Substrate processing method and substrate processing apparatus

Abstract

The present invention provides a substrate processing method and a substrate processing apparatus. The substrate processing method and the substrate processing apparatus, which process a substrate having an unpatterned resist film on a surface after immersion exposure, can cause water used for the immersion exposure and a cleaning liquid to not remain on the surface of the substrate after the processing, regardless of the size of a contact angle of the surface of the substrate before the processing. The substrate processing method includes: a step of supplying a solution of a water-soluble polymer to the surface of the substrate having the unpatterned resist film after the immersion exposure processing; a step of hydrophilizing the surface of the resist film with the supplied solution of the water-soluble polymer; a step of removing a water solution of the water-soluble polymer, which does not contribute to the hydrophilization, by supplying a cleaning liquid to the surface of the substrate while rotating the substrate after the hydrophilizing step; and a step of drying the substrate to which the cleaning liquid is supplied. The solution of the water-soluble polymer has a pH value that causes the concentration of an acid of the resist film to be within an allowable range.

Description

Technical Field

[0001] This invention relates to a substrate processing method and a substrate processing apparatus. Background Technology

[0002] Patent Document 1 discloses a substrate cleaning apparatus, comprising: a rotatable substrate holding portion for horizontally holding a substrate; a cleaning fluid nozzle for supplying cleaning fluid to the surface of the substrate held by the substrate holding portion; and a drive portion for moving the cleaning fluid nozzle. In this substrate cleaning apparatus, the drive portion moves the cleaning fluid nozzle such that, when the substrate rotates, the supply position of the cleaning fluid from the cleaning fluid nozzle moves from the center of the substrate to the periphery.

[0003] Existing technical documents

[0004] Patent documents

[0005] Patent Document 1: Japanese Patent Application Publication No. 2011-14935 Summary of the Invention

[0006] The technical problem that the invention aims to solve

[0007] The technology of the present invention, in a substrate processing method and substrate processing apparatus for processing a substrate having a resist film without pattern after immersion exposure, ensures that the water and cleaning solution used for immersion exposure do not remain on the surface of the substrate after processing, regardless of the size of the contact angle of the substrate surface before processing.

[0008] Technical solutions for solving technical problems

[0009] One aspect of the present invention is a substrate processing method, comprising: a step of supplying a solution of a water-soluble polymer to the surface of a substrate having an unpatterned resist film after immersion exposure; a step of hydrophilizing the surface of the resist film with the supplied solution of the water-soluble polymer; a step of, after the hydrophilization step, removing an aqueous solution of the water-soluble polymer that does not contribute to the hydrophilization by supplying a cleaning solution to the surface of the substrate while rotating the substrate; and a step of drying the substrate to which the cleaning solution has been supplied, wherein the solution of the water-soluble polymer has a pH value that keeps the acid concentration of the resist film within an acceptable range.

[0010] Invention Effects

[0011] According to the present invention, in the substrate processing method and substrate processing apparatus for processing substrates having a resist film without pattern after immersion exposure, the water and cleaning solution used for immersion exposure can be made to remain on the surface of the substrate after processing, regardless of the size of the contact angle of the substrate surface before processing. Attached Figure Description

[0012] Figure 1 This is a longitudinal cross-sectional view showing the general structure of the cleaning apparatus of the substrate processing apparatus in this embodiment.

[0013] Figure 2 This is a cross-sectional view showing the general structure of the cleaning apparatus of the substrate processing apparatus in this embodiment.

[0014] Figure 3 It means Figure 1 A flowchart illustrating an example of a cleaning process in a cleaning apparatus.

[0015] Figure 4 It is a three-dimensional diagram schematically showing the appearance of the wafers and nozzles in each step of the cleaning process.

[0016] Figure 5 It is a cross-sectional view schematically showing the state of the wafer surface before or after the cleaning process.

[0017] Figure 6 This is a graph showing the state changes of the resist film under conditions of high pH in aqueous solution.

[0018] Figure 7 This is a graph showing the state changes of the resist film when the pH value of the aqueous solution is low.

[0019] Figure 8 This is a side view used to illustrate the structure of the cleaning fluid supply nozzle.

[0020] Explanation of reference numerals in the attached figures

[0021] 1. Cleaning device

[0022] 20 Rotary suction cups

[0023] 21 Suction Cup Drive Unit

[0024] 33 Solution supply nozzle

[0025] 34 Nozzle drive unit

[0026] 36 Cleaning fluid supply nozzle

[0027] 37 Nozzle drive unit

[0028] 200 Control Department

[0029] P water-soluble polymer

[0030] R Resist Film

[0031] W chip. Detailed Implementation

[0032] In the photolithography process of semiconductor device manufacturing, a series of processes are performed to form a desired resist pattern on a semiconductor wafer (hereinafter referred to as "wafer"). These processes include, for example, resist coating process, in which a resist solution is supplied to the wafer to form a resist film; exposure process, in which the resist film is exposed; and development process, in which a developer solution is supplied to the exposed resist film for development.

[0033] One type of exposure described above is immersion exposure. Immersion exposure is a method of exposure using a water film formed between a lens located at the front end of the exposure head and the wafer surface. The exposure head scans while the water film is formed, and repeated exposures are performed to sequentially transfer the desired pattern onto the wafer. In this immersion exposure, to ensure that the water film tracks the exposure head, it is necessary to improve the hydrophobicity of the wafer surface, specifically the resist film.

[0034] However, sometimes the water used for immersion exposure (hereinafter referred to as immersion water) remains as water droplets on the surface of the exposed wafer. These water droplets are dried by post-exposure heating (PEB) after exposure and before development, becoming water immersions as defects.

[0035] Therefore, a process is performed to clean the surface of the exposed wafer to remove water droplets from the liquid immersion. For example, in Patent Document 1, as described above, the cleaning fluid nozzle is moved while the substrate is rotated, so that the supply position of the cleaning fluid from the cleaning fluid nozzle moves from the center of the substrate to the periphery, thereby reducing the number of water droplets remaining on the substrate.

[0036] However, conventional post-exposure cleaning processes, which simply move the cleaning solution nozzle while rotating the wafer at a constant speed to shift the supply position of the cleaning solution from the center of the wafer to the periphery, sometimes fail to remove water droplets from the immersion water, depending on the degree of hydrophobicity of the wafer surface before cleaning. This will be explained below.

[0037] In the aforementioned existing post-exposure cleaning process, when the wafer rotation speed is appropriate, the cleaning fluid released from the cleaning fluid nozzle forms a liquid block on the wafer. This liquid block travels towards the wafer periphery in a spiral motion while expanding its circumferential width, and is discharged outside the wafer as a liquid block. During this process, water droplets from the liquid immersion on the wafer are collected by the aforementioned liquid block of cleaning fluid and discharged outside the wafer together with the liquid block.

[0038] On the other hand, in the existing post-exposure cleaning process described above, when the wafer rotates at high speeds, the cleaning solution released from the nozzle collides with the wafer and scatters, failing to form a liquid mass. This not only makes it impossible to collect the liquid droplets but also creates new small droplets of cleaning solution. Furthermore, even if a liquid mass forms, it breaks down at the periphery, resulting in the formation of new small droplets. These small droplets, due to their small mass, generate little centrifugal force even at high rotation speeds, making them difficult to remove.

[0039] However, the surface of the wafer used for immersion exposure is highly hydrophobic, as mentioned above, meaning it has a large contact angle with water. Therefore, the upper limit of the wafer rotation speed that prevents the cleaning solution from scattering upon impact is low. Furthermore, in the existing post-exposure cleaning process described above, when the wafer rotation speed is too low, the centrifugal force acting on the cleaning solution decreases, and water droplets remain on the wafer. Therefore, depending on the contact angle of the wafer surface after immersion exposure, the permissible range of suitable wafer rotation speed is narrow, and determining the processing conditions for this speed is time-consuming; sometimes, it is practically impossible to completely remove the immersion water and cleaning solution droplets from the wafer. Additionally, when the upper limit of the wafer rotation speed that prevents cleaning solution scattering is lower than the lower limit of the wafer rotation speed that prevents water droplets from remaining on the wafer, even adjusting the rotation speed cannot practically remove the immersion water and cleaning solution droplets from the wafer.

[0040] Therefore, the technology of the present invention, in the substrate processing method and substrate processing apparatus for processing substrates with an unpatterned resist film on the surface after immersion exposure, ensures that the water and cleaning solution used for immersion exposure do not remain on the surface of the substrate after processing, regardless of the size of the contact angle of the substrate surface before processing.

[0041] The substrate processing method and substrate processing apparatus of this embodiment will now be described with reference to the accompanying drawings. Furthermore, in this specification and the accompanying drawings, elements having substantially the same functional structure are labeled with the same reference numerals, and repeated descriptions are omitted.

[0042] Figure 1 and Figure 2 These are longitudinal and cross-sectional views showing the general structure of the cleaning apparatus 1, which is the substrate processing apparatus of this embodiment.

[0043] The cleaning apparatus 1 takes a wafer W, which is a substrate with an unpatterned resist film on its surface after immersion exposure, as the object to be processed, i.e., the object to be cleaned. Specifically, the wafer W to be cleaned by the cleaning apparatus 1 is the wafer after immersion exposure and before PEB processing. Furthermore, the material of the resist film formed on the wafer W to be cleaned is a chemically amplified resist, which can be either positive or negative. In the following text, the resist film is a positive resist film.

[0044] Cleaning device 1 as follows Figure 1 The diagram shows a processing container 10 that can seal its interior. A wafer W feed outlet (not shown) is formed on the side of the processing container 10, and an opening and closing member (not shown) is provided at the feed outlet.

[0045] A rotary chuck 20, serving as a substrate holding part, is provided inside the processing container 10 to hold the wafer W and rotate it about a vertical axis. The rotary chuck 20 has a horizontal upper surface, on which a suction port (not shown) for attracting, for example, the wafer W is provided. By suction from this suction port, the wafer W can be adsorbed and held on the rotary chuck 20.

[0046] Furthermore, a suction cup drive unit 21, serving as a rotation mechanism, is provided below the rotating suction cup 20. The suction cup drive unit 21 includes, for example, a motor, which enables the rotating suction cup 20 to rotate at various speeds. In addition, the suction cup drive unit 21 is provided with a lifting drive mechanism including a cylinder (not shown), and the rotating suction cup 20 is configured to be able to be raised and lowered by the lifting drive mechanism.

[0047] A cup-shaped body 22 is provided around the rotating chuck 20 in such a way that it surrounds and holds the wafer W held by the rotating chuck 20. The cup-shaped body 22 receives and recovers liquid that spills or falls from the wafer W. A discharge pipe 23 for discharging the recovered liquid and an exhaust pipe 24 for venting air from the inside of the cup-shaped body 22 are connected to the lower surface of the cup-shaped body 22.

[0048] like Figure 2 As shown, in the negative X direction of the cup-shaped body 22 ( Figure 2 The lower side is formed along the Y direction ( Figure 2 Guide rails 30A and 30B extend in the left and right directions. For example, guide rails 30A and 30B extend from the cup-shaped body 22 in the negative Y direction (...). Figure 2 The outer side of the left direction forms to the positive direction of the Y direction. Figure 2 (To the right) on the outer side. Corresponding arms 31 and 32 are installed on guide rails 30A and 30B respectively.

[0049] A solution supply nozzle 33 for supplying a solution of a water-soluble polymer is supported on the first arm 31. The first arm 31 is movable on the guide rail 30A via a nozzle drive unit 34, which serves as a moving mechanism. Thus, the solution supply nozzle 33 can be moved from a standby unit 35, located on the outer side of the cup-shaped body 22 in the Y direction, to above the center of the wafer W within the cup-shaped body 22. Furthermore, the first arm 31 can be raised and lowered via the nozzle drive unit 34, allowing adjustment of the height of the solution supply nozzle 33.

[0050] The solution supplied by the solution supply nozzle 33 is a solution of water-soluble polymer, used to collect and drain water droplets of water remaining on the surface of the resist film after immersion exposure, and to reduce the contact angle of the resist pattern with water after immersion exposure.

[0051] A solution of a water-soluble polymer contains a water-soluble polymer, such as a water-soluble polymer containing a hydrophilic group and having an alkyl backbone. Specific examples of water-soluble polymers include polyvinyl alcohol, polyacrylic acid derivatives, polyvinylpyrrolidone, cellulose derivatives, vinyl sulfonic acid, fluorinated acrylic acid, fluorosulfonic acid, acrylates or methacrylates, and their salts. These water-soluble polymers can be used alone or in combination of two or more.

[0052] Water-soluble polymers have molecular weights, for example, below 2000.

[0053] Furthermore, the concentration of the water-soluble polymer in the above solution is preferably less than 10%, more preferably less than 3%. This is because when the aqueous solution of the water-soluble polymer needs to cover the entire surface of the wafer W, a high concentration of the water-soluble polymer will result in poor coverage.

[0054] For solutions of water-soluble polymers, a neutral solution is used. The reasons for this will be explained later.

[0055] The solvent for solutions of water-soluble polymers is water, specifically pure water. In the following text, solutions of water-soluble polymers will be referred to as polymer aqueous solutions.

[0056] Surfactants can be added to the polymer aqueous solution, primarily to improve the coatability of the wafer W and to control the pH (liquidity). Specific examples of surfactants include sorbitan monooleate, glycerol α-monooleate, polyethylene glycol sorbitan fatty acid ester, polyethylene glycol linear alkyl ethers, polyethylene glycol phenyl ethers (linear alkyl addition type, branched alkyl addition type), acetylenide glycol, anionic surfactants such as sodium laurylate, sodium stearate, sodium oleate, sodium dodecyl sulfate, or sodium dodecylbenzene sulfonate. These surfactants can be used alone or in combination of two or more. The concentration of surfactant in the polymer aqueous solution is preferably less than 3%. However, when the pH of the water-soluble polymer is within the range described later, the concentration of surfactant in the polymer aqueous solution can exceed 3%.

[0057] In addition, other additives can be added to the polymer aqueous solution to adjust the pH.

[0058] Alternatively, the organic solvent used to improve the coating properties may not be added to the polymer aqueous solution.

[0059] The second arm 32 supports a cleaning fluid supply nozzle 36 for supplying cleaning fluid.

[0060] The second arm 32 is movable on the guide rail 30B via the nozzle drive unit 37, which serves as a moving mechanism. This allows the cleaning fluid supply nozzle 36 to move from the standby section 38 located on the outer side of the cup-shaped body 22 in the negative Y direction to above the center of the wafer W within the cup-shaped body 22. Furthermore, the second arm 32 can be raised and lowered via the nozzle drive unit 37, allowing adjustment of the height of the cleaning fluid supply nozzle 36.

[0061] The cleaning fluid supplied by the cleaning fluid supply nozzle 36 is a water-based cleaning fluid, specifically DIW (Deionized Water).

[0062] The solution supply nozzle 33 and the cleaning fluid supply nozzle 36 are connected to a liquid supply mechanism 100 that supplies the corresponding liquid to each nozzle. The liquid supply mechanism 100 is equipped with a pump (not shown) for pressurizing and delivering each liquid, and a supply valve (not shown) for switching the supply of each liquid and stopping the supply, etc., for each nozzle.

[0063] In the cleaning device 1 described above, such as Figure 1 A control unit 200 is shown. The control unit 200 is, for example, a computer equipped with a CPU, memory, etc., and has a program storage unit (not shown). The program storage unit stores programs for controlling various processes in the cleaning apparatus 1. Furthermore, the program storage unit also stores programs for controlling the suction cup drive unit 21, nozzle drive units 34 and 37, liquid supply mechanism 100, etc., to achieve the developing process described later. Alternatively, the above programs can be stored on a computer-readable storage medium and installed from that storage medium onto the control unit 200. Part or all of the program can also be implemented using dedicated hardware (circuit board).

[0064] Here, use Figures 3-5 An example of the cleaning process in cleaning device 1 will be described. Figure 3 This is a flowchart illustrating an example of a cleaning process. Figure 4 It is a three-dimensional diagram schematically showing the appearance of the wafer W and each nozzle in each step of the cleaning process. Figure 5 This is a schematic cross-sectional view showing the state of the wafer surface before or after the cleaning process. Furthermore, in the following description, a protective film may not be formed on the surface of the resist film, but it is also possible for a protective film to be formed on the surface of the resist film. In this case, "the surface of the resist film" refers to the surface of the protective film.

[0065] (Aqueous solution supply process)

[0066] During the cleaning process in cleaning device 1, firstly, as follows: Figure 3As shown, a polymer aqueous solution is supplied to the wafer W (step S1). Specifically, firstly, the wafer W, which has a flat surface without a pattern after immersion exposure, is placed into the processing container 10, and then mounted and adsorbed onto the rotating chuck 20. Next, as... Figure 4 As shown in (A), the liquid supply nozzle 33 is moved upwards and towards the center of the wafer W. Then, as... Figure 4 As shown in (B), the wafer W is rotated, and a polymer aqueous solution is supplied to the wafer W from the solution supply nozzle 33, thereby forming a liquid film F of polymer aqueous solution on the entire surface of the wafer W. The rotational speed of the wafer W in this process is, for example, 100 to 1500 rpm. Furthermore, the polymer aqueous solution has a lower surface tension than aqueous cleaning solutions, therefore it is less likely to scatter upon impact with the surface of the wafer W, and it has strong coverage. During the supply of the polymer aqueous solution, the solution supply nozzle 33 is fixed above the center of the wafer W. Afterwards, the solution supply nozzle 33 is moved away from the cup-shaped body 22.

[0067] The surface of wafer W before this process is as follows Figure 5 In the case shown in (A) where water droplets D remain after immersion in liquid water, as Figure 5 As shown in (B), the water droplets D are collected through a liquid film F of the polymer aqueous solution formed on the surface of the wafer W in this process. The result of this collection is that the water droplets D are either discharged to the outside of the wafer W along with the polymer aqueous solution, or remain within the liquid film F of the polymer aqueous solution formed on the surface of the wafer W.

[0068] (Hydrophilization process)

[0069] Next, as Figure 3 As shown, the surface of the resist film is hydrophilized by a polymer aqueous solution supplied to the surface of the wafer W (step S2). Specifically, for example, as... Figure 4 As shown in (C), without supplying the polymer aqueous solution, cleaning solution, etc., the wafer W is placed while rotating for a predetermined period of time. The rotational speed of the wafer W at this time is, for example, 1500–2500 rpm. Due to the rotation, the fluidity of the polymer aqueous solution film F formed on the surface of the wafer W decreases. Simultaneously, through placement, as… Figure 5 As shown in (C), the surface of the resist film R undergoes a crosslinking reaction with the water-soluble polymer P with hydrophilic groups within the liquid film F, and the surface of the resist film R is coated with the water-soluble polymer P with hydrophilic groups. As a result, the contact angle of the surface of the resist film R relative to water is reduced.

[0070] By adjusting the duration of the hydrophilization process, the contact angle of the resist film R relative to water can be adjusted. For example, increasing the duration of the hydrophilization process can further reduce the contact angle. The duration of the hydrophilization process is, for example, 3 to 60 seconds.

[0071] Furthermore, during the hydrophilization process, the fluidity of the polymer aqueous solution film disappears, and the possibility of the polymer aqueous solution flowing around the back of the wafer W disappears, so the rotation of the wafer W can be stopped.

[0072] Here, use Figure 6 and Figure 7 The pH value of the polymer aqueous solution is explained. Figure 6 and Figure 7 These are graphs showing the state changes of the resist film R under different pH conditions for the aqueous solution.

[0073] The cleaning process performed by cleaning device 1 occurs before the PEB treatment. Therefore, when the pH value of the polymer aqueous solution is high, such as... Figure 6 As shown, the acid (H+) generated from the photoacid generator (PAG) within the resist film R by immersion exposure reacts with and disappears from the alkaline components in the polymer aqueous solution film F. As a result, the desired resist pattern shape cannot be obtained during development. For example, an unwanted T-shaped pattern will be obtained when viewed in cross-section.

[0074] Additionally, when the pH of the aqueous solution of the water-soluble polymer is low, such as... Figure 7 As shown, acidic components (H+) are supplied from the liquid film F of the polymer aqueous solution to the resist film R, especially the surface of the resist film R. As a result, the desired shape of the resist pattern cannot be obtained during development. For example, the desired film thickness cannot be obtained. Additionally, sometimes an unwanted resist pattern with a chamfered top is also obtained.

[0075] Therefore, the aqueous solution of the water-soluble polymer is used with a pH value that keeps the concentration variation of the acid in the resist film within an acceptable range, i.e., a pH value that does not hinder the reaction between the acid in the resist film and the base resin. In other words, a neutral aqueous solution is used as the aqueous solution of the water-soluble polymer. Specifically, the pH value of the aqueous solution of the water-soluble polymer is, for example, 5 to 9, more preferably 6 to 8.

[0076] Back to use Figures 3-5 Instructions for cleaning and treatment.

[0077] (Cleaning solution supply process)

[0078] After the hydrophilization process, such as Figure 3As shown, while the wafer W is rotated, a cleaning solution is supplied to the surface of the wafer W to remove the polymer aqueous solution that does not contribute to hydrophilicity (step S3). Specifically, the polymer aqueous solution that does not contribute to hydrophilicity refers to the water-soluble polymer and solvent in the liquid film F of the polymer aqueous solution that are not bound to the surface of the resist film R. By removing it in this way, the water droplets D of the liquid water collected by the polymer aqueous solution and remaining in the liquid film F are also discharged outside the wafer W.

[0079] In this cleaning solution supply process, for example, the drying of the cleaning solution coating area in the wafer W can be performed simultaneously and in parallel. Specifically, for example, Figure 4 As shown in (D) and (E), while rotating the wafer W and moving the cleaning fluid supply nozzle 36 such that the contact point of the cleaning fluid from the nozzle 36 moves from the center of the wafer W to the periphery, cleaning fluid is supplied from the nozzle 36 to the outside of the wafer. This allows the unwanted polymer aqueous solution film F to be removed with the cleaning fluid while the area coated with the cleaning fluid in the wafer W dries from the inside. When the cleaning fluid supply nozzle is moved in this way, an inert gas such as N2 can be used to assist drying.

[0080] Furthermore, when the cleaning fluid supply nozzle 36 is moved as described above, the rotational speed of the wafer W gradually decreases, for example. Specifically, when the contact point of the cleaning fluid from the cleaning fluid supply nozzle 36 is at the center of the wafer W, the rotational speed of the wafer W is, for example, 1500 to 2000 rpm; when the contact point of the cleaning fluid from the cleaning fluid supply nozzle 36 is at the periphery of the wafer W, the rotational speed of the wafer W is, for example, 200 to 1000 rpm.

[0081] However, the rotational speed of the wafer W can also be fixed when the cleaning fluid supply nozzle 36 is moved as described above. In this case, the rotational speed of the wafer W is 200 to 1000 rpm.

[0082] Furthermore, when the cleaning solution supply nozzle 36 is moved as described above, the moving speed of the nozzle 36 is 20 to 60 mm / s. By increasing the moving speed of the cleaning solution supply nozzle 36 without increasing the rotational speed of the wafer W to the upper limit, even with the addition of a polymer aqueous solution supply step, the time required for the entire cleaning process can be the same as that of the existing post-exposure cleaning process.

[0083] After the contact point of the cleaning fluid from the cleaning fluid supply nozzle 36 is moved to the periphery of the wafer W, the nozzle 36 is moved away from the cup-shaped body 22.

[0084] (Drying process)

[0085] After the cleaning fluid supply process, such as Figure 3As shown, the wafer W, which has been supplied with cleaning solution, is dried (step S4). Specifically, as... Figure 4 As shown, without supplying cleaning fluid or the like, the wafer W is rotated, thereby drying the wafer W. On the surface of the resist film R on the dried wafer W, as... Figure 5 As shown in (D), a layer of water-soluble polymer P with hydrophilic groups remains, but this is not a problem during development. This is because the upper part of the surface containing the resist film R is removed during development.

[0086] Furthermore, in step S3, as described above, if the drying process in step S4 can be omitted when the cleaning fluid supply nozzle 36 is moved and the liquid film of the polymer aqueous solution is removed simultaneously with the removal of the cleaning fluid, the drying process in step S4 can also be omitted.

[0087] After the drying process is completed, the wafer W is removed from the processing container 10.

[0088] Thus, the cleaning process is complete.

[0089] In addition, the processing conditions in the cleaning solution supply process, except for the rotational speed of the wafer W (including the shape of the cleaning solution supply nozzle), can be the same as those in the existing post-exposure cleaning process.

[0090] As described above, the cleaning method for the wafer W in this embodiment includes: a step of supplying an aqueous solution of a water-soluble polymer to the surface of the wafer W, which has an unpatterned resist film after immersion exposure; and a step of hydrophilizing the surface of the resist film using the supplied aqueous solution of the water-soluble polymer. Furthermore, the cleaning method includes: after the hydrophilization step, a step of supplying a cleaning solution to the surface of the wafer W while rotating the wafer W to remove the aqueous solution of the water-soluble polymer on the surface of the wafer W that does not contribute to the hydrophilization; and a step of drying the wafer W to which the cleaning solution has been supplied.

[0091] According to this embodiment, even if droplets of immersion water remain on the surface of the resist film, these droplets can be removed during the process of supplying an aqueous solution of the water-soluble polymer, or, during this process, the droplets can be collected into a liquid film of the aqueous solution and removed together with the liquid film in a subsequent process of supplying the cleaning solution. Furthermore, according to this embodiment, during the cleaning solution supply process, the surface of the resist film is hydrophilized. Therefore, even if the rotational speed of the wafer W is increased during the cleaning solution supply process, it is less likely for the cleaning solution to scatter, and tiny droplets of the cleaning solution will not remain on the wafer W. This is the same whether the cleaning solution is supplied using the method described above or in the same manner as in conventional post-exposure cleaning processes. Therefore, according to this embodiment, compared to conventional post-exposure cleaning processes, regardless of the contact angle of the wafer surface before cleaning, it is possible to ensure that the water used for immersion exposure and the cleaning solution do not remain on the surface of the resist film after processing. Furthermore, by making the surface of the resist film hydrophilic, the lower limit of the permissible range of the rotational speed of the wafer W in the cleaning solution supply process is also increased. However, in methods that control the spread and drying of the cleaning solution by rotating the wafer W, increasing the upper limit of the permissible range is more meaningful than increasing the lower limit of the permissible range of the wafer W's rotational speed.

[0092] Furthermore, in this embodiment, the solution of the water-soluble polymer has a pH value that keeps the acid concentration of the resist film within an acceptable range. Therefore, by using the solution of the water-soluble polymer, it is not impossible to obtain a resist pattern of the desired shape.

[0093] Through dedicated research, the inventors discovered that when the contact angle of the resist film surface relative to water is approximately 80°, supplying an aqueous solution of a water-soluble polymer to the surface to hydrophilize it, followed by the supply of a cleaning solution, reduces the contact angle by approximately 5 to 15°, to approximately 75° to 65°. Furthermore, when the cleaning solution is supplied to the periphery of the wafer W, where the cleaning solution is most prone to scattering, scattering occurs when the contact angle is 80° to 90° and the wafer W's rotational speed is below 600 rpm. Conversely, when the contact angle is 70° to 75°, scattering of the cleaning solution does not occur even when the wafer W's rotational speed is 800 rpm.

[0094] Based on this, it can also be said that, according to this embodiment, compared with the existing post-exposure cleaning process, regardless of the size of the contact angle of the wafer surface before cleaning, the water and cleaning solution used for immersion exposure can be left on the surface of the resist film after the process.

[0095] Furthermore, in this embodiment, even if it is necessary to increase the flow rate of the cleaning fluid to remove the liquid film of the aqueous solution of the water-soluble polymer, the surface of the resist film is also hydrophilized during the process of supplying the cleaning fluid. Therefore, even if the flow rate of the cleaning fluid is increased, the cleaning fluid will not scatter.

[0096] Furthermore, in this embodiment, the solvent for the water-soluble polymer solution is water, and it does not contain any organic solvents. This is because if the water-soluble polymer solution contains organic solvents, there is a possibility of pattern shape degradation, such as unevenness in the resist film, when the water-soluble polymer solution is supplied to the wafer W. Additionally, if the polymer aqueous solution contains organic solvents, and the wastewater pipeline for the cleaning solution using pure water and the polymer aqueous solution is a shared pipeline, the organic solvent needs to be separated when discharging the wastewater.

[0097] As described above, in the cleaning solution supply process, the nozzle 36 is moved such that the contact point of the cleaning solution from the cleaning solution supply nozzle 36 moves from the center of the wafer W to the periphery. Alternatively, in the cleaning solution supply process, the nozzle 36 is moved such that the contact point of the cleaning solution from the cleaning solution supply nozzle 36 reaches the inclined surface of the periphery of the wafer W. Thus, the inclined surface of the wafer W can be cleaned with the cleaning solution. Specifically, foreign matter adhering to the inclined surface of the wafer W during immersion exposure processing or previous processing can be cleaned with the cleaning solution.

[0098] In addition, to clean the slope, the movement of the cleaning fluid supply nozzle 36 can be stopped at the position where the contact point of the cleaning fluid is the slope.

[0099] Figure 8 This is a side view illustrating the structure of the cleaning fluid supply nozzle 36.

[0100] The nozzle diameter of the cleaning fluid supply nozzle 36 is the same as that of the nozzles used for existing post-exposure cleaning processes, for example, 1.0 to 2.5 mm.

[0101] Furthermore, the cleaning fluid supply nozzle 36 is inclined relative to the surface of the wafer W as shown in the figure, so that the liquid film of the polymer aqueous solution can be effectively removed with the cleaning fluid. The release angle θ1 of the cleaning fluid relative to the surface of the wafer W is specifically, for example, 15° to 50°.

[0102] The flow rate of the cleaning fluid from the cleaning fluid supply nozzle 36 is relatively large, ranging from 150 to 400 ml / min. When the nozzle diameter of the cleaning fluid supply nozzle 36 is the same as that of a conventional nozzle, the flow rate is increased, thus increasing the flow velocity of the cleaning fluid from the nozzle 36. By increasing the flow velocity of the cleaning fluid, the unwanted aqueous film of the water-soluble polymer can be easily removed. Furthermore, as described above, during the cleaning fluid supply process, the surface of the resist film becomes hydrophilic; therefore, even with an increased flow velocity, there is no problem of cleaning fluid scattering.

[0103] Furthermore, the release angle of the cleaning fluid from the cleaning fluid supply nozzle 36 is tilted to the opposite side of the inclined surface of the wafer W relative to the periphery of the wafer W. This allows for reliable cleaning of the inclined surface with the cleaning fluid. Additionally, the angle θ2 of the cleaning fluid supply nozzle 36 relative to the inclined surface of the wafer W is, for example, 5 to 15°.

[0104] The embodiments disclosed in this invention are illustrative in all respects and should not be considered limiting. The above embodiments can be omitted, substituted, and modified in various ways without departing from the scope and spirit of the appended claims.

[0105] Furthermore, the following configurations also fall within the scope of the present invention.

[0106] (1) A substrate processing method, comprising:

[0107] A process of supplying a solution of a water-soluble polymer to the surface of a substrate with an unpatterned resist film after immersion exposure treatment;

[0108] The process of hydrophilizing the surface of the resist film using the supplied solution of the above-mentioned water-soluble polymer;

[0109] Following the hydrophilization process described above, a step is performed in which the substrate is rotated while a cleaning solution is supplied to its surface to remove the aqueous solution of the water-soluble polymer that does not contribute to the hydrophilization process; and

[0110] The process of drying the substrate that has been supplied with the cleaning solution.

[0111] The solution of the water-soluble polymer described above has a pH value that keeps the acid concentration of the resist film within an acceptable range.

[0112] According to (1) above, regardless of the size of the contact angle of the substrate surface before treatment, it is possible to ensure that the water and cleaning solution used for immersion exposure do not remain on the surface of the substrate after treatment.

[0113] (2) The substrate processing method described in (1) above, wherein:

[0114] The substrate to be processed is a substrate after immersion exposure treatment, and a substrate before post-exposure heat treatment performed between the immersion exposure treatment and the development treatment.

[0115] (3) The substrate processing method described in (1) or (2) above, wherein:

[0116] The pH value of the solution of the above water-soluble polymer is 5 to 9.

[0117] (4) The substrate processing method described in any one of (1) to (3) above, wherein:

[0118] The solvent for the solution of the above-mentioned water-soluble polymer is water, and it does not contain any organic solvents.

[0119] (5) The substrate processing method described in any one of (1) to (4) above, wherein,

[0120] The solution of the above water-soluble polymer contains a surfactant.

[0121] (6) The substrate processing method described in any one of (1) to (5) above, wherein:

[0122] The cleaning solution mentioned above is water.

[0123] (7) The substrate processing method described in any one of (1) to (6) above, wherein:

[0124] The above-mentioned process of supplying the cleaning solution and the above-mentioned process of drying the substrate are performed simultaneously and in parallel.

[0125] In this process, while moving the supply nozzle so that the contact point of the cleaning fluid from the supply nozzle moves from the center of the substrate to the periphery of the substrate, the cleaning fluid released from the supply nozzle to the outside of the substrate is supplied.

[0126] (8) The substrate processing method described in (7) above, wherein:

[0127] When supplying the cleaning fluid, the rotational speed of the substrate is reduced as the supply nozzle moves.

[0128] (9) The substrate processing method described in (7) or (8) above, wherein:

[0129] When supplying the cleaning fluid, the supply nozzle is moved so that the liquid contact point reaches the inclined surface of the periphery of the substrate.

[0130] (10) The substrate processing method described in (9) above, wherein:

[0131] The release angle of the cleaning fluid supplied to the nozzle is inclined to the opposite side of the substrate surface relative to the bevel of the substrate periphery.

[0132] (11) A substrate processing apparatus for processing substrates after immersion exposure treatment, wherein:

[0133] The aforementioned substrate has an unpatterned resist film on its surface.

[0134] The substrate processing apparatus includes:

[0135] Maintain the substrate holding portion of the aforementioned substrate;

[0136] A rotating mechanism that rotates the substrate holding section;

[0137] A solution supply nozzle for an aqueous solution of a water-soluble polymer is supplied to the substrate held by the substrate holding portion.

[0138] A cleaning fluid supply nozzle supplies cleaning fluid to the substrate held by the substrate holding section; and

[0139] The control unit is configured to control the aforementioned rotating mechanism, the supply from the aforementioned solution supply nozzle, and the supply from the aforementioned cleaning fluid supply nozzle.

[0140] The control unit described above is configured to control the execution of the following processes:

[0141] The process of supplying a solution of a water-soluble polymer to the surface of the above-mentioned substrate;

[0142] The process of hydrophilizing the surface of the resist film using the supplied solution of the above-mentioned water-soluble polymer;

[0143] Following the hydrophilization process described above, a step is performed in which the substrate is rotated while a cleaning solution is supplied to its surface to remove the aqueous solution of the water-soluble polymer that does not contribute to the hydrophilization process; and

[0144] The process of drying the substrate that has been supplied with the cleaning solution.

[0145] The solution of the water-soluble polymer described above has a pH value that keeps the acid concentration of the resist film within an acceptable range.

Claims

1. A substrate processing method, characterized in that, include: A process of supplying a solution of a water-soluble polymer to the surface of a substrate having an unpatterned resist film after immersion exposure and before post-exposure heat treatment between the immersion exposure and development processes. The process of hydrophilizing the surface of the resist film using a solution of the supplied water-soluble polymer; The process after the hydrophilization step involves rotating the substrate while supplying a cleaning solution to the surface of the substrate to remove an aqueous solution of a water-soluble polymer that does not contribute to the hydrophilization. and The process of drying the substrate to which the cleaning solution has been supplied. The resist film contains a photoacid generator. The solution of the water-soluble polymer has a pH value of 5 to 9, so that the acid concentration of the unpatterned resist film containing the photoacid generator on the substrate after the immersion exposure treatment and before the post-exposure heat treatment is within the allowable range.

2. The substrate processing method as described in claim 1, characterized in that: The solvent of the solution of the water-soluble polymer is water, and it does not contain any organic solvents.

3. The substrate processing method as described in claim 1 or 2, characterized in that: The solution of the water-soluble polymer contains a surfactant.

4. The substrate processing method as described in claim 1 or 2, characterized in that: The cleaning solution is water.

5. The substrate processing method as described in claim 1 or 2, characterized in that: The process of supplying the cleaning solution and the process of drying the substrate are performed simultaneously and in parallel. In this process, the cleaning fluid is supplied from the supply nozzle to the outside of the substrate while the supply nozzle is moved so that the contact point of the cleaning fluid from the supply nozzle moves from the center of the substrate to the periphery of the substrate.

6. The substrate processing method as described in claim 5, characterized in that: During the supply of the cleaning fluid, the rotational speed of the substrate is reduced as the supply nozzle moves.

7. The substrate processing method as described in claim 5, characterized in that: When supplying the cleaning fluid, the supply nozzle is moved so that the contact point reaches the inclined surface of the periphery of the substrate.

8. The substrate processing method as described in claim 7, characterized in that: The release angle of the cleaning fluid from the supply nozzle is inclined to the opposite side of the substrate surface relative to the bevel of the substrate periphery.

9. A substrate processing apparatus, characterized in that: The substrate processing apparatus processes substrates after immersion exposure and before post-exposure heat treatment, which occurs between the immersion exposure and development processes. The substrate has an unpatterned resist film on its surface, the resist film containing a photoacid-generating agent. The substrate processing apparatus includes: The substrate holding portion of the substrate is retained; A rotating mechanism that rotates the substrate holding portion; A solution supply nozzle for an aqueous solution of a water-soluble polymer is supplied to the substrate held by the substrate holding portion; A cleaning fluid supply nozzle supplies cleaning fluid to the substrate held by the substrate holding portion; and The control unit is configured to control the rotation mechanism, the supply from the solution supply nozzle, and the supply from the cleaning fluid supply nozzle. The control unit is configured to control the execution of the following steps: The process of supplying a solution of a water-soluble polymer to the surface of the substrate; The process of hydrophilizing the surface of the resist film using a solution of the supplied water-soluble polymer; Following the hydrophilization process, a step is taken to remove an aqueous solution of a water-soluble polymer that does not contribute to the hydrophilization by rotating the substrate and supplying a cleaning solution to its surface; and The process of drying the substrate to which the cleaning solution has been supplied. The solution of the water-soluble polymer has a pH value of 5 to 9, so that the acid concentration of the resist film containing the photoacid generator on the substrate, which is unpatterned and contains the photoacid generator, is within an acceptable range after immersion exposure treatment and before the post-exposure heat treatment.

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