JPH1039493A - Manufacture of pellicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make it possible to strip the pellicle film easily from a base and to use the base repeatedly by coating the base with a layer containing a silicon compound having perfluoroalkyl group and forming a pellicle film on this surface-coated based and then stripping it from the base. SOLUTION: The pellicle film having a reflection preventive layer and a thin transparent central layer is formed on the specified of the base and stripped from the base. The base is coated with the layer containing the silicon compound having the perfluoroalkyl groups. The method for forming the pellicle film is not especially limited but the spin coating process using the flat smooth surface is desirable from the view point of film thickness accuracy and surface property and the formed pellicle film can be easily stripped, because the silicon compound having the perfluoroalkyl groups is vapor deposited on the surface of the base.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a dust cover for protecting a mask used in a photolithography process in the manufacture of a semiconductor integrated circuit, that is, a pellicle.

[0002]

2. Description of the Related Art A pellicle, which is a transparent thin film, is fixed to a photomask or a reticle (hereinafter, both referred to as a "mask") used in a photolithography process in the manufacture of a semiconductor integrated circuit. The pellicle is located on the mask at a predetermined distance. for that reason,
In the photolithography process, even if fine foreign substances adhere to the pellicle, they do not form an image on the semiconductor wafer coated with the photoresist. Therefore, by protecting the mask with the pellicle, a short circuit or disconnection of the semiconductor integrated circuit due to an image of a foreign substance can be prevented, and the production yield of the photolithography process is improved. Further, the pellicle has the effect of reducing the number of times of cleaning of the mask and extending the life thereof.

In such a pellicle, it is required that the transmittance of light to be exposed is high in order to improve the throughput in the exposure step. For this purpose, an antireflection layer is provided on one or both sides of the transparent thin film. The antireflection layer is composed of a single layer or two or more layers.

As the material of the antireflection layer used for the outermost layer, a tetrafluoroethylene-vinylidene fluoride-hexafluoropropylene polymer (Japanese Patent Application Laid-Open No. 61-2 / 1986)
No. 09449), polyfluoroacrylate (described in JP-A-1-100549), and Teflon AF manufactured by DuPont, which is a fluoropolymer having a cyclic structure in the main chain (described in JP-A-3-39963). Described), CYTOP (trade name) manufactured by Asahi Glass Co., Ltd., and the like.

Many of the outermost antireflection layers are made of fluorine-containing polymers or inorganic fluorine-based materials such as calcium fluoride and magnesium fluoride. Many of the transparent thin film layer (center layer) materials use cellulose derivatives such as nitrocellulose, cellulose acetate propionate, and carbonated acetyl cellulose. For such a pellicle, a method is used in which a pellicle film is formed on a substrate such as glass, quartz, or a Si wafer having good smoothness, and the pellicle is separated from the substrate to obtain a pellicle. When the pellicle film is continuously formed on the substrate in order from the outermost layer, the outermost antireflection layer is made of fluorine, has high adhesion to the substrate, and is hardly peeled off from the substrate.

[0006] As a method of peeling from a substrate, a method of immersing in water and peeling (Japanese Patent Laid-Open No. 58-219023,
JP-A-60-35733, JP-A-2-64, etc.), a method of immersing in a chemical solution and immersing in water to peel off (JP-A-56-83941), A method of peeling (JP-A-62-39859), a method of peeling in an atmosphere with a relative humidity of 60% or more (JP-A-6-67410), and a method of peeling after cooling to 5 ° C. or less (Japanese Patent Laid-Open No. 166,045) has been proposed.

However, when immersed in water or a chemical solution, there is a problem that the pellicle film is contaminated.
In addition, the method of peeling in a wet state or the peeling in an atmosphere having a relative humidity of 60% or more causes a problem of contamination of the pellicle film,
Problems such as difficulty in process control arise. 5 ° C
The method of peeling while cooling as described below has problems such as being ineffective depending on the material constituting the pellicle and complicating the process. Further, the substrate which has been peeled off after forming the pellicle once has contamination on the substrate surface, and the substrate must be cleaned or polished again when used next time.

[0008]

SUMMARY OF THE INVENTION In view of the above prior art, an object of the present invention is to immerse a pellicle film having an antireflection layer and a transparent thin film layer made of a fluorine-based material from a substrate in water or a compound solution in a step of peeling the pellicle film from the substrate. An object of the present invention is to provide a method for manufacturing a pellicle in which a pellicle film can be easily peeled off from a substrate without being subjected to humidification or humidification, and a substrate can be repeatedly used.

[0009]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies to solve the above-mentioned problems, and as a result, a step of peeling a pellicle film having an antireflection layer made of a fluorine-based material and a transparent thin film layer from a substrate has been carried out. According to the present invention, it has been found that a pellicle can be easily formed on a substrate having a specific silicon compound formed on the surface thereof, and that the substrate can be used repeatedly.

That is, the first invention of the present application is to form a layer containing a silicon compound having a perfluoroalkyl group in a step of peeling a pellicle film having an antireflection layer made of a fluorine-based material and a transparent thin film layer from a substrate. A method for manufacturing a pellicle, comprising: forming a pellicle film on the surface of a substrate, and peeling the pellicle film. Further, the second invention of the present application is characterized in that a silicon compound having a perfluoroalkyl group is vapor-deposited on the substrate to form a layer containing a silicon compound having a perfluoroalkyl group. An object of the present invention is to provide a method for manufacturing a pellicle of the present invention.

Further, the third invention of the present application provides a method for producing a pellicle according to the first invention or the second invention, wherein the silicon compound having a perfluoroalkyl group is represented by the following general formula (1). To provide. CF ₃ (CF ₂ ) _n CH ₂ CH ₂ Si (OMe) ₃ (1) (where n is an integer of 5 to 7)

Hereinafter, the present invention will be described in detail. Glass such as soda lime, quartz, a Si wafer, or the like can be used as the film forming substrate material of the present invention. The surface of these substrates should be sufficiently smooth. A layer of a silicon compound having a perfluoroalkyl group is formed on the surface of the substrate. The method for forming the silicon compound layer having a perfluoroalkyl group on the substrate may be any method, but is preferably a spin coating method or a vapor deposition method, and particularly preferably a vapor deposition method. Here, the term “evaporation” means that a vapor of a silicon compound having a perfluoroalkyl group is attached to a substrate. The substrate on which the silicon compound containing a perfluoroalkyl group is formed in this manner is used as a substrate for pellicle film formation.

As the silicon compound containing a perfluoroalkyl group, the following general formula (2): CF ₃ (CF ₂ ) ₇ CH ₂ CH ₂ Si (OMe) ₃ ... (2) Formula (3) CF ₃ (CF ₂ ) ₅ CH ₂ CH ₂ Si (OMe) ₃ ... (3) or the following general formula (4) CF ₃ (CF ₂ ) ₇ CH ₂ CH ₂ SiMe (OMe) ₂ ... (4) or the following general formula (5): CF ₃ (CF ₂ ) ₅ CH ₂ CH ₂ SiMe (OMe) ₂ ... (5), silazane having a perfluoroalkyl group, and these And the like can be used. Among these compounds, the compound [1] represented by the general formula (2)
0,10,10,9,9,8,8,7,7,6,6
5,5,4,4,3,3-heptadecafluorodecyltrimethoxysilane] is preferred.

The silicon compound containing the perfluoroalkyl group may be deposited on the substrate under normal pressure, reduced pressure or increased pressure. The silicon compound having the perfluoroalkyl group and the substrate are placed in a container. The substrate is coated with a vapor of a silicon compound having a perfluoroalkyl group. The pressure is preferably normal pressure or reduced pressure. The coating temperature is preferably from 5 to 200C, more preferably from 20 to 130C. The container is preferably sealed, but may have a vent hole to the outside. The coating time is preferably from 1 minute to 1 week, and more preferably from 1 hour to 3 days.

A pellicle film is formed on the substrate on which the silicon compound having a perfluoroalkyl group is deposited.
The pellicle film is a film in which an antireflection layer is provided on a transparent thin film layer (center layer). The method for forming the pellicle film of the present invention may be any method, but spin coating on a smooth substrate is preferred because of its excellent film thickness accuracy and surface properties. The spin coating conditions include many factors such as solution viscosity, solvent evaporation rate, temperature around the spin coater, humidity, spin rotation speed, and spin time, and the conditions should be properly selected from these factors.

The double-sided single-layer antireflection pellicle is obtained by forming an antireflection layer on a substrate, drying the solvent sufficiently, forming a transparent thin film layer (center layer) thereon, and further drying the solvent sufficiently. An anti-reflection layer is formed thereon. A frame made of metal or plastic with a double-sided tape or the like is bonded to the three-layer film formed on the substrate at room temperature and in the air. A pellicle three-layer film can be obtained by peeling this off, but it can be easily peeled off since the silicon compound containing a perfluoroalkyl group is deposited on the substrate surface.

Further, the substrate from which the pellicle film has been peeled can be used for repeatedly forming and peeling a pellicle without washing. Similarly, a double-sided two-layer antireflection pellicle is formed by sequentially forming a low-refractive-index antireflective layer, a high-refractive-index antireflective layer, a transparent thin film layer (center layer), a high-refractive antireflective layer, and a low-refractive antireflective layer on a substrate. As described above, a five-layer film which is easily peeled from the substrate and adhered to the frame can be obtained. Examples of the transparent thin layer material (center layer) include nitrocellulose, cellulose acetate, cellulose acetate butyrate, cellulose acetate propionate, ethyl cellulose,
Cellulose derivatives such as carbonated acetylcellulose can be used.

These cellulose derivatives may be used alone. Nitrocellulose is excellent in film strength and shape retention under high humidity, but is inferior to other cellulose derivatives in light resistance and cellulose. acetate,
Cellulose acetate propionate and cellulose acetate butyrate are excellent in light resistance, but are inferior in film strength and shape retention under high humidity. Therefore, a mixture of nitrocellulose and a cellulose derivative other than nitrocellulose can be preferably used.

The mixing ratio of nitrocellulose and other cellulose derivatives is determined in consideration of film strength, shape retention under high humidity, and light resistance. The content of nitrocellulose is preferably 10 to 50% by weight. Preferably, it is more preferably 20 to 40% by weight. As the cellulose derivative to be used, a high molecular weight one is preferable because the shape retention of the thin film is good. That is, the number average molecular weight is 30,000 or more, preferably 50,000 or more. Among these materials, nitrocellulose is commercially available from Asahi Kasei Kogyo Co., Ltd., and cellulose acetate, cellulose acetate butyrate, and cellulose acetate propionate are commercially available from Eastman Kodak Company, and can be easily obtained.

As the solvent for the cellulose derivative, 2-butanone, methyl isobutyl ketone, cyclohexanone,
Butyl acetate, isobutyl acetate, ethyl lactate, cellosolve acetate, propylene glycol monomethyl ether acetate and the like and a mixture of these solvents are used. The solution such as a cellulose derivative is filtered in advance to remove foreign substances, and then spin-coated. The thickness of the transparent thin film (center layer) can be appropriately changed by changing the solution viscosity or the rotation speed of the substrate. The solvent contained in the thin film formed on the substrate is volatilized on a hot plate, an oven, or the like.

The anti-reflection layer is composed of a single layer or two or more layers. In the case of a single layer (the number of pellicle layers is three when the anti-reflection layer is formed on the front and back), the refractive index of the anti-reflection layer is n
1 is n1 = nC for the refractive index nC of the transparent thin film (center layer).
The antireflection effect is maximized when (nC) ^1/2 , and the antireflection effect increases as the antireflection layer material closer to this value is selected. The thickness d of the antireflection layer may be n1 · d = λ / 4, where λ is the wavelength to be antireflection.

In the case of two-layer anti-reflection (the number of pellicle layers is five if anti-reflection layers are formed on the front and back surfaces as described above)
Is that the layer in contact with the transparent thin film layer is a high-refractive-index antireflection layer, and the outermost layer is a low-refractive-index antireflection layer. The refractive index and thickness are n1, d1, and n in order from the outermost antireflection layer.
Assuming that 2, d2, the antireflection effect is maximized when n2 / n1 = (nC) ^1/2 , and the antireflection effect increases as the n2 / n1 antireflection layer material closer to this value is selected. The thicknesses d1 and d2 of the antireflection layer may be n1 · d1 = n2 · d2 = λ / 4, where λ is the wavelength to be antireflection. For the central layer, a cellulose derivative, polyvinyl butyral, polyvinyl propional, or the like can be used. Since the refractive index of these is about 1.5, the (nC) ^1/2 is about 1.22. . Therefore, as the refractive index of the antireflection layer material, in the case of single-layer antireflection,
As n2 / n1 is closer to 1.22, the antireflection effect increases, which is preferable.

Materials for the low refractive index antireflection layer used as the outermost layer include tetrafluoroethylene-vinylidene fluoride-hexafluoropropylene polymer, polyfluoroacrylate, and DuPont, a fluoropolymer having a cyclic structure in the main chain. Fluorine-based materials such as Teflon AF (trade name) manufactured by Asahi Glass Co., Ltd. and Cytop (trade name) manufactured by Asahi Glass Co., Ltd. can be used. As the polyfluoroacrylate, FC-722 (trade name) manufactured by Sumitomo 3M can be preferably used. Teflon AF improves the filterability, the antistatic property, and the adhesion between the pellicle film and the support frame by irradiating radiation such as γ-rays, electron beams, and α-rays, or light such as far ultraviolet rays.

Each of these fluorine-based antireflection layer materials may be used alone, or may be a mixture with another polymer. This fluoropolymer is perfluorobenzene, perfluoro (2-butyltetrahydrofuran),
Although dissolved in a fluorine-based solvent such as trichlorotrifluoroethane or perfluorotributylamine, a solvent having a higher boiling point is preferable in order to obtain a film having a smooth film surface and no color spots. The boiling point is preferably at least 130 ° C, more preferably at least 160 ° C.

The fluoropolymer solution is filtered in advance to remove foreign substances, and then spin-coated. The thickness of the low-refractive-index antireflection layer used as the outermost layer can be appropriately changed by changing the solution viscosity or the rotation speed of the substrate. The solvent contained in the thin film formed on the substrate is volatilized by air drying, a hot plate, an oven, or the like.

In the case of a two-layer antireflection pellicle, the material of the high refractive index antireflection layer in contact with the transparent thin film layer can be polyvinyl naphthalene, polystyrene, polyether sulfone, or the like. The above-mentioned pellicle film with an antireflection layer is bonded to a support frame using an ultraviolet-curable adhesive or a thermosetting adhesive as an adhesive. From the viewpoint of simplicity of the process and less damage to the pellicle film, it is preferable to use an ultraviolet curable adhesive.

[0027]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in more detail with reference to examples and the like. (Example 1) 10, 10, 10, 9, 9, 8, 8, 7,
7,6,6,5,5,4,4,3,3-heptadecafluorodecyltrimethoxysilane containing about 20 cc of diameter 5
Put the polyethylene container with the upper part of cm open and the polished silicon wafer in a 30 cm square metal container,
Sealed. The metal container and the inside were heated to 105 ° C. and left in this state for 36 hours. Thereafter, the temperature was returned to room temperature, and the silicon wafer was taken out of the metal container. The contact angle of water on this silicon wafer surface was 110 °, and the surface of the polished silicon wafer was 51 °.

Next, Teflon AF2400 manufactured by DuPont
(Trade name) was irradiated with gamma rays in the air. Irradiation dose is 30
0 kGy (Gy: unit of dose) (hereinafter referred to as “γAF2
400 "). γAF2400 was dissolved in perfluorotributylamine to prepare a 1% by weight solution. Cellulose acetate propionate (“CAP482-20” manufactured by Eastman Kodak Company, hereinafter abbreviated as CAP)
Was dissolved in propylene glycol monomethyl ether acetate. The solution viscosity is 400 cpoise (25
° C).

First, the silicon wafer after the above treatment was set on a spin coater, and the adjusted γAF2400 solution was filtered through a membrane filter having a pore diameter of 0.2 μm, 5 cc of the filtrate was dropped, and the solution was rotated at 600 rpm for 30 seconds. Thereafter, it was air-dried and further dried on a hot plate to form an antireflection layer. The prepared CAP solution was filtered through a membrane filter having a pore size of 0.2 μm, and 20 cc of the filtrate was dropped on the antireflection layer.
The silicon wafer was rotated at 1000 rpm for 45 seconds, and then the solvent was evaporated on a hot plate to form a 1.2 μm thick thin film (center layer) made of CAP on the silicon wafer.

Further, the filtrate 5c of the γAF2400 solution
c was dropped on the above-mentioned central layer, rotated at 600 rpm for 30 seconds, air-dried, and further dried on a hot plate,
An antireflection layer was formed to obtain a three-layer film. The thickness of the antireflection layers formed on both sides was 73 nm, respectively. Next, a metal or plastic frame with a double-sided tape is adhered on the three-layer film formed on the silicon wafer,
Under conditions of 50 ° C. and a relative humidity of 50%, the three-layer film could be easily removed from the silicon wafer. The obtained three-layer pellicle film was good without color spots, traces of peeling, or transferred matter from the substrate. The silicon wafer surface after pellicle peeling has no peeling marks, and the contact angle of water on the surface is the same as before the pellicle film formation.
10 °.

Next, on the silicon wafer from which the pellicle was once formed and peeled, a three-layer pellicle film was formed again by the spin coating method as described above. As above,
A metal or plastic frame with a double-sided tape, etc., is adhered on the three-layer film formed on the silicon wafer,
Under a condition of 23 ° C. and a relative humidity of 50%, the three-layer film could be easily peeled off from the silicon wafer. The obtained three-layer pellicle film was good without color spots, traces of peeling, or transferred matter from the substrate. This silicon wafer surface has no trace of peeling,
The contact angle of water on the surface was 110 °.

Further, a three-layer pellicle film was formed on the silicon wafer, peeled from the silicon wafer, and used repeatedly 30 times. All of the obtained three-layer pellicle films were good without any color spots, traces of peeling, or transferred matters from the substrate. The silicon wafer surface after 30 repetitive uses had no trace of peeling, and the contact angle of water on the surface was 110 °, the same as before the pellicle film formation.

(Embodiment 2) As in Embodiment 1, 10, 1
0,10,9,9,8,8,7,7,6,6,5,5
4,4,3,3-heptadecafluorodecyltrimethoxysilane and the polished silicon wafer were placed in a metal container and sealed. Heat the metal container and the inside to 30 ° C,
This state was left for 24 hours. Then return to room temperature,
The silicon wafer was taken out of the metal container. The contact angle of water on the surface of this silicon wafer is 103 °,
The surface of the polished silicon wafer was 51 °.

In the same manner as in Example 1, an antireflection layer, a center layer and an antireflection layer were formed on the silicon wafer after the above treatment, and a three-layer pellicle film was formed by spin coating. A metal or plastic frame with a double-sided tape or the like is adhered to the three-layer film formed on the silicon wafer, and the three-layer film is easily peeled off from the silicon wafer at 23 ° C. and 50% relative humidity. did it. The obtained three-layer pellicle film was good without color spots, traces of peeling, or transferred matter from the substrate. The silicon wafer surface had no trace of peeling, and the contact angle of water on the surface was 103 °.

Further, a three-layer pellicle film was formed on the silicon wafer, peeled off from the silicon wafer, and used repeatedly 10 times. All of the obtained three-layer pellicle films were good without any color spots, traces of peeling, or transferred matters from the substrate. Further, the silicon wafer surface after ten times of repeated use had no trace of peeling, and the contact angle of water on the surface was 103 °, which was the same as before the pellicle film formation.

(Embodiment 3) As in Embodiment 1, 10, 1
0,10,9,9,8,8,7,7,6,6,5,5
The 4,4,3,3-heptadecafluorodecyltrimethoxysilane and the polished silicon wafer are placed in a metal container, and the pressure in the container is set to 660 mmHg (-100 mmH).
g) and sealed. The metal container and the inside were heated to 30 ° C. and left in this state for 24 hours. Thereafter, the temperature was returned to room temperature, and the silicon wafer was taken out of the metal container. The contact angle of water on the surface of this silicon wafer is 104 °
And the surface of the silicon wafer after polishing was 51 °.

In the same manner as in Example 1, an antireflection layer, a center layer and an antireflection layer were formed on the silicon wafer after the above treatment, and a three-layer pellicle film was formed by spin coating. A metal or plastic frame with a double-sided tape or the like is adhered to the three-layer film formed on the silicon wafer, and the three-layer film is easily peeled off from the silicon wafer at 23 ° C. and 50% relative humidity. did it. The obtained three-layer pellicle film was good without color spots, traces of peeling, or transferred matter from the substrate. The silicon wafer surface had no trace of peeling, and the contact angle of water on the surface was 104 °.

Further, a three-layer pellicle film was formed on the silicon wafer, peeled off from the silicon wafer, and used repeatedly 10 times. All of the obtained three-layer pellicle films were good without any color spots, traces of peeling, or transferred matters from the substrate. Further, the silicon wafer surface after ten times of repeated use had no trace of peeling, and the contact angle of water on the surface was 104 °, the same as before the pellicle film formation.

Example 4 A compound represented by the following general formula (3) CF ₃ (CF ₂ ) ₅ CH ₂ CH ₂ Si (OMe) ₃ ... Placed in a container and sealed. The metal container and the inside were heated to 105 ° C. and left in this state for 36 hours. Thereafter, the temperature was returned to room temperature, and the silicon wafer was taken out of the metal container. The contact angle of water on the surface of the silicon wafer was 108 °, and the surface of the silicon wafer after polishing was 51 °.

In the same manner as in Example 1, an antireflection layer, a center layer and an antireflection layer were formed on the silicon wafer after the above treatment, and a three-layer pellicle film was formed by spin coating. A metal or plastic frame with a double-sided tape or the like is adhered to the three-layer film formed on the silicon wafer, and the three-layer film is easily peeled off from the silicon wafer at 23 ° C. and 50% relative humidity. did it. The obtained three-layer pellicle film was good without color spots, traces of peeling, or transferred matter from the substrate. The silicon wafer surface had no trace of peeling, and the contact angle of water on the surface was 108 °.

Further, a three-layer pellicle film was formed on the silicon wafer, peeled off from the silicon wafer, and used repeatedly 10 times. All of the obtained three-layer pellicle films were good without any color spots, traces of peeling, or transferred matters from the substrate. In addition, the silicon wafer surface after ten times of repeated use had no trace of peeling, and the contact angle of water on the surface was 108 °, which was the same as before the pellicle film formation.

Comparative Example 1 An anti-reflection layer, a center layer and an anti-reflection layer were formed on a polished silicon wafer in the same manner as in Example 1, and a three-layer pellicle film was formed by spin coating. A metal or plastic frame with a double-sided tape or the like is adhered on the three-layer film formed on the silicon wafer and peeled off from the silicon wafer at 23 ° C. and 50% relative humidity. The pellicle film peeled off at the interface between the contacted antireflection layer and the center layer and adhered to the frame was a two-layer film. The antireflection layer remained on the silicon wafer side.

[0043]

According to the method for producing a pellicle of the present invention, a pellicle film having an antireflection layer and a transparent thin film layer made of a fluorine-based material is separated from a substrate by immersion in water or a chemical solution or in a wet state. Or, without humidifying, the pellicle film can be easily peeled off from the substrate,
Further, repetitive substrates can be used.

Claims (3)

[Claims] 1. A pellicle film formed on a surface of a substrate on which a layer containing a silicon compound having a perfluoroalkyl group is formed in a step of peeling the pellicle film having an antireflection layer made of a fluorine-based material and a transparent thin film layer from the substrate. Forming a pellicle, and then peeling off the pellicle film. 2. The substrate according to claim 1, wherein a layer containing a silicon compound having a perfluoroalkyl group is formed by depositing a silicon compound having a perfluoroalkyl group on the substrate. Pellicle manufacturing method. 3. The method for producing a pellicle according to claim 1, wherein the silicon compound having a perfluoroalkyl group is a compound represented by the following general formula (1). CF ₃ (CF ₂ ) _n CH ₂ CH ₂ Si (OMe) ₃ (1) (where n is an integer of 5 to 7)