4, 5, and Comparative Example 3. In Test Examples 3 and 4, processing was performed up to the ultraviolet irradiation processing of Processing Sequence Example 2. In Test Example 5, processing was performed up to the end of Processing Sequence Example 2. In Comparative Examples 2 and 3, processing was performed according to the conventional processing sequence described above. In all of Test Examples 3-5 and Comparative Examples 2 and 3, line-and-space patterns were formed, and the thickness of the chemically amplified resist film was set to 50 nm. In Test Examples 3-5 and Comparative Examples 2 and 3, the temperature of the wafer W during PEB processing was set to 110° C., and the heating time was set to 60 seconds. In the first development in Test Examples 3-5 and the development in Comparative Examples 2 and 3, a TMAH aqueous solution, which is a strongly polar developing material, was used. Furthermore, in the ultraviolet treatment in Test Example 3, ultraviolet light having a wavelength of 172 nm was used, and the exposure dose was 500 mJ / cm ２ Furthermore, in the second development in Test Example 5, water, which is a developing material with weak polarity, was used.

[0095] FIG. 12 shows the results of Test Example 3, which was processed under conditions that resulted in a line width of 22 nm after the first development, and Comparative Example 2, which was processed under conditions that ultimately resulted in a line width of 22 nm according to the conventional processing sequence described above. As is clear from FIG. 12 , Test Example 3 had a lower surface roughness power spectral density in almost all spatial frequency bands compared to Comparative Example 2. That is, by performing processing up to the ultraviolet irradiation treatment of Processing Sequence Example 2, surface roughness can be reduced regardless of the spatial appearance interval compared to the conventional processing sequence described above. In particular, Test Example 3 had a lower surface roughness power spectral density in the low spatial frequency band, which is difficult to improve with the conventional processing sequence. That is, by performing processing up to the ultraviolet irradiation treatment of Processing Sequence Example 2, surface roughness with a short appearance interval, which is difficult to improve with the conventional processing sequence described above, can be improved. Furthermore, although not shown, according to tests conducted by the present inventors, when processing was performed under conditions that resulted in a line width of 22 nm according to Processing Sequence Example 2, the surface roughness power spectral density was similar to that of Test Example 3 shown in FIG. 12 .

[0096] 13, in Test Example 5, when the dimension (CD) of the chemically amplified resist pattern is equivalent to that of Comparative Example 3, the surface roughness of the pattern is smaller than that of Comparative Example 3. Therefore, according to Processing Sequence Example 2, when positive development is performed, it is possible to improve the surface roughness of the chemically amplified resist pattern while suppressing deterioration in exposure dose sensitivity.

[0097] As is clear from FIG. 13, the surface roughness can be improved by simply performing the ultraviolet irradiation treatment without performing the second development.

[0098] 14 is a graph showing the relationship between the irradiation intensity during ultraviolet irradiation and the surface roughness (specifically, the arithmetic mean roughness) of the photo-amplified resist pattern when processing was performed up to the ultraviolet irradiation process of processing sequence example 2. Note that an ultraviolet irradiation intensity of "0" indicates that no ultraviolet irradiation processing was performed, i.e., that processing was performed according to the conventional processing sequence described above. The arithmetic mean roughness was calculated based on the results of detection using an atomic force microscope.

[0099] 14, the surface roughness (specifically, the arithmetic mean roughness) of the photo-amplified resist pattern can be improved by the ultraviolet irradiation treatment of the processing sequence example 2. Furthermore, by increasing the ultraviolet irradiation intensity during the ultraviolet irradiation treatment, the surface roughness can be further improved.

[0100] <Processing Sequence Example 3> Fig. 15 is a flowchart showing the main steps of Processing Sequence Example 3. Fig. 16 is a diagram showing the state on the wafer W when Processing Sequence Example 3 is being executed. In Processing Sequence Example 3, as shown in Fig. 15, first, the steps up to step S5 in Processing Sequence Example 1 are performed. However, the PEB treatment in step S5 provides energy that activates a reaction catalyzed by the acid generated in the pattern exposure treatment, and the resin in the chemically amplified resist changes from non-polar to polar due to the acid-catalyzed reaction, making it insoluble in a predetermined developer used in the negative first development.

[0101] Next, the wafer W is subjected to a negative first development using a predetermined developer (step S21). Specifically, for example, the wafer W is transferred to the third developing module 32 by the transfer module R2. Then, in the third developing module 32, a liquid film of the predetermined developer is formed on the wafer W, and the unexposed portions of the chemically amplified resist film are selectively removed by the developer. Next, in the third developing module 32, a process for stopping the first development is performed on the wafer W using a rinse liquid, and the predetermined developer is removed from the wafer W. This process may be omitted. Thereafter, the wafer W is rotated and dried. In step S21, as shown in FIG. 16A , the unexposed portions F12 of the exposed portions F11 and unexposed portions F12 of the chemically amplified resist film are selectively removed, and the exposed portions F11 remain on the wafer W as protrusions P21, thereby forming a chemically amplified resist pattern P2. Furthermore, the dimension (CD: Critical Dimension) of the convex portion P21 constituting the pattern P2 formed at this time is a first dimension L1 that is smaller than the target dimension Lt.

[0102] Next, the wafer W is subjected to an additional PEB process as a process for changing the characteristics of the pattern of the chemically amplified resist (step S7).

[0103] This step S7 imparts fluidity to the chemically amplified resist pattern P2, smoothing the surface of the pattern P2 (specifically, the convex portions P21 of the chemically amplified resist that constitute the pattern P2). However, by imparting fluidity, as shown in FIG. 16B, the dimension Lb of the convex portions P21 that constitute the pattern P2 becomes larger than the first dimension L1, i.e., the convex portions P21 become thicker. Furthermore, the additional PEB process promotes the change of the constituent resin of the chemically amplified resist on the wafer W from non-polar to polar.

[0104] Next, the wafer W is subjected to a second development using a predetermined developer (step S23). Specifically, for example, the wafer W is transferred to the fourth developing module 33 by the transfer module R2. Then, in the fourth developing module 33, a liquid film of water as the predetermined developer is formed on the wafer W. As a result, of the chemically amplified resist on the wafer W, whose constituent resin has changed from non-polar to polar as described above, that located on the surface of the chemically amplified resist pattern P2 on the wafer W is removed by the water. Thereafter, the wafer W is rotated and dried.

[0105] By this step S23, while suppressing deterioration of the surface roughness of the pattern P1, as shown in FIG. 16(C), the convex portion P21 constituting the pattern P2 can be reduced to a third dimension L3 that is larger than the aforementioned first dimension L1 and approximately equal to the target dimension Lt.

[0106] Then, the wafer W is unloaded from the wafer processing apparatus 1 (step S9).

[0107] <Major Effects of Process Sequence Example 3> In process sequence example 3, a negative first development is performed on the wafer W to form a chemically amplified resist pattern P2. Thereafter, an additional PEB process is performed on the wafer W as a process to change the properties of the chemically amplified resist in the pattern. Thereafter, a second development is performed on the wafer W using a developer different from that used in the first development (specifically, a developer having a higher polarity than the developer used in the negative first development).

[0108] In the example 3 of the processing sequence, the chemically amplified resist pattern P2 formed by the negative first development, which is development for pattern formation, may have a first dimension L1 of its convex portion P21, which is smaller than the target dimension Lt. Therefore, the pattern exposure dose may be small. Then, an additional PEB process, which is performed on the wafer W after the first development and serves to change the characteristics of the chemically amplified resist in the pattern, improves the surface roughness of the chemically amplified resist pattern P2. Furthermore, although the additional PEB process causes the dimension of the convex portion P21 constituting the chemically amplified resist pattern P2 to be larger than the target dimension Lt, the second development can reduce the dimension of the convex portion P21 to a third dimension L3, which is approximately equal to the target dimension Lt. Furthermore, the developer for the second development is different from the developer for the negative-tone first development. Specifically, the developer for the second development is a developer with a higher polarity than the developer for the negative-tone first development. More specifically, the developer for the second development is an organic solvent or water with a higher polarity than the organic solvent used as the developer for the negative-tone first development. That is, the developer for the second development has a moderate polarity. Therefore, the chemically amplified resist on the wafer W, which has changed from non-polar to polar due to the additional PEB treatment, is removed by the second development. Specifically, the surface roughness caused by polar molecules such as decomposed acid in the chemically amplified resist is removed. However, because the developer for the second development does not have a strong polarity like the developer for the positive-tone first development, but has a moderate polarity, the chemically amplified resist on the wafer W, which has changed to polar, is not excessively removed by the second development, thereby suppressing deterioration of the roughness of the pattern surface. Furthermore, the additional PEB treatment partially deprotects the chemically amplified resist on the wafer W, increasing the polarity of the resist, which increases the affinity of the resist with the developer for the second development, such as water, and thus smoothing the surface of the resist pattern. Therefore, according to the example 3 of the processing sequence, even if the pattern exposure dose is small, the dimensions of the chemically amplified resist pattern P2 that is finally formed can be increased to the target dimension Lt, and the roughness of the pattern surface can be reduced.That is, according to the processing sequence example 3, when negative-tone development is performed on the chemically amplified resist, it is possible to improve both the surface roughness of the pattern P1 while suppressing deterioration of exposure sensitivity. Furthermore, as described above, the chemically amplified resist on the wafer W, which has been converted from non-polar to polar by the additional PEB treatment, is not excessively removed by the second development, thereby suppressing the occurrence of poor resolution. Furthermore, by using water as the developer for the second development, it is possible to remove residues resulting from polar molecules such as decomposed acid in the chemically amplified resist, thereby suppressing the occurrence of defects. When water is used as the developer for the second development, a surfactant may be added to the water to suppress pattern collapse due to water.

[0109] Furthermore, according to processing sequence example 3, there is no need to adopt processing or processing conditions that result in a deterioration in resolution (for example, development using a developer with a stronger development power than a general developer, or prolonged heating in a PEB process before pattern formation, etc.), so that deterioration in resolution can be suppressed.

[0110] <Processing Sequence Example 4> Figure 17 is a flowchart showing the main steps of Processing Sequence Example 4. In Processing Sequence Example 4, as shown in Figure 17, first, steps up to step S22 in Processing Sequence Example 1 are performed. As a result, a negative chemically amplified resist pattern P2 is formed on the wafer W. Furthermore, the dimension (CD) of the convex portion P11 constituting the pattern P2 formed at this time is a first dimension L1 that is smaller than the target dimension Lt.

[0111] Next, as a process for changing the characteristics of the pattern of the chemically amplified resist, the wafer W is subjected to an ultraviolet irradiation process (step S31) instead of the additional PEB process of process sequence example 3. Specifically, the wafer W is transferred by the transfer module R2 to the ultraviolet irradiation module 45, and the entire surface of the wafer W is irradiated with ultraviolet rays.

[0112] In step S31, the constituent resins, PAG, and quencher in the chemically amplified resist on the wafer W are decomposed by the ultraviolet light, and the resist is reduced in molecular weight. As a result, distortion in the surface of the chemically amplified resist pattern P2 (specifically, the convex portions P21 of the chemically amplified resist that constitute the pattern P2) is reduced, and the pattern surface is smoothed. Furthermore, the ultraviolet irradiation process decomposes the PAG and quencher in the chemically amplified resist on the wafer W, changing them from non-polar to polar, and as a result, the chemically amplified resist on the wafer W also changes from non-polar to polar.

[0113] Subsequently, the wafer W is subjected to a second development using a predetermined developer (step S8).

[0114] This step S8 makes it possible to reduce the convex portion P11 constituting the pattern P1 to a third dimension L3 that is larger than the aforementioned first dimension L1 and approximately equal to the target dimension Lt, while suppressing deterioration of the surface roughness of the pattern P1.

[0115] Then, the wafer W is unloaded from the wafer processing apparatus 1 (step S9).

[0116] <Major Effects of Processing Sequence Example 4> According to processing sequence example 4, when negative development is performed on a chemically amplified resist, it is possible to improve the surface roughness of pattern P2 while suppressing deterioration in exposure sensitivity, and to suppress the occurrence of poor resolution, for the same reasons as in processing sequence example 3. Furthermore, according to processing sequence example 4, it is possible to suppress deterioration in resolution, for the same reasons as in processing sequence example 3.

[0117] <Processing Sequence Example 5> In processing sequence example 5, an additional PEB process in processing sequence example 1 and an ultraviolet irradiation process in processing sequence example 2 are performed between the first development and the second development in processing sequence example 1.

[0118] <Processing Sequence Example 6> In processing sequence example 6, an additional PEB process in processing sequence example 3 and an ultraviolet irradiation process in processing sequence example 4 are performed between the first development and the second development in processing sequence example 3.

[0119] <Variation of Example 2 of Processing Sequence> When performing positive development and performing ultraviolet irradiation processing as a process for changing the characteristics of the pattern of the chemically amplified resist, during the second development using a developer with weak polarity, a developer for the negative second development may be used to remove residues of non-polar components on the wafer W.

[0120] <Other Modifications of Processing Sequence Examples 1 to 5> In the processing sequence examples 1 to 6 and their modifications described above, the pattern exposure process uses EUV light, but it may also use electron beams. Furthermore, the pattern exposure process may also use ultraviolet light (KrF radiation, ArF radiation) or may be performed by immersion. However, when the pattern dimension (CD) of a chemically amplified resist is small, uneven distribution of components in the resist has a more significant impact on the roughness of the pattern surface. Therefore, the technology disclosed herein is more suitable for use in pattern exposure processes using short-wavelength light, such as EUV light, for the purpose of forming small-dimension patterns. Furthermore, in processing sequence examples 1 to 6 and their modifications, the wafer W is not subjected to a post-bake process, but it may be subjected to a post-bake process. The post-bake process is performed by a thermal treatment module 40 for that process.

[0121] Furthermore, in the processing sequence examples 1 to 6 and their variations, a one-shot exposure of the entire surface of the wafer W using ultraviolet light may be performed between the pattern exposure process and the PEB process, or between the PEB process and the first development.

[0122] Furthermore, in the process sequence examples 1 to 6 and their modified examples, wet development was performed as the development, but some or all of the development in each process sequence may be dry development. When dry development is performed, for example, dry development modules 121 to 124 are used depending on the type of developing material used in the development. After the first development and the second development are performed wet, residue remaining on the wafer W after the second development may be removed using one of the dry development modules 121 to 124. In the process using the dry development modules 121 to 124, the processing temperature may be set to a high temperature exceeding 40°C in order to promote vaporization of the material to be removed and shorten the processing time.

[0123] <Modifications of the Wafer Processing Apparatus 1> In the above examples, the first development module and the second development module are provided separately. However, if the same processing material is used for the process of stopping the first development and the second development (for example, water (pure water)), the first development module and the second development module may be integrated. In other words, a common module may be used for the first development and the second development. In this case, the second development is performed by the module used for the process of stopping the first development.

[0124] Components of the wafer processing apparatus 1 may be omitted as appropriate depending on the processing sequence performed by the wafer processing apparatus 1. That is, when the wafer processing apparatus 1 performs only a part of the above-described exemplary processing sequences, components of the wafer processing apparatus 1 that are not used in the processing sequence may be omitted.

[0125] The embodiments disclosed herein should be considered to be illustrative in all respects and not restrictive. The above-described embodiments may be omitted, substituted, or modified in various ways without departing from the scope and spirit of the appended claims. For example, the components of the above-described embodiments may be arbitrarily combined. Such an arbitrary combination naturally provides the functions and effects of each of the components involved in the combination, and also provides other functions and effects that are apparent to those skilled in the art from the description of this specification.

[0126] Furthermore, the effects described herein are merely descriptive or exemplary and are not limiting. In other words, the technology according to the present disclosure may achieve other effects that are apparent to those skilled in the art from the description of this specification, in addition to or in place of the above-described effects.

[0127] The following configuration examples also fall within the technical scope of the present disclosure: (1) A substrate processing method including: (A) preparing a substrate on which a chemically amplified resist film has been formed and which has been subjected to an exposure process and a post-exposure heat treatment; (B) performing a first development process on the substrate to remove either an exposed portion or an unexposed portion of the film to form a pattern of the chemically amplified resist; (C) after the process (B), performing a process on the substrate to change the properties of the chemically amplified resist in the pattern; and (D) after the process (C), performing a second development process on the substrate using a developer material different from that used in the first development process to modify the shape of the pattern. (2) The substrate processing method according to (1), in which the process to change the properties is a heat treatment; and (3) The substrate processing method according to (2), in which the target temperature of the substrate in the heat treatment as the process to change the properties is higher than that in the heat treatment after the exposure process. (4) The substrate processing method according to any one of (1) to (3), wherein the characteristic-changing treatment is ultraviolet irradiation treatment. (5) The substrate processing method according to any one of (1) to (4), wherein the developing material used in the first development is a tetraethylammonium hydroxide aqueous solution, and the developing material used in the second development is water. (6) The substrate processing method according to any one of (1) to (5), further comprising (E) a step of subjecting the substrate to a treatment to stop the first development after the step (B) and before the step (C), wherein the same treatment material is used in the treatment to stop the first development and the second development. (7) The substrate processing method according to claim 6, wherein in the step (D), the second development is performed using a module used in the treatment to stop the first development. (8) The substrate processing method according to any one of (1) to (4), wherein the developing material used in the first development is an organic solvent, and the developing material used in the second development is another organic solvent having a higher polarity than the organic solvent used in the first development, or water. (9) The substrate processing method according to any one of (1) to (7), wherein the step (C) enlarges the surfaces of the convex portions constituting the pattern from a first dimension by a treatment for changing the characteristics, and the step (D) reduces the convex portions to a second dimension smaller than the first dimension by the second development.(10) The substrate processing method according to any one of (1) to (9), wherein the exposure process is an exposure process using EUV light. (11) A substrate processing apparatus comprising: a first developing unit that performs a first development on a substrate that has been coated with a chemically amplified resist film and that has been subjected to an exposure process and a heat treatment after the exposure process, the first development removing either an exposed portion or an unexposed portion of the film by the exposure process to form a pattern of the chemically amplified resist; a property changing unit that performs a process on the substrate after the first development to change properties of the chemically amplified resist in the pattern; and a second developing unit that performs a second development on the substrate after the property changing process using a developing material different from that used for the first development to modify a shape of the pattern.

[0128] REFERENCE SIGNS LIST 1 wafer processing device 30 first developing module 31 second developing module 32 third developing module 33 fourth developing module 40 heat treatment module 45 ultraviolet irradiation module 121 first dry developing module 122 second dry developing module 123 third dry developing module 124 fourth dry developing module E exposure device P1 pattern P2 pattern W wafer

Claims

1. A substrate processing method comprising: (A) preparing a substrate on which a chemically amplified resist film has been formed and which has been subjected to an exposure process and a post-exposure heat treatment; (B) performing a first development process on the substrate to remove either the exposed or unexposed portions of the film by the exposure process to form a pattern of the chemically amplified resist; (C) after step (B), performing a process on the substrate to change the characteristics of the chemically amplified resist in the pattern; and (D) after step (C), performing a second development process on the substrate using a developer material different from that used in the first development process to modify the shape of the pattern.

2. The substrate processing method according to claim 1, wherein the process for changing the characteristics is a heat treatment.

3. The substrate processing method according to claim 2, wherein the target temperature of the substrate in the heat treatment as the characteristic-changing treatment is higher than that of the heat treatment after the exposure treatment.

4. The substrate processing method according to claim 1, wherein the process for changing the characteristics is ultraviolet irradiation process.

5. A substrate processing method according to any one of claims 1 to 4, wherein the developing material used in the first development is an aqueous solution of tetraethylammonium hydroxide, and the developing material used in the second development is water.

6. A substrate processing method according to any one of claims 1 to 4, further comprising the step of (E) subjecting the substrate to a process for stopping the first development after the step (B) and before the step (C), wherein the same processing material is used for the process for stopping the first development and the second development.

7. The substrate processing method according to claim 6, wherein in step (D), the second development is performed by the module used in the process of stopping the first development.

8. A substrate processing method according to any one of claims 1 to 4, wherein the developing material used in the first development is an organic solvent, and the developing material used in the second development is another organic solvent having a higher polarity than the organic solvent used in the first development, or water.

9. A substrate processing method according to any one of claims 1 to 4, wherein the step (C) enlarges the surface of the convex portions constituting the pattern from a first dimension by a process that changes the characteristics, and the step (D) reduces the convex portions to a second dimension smaller than the first dimension by the second development.

10. The substrate processing method according to any one of claims 1 to 4, wherein the exposure processing is an exposure processing using EUV light.

11. A substrate processing apparatus comprising: a first developing unit that performs a first development on a substrate that has been coated with a chemically amplified resist film and that has been subjected to an exposure process and a post-exposure heating process, thereby removing either the exposed or unexposed portions of the film to form a pattern of the chemically amplified resist; a characteristic changing unit that performs a process on the substrate after the first development to change the characteristics of the chemically amplified resist in the pattern; and a second developing unit that performs a second development on the substrate after the characteristic changing process, using a developing material different from that used for the first development, to modify the shape of the pattern.

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