阅读说明：本技术 基片处理方法和基片处理装置 (Substrate processing method and substrate processing apparatus ) 是由 甲斐亚希子 于 2020-10-22 设计创作，主要内容包括：本发明提供基片处理方法和基片处理装置。处理液浸曝光后的、表面具有未形成图案的抗蚀剂膜的基片的基片处理方法和基片处理装置中,与处理前的基片表面的接触角的大小无关地,能够使得用于液浸曝光的水、清洗液在处理后不残留在基片的表面。基片处理方法包括：对液浸曝光处理后的、具有未形成图案的抗蚀剂膜的基片的表面,供给水溶性聚合物的溶液的工序；用供给的水溶性聚合物的溶液,使抗蚀剂膜的表面亲水化的工序；在亲水化的工序后,一边使基片旋转,一边对基片的表面供给清洗液,将对亲水化没有贡献的水溶性聚合物的水溶液除去的工序；和使被供给了清洗液的基片干燥的工序,水溶性聚合物的溶液具有使抗蚀剂膜的酸的浓度处于容许范围内的pH值。(The invention provides a substrate processing method and a substrate processing apparatus. A substrate processing method and a substrate processing apparatus for processing a substrate having a resist film without a pattern formed on the surface thereof after immersion exposure of a processing liquid, wherein water or a cleaning liquid used for immersion exposure can be prevented from remaining on the surface of the substrate after the processing regardless of the magnitude of a contact angle of the surface of the substrate before the processing. The substrate processing method comprises the following steps: supplying a solution of a water-soluble polymer to the surface of the substrate having the unpatterned resist film after the liquid immersion exposure treatment; hydrophilizing the surface of the resist film with the supplied solution of the water-soluble polymer; a step of removing an aqueous solution of a water-soluble polymer that does not contribute to hydrophilization by supplying a cleaning liquid to the surface of the substrate while rotating the substrate after the hydrophilization step; and a step of drying the substrate to which the cleaning liquid has been supplied, wherein the solution of the water-soluble polymer has a pH value at which the acid concentration of the resist film is within an allowable range.)

1. A method of processing a substrate, comprising:

supplying a solution of a water-soluble polymer to the surface of the substrate having the unpatterned resist film after the liquid immersion exposure treatment;

hydrophilizing the surface of the resist film with the supplied solution of the water-soluble polymer;

a step of removing an aqueous solution of a water-soluble polymer that does not contribute to hydrophilization by supplying a cleaning liquid to the surface of the substrate while rotating the substrate after the hydrophilization 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 at which the concentration of the acid of the resist film is within an allowable range.

2. The substrate processing method according to claim 1, wherein:

the substrate to be processed is a substrate after a liquid immersion exposure process, and is a substrate before a post-exposure heat treatment performed between the liquid immersion exposure process and a development process.

3. The substrate processing method according to claim 1 or 2, wherein:

the pH value of the solution of the water-soluble polymer is 5-9.

4. The substrate processing method according to claim 1 or 2, wherein:

the solvent of the solution of the water-soluble polymer is water, and does not contain an organic solvent.

5. The substrate processing method according to claim 1 or 2, wherein:

the solution of the water-soluble polymer is added with a surfactant.

6. The substrate processing method according to claim 1 or 2, wherein:

the cleaning liquid is water.

7. The substrate processing method according to claim 1 or 2, wherein:

the step of supplying the cleaning liquid and the step of drying the substrate are performed simultaneously and in parallel,

in this step, the cleaning liquid discharged from the supply nozzle to the outside of the substrate is supplied while the supply nozzle is moved so that the landing point of the cleaning liquid from the supply nozzle moves from the center of the substrate to the peripheral edge of the substrate.

8. The substrate processing method according to claim 7, wherein:

when the cleaning liquid is supplied, the rotation speed of the substrate is reduced along with the movement of the supply nozzle.

9. The substrate processing method according to claim 7, wherein:

when the cleaning liquid is supplied, the supply nozzle is moved so that the liquid landing point reaches the slope of the peripheral edge of the substrate.

10. The substrate processing method according to claim 9, wherein:

the discharge angle of the cleaning liquid from the supply nozzle is inclined to the opposite side of the surface of the substrate with respect to the inclined surface of the peripheral edge of the substrate.

11. A substrate processing apparatus for processing a substrate after immersion exposure processing of a processing liquid, characterized in that:

the substrate has an unpatterned resist film on the surface,

the substrate processing apparatus includes:

a substrate holding section for holding the substrate;

a rotation mechanism for rotating the substrate holding portion;

a solution supply nozzle for supplying an aqueous solution of a water-soluble polymer to the substrate held by the substrate holding portion;

a cleaning liquid supply nozzle for supplying a cleaning liquid to the substrate held by the substrate holding portion; and

a control unit configured to control the rotation mechanism, the supply from the solution supply nozzle, and the supply from the cleaning solution supply nozzle,

the control unit is configured to be capable of controlling so as to execute:

supplying a solution of a water-soluble polymer to the surface of the substrate;

hydrophilizing the surface of the resist film with the supplied solution of the water-soluble polymer;

a step of removing an aqueous solution of a water-soluble polymer that does not contribute to hydrophilization by supplying a cleaning liquid to the surface of the substrate while rotating the substrate after the hydrophilization 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 at which the concentration of the acid of the resist film is within an allowable range.

Technical Field

The present invention relates to a substrate processing method and a substrate processing apparatus.

Background

Patent document 1 discloses a substrate cleaning apparatus including: a rotatable substrate holding section for horizontally holding the substrate; a cleaning liquid nozzle for supplying a cleaning liquid to the surface of the substrate held by the substrate holding portion; and a driving unit for moving the cleaning liquid nozzle. In the substrate cleaning apparatus, the driving unit moves the cleaning liquid nozzle so that the supply position of the cleaning liquid from the cleaning liquid nozzle moves from the center portion to the peripheral edge of the substrate when the substrate rotates.

Documents of the prior art

Patent document

Patent document 1: japanese patent laid-open publication No. 2011-

Disclosure of Invention

Technical problem to be solved by the invention

The present invention relates to a substrate processing method and a substrate processing apparatus for processing a substrate having a resist film without a pattern formed on the surface thereof after immersion exposure of a processing solution, wherein water or a cleaning solution used for immersion exposure does not remain on the surface of the substrate after the processing regardless of the magnitude of a contact angle of the surface of the substrate before the processing.

Technical solution for solving technical problem

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

Effects of the invention

According to the present invention, in a substrate processing method and a substrate processing apparatus for processing a substrate having a resist film on the surface thereof on which an unpatterned pattern is formed after immersion exposure, water or a cleaning liquid used for immersion exposure can be prevented from remaining on the surface of the substrate after processing regardless of the magnitude of the contact angle of the surface of the substrate before processing.

Drawings

Fig. 1 is a longitudinal sectional view showing a schematic configuration of a cleaning apparatus as a substrate processing apparatus according to the present embodiment.

Fig. 2 is a cross-sectional view showing a schematic configuration of a cleaning apparatus as a substrate processing apparatus according to the present embodiment.

Fig. 3 is a flowchart showing an example of a cleaning process in the cleaning apparatus of fig. 1.

Fig. 4 is a perspective view schematically showing the appearance of the wafer and the nozzles in each step of the cleaning process.

Fig. 5 is a cross-sectional view schematically showing a state of a wafer surface before or after a step of performing a cleaning process.

Fig. 6 is a diagram showing a state change of the resist film in the case where the pH of the aqueous solution is large.

Fig. 7 is a diagram showing a state change of the resist film when the pH of the aqueous solution is small.

Fig. 8 is a side view for explaining the structure of the cleaning liquid supply nozzle.

Description of the reference numerals

1 cleaning device

20 rotating suction cup

21 suction cup driving part

33 solution supply nozzle

34 nozzle driving part

36 cleaning liquid supply nozzle

37 nozzle driving part

200 control part

P Water-soluble Polymer

R resist film

W wafer.

Detailed Description

In a photolithography process in a manufacturing process of a semiconductor device or the like, a series of processes are performed to form a desired resist pattern on a semiconductor wafer (hereinafter, referred to as a "wafer"). The series of processes includes, for example, a resist coating process for supplying a resist solution onto a wafer to form a resist film, an exposure process for exposing the resist film to light, a development process for supplying a developing solution to the exposed resist film to develop the resist film, and the like.

As the type of exposure, there is immersion exposure. The liquid immersion exposure is a method of performing exposure through a water film formed between a lens provided at the tip of an exposure head and the surface of a wafer, and repeating exposure while scanning the exposure head in a state where the water film is formed, thereby sequentially transferring a desired pattern onto the wafer. In the liquid immersion exposure, it is required to increase the hydrophobicity of the wafer surface, specifically, the surface of the resist film, for the purpose of causing the water film to follow the exposure head or the like.

However, water used for immersion exposure (hereinafter referred to as immersion water) sometimes remains as water droplets on the wafer surface after exposure. The water droplets are dried by a post-exposure heat (PEB) treatment performed after exposure and before a development treatment, and become water-immersed as defects.

Therefore, the surface of the wafer after exposure is cleaned to remove water droplets of the immersion liquid. For example, in patent document 1, as described above, when the substrate is rotated, the cleaning liquid nozzle is moved so that the supply position of the cleaning liquid from the cleaning liquid nozzle is moved from the center portion to the peripheral edge of the substrate, thereby reducing water droplets remaining on the substrate.

However, in the conventional post-exposure cleaning process in which the cleaning liquid nozzle is moved to move the supply position of the cleaning liquid from the central portion to the peripheral edge of the wafer while rotating the wafer at a constant speed, the water droplets of the immersion liquid may not be removed depending on the degree of hydrophobicity of the wafer surface before cleaning. This point will be explained below.

In the conventional post-exposure cleaning process described above, when the rotation speed of the wafer is appropriate, the cleaning liquid discharged from the cleaning liquid nozzle forms a liquid lump on the wafer, and the liquid lump goes to the wafer periphery so as to draw a spiral while expanding the circumferential width, and is discharged out of the wafer in a state of the liquid lump. In this process, the water droplets of the immersion liquid on the wafer are collected by the above-mentioned liquid cake of the cleaning liquid, and are discharged out of the wafer together with the liquid cake.

On the other hand, in the above-described conventional post-exposure cleaning process, when the rotation speed of the wafer is high, the cleaning liquid discharged from the cleaning liquid nozzle collides with the wafer and scatters, so that a liquid mass of the cleaning liquid is not formed, and not only the liquid droplets immersed in the cleaning liquid but also new liquid droplets of the cleaning liquid are not collected. Even if a liquid cake of the cleaning liquid is formed, the liquid cake collapses at the peripheral edge portion, and new droplets of the cleaning liquid are formed. The small droplets of the cleaning liquid formed in this manner have a small mass, and therefore, the centrifugal force acting even at high rotation is small, and therefore, the droplets are difficult to be discharged.

However, since the surface of the wafer used for the immersion exposure has high hydrophobicity, that is, a large contact angle with water, as described above, the upper limit of the rotation speed of the wafer, at which scattering of the cleaning liquid does not occur when the cleaning liquid is collided, is low. In the conventional post-exposure cleaning process, when the rotation speed of the wafer is set too low, the centrifugal force acting on the cleaning liquid or the like is reduced, and water droplets remain on the wafer. Therefore, depending on the magnitude of the contact angle of the wafer surface after immersion exposure, the allowable range of the rotation speed of the wafer to be suitable is narrow, and the determination of the processing conditions for the rotation speed takes time, and it may be practically impossible to remove the immersion liquid or the water droplets of the cleaning liquid from the wafer. It is to be noted that, of course, if the upper limit of the rotation speed of the wafer, at which the scattering of the cleaning liquid does not occur, is set lower than the lower limit of the rotation speed of the wafer, at which the water droplets are not left on the wafer, the cleaning liquid cannot be immersed into the wafer and the water droplets of the cleaning liquid cannot be removed from the wafer in practice even if the rotation speed is adjusted.

Therefore, the present invention provides a substrate processing method and a substrate processing apparatus for processing a substrate having a resist film on the surface thereof, on which a pattern is not formed, after immersion exposure of a processing liquid, wherein water or a cleaning liquid used for immersion exposure does not remain on the surface of the substrate after the processing regardless of the magnitude of the contact angle of the surface of the substrate before the processing.

Next, a substrate processing method and a substrate processing apparatus according to the present embodiment will be described with reference to the drawings. In the present specification and the drawings, elements having substantially the same functional configuration are denoted by the same reference numerals, and redundant description thereof is omitted.

Fig. 1 and 2 are a longitudinal sectional view and a cross sectional view showing a schematic configuration of a cleaning apparatus 1 as a substrate processing apparatus according to the present embodiment.

The cleaning apparatus 1 is configured to clean a wafer W, which is a substrate having a resist film without a pattern formed on the surface thereof after liquid immersion exposure, as a processing target. The wafer W to be cleaned by the cleaning apparatus 1 is, specifically, a wafer after liquid immersion exposure and before PEB treatment. The material of the resist film formed on the wafer W to be cleaned is a chemically amplified resist, and may be a positive type or a negative type. Hereinafter, the resist film is a positive resist film.

As shown in fig. 1, the cleaning apparatus 1 includes a processing container 10 whose inside can be sealed. A loading/unloading port (not shown) for the wafers W is formed in a side surface of the processing container 10, and an opening/closing member (not shown) is provided at the loading/unloading port.

A spin chuck 20 as a substrate holding portion for holding and rotating the wafer W about a vertical axis is provided in the processing container 10. The spin chuck 20 has a horizontal upper surface, and a suction port (not shown) for sucking the wafer W, for example, is provided in the upper surface. The wafer W can be sucked and held by the spin chuck 20 by suction from the suction port.

Further, a suction cup driving unit 21 as a rotation mechanism is provided below the rotary suction cup 20. The suction cup driving unit 21 includes, for example, a motor, and can rotate the rotary suction cup 20 at various rotation speeds. The suction cup driving unit 21 is provided with an elevating drive mechanism having an air cylinder and the like, not shown, and the rotary suction cup 20 is configured to be capable of being elevated by the elevating drive mechanism.

The cup 22 is provided around the spin chuck 20 so as to surround the wafer W held by the spin chuck 20. The cup 22 receives and collects liquid scattered or dropped from the wafer W. A discharge pipe 23 for discharging the collected liquid and an exhaust pipe 24 for exhausting the inside of the cup 22 are connected to the lower surface of the cup 22.

As shown in fig. 2, guide rails 30A and 30B extending in the Y direction (the left-right direction in fig. 2) are formed on the negative X direction (the lower direction in fig. 2) side of cup member 22. The guide rails 30A, 30B are formed, for example, from the outer side of the cup-shaped body 22 on the negative Y-direction (left direction in fig. 2) side to the outer side on the positive Y-direction (right direction in fig. 2) side. The guide rails 30A and 30B are respectively provided with corresponding arms 31 and 32.

A solution supply nozzle 33 for supplying a solution of the water-soluble polymer is supported by the first arm 31. The first arm 31 is movable on the guide rail 30A by a nozzle driving unit 34 as a moving mechanism. Thus, the solution supply nozzle 33 can be moved from the standby unit 35 provided outside the Y-direction positive side of the cup 22 to above the center of the wafer W in the cup 22. The first arm 31 is movable up and down by the nozzle driving unit 34, and the height of the solution supply nozzle 33 can be adjusted.

The solution of the water-soluble polymer supplied from the solution supply nozzle 33 collects and discharges water droplets of immersion water remaining on the surface of the resist film after immersion exposure and reduces the contact angle of the resist pattern after immersion exposure with respect to water.

The water-soluble polymer contained in the water-soluble polymer solution is, for example, a water-soluble polymer containing a hydrophilic group and having an alkyl group as a main chain. Specific examples of the water-soluble polymer include polyvinyl alcohol, polyacrylic acid derivative, polyvinyl pyrrolidone, cellulose derivative, vinylsulfonic acid, fluorinated acrylic acid, fluorosulfonic acid, acrylic acid ester or methacrylic acid ester, and salts thereof. These water-soluble polymers may be used alone or in combination of two or more.

The molecular weight of the water-soluble polymer is, for example, 2000 or less.

In addition, 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 it is necessary to cover the entire surface of the wafer W with an aqueous solution of a water-soluble polymer, the coverage is poor if the concentration of the water-soluble polymer is high.

As the solution of the water-soluble polymer, a neutral solution is used. The reason for this will be described later.

The solvent of the solution of the water-soluble polymer is water, specifically pure water. Hereinafter, the solution of the water-soluble polymer is referred to as an aqueous polymer solution.

The surfactant may be added to the aqueous polymer solution, and is mainly used for improving the coating property of the wafer W and for pH (liquid) control. Specific examples of the surfactant include sorbitan monooleate, glycerol α -monooleate, polyethylene glycol sorbitan fatty acid ester, polyethylene glycol linear alkyl ether, polyethylene glycol phenyl ether linear alkyl adduct, branched alkyl adduct, acetylenic diol, anionic sodium laurate, sodium stearate, sodium oleate, sodium lauryl sulfate, and sodium dodecylbenzenesulfonate. The surfactants may be used alone or in combination of two or more. The concentration of surfactant in the aqueous polymer solution is preferably less than 3%. However, when the pH of the water-soluble polymer is within the range described later, the concentration of the surfactant in the aqueous polymer solution may be more than 3%.

In addition, other additives may be added to the aqueous polymer solution to perform the pH operation.

In addition, an organic solvent for improving the coating property may not be added to the aqueous polymer solution.

A cleaning liquid supply nozzle 36 for supplying a cleaning liquid is supported by the second arm 32.

The second arm 32 is movable on the guide rail 30B by a nozzle driving section 37 as a moving mechanism. Thus, the cleaning liquid supply nozzle 36 can be moved from the standby portion 38 provided on the outer side of the Y direction negative side of the cup 22 to above the center portion of the wafer W in the cup 22. The second arm 32 is movable up and down by the nozzle driving unit 37, and the height of the cleaning liquid supply nozzle 36 can be adjusted.

The cleaning liquid supplied from the cleaning liquid supply nozzle 36 is a Water-based cleaning liquid, specifically, DIW (Deionized Water).

The solution supply nozzle 33 and the cleaning liquid supply nozzle 36 are connected to a liquid supply mechanism 100 that supplies a corresponding liquid to each nozzle. The liquid supply mechanism 100 is provided with a pump (not shown) for pressurizing and conveying each liquid, a supply valve (not shown) for switching supply and stop of each liquid, and the like for each nozzle.

In the above-described cleaning apparatus 1, as shown in fig. 1, a control unit 200 is provided. The control unit 200 is a computer provided with, for example, a CPU, a memory, and the like, and includes a program storage unit (not shown). The program storage unit stores programs for controlling various processes in the cleaning apparatus 1. The program storage unit also stores a program for controlling the above-described suction cup driving unit 21, nozzle driving units 34 and 37, liquid supply mechanism 100, and the like to realize a developing process described later. The program may be stored in a computer-readable storage medium, and installed from the storage medium to the control unit 200. Part or all of the program may also be implemented by dedicated hardware (circuit board).

Here, an example of the cleaning process in the cleaning apparatus 1 will be described with reference to fig. 3 to 5. Fig. 3 is a flowchart showing an example of the cleaning process. Fig. 4 is a perspective view schematically showing the appearance of the wafer W and the nozzles in each step of the cleaning process. Fig. 5 is a cross-sectional view schematically showing a state of a wafer surface before or after a step of performing a cleaning process. In the following description, the protective film is not formed on the surface of the resist film, but a protective film may 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.

(aqueous solution supplying step)

In the cleaning process in the cleaning apparatus 1, first, as shown in fig. 3, the polymer aqueous solution is supplied to the wafer W (step S1). Specifically, first, the wafer W having the unpatterned flat surface after the liquid immersion exposure is carried into the processing chamber 10, and placed on and adsorbed by the spin chuck 20. Next, as shown in fig. 4 (a), the liquid supply nozzle 33 is moved upward from the center of the wafer W. Then, as shown in fig. 4 (B), the wafer W is rotated, and the polymer aqueous solution is supplied from the solution supply nozzle 33 to the wafer W, whereby a liquid film F of the polymer aqueous solution is formed on the entire surface of the wafer W. The rotation speed of the wafer W in this step is, for example, 100 to 1500 rpm. The aqueous polymer solution has a lower surface tension than the aqueous cleaning solution, and therefore is less likely to scatter when it hits the surface of the wafer W, and has a high covering property. The solution supply nozzle 33 is fixed above the center of the wafer W during the supply of the polymer aqueous solution. Thereafter, the solution supply nozzle 33 is retracted out of the cup 22.

When the water droplets D of the immersion liquid remain on the surface of the wafer W before the present step as shown in fig. 5 (a), the water droplets D are collected by the liquid film F of the aqueous polymer solution formed on the surface of the wafer W in the present step as shown in fig. 5 (B). As a result of the collection, the water droplets D are discharged to the outside of the wafer W together with the polymer aqueous solution, or remain in the liquid film F of the polymer aqueous solution formed on the surface of the wafer W.

(hydrophilization step)

Subsequently, as shown in fig. 3, the surface of the resist film is hydrophilized with the aqueous polymer solution supplied to the surface of the wafer W (step S2). Specifically, for example, as shown in fig. 4 (C), the wafer W is left standing while being rotated for a predetermined time period in a state where the polymer aqueous solution, the cleaning liquid, or the like is not supplied. The rotation speed of the wafer W is, for example, 1500 to 2500 rpm. The rotation reduces the fluidity of the liquid film F of the polymer aqueous solution formed on the surface of the wafer W. With this, as shown in fig. 5 (C), the surface of the resist film R coated with the water-soluble polymer P having a hydrophilic group is subjected to a crosslinking reaction with the water-soluble polymer P having a hydrophilic group in the liquid film F by leaving. As a result, the contact angle of the surface of the resist film R with respect to water decreases.

By adjusting the length of time for which the hydrophilization step is performed, the contact angle of the surface of the resist film R with respect to water can be adjusted. For example, when the execution time of the hydrophilization step is increased, the contact angle can be further decreased. The duration of the hydrophilization step is, for example, 3 to 60 seconds.

In the hydrophilization step, the fluidity of the liquid film of the polymer aqueous solution is lost, and after the possibility that the polymer aqueous solution will wrap around the back surface of the wafer W is lost, the rotation of the wafer W can be stopped.

Here, the pH of the aqueous polymer solution will be described with reference to fig. 6 and 7. Fig. 6 and 7 are diagrams showing changes in the state of the resist film R in the case where the pH of the aqueous solution is large and small, respectively.

The time for the cleaning process by the cleaning apparatus 1 is before the PEB process. Therefore, when the pH of the aqueous polymer solution is high, as shown in FIG. 6, the Acid (H +) generated from the Photo Acid Generator (PAG: Photo Acid Generator) in the resist film R by the liquid immersion exposure reacts with the alkali component in the liquid film F of the aqueous polymer solution and disappears. As a result, a resist pattern having a desired shape cannot be obtained during development. For example, an undesirable T-shaped pattern may be obtained when viewed in cross-section.

In addition, when the pH of the aqueous solution of the water-soluble polymer is small, as shown in fig. 7, an acid component (H +) is supplied from the liquid film F of the aqueous solution of the polymer into the resist film R, particularly the surface of the resist film R. As a result, a resist pattern having a desired shape cannot be obtained during development. For example, a resist pattern having a desired film thickness cannot be obtained. In addition, an unwanted resist pattern having a shape with a chamfered top portion may be obtained.

Therefore, as the aqueous solution of the water-soluble polymer, an aqueous solution having a pH value at which the concentration change of the acid of the resist film is within an allowable range, that is, a pH value at which the reaction of the acid of the resist film with the base resin is not inhibited is used. In other words, as the aqueous solution of the water-soluble polymer, a neutral aqueous solution is used. Specifically, the pH of the aqueous solution of the water-soluble polymer is, for example, 5 to 9, more preferably 6 to 8.

The cleaning process will be described with reference to fig. 3 to 5.

(cleaning liquid supplying step)

After the hydrophilization step, as shown in fig. 3, a cleaning liquid is supplied to the surface of the wafer W while rotating the wafer W, and the aqueous polymer solution that does not contribute to hydrophilization is removed (step S3). The aqueous polymer solution that does not contribute to hydrophilization is, specifically, a water-soluble polymer and a solvent that are not bonded to the surface of the resist film R in the liquid film F of the aqueous polymer solution. By removing the polymer solution in this manner, the water droplets D of the immersion liquid collected by the polymer aqueous solution and remaining in the liquid film F are also discharged to the outside of the wafer W.

In the cleaning liquid supply step, for example, the drying of the cleaning liquid applied region on the wafer W may be performed simultaneously and concurrently. Specifically, as shown in fig. 4 (D) and (E), for example, the cleaning liquid discharged from the nozzle 36 to the outside of the wafer is supplied while the wafer W is rotated and the cleaning liquid supply nozzle 36 is moved so that the landing point of the cleaning liquid from the nozzle 36 moves from the center to the peripheral edge of the wafer W. This makes it possible to dry the coating region of the cleaning liquid on the wafer W from the inside while removing the unnecessary liquid film F of the aqueous polymer solution with the cleaning liquid. When the cleaning liquid supply nozzle is moved in this manner, N may be used₂Drying with assistance of inactive gas such as gas.

When the cleaning liquid supply nozzle 36 is moved as described above, the rotation speed of the wafer W is gradually lowered, for example. Specifically, the rotation speed of the wafer W is, for example, 1500 to 2000rpm when the liquid applying point of the cleaning liquid from the cleaning liquid supply nozzle 36 is the center of the wafer W, and the rotation speed of the wafer W is, for example, 200 to 1000rpm when the liquid applying point of the cleaning liquid from the cleaning liquid supply nozzle 36 is the peripheral edge of the wafer W.

However, the rotation speed of the wafer W may be fixed when the cleaning liquid supply nozzle 36 is moved as described above. In this case, the rotation speed of the wafer W is set to 200 to 1000 rpm.

When the cleaning liquid 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 liquid supply nozzle 36 without increasing the rotation speed of the wafer W to the allowable upper limit, the time required for the entire cleaning process can be made the same as that of the conventional post-exposure cleaning process even if the supply step of the polymer aqueous solution is increased.

After the landing point of the cleaning liquid from the cleaning liquid supply nozzle 36 is moved to the peripheral edge of the wafer W, the nozzle 36 is retracted out of the cup 22.

(drying Process)

After the cleaning liquid supply step, as shown in fig. 3, the wafer W supplied with the cleaning liquid is dried (step S4). Specifically, as shown in fig. 4, the wafer W is dried by rotating the wafer W without supplying the cleaning liquid or the like. On the surface of the resist film R on the dried wafer W, as shown in fig. 5 (D), a layer to which a water-soluble polymer P having a hydrophilic group is bonded remains, but this does not become a problem at the time of development. This is because the upper portion of the surface including the resist film R is removed in the process of development.

In step S3, when the cleaning liquid supply nozzle 36 is moved to dry the polymer aqueous solution simultaneously with the removal of the liquid film by the cleaning liquid as described above, the drying step of step S4 may be omitted.

After the drying process is completed, the wafer W is carried out of the processing container 10.

Thereby, the cleaning process is ended.

In the cleaning liquid supply step, the process conditions (including the shape of the cleaning liquid supply nozzle) other than the rotation speed of the wafer W may be the same as those in the conventional post-exposure cleaning process.

As described above, the method for cleaning the wafer W according to the present embodiment includes: supplying an aqueous solution of a water-soluble polymer to the surface of the wafer W having the unpatterned resist film after the immersion exposure; and hydrophilizing the surface of the resist film with the supplied aqueous solution of the water-soluble polymer. Further, the cleaning method includes: a step of removing the aqueous solution of the water-soluble polymer on the surface of the wafer W, which does not contribute to hydrophilization, by supplying a cleaning liquid to the surface of the wafer W while rotating the wafer W after the hydrophilization step; and a step of drying the wafer W supplied with the cleaning liquid.

According to this embodiment, even if liquid immersion droplets remain on the surface of the resist film, the liquid droplets can be removed in the step of supplying the aqueous solution of the water-soluble polymer, or can be removed together with the liquid film in the step of supplying the cleaning liquid after collecting the liquid droplets in the liquid film of the aqueous solution in the step. Further, according to the present embodiment, since the surface of the resist film is hydrophilized in the cleaning liquid supply step, even if the rotation speed of the wafer W is increased in the cleaning liquid supply step, scattering of the cleaning liquid or the like is less likely to occur, and minute droplets of the cleaning liquid do not remain on the wafer W. In this regard, in the cleaning liquid supply step, the same applies to both the case where the cleaning liquid is supplied by the above-described method and the case where the cleaning liquid is supplied in the same manner as in the conventional post-exposure cleaning process. Therefore, according to the present embodiment, compared to the conventional post-exposure cleaning process, water or a cleaning liquid used for liquid immersion exposure can be prevented from remaining on the surface of the resist film after the process regardless of the magnitude of the contact angle of the wafer surface before cleaning. Further, the lower limit of the allowable range of the rotation speed of the wafer W in the cleaning liquid supply step is also increased by hydrophilizing the surface of the resist film. However, in the method of controlling the spreading and drying of the cleaning liquid by the rotation of the wafer W, it is more significant to increase the upper limit of the allowable range of the rotation speed of the wafer W than to increase the lower limit of the allowable range.

In addition, in this embodiment, the solution of the water-soluble polymer has a pH value at which the concentration of the acid in the resist film is within an allowable range. Therefore, a resist pattern having a desired shape cannot be obtained by using a solution of a water-soluble polymer.

The present inventors have made extensive studies and found that when the contact angle of the surface of a resist film with respect to water is about 80 °, the contact angle is reduced by about 5 to 15 ° to about 75 to 65 ° by supplying an aqueous solution of a water-soluble polymer to the surface to hydrophilize the surface and then supplying a cleaning solution. In addition, when the cleaning liquid is supplied to the peripheral edge portion of the wafer W, which is most likely to scatter the cleaning liquid, the cleaning liquid is scattered when the rotation speed of the wafer W is lower than 600rpm when the contact angle is 80 ° to 90 °. On the other hand, when the contact angle is 70 ° to 75 °, the cleaning liquid does not scatter even when the rotation speed of the wafer W is 800 rpm.

From this point of view, it can be said that according to the present embodiment, compared to the conventional post-exposure cleaning process, water or a cleaning liquid used for liquid immersion exposure can be prevented from remaining on the surface of the resist film after the process regardless of the magnitude of the contact angle of the wafer surface before cleaning.

In addition, in the present embodiment, even if it is necessary to increase the flow rate of the cleaning liquid to remove the liquid film of the aqueous solution of the water-soluble polymer, the surface of the resist film is hydrophilized in the step of supplying the cleaning liquid, and therefore, the cleaning liquid does not scatter even if the flow rate of the cleaning liquid is increased.

In the present embodiment, the solvent of the solution of the water-soluble polymer is water, and does not contain an organic solvent. This is because, when the solution of the water-soluble polymer contains an organic solvent, there is a possibility that pattern shape deterioration such as film unevenness of the resist film occurs when the solution of the water-soluble polymer is supplied to the wafer W. In addition, when the polymer aqueous solution contains an organic solvent, if a cleaning liquid using pure water and a waste liquid line of the polymer aqueous solution are used as a common line, the organic solvent needs to be separated when the waste liquid is discharged.

As described above, in the cleaning liquid supply step, the nozzle 36 is moved so that the landing point of the cleaning liquid from the cleaning liquid supply nozzle 36 moves from the center to the peripheral edge of the wafer W. In the cleaning liquid supply step, the nozzle 36 may be moved so that the landing point of the cleaning liquid from the cleaning liquid supply nozzle 36 reaches the inclined surface of the peripheral edge of the wafer W. This enables the bevel of the wafer W to be cleaned with the cleaning liquid. Specifically, foreign matter adhering to the bevel of the wafer W during the immersion exposure process or during a previous process can be cleaned with the cleaning liquid.

In order to clean the inclined surface, the movement of the cleaning liquid supply nozzle 36 may be stopped at a position where the landing point of the cleaning liquid is the inclined surface.

Fig. 8 is a side view for explaining the structure of the cleaning liquid supply nozzle 36.

The nozzle diameter of the cleaning liquid supply nozzle 36 is the same as that of a nozzle used in a conventional post-exposure cleaning process, and is, for example, 1.0 to 2.5 mm.

In addition, the cleaning liquid supply nozzle 36 is inclined with respect to the surface of the wafer W as shown in the drawing, so that the liquid film of the polymer aqueous solution can be efficiently removed with the cleaning liquid. Specifically, the release angle θ 1 of the cleaning liquid with respect to the surface of the wafer W is, for example, 15 ° to 50 °.

The flow rate of the cleaning liquid from the cleaning liquid supply nozzle 36 is relatively large and is 150 to 400 ml/min. When the nozzle diameter of the cleaning liquid supply nozzle 36 is the same as that of the conventional nozzle, the flow rate is increased, and the flow velocity of the cleaning liquid from the nozzle 36 is increased. By increasing the flow rate of the cleaning liquid, it is possible to easily remove the liquid film of the unnecessary aqueous solution of the water-soluble polymer. Further, as described above, since the surface of the resist film is hydrophilized in the step of supplying the cleaning liquid, there is no problem of scattering of the cleaning liquid even if the flow rate of the cleaning liquid is increased.

The angle of discharge of the cleaning liquid from the cleaning liquid supply nozzle 36 is inclined to the opposite side of the front surface of the wafer W with respect to the inclined surface of the peripheral edge of the wafer W. This enables the inclined surface to be reliably cleaned with the cleaning liquid. The angle θ 2 of the cleaning liquid supply nozzle 36 with respect to the cleaning liquid on the inclined surface of the peripheral edge of the wafer W is, for example, 5 to 15 °.

The disclosed embodiments of the invention are illustrative in all respects and should not be considered restrictive. The above-described embodiments can be omitted, replaced, and changed in various ways without departing from the scope of the appended claims and their ideas.

The following configurations also fall within the technical scope of the present invention.

(1) A method of processing a substrate, comprising:

supplying a solution of a water-soluble polymer to the surface of the substrate having the unpatterned resist film after the liquid immersion exposure treatment;

hydrophilizing the surface of the resist film with the supplied solution of the water-soluble polymer;

a step of removing the aqueous solution of the water-soluble polymer that does not contribute to hydrophilization by supplying a cleaning liquid to the surface of the substrate while rotating the substrate after the hydrophilization step; and

drying the substrate to which the cleaning liquid has been supplied,

the solution of the water-soluble polymer has a pH value at which the concentration of the acid in the resist film is within an allowable range.

According to the above item (1), water or a cleaning liquid used for liquid immersion exposure can be prevented from remaining on the surface of the substrate after the treatment, regardless of the magnitude of the contact angle of the surface of the substrate before the treatment.

(2) The substrate processing method according to item (1) above, wherein:

the substrate to be processed is a substrate after the liquid immersion exposure process, and is a substrate before the post-exposure heat treatment performed between the liquid immersion exposure process and the development process.

(3) The substrate processing method according to the above (1) or (2), wherein:

the pH value of the solution of the water-soluble polymer is 5-9.

(4) The substrate processing method according to any one of the above (1) to (3), wherein:

the solvent of the solution of the water-soluble polymer is water, and does not contain an organic solvent.

(5) The method for treating a substrate according to any one of (1) to (4) above, wherein,

the solution of the water-soluble polymer is added with a surfactant.

(6) The substrate processing method according to any one of the above (1) to (5), wherein:

the cleaning liquid is water.

(7) The substrate processing method according to any one of the above (1) to (6), wherein:

the step of supplying the cleaning liquid and the step of drying the substrate are performed simultaneously and concurrently,

in this step, the cleaning liquid discharged from the supply nozzle to the outside of the substrate is supplied while the supply nozzle is moved so that the landing point of the cleaning liquid from the supply nozzle moves from the center of the substrate to the peripheral edge of the substrate.

(8) The substrate processing method according to item (7) above, wherein:

when the cleaning liquid is supplied, the rotation speed of the substrate is reduced along with the movement of the supply nozzle.

(9) The substrate processing method according to the above (7) or (8), wherein:

when the cleaning liquid is supplied, the supply nozzle is moved so that the liquid applying point reaches the inclined surface of the peripheral edge of the substrate.

(10) The substrate processing method according to item (9) above, wherein:

the discharge angle of the cleaning liquid from the supply nozzle is inclined to the opposite side of the surface of the substrate with respect to the inclined surface of the peripheral edge of the substrate.

(11) A substrate processing apparatus for processing a substrate after immersion exposure processing, comprising:

the substrate has an unpatterned resist film on the surface,

the substrate processing apparatus includes:

a substrate holding section for holding the substrate;

a rotation mechanism for rotating the substrate holding portion;

a solution supply nozzle for supplying an aqueous solution of a water-soluble polymer to the substrate held by the substrate holding portion;

a cleaning liquid supply nozzle for supplying a cleaning liquid to the substrate held by the substrate holding portion; and

a control unit configured to control the rotation mechanism, the supply from the solution supply nozzle, and the supply from the cleaning liquid supply nozzle,

the control unit is configured to be capable of controlling so as to execute:

supplying a solution of a water-soluble polymer to the surface of the substrate;

hydrophilizing the surface of the resist film with the supplied solution of the water-soluble polymer;

a step of removing the aqueous solution of the water-soluble polymer that does not contribute to hydrophilization by supplying a cleaning liquid to the surface of the substrate while rotating the substrate after the hydrophilization step; and

drying the substrate to which the cleaning liquid has been supplied,

the solution of the water-soluble polymer has a pH value at which the concentration of the acid in the resist film is within an allowable range.