JPH0720623A - Method and device for removing unnecessary film and production of phase-shift mask blank - Google Patents

Abstract

PURPOSE:To provide a method and an equipment to dissolve off only an unnecessary film by a relatively simple method and to produce a phase-shift mask blank by this method. CONSTITUTION:The periphery 1a of the surface of a substrate 11 and the side face 1b of the substrate 11 are covered by the lower covering part 32 of a covering member 3 with a clearance 5 in between. A gas 6 is introduced from the gas inlet 31a of an upper covering part 31 to form a gas current flowing from the center of the substrate toward the periphery in the clearance 5, hence the intrusion of an unnecessary film removing soln. 41 supplied outside the covering member 3 from an injection nozzle 4 into the substrate center is blocked, and then the substrate 11 and the covering member 3 are simultaneously rotated by a spin chuck 2 to circulate the soln. 41 in the clearance 5 and to dissolve off the unnecessary film.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is formed on a peripheral portion of a surface other than a main portion of a substrate surface when forming a film on the substrate surface such as a photomask blank, a semiconductor substrate, a magnetic disk substrate and a color filter. The present invention relates to an unnecessary film removing method and an apparatus for removing an unnecessary film and an unnecessary film formed on a side surface of a substrate, and a phase shift mask blank manufacturing method using the unnecessary film removing method.

[0002]

2. Description of the Related Art For example, in the field of manufacturing a photomask and a reticle substrate used for manufacturing a semiconductor integrated circuit, a spin coating method (SOG (spin on glass), resist or the like is coated on the substrate. Spin coating method) is known.

In this method, for example, a substrate is fixed on a spin chuck substantially horizontally, a coating solution is dropped on the substrate, and the spin chuck is rotated to make uniform on the substrate by utilizing its centrifugal force. A coating film is formed. In this spin coating method, the number of rotations, the rotation time, etc. are adjusted depending on the type of coating liquid, the viscosity of the coating liquid, and the desired coating film thickness. A bulge of the coating film, that is, a remarkably thick portion is generated in the portion. In addition, an unnecessary coating film is formed on the side surface of the substrate. In particular, when a low-viscosity coating liquid is used, when the coating film is applied at low speed to increase the coating film thickness, swelling of the coating film on the peripheral portion of the substrate and formation of an unnecessary film on the side surface of the substrate become more remarkable. Become.

FIG. 5 is a plan view showing a raised portion 112 which is an unnecessary film of a coating film formed on the peripheral portion of the surface of the substrate 101 on which SOG or resist is spin coated, and FIG. 6 is a sectional view taken along line XX of FIG. Is. As shown in these drawings, when the coating film on the peripheral portion of the substrate becomes thick, for example, SOG
Causes cracking or peeling. As shown in FIG. 7, the peeled small pieces 112a of SOG adhere to the main surface portion of the substrate 101 to directly form a defect, or cause a defect, or the subsequent photomask blank manufacturing process, photo In the mask manufacturing process and the photomask using process, there is a risk of becoming a source of dust and contaminating each process.

Further, there is a case where the substrate peripheral portion is supported when the phase shift mask having the SOG as a coating film formed on the substrate surface is attached to the exposure apparatus. If it is raised, it will not be held well.

As a technique for solving such a problem, for example, there is a method disclosed in Japanese Patent Publication No. 58-19350.

According to this method, the unnecessary film located on the peripheral portion of the coating film on the substrate is dissolved and removed by a removing liquid. That is, as shown in FIGS. 8 and 9, a hollow pyramid is used as a guide member for the removal liquid when removing the unnecessary film located on the peripheral portion of the coating film 113 on the substrate 111 mounted on the spin chuck 102. The main part of the substrate surface is covered with the shaped cover 103, the substrate 111 and the cover 103 are integrally rotated, and the removing liquid 141 is supplied from above the cover 103 through the nozzle 104 to form the unnecessary film portion through the slope of the cover 103. And the unnecessary film on the substrate 111 is dissolved and removed.

[0008]

However, in the above-mentioned method, the removing liquid which flows through the slope of the pyramid-shaped cover which is the guide member and is supplied to the unnecessary film removing region of the substrate is between the substrate and the cover. There is a problem in that the main film portion of the substrate, which should not be removed, is also partially dissolved by penetrating through the gap formed in the substrate and flowing toward the center of the substrate.

The present invention has been made under the background described above, and is a method and apparatus for removing an unnecessary film capable of dissolving and removing only an unnecessary film by a relatively simple method, and a phase using the method for removing an unnecessary film. An object of the present invention is to provide a shift mask blank manufacturing method.

[0010]

In order to solve the above-mentioned problems, an unnecessary film removing method according to the present invention comprises: (Structure 1) An unnecessary film removing method for removing an unnecessary film formed on at least a peripheral portion of a surface of a substrate. In addition, at least the vicinity of the peripheral portion of the substrate surface is covered with a cover member to form a gap between the cover member and the peripheral portion of the substrate surface, and the unnecessary film removing liquid supplied from the outside of the cover member is at least A liquid flow path that can reach an unnecessary film at the peripheral portion of the substrate surface is formed, and an air flow is formed in the gap from the central portion of the substrate toward the outer peripheral portion to supply unnecessary liquid from the outside of the cover member. By preventing the film removing liquid from entering toward the central part of the substrate, and by rotating the substrate and the cover member integrally, the removing liquid becomes an unnecessary film at least at the peripheral portion of the substrate surface. A constitution is characterized in that the unnecessary film is dissolved and removed by being supplied. As a mode of the constitution 1, (constitution 2), in the unnecessary film removing method of constitution 1, the cover member is a substrate. A liquid introducing port is formed to cover the surface peripheral portion and the side surface portion and form a gap between the substrate surface peripheral portion and the side surface portion, and to introduce the unnecessary film removing liquid into the gap in the vicinity of the substrate peripheral portion. The liquid flow path is provided with
The substrate surface peripheral portion is formed by a gap formed between the substrate surface peripheral portion and the side surface portion, and the unnecessary film removing liquid supplied from the outside of the cover member is introduced from the liquid introduction port, The unnecessary film is dissolved and removed while passing through the liquid flow path constituted by the gap formed between the portion and the side surface portion.

Further, the unnecessary film removing apparatus according to the present invention is (Structure 3) is an unnecessary film removing apparatus for removing an unnecessary film formed on at least a peripheral edge portion and a side surface portion of a substrate,
A cover that covers at least the vicinity of the peripheral portion of the substrate surface and forms a gap between the peripheral portion of the substrate surface and a gas inlet for forming an airflow in the gap from the central portion of the substrate toward the outer peripheral portion. A member, an unnecessary film removing liquid supply device that supplies an unnecessary film removing liquid to the cover member, and a rotating device that integrally rotates the substrate and the cover member, and integrates the substrate and the cover member. And removing the unwanted film by dissolving the unwanted solution at least in the peripheral portion and the side surface of the substrate surface by rotating the spinning solution. As an aspect, (Structure 4) In the unnecessary film removing apparatus of Structure 3, the cover member covers the substrate surface peripheral portion and the side surface portion and forms a gap between the substrate surface peripheral portion and the side surface portion, and , In the vicinity of the peripheral portion of the substrate, a liquid introducing port for introducing the unnecessary film removing liquid into the gap is provided, and the unnecessary film removing liquid supplied from the outside of the cover member is introduced from the liquid introducing port, An unnecessary film is dissolved and removed while passing through a gap formed between the peripheral portion and the side surface portion of the substrate surface.

Further, the method of manufacturing a phase shift mask blank according to the present invention is (Structure 5): In the method of manufacturing a phase shift mask blank, the method comprising the step of forming a film to be a phase shift layer on a transparent substrate. In the forming step, there is a step of removing the film formed in the unnecessary portion by the unnecessary film removing method according to the first and second aspects.

[0013]

According to the above configuration 1, at least the vicinity of the peripheral portion of the substrate surface is covered with the cover member to form a gap between the cover member and the peripheral portion of the substrate surface, and the central portion of the substrate is directed toward the central portion of the substrate. Since an air flow is formed from the outer peripheral direction to prevent the unnecessary film removing liquid supplied from the outside of the cover member from entering toward the central portion of the substrate,
It is possible to prevent the unnecessary film removing liquid from reaching a portion other than the unnecessary film and remove only the unnecessary film.

According to the configuration 2, the cover member covers the peripheral edge portion and the side surface portion of the substrate to form a gap between the peripheral edge portion and the side surface portion of the substrate, and in the vicinity of the peripheral edge portion of the substrate, Using a liquid inlet that introduces the unnecessary film removing liquid into the gap, a liquid flow path is formed by the gap formed between the peripheral portion and the side surface of the substrate surface, and the liquid is supplied from the outside of the cover member. The unnecessary film removing liquid is introduced from the liquid introduction port, and the unnecessary film is dissolved and removed while passing through the liquid flow path, thereby making it possible to remove the unnecessary film more reliably. is there.

According to the configurations 3 and 4, the above configurations 1 and 2
It is possible to obtain an apparatus capable of carrying out the method.

Further, according to the constitution 5, only the unnecessary film can be surely removed and a high quality phase shift mask blank can be obtained.

[0017]

1 is a sectional view showing the structure of an unnecessary film removing apparatus according to an embodiment of the present invention, FIG. 2 is a plan view of an unnecessary film removing apparatus according to one embodiment, and FIG. 3 is an embodiment. FIG. 4 is a partially enlarged view of FIG. 1 of the unnecessary film removing device. Hereinafter, an unnecessary film removing method, an apparatus therefor, and a phase shift mask blank according to an embodiment will be described with reference to these drawings.

In FIG. 1, reference numeral 1 is a phase shift mask blank, reference numeral 2 is a spin chuck, reference numeral 3 is a cover member, reference numeral 4 is an unnecessary film removing liquid jet nozzle, and reference numeral 41 is an unnecessary film removing liquid.

The apparatus according to this embodiment comprises a spin chuck 2
The phase shift mask blanks 1 is placed on the mounting table 21 of the above, and the phase shift mask blanks 1 are covered so as to cover the surface peripheral portion 1a and the side surface portions 1b.
The cover member 3 forming a gap 5 between the surface peripheral portion 1a and the side surface portion 1b is fixed on the spin chuck 2, and the unnecessary film removing liquid 41 supplied from the outside of the cover member 3 is supplied to the cover member 3. The gas 6 is introduced from the liquid introduction port 33 into the gap 5, while the gas 6 is introduced into the inside of the cover member 3 to generate an air flow in the gap 5 from the central portion of the phase shift mask blank 1 toward the outer peripheral portion. The unnecessary film removing liquid 41 formed and supplied from the outside of the cover member 3 is prevented from invading toward the center of the phase shift mask blanks 1, and the phase shift mask blanks 1 and the cover member 3 are separated from each other. By rotating integrally, the unnecessary film removing liquid 41 is supplied to the unnecessary films on the surface peripheral portion 1a and the side surface portion 1b of the phase shift mask blank 1 to dissolve and remove the unnecessary film. In which was to so that.

The phase shift mask blank 1 comprises a semitransparent chromium film (film thickness: 210 Å, wavelength 365 nm) on a transparent substrate (6 inch square, thickness 0.25 inch) 11 made of synthetic quartz; 15%) 1
2 is formed, and the SOG film (film thickness;
3700 angstrom) 13 is formed, and the unnecessary film formed on the substrate peripheral edge portion 1a of the SOG film 13 is formed to have a width of about 2 mm from the outer peripheral edge of the substrate toward the central portion of the substrate. The SOG film 13 constitutes a phase shift layer of a known phase shift mask,
The phase shift mask blanks 1 are used as a raw material when manufacturing this phase shift mask, and in many cases, the phase shift mask blanks 1 themselves are targeted for trade.

In the spin chuck 2, a mounting table 21 on which the phase shift mask blanks 1 are mounted is supported by a rotating shaft 22, and this rotating shaft can be rotationally driven by a motor or the like (not shown). This is an apparatus used for (spin coating method).

The cover member 3 comprises an upper cover portion 31 and a lower cover portion 32. The upper cover portion 31 has a hollow shape such that the vicinity of the top of the conical body is cut and removed, and its upper opening portion constitutes the gas introduction port 31a. In addition, the lower cover part 32 continuously faces the upper cover part 31 and faces the surface part and the side surface part of the phase shift mask blanks 1 to cover them so as to form a gap 5 therebetween. The appearance is a square shape that is substantially the same as the outer shape of the phase shift mask blank 1.
In addition, the peripheral edge portion 1a of the lower cover portion 33 on the substrate 11
A large number of liquid inlets 33 having a substantially rectangular shape are formed along the substantially quadrangular line of the part facing each other.
In this case, the connection portions 33a are formed between the adjacent liquid introduction ports 33, respectively. The cover member 3 is fixed on the mounting table 21 of the spin chuck 2 by the support bodies 34 attached to the outer peripheral portion at four positions. In this example,
The inner diameter of the gas inlet 31a of the upper cover portion 31 is set to about 110
mmφ, inner diameter of the lower end is about 140 mmφ, height is about 40
mm. Further, one side of a square in a plan view showing the outer shape of the lower cover part 32 is set to about 160 mm, and each liquid introduction port 33 is arranged so that its inner side is in contact with a quadrangular line having a side length of about 146 mm. The width was about 5 mm. Further, the distance between the cover member 3 and the substrate 1 in the gap 5 is set to about 2 mm.

The unnecessary film removing liquid jet nozzle 4 is provided with an unnecessary film removing liquid 41 supplied from an unnecessary film removing liquid supply device (not shown).
Is ejected to the outside of the upper cover portion 31 of the cover member 3.

Next, the SOG film 13 (phase shift film) of the phase shift mask blank 1 is formed by using the apparatus having the above-mentioned structure.
An example in which the unnecessary film is removed will be described.

First, the phase shift mask blanks 1 is placed on the mounting table 21 of the spin chuck 2, and the cover member 3 is fixed to the mounting table 21 so as to cover it.

Next, the air 6 having a flow rate of about 1 m / sec is supplied from the gas inlet 31a of the cover member 3.

Next, while the phase shift mask blanks 1 and the cover member 3 are integrally rotated by the spin chuck 2 at 100 rpm, isopropyl alcohol is used as the unnecessary film removing liquid 41, and the unnecessary film removing liquid jet nozzle 4 is used. From the upper cover portion 31 toward the outside. The jet flow velocity at this time is about 60 cc / min, and the jet time is about 10 seconds. Thereby, the unnecessary film removing liquid 41 is
By the rotating action, it spreads over the entire slope of the upper cover portion 31, flows down the slope, is introduced into the gap 5 through the liquid introduction port 33, and is discharged to the outside through the gap 5, while the surface peripheral edge of the substrate 11 is being discharged. The unnecessary film formed on the portion 1a and the side surface portion 1b is dissolved and removed.

Next, after about 2 seconds have passed since the supply of the unnecessary film removing liquid 41 was stopped, the supply of air from the gas inlet 31 was stopped, and then the substrate 11 was rotated at 1000 rpm for 15 seconds to eliminate the need. Dry the film removal area.

As a result, the removing liquid does not enter the central portion of the substrate 11 and the unnecessary film having a width of 2 mm formed on the peripheral edge portion 1a and the unnecessary film formed on the side surface portion 1b of the substrate are completely removed. Thus, it was possible to obtain a phase shift mask blank in which the SOG film in an unnecessary portion was completely removed.

In the above-mentioned one embodiment, the example of removing the unnecessary SOG film of the phase shift mask blanks has been described, but the present invention is not limited to this, and the peripheral edge portion and the side surface portion on the substrate are not limited to this. It can also be applied to the case of removing other unnecessary films formed, for example, a resist coating film or a light shielding film.

Further, the present invention is not limited to the phase shift mask blanks, and it is needless to say that the present invention can be applied to a substrate having an unnecessary film on its peripheral portion, such as a color filter substrate or a magnetic disk substrate.

Further, the unnecessary film removing liquid may be any solution that is compatible with the unnecessary film to be removed. For example, when the unnecessary film is an SOG coating film, acetone, isopropyl alcohol, alkaline aqueous solution or the like is used. Further, when the unnecessary film is a resist coating film, a liquid such as ketone, ester, aromatic hydrocarbon can be used.

Further, the shape of the cover member is not limited to the shape of the above-mentioned embodiment, and it is a cover having an inclined outer wall surface through which the unnecessary film removing liquid flows down, and is provided with a gas introduction port at the upper part,
Any shape may be used as long as a gap space is formed between the desired peripheral portion of the substrate and the side surface of the substrate and the unnecessary film removing liquid can be supplied to the desired unnecessary film removing region. As the gas, other than air, an inert gas such as nitrogen or helium or other gas may be used.

[0034]

As described above in detail, according to the method for removing an unnecessary film, the apparatus therefor, and the method for manufacturing a phase shift mask blank according to the present invention, at least the vicinity of the peripheral portion of the substrate surface is covered with a cover member. A gap is formed between the peripheral surface of the substrate surface and an air flow from the central portion of the substrate toward the outer peripheral portion is formed in the gap so that the unnecessary film removing liquid supplied from the outside of the cover member is central to the substrate. Since it is prevented from invading toward the part, it is possible to prevent the unnecessary film removing liquid from reaching a portion other than the unnecessary film, and it is possible to reliably remove only the unnecessary film. It is possible to obtain a good phase shift mask blank.

[Brief description of drawings]

FIG. 1 is a sectional view showing a configuration of an unnecessary film removing device according to an embodiment of the present invention.

FIG. 2 is a plan view of an unnecessary film removing device according to an embodiment.

FIG. 3 is a perspective view of an unnecessary film removing device according to an embodiment.

FIG. 4 is a partially enlarged view of FIG.

FIG. 5 is an explanatory diagram of an unnecessary film.

6 is a sectional view taken along line XX of FIG.

FIG. 7 is an explanatory diagram showing a state in which an unnecessary film is peeled off.

FIG. 8 is an explanatory diagram of a conventional unnecessary film removing device.

FIG. 9 is an explanatory diagram of a conventional unnecessary film removing device.

[Explanation of symbols]

1 ... Phase shift mask blanks, 11 ... Substrate, 12 ...
Semi-transparent film, 13 ... SOG film, 2 ... Spin chuck, 21
Mounting table, 22 ... Rotating shaft, 3 ... Cover member, 31 ... Upper cover part, 31a ... Gas inlet port, 32 ... Lower cover part, 3
3 ... Liquid introducing port, 4 ... Unwanted film removing liquid ejection nozzle, 41 ...
Unnecessary film removing liquid, 5 ... gap, 6 ... gas.

Claims (5)

[Claims] 1. A method for removing an unnecessary film formed on at least a peripheral portion of a surface of a substrate, comprising: covering at least a peripheral portion of the substrate surface with a cover member; A gap is formed between the cover member and the unnecessary film removing liquid supplied from the outside of the cover member to form a liquid flow path that can reach at least the unnecessary film on the peripheral edge of the substrate surface. An air flow is formed from the part direction toward the outer peripheral part to prevent the unnecessary film removing liquid supplied from the outside of the cover member from entering toward the center part of the substrate, and the substrate and the cover member are integrated. The unnecessary film removing method is characterized in that the removing liquid is supplied to at least the unnecessary film on the peripheral portion of the substrate surface to dissolve and remove the unnecessary film by being rotated. 2. The unnecessary film removing method according to claim 1, wherein the cover member covers the substrate surface peripheral portion and the side surface portion and forms a gap between the substrate surface peripheral portion and the side surface portion, and A liquid introduction port for introducing an unnecessary film removing liquid into the gap is provided in the vicinity of the substrate peripheral portion, and the liquid flow channel is formed between the substrate surface peripheral portion and the side surface portion. A gap formed between the substrate surface peripheral portion and the side surface portion by introducing the unnecessary film removing liquid supplied from the outside of the cover member from the liquid introduction port. A method for removing an unnecessary film, characterized in that the unnecessary film is dissolved and removed while passing through the liquid flow path. 3. An unnecessary film removing device for removing an unnecessary film formed on at least a peripheral portion of a surface of a substrate, wherein at least a vicinity of the peripheral portion of the substrate surface is covered and a gap is formed between the peripheral portion and the peripheral surface of the substrate. A cover member provided with a gas introduction port for forming an airflow in the gap from the substrate center direction toward the outer peripheral direction, and an unnecessary film removal liquid supply device for supplying an unnecessary film removal liquid to the cover member, A rotation device that integrally rotates the substrate and the cover member is provided, and the removal liquid is supplied to at least the unnecessary film at the peripheral portion of the substrate surface by rotating the substrate and the cover member integrally. An unnecessary film removing device characterized in that the unnecessary film is dissolved and removed in this manner. 4. The unnecessary film removing apparatus according to claim 3, wherein the cover member covers the substrate surface peripheral portion and the side surface portion to form a gap between the substrate surface peripheral portion and the side surface portion, Further, in the vicinity of the substrate peripheral portion, a liquid introduction port for introducing the unnecessary film removing liquid into the gap is provided, and the unnecessary film removing liquid supplied from the outside of the cover member is introduced from the liquid introducing port. The unnecessary film removing device is characterized in that the unnecessary film is dissolved and removed while passing through a gap formed between the peripheral edge portion and the side surface portion of the substrate. 5. A method of manufacturing a phase shift mask blank comprising a step of forming a film to be a phase shift layer on a transparent substrate, wherein in the step of forming the film, a film formed in an unnecessary portion is formed. A method of manufacturing a phase shift mask blank, comprising a step of removing by the unnecessary film removing method according to the items 1 and 2.