JPH0558678A - Method for forming colored pattern - Google Patents

Abstract

PURPOSE:To improve the exposure efficiency by applying a coating liquid composed of specific components to the surface of a transparent substrate, baking the coating to vitrify the component, contacting Ag ion to effect the ion exchange and irradiating the obtained Ag ion-containing glass film with electron beam. CONSTITUTION:A coating liquid is prepared by adding a salt capable of forming an alkali metal ion and Cl ion to a hydrolyzed solution of an Si alkoxide and mixing the mixture. A transparent substrate 2 having high ultraviolet transmittance (e.g. quartz glass plate) is immersed in the coating liquid to form a film of 0.1-1.5mum thick on the surface. After heating and drying the film, the product is baked at 200-1000 deg.C to vitrify the coating component obtaining a transparent substrate 1 having a glass film 3. The substrate is immersed in a molten salt 4 containing Ag ion such as AgNO3 to effect the ion exchange of the alkali metal ion in the glass film 3 to the Ag ion and introduce Ag ion into the glass film. Carbon is deposited on the surface to form an electrically conductive film 7, selectively irradiated with electron beam 5 to color the irradiated part 6 and etched with O2 plasma to remove the unnecessary part and obtain a colored pattern.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for forming a colored pattern, and more particularly to a method for forming a negative pattern by generating silver colloid in a glass film by irradiating an electron beam. The colored pattern obtained by the colored pattern forming method of the present invention is used for microprocessing such as a photomask used for manufacturing a semiconductor in the electronic industry.

[0002]

2. Description of the Related Art Conventionally, as a method of forming a colored pattern, there is a method of forming a negative colored pattern by generating silver colloid in the surface layer of a glass substrate by irradiation with an electron beam. For example, in Japanese Patent Publication No. 60-501950, glass containing components such as alkali metal oxide, silicon oxide and chlorine is melted and the melt is formed into a plate to form a glass substrate. By immersing a glass substrate in a molten salt containing silver ions, the alkali metal ions near the surface of the glass substrate are exchanged with the silver ions, and the silver ions are introduced into the glass substrate surface to a depth of several μm from the surface. Then, a method of forming a negative type colored pattern by selectively irradiating an electron beam on a glass substrate having silver ions introduced on the surface to reduce silver ions in the vicinity of the glass substrate surface to form a silver colloid. It is disclosed.

[0003]

However, in this method, since the multi-component glass containing an alkali metal is used as the substrate, the substrate of the obtained colored pattern has a large thermal expansion coefficient and is not irradiated with the electron beam. The transmittance of the ultraviolet light, especially in the vicinity of i-line (wavelength = 365 nm) is low. Therefore, for example, when the colored pattern is used as a photomask, the width and relative position of the pattern change due to heat generated during pattern transfer,
There is a problem in that the required pattern cannot be obtained and the exposure efficiency is poor because the transmittance of light having a short wavelength such as i-line (wavelength = 365 nm) required as exposure light is low. The present invention has been made to solve the above-mentioned problems, and provides a method for forming a desired pattern, and forming a colored pattern having a high transmittance of ultraviolet light and a good exposure efficiency. ..

[0004]

A method for forming a colored pattern according to the present invention comprises a coating solution containing a hydrolyzing solution of silicon alkoxide, alkali metal ions and chlorine ions on a transparent substrate having a high ultraviolet light transmittance. Coating, drying and baking the coating solution to vitrify it to produce a transparent substrate with a glass film, and bringing the glass film into contact with silver ions to ionize alkali metal ions and silver ions in the glass film. The method is characterized by including the steps of replacing the glass film with a silver ion-containing glass film and selectively irradiating the glass film containing a silver ion with an electron beam. Incidentally, the silicon alkoxide means that at least one alkoxyl group is bonded to silicon, and in addition to the one having four alkoxyl groups bonded to silicon, the alkoxyl group and the alkoxyl group such as an alkyl group and a halogen group are bonded to silicon. It also includes groups to which groups other than are bonded.

The present invention will be described below with reference to FIGS. 1 (a) to 1 (c). First, the coating liquid will be described. The coating solution contains a hydrolyzed solution of silicon alkoxide, and the silicon alkoxide includes Si (OCH
₃ ) ₄ , Si (OC ₂ H ₅ ) ₄ , Si (OC
₃ H ₇ ) ₄ , Si (OC ₄ H ₉ ) ₄ , CH ₃ Si (OC
_{H 3) 3, C 2 H} 5 Si (OC 2 H 5) 3, CH 3 Si
(OC ₂ H ₅ ) ₃ , ClSi (OCH ₃ ) ₃ , ClSi
(OC ₂ H ₅ ) ₃ or the like can be used. The hydrolysis of the silicon alkoxide can be performed by mixing the silicon alkoxide in an alcohol-water solvent and then adding a hydrochloric acid aqueous solution. When the silicon alkoxide is hydrolyzed and baked, it becomes SiO ₂ and becomes a matrix of the glass film.

As alkali metal ions, alkali metal nitrates, sulfates, chlorides, alkoxides or hydrolysates of alkoxides can be added to the coating solution. When a salt such as NaCl is used as the alkali metal ion, the alcohol-water solvent composition must be selected in consideration of the solubility of the salt. The alkali metal ions are ion-exchanged with silver ions in the step of bringing a transparent substrate with a glass film into contact with silver ions, which will be described later.

As the chlorine ion, ClSi described above is used.
Alkoxides such as (OCH ₃ ) ₃ and ClSi (OC ₂ H ₅ ) ₃ and their hydrolysates, or NaCl and KC.
A compound such as 1 can be added to the coating solution. When the glass film described below is irradiated with an electron beam, the chloride ion enhances the sensitivity to the electron beam and enhances the efficiency of silver ion reduction due to the electron beam irradiation, and the optical density (O. D.) is also increased.

When a metal oxide such as TiO ₂ , ZrO ₂ or Al ₂ O ₃ is added as a component of the glass film for the purpose of improving the film forming property of the glass film, Ti, An alkoxide such as Zr or Al, a hydrolyzate of the alkoxide, a nitrate, a sulfate or a chloride can be added. A coating liquid is obtained by thoroughly mixing the above components with stirring.

Next, the obtained coating liquid is applied onto the transparent substrate 2 by spin coating or dip coating. The thickness of the glass film formed by one coating is 0.1
1.5 μm is preferable. Because, when the thickness is 0.1 μm or less, the coloring due to the silver colloid is small even if the electron beam is irradiated,
This is because if the thickness is more than μm, the film is likely to be cracked and it is difficult to form a uniform film. As a method for controlling the film thickness, it is possible to control the concentration and viscosity of the coating solution, the number of revolutions at the time of coating in the case of spin coating, and the pulling rate in the case of dip coating. It is also possible to apply the coating liquid several times to form a multilayer film.

The transparent substrate having a high ultraviolet light transmittance has a coefficient of thermal expansion of 50 × 10 ⁻⁷ / ° C. or less and a thickness of 3
In a transparent substrate of mm, the transmittance is i-line (wavelength = 365n
It is preferably 80% or more in m). For example, it is preferable to use quartz glass having a transmittance of about 90% for i-line (wavelength = 365 nm) and a thermal expansion coefficient of 5 × 10 ⁻⁷ , or low expansion glass.

Next, the coating liquid 3 applied to the transparent substrate 2 is dried and then fired to be vitrified to prepare a glass film-coated transparent substrate 1 as shown in FIG. 1 (a). The firing temperature is preferably 200 to 1000 ° C., more preferably 400.
~ 800 ° C. If the temperature is lower than 200 ° C., organic residues are likely to exist in the film, and reduction of silver ions introduced into the glass film during ion exchange described later easily occurs.
If the temperature exceeds ℃, the amount of Cl in the film will decrease greatly due to decomposition,
Electron beam sensitivity and optical density (O.
D. ) Is reduced. In order to further reduce the amount of organic residues in the film during the firing process, it is advisable to carry out the firing atmosphere in an oxygen atmosphere to promote the oxidative decomposition of the organic matter.

Next, the glass substrate-coated transparent substrate 1 obtained as described above is immersed in a molten salt 4 containing silver ions as shown in FIG.
Ion exchange is performed between the alkali metal ion in the glass film and the silver ion in the molten salt to introduce the silver ion into the glass film. Molten salts containing silver ions are AgNO ₃ , A
Compounds such as gCl and Ag ₂ SO ₄ can be used, and in order to prevent thermal decomposition of the above silver compounds during ion exchange, the above silver compounds and nitrates of elements such as K, Na, Cs and Zn, A mixture with chloride, sulfate or the like may be used. At that time, it is desirable to select the composition of the molten salt in consideration of the chemical durability of the transparent substrate and the glass film. The higher the ion exchange temperature, the faster the ion exchange rate and the shorter the ion exchange process, and the higher the concentration of silver ions in the glass membrane after the ion exchange. However, it is desirable to set the ion exchange temperature to a temperature lower than the above temperature in consideration of the glass transition point of the glass film and the temperature at which the silver ions in the molten salt are thermally reduced.

Next, as shown in FIG. 1 (c), the glass film is selectively irradiated with an electron beam 5 to reduce silver ions in the electron beam irradiated portion 6 to generate a silver colloid, which is colored. .. When irradiating with an electron beam, the acceleration voltage is 5-40 kV
Is preferred. If the accelerating voltage is smaller than the above value, the electrons do not penetrate to a sufficient depth and coloring is not sufficiently performed, and the electrons may spread and a clear pattern may not be obtained. May pass through the glass film containing silver ions, and the efficiency of electron beam irradiation may decrease. Further, a conductive film 7 is provided above or below the glass film in order to prevent charge-up due to electron beam irradiation and pattern shift. In FIG. 1C, a conductive film is provided on the glass film. When the conductive film is provided below the glass film, it is preferably a transparent conductive film having a high transmittance of ultraviolet light, but when provided on the glass film, it is possible to remove it after drawing, so that it has particularly high transparency. You don't have to have it.

[0014]

The method for forming a colored pattern of the present invention comprises forming a glass film containing silver ions on a transparent substrate having a low coefficient of thermal expansion and a high transmittance of ultraviolet light, and selectively coloring the glass film. Since a negative pattern is obtained, the coefficient of thermal expansion of the obtained colored pattern and the transmittance of ultraviolet light of the uncolored portion are almost the same as the coefficient of thermal expansion and the transmittance of ultraviolet light of the transparent substrate, There is almost no increase in the coefficient of thermal expansion and decrease in the transmittance of ultraviolet light due to the glass film containing silver ions formed on the transparent substrate.

[0015]

【Example】

Example 1 8 mol of Si (OC ₂ H ₅ ) _{4 was} added to C ₂ H ₅ O
After uniformly mixing with 5 mol of H and stirring, 1% HCl aqueous solution was added in an amount corresponding to 16 mol of H ₂ O for hydrolysis. Then T
A mixed solution of 1 mol of i (OC ₄ H ₉ ) _{4 and} 10 mol of C ₂ H ₅ OH was added and stirred, and 1 mol of NaCl was added to H ₂
A coating solution was obtained by adding a solution dissolved in 16 mol of O and mixing them uniformly. A film thickness of 1.2 μm is formed on the transparent substrate 2 by a so-called dip coating method in which the transparent substrate 2 made of quartz glass having a thickness of 3 mm is immersed in the coating liquid.
To form a uniform film. Next, the film was dried at 200 ° C. and then baked at 600 ° C. to vitrify the film to form a transparent substrate 1 with a glass film as shown in FIG.

Next, the transparent substrate 1 with a glass film is shown in FIG.
As shown in (b), by immersing in AgNO ₃ molten salt 4 at 240 ° C., Na ⁺ in the glass film 3 and molten salt 4
Ion exchange was carried out with the Ag ⁺ inside. Next, after the ion-exchanged transparent substrate 1 with a glass film was washed and dried, carbon was vacuum-deposited on the surface of the glass film 3 to form a conductive film 7. Further, an electron beam irradiation device was used to selectively irradiate the electron beam 5 at an accelerating voltage of 15 kV as shown in FIG. 1C, and the electron beam irradiated portion 6 was colored.
Then, the conductive film 7 on the surface of the glass film 3 was removed by dry etching using oxygen plasma.

The colored pattern obtained in this example is
The transmittance of ultraviolet light in the non-colored portion was as high as about 80% near the i-line (wavelength = 365 nm) as shown in FIG. 2 (a). The reason why the curve of FIG. 2A has a waveform at a wavelength longer than about 350 nm is considered to be because the exposure light causes interference due to the thickness of the glass film. The coefficient of thermal expansion is almost the same as the coefficient of thermal expansion of quartz glass. When the obtained colored pattern was used for pattern transfer, the required pattern was obtained. Further, the optical density (OD) in the colored portion of the colored pattern obtained in this example.
Was 1.8 and could be used as a photomask.

Example 2 4 mol of Si (OC ₂ H ₅ ) _{4 and} 5 mol of C ₂ H ₅ OH were uniformly mixed and stirred, and then 1% H
The Cl aqueous solution was added with 8 mol of H ₂ O and hydrolyzed. Then 1 mol of Ti (OC ₄ H ₉ ) ₄ and C ₂ H ₅ OH
A 5 mol mixed solution was added and stirred, and the liquid was once cooled to 3 ° C. in order to prevent volatilization of Cl, and then ClSi (OC ₂
H ₅ ) ₃ 4 mol were added and mixed, and further NaCl 0.5
Mol and NaNO ₃ 0.5 mol dissolved in 87 mol of H ₂ O were added and mixed uniformly to obtain a coating liquid.
A uniform film having a thickness of 1.2 μm was formed on the transparent substrate 2 by a so-called dip coating method in which the transparent substrate 2 made of quartz glass having a thickness of 3 mm was dipped in the coating liquid. Next, the film was dried at 200 ° C. and then baked at 600 ° C. to vitrify the film to form a transparent substrate 1 with a glass film as shown in FIG.

Next, the transparent substrate 1 with a glass film is shown in FIG.
As shown in (b), by immersing in AgNO ₃ molten salt 4 at 240 ° C., Na ⁺ in the glass film 3 and molten salt 4
Ion exchange was carried out with the Ag ⁺ inside. Next, after the ion-exchanged transparent substrate 1 with a glass film was washed and dried, carbon was vacuum-deposited on the surface of the glass film 3 to form a conductive film 7. Further, an electron beam irradiation device was used to selectively irradiate the electron beam 5 at an accelerating voltage of 15 kV as shown in FIG. 1C, and the electron beam irradiated portion 6 was colored.
Then, the conductive film 7 on the surface of the glass film 3 was removed by dry etching using oxygen plasma.

In the colored pattern obtained in this example, the ultraviolet light transmittance of the non-colored portion was as high as about 80% near the i-line (wavelength = 365 nm). The coefficient of thermal expansion is almost the same as the coefficient of thermal expansion of quartz glass. When the obtained colored pattern was used for pattern transfer, the required pattern was obtained. Also,
The optical density (OD) in the colored portion of the colored pattern obtained in this example was 2.0, and it could be used as a photomask.

Example 3 8 mol of Si (OC ₂ H ₅ ) _{4 and 5} mol of C ₂ H ₅ OH were uniformly mixed and stirred, and then 1% H
An aqueous solution of Cl was added for 16 mol of H ₂ O to carry out hydrolysis. Then 1 mol of Ti (OC ₄ H ₉ ) ₄ and C ₂ H ₅ OH
A 10 mol mixed solution was added and stirred, and KCl1 was added.
A coating solution was obtained by adding a solution prepared by dissolving 18 mol of H ₂ O in H ₂ O and mixing them uniformly. Thickness 3 in this coating solution
It is said that the transparent substrate 2 which is a quartz glass of mm is immersed.
A uniform film having a film thickness of 1.1 μm was formed on the transparent substrate 2 by a so-called dip coating method. Then, the film is replaced with 20
After being dried at 0 ° C., it is baked at 600 ° C. to vitrify the film, and a transparent substrate 1 with a glass film as shown in FIG.
Formed.

Next, the transparent substrate 1 with a glass film is shown in FIG.
As shown in (b), AgNO at 240 ° C₃In molten salt 4
By immersing, K in the glass film 3⁺And in molten salt 4
Ag ⁺Ion exchange with. Next, after ion exchange
After cleaning and drying the transparent substrate 1 with a glass film, the glass film
Conductivity by vacuum-depositing carbon on the surface of 3
The film 7 was formed. Furthermore, it accelerates using an electron beam irradiation device.
At a voltage of 15 kV, electrons are selectively emitted as shown in FIG.
Irradiation with the beam 5 was performed to color the electron beam irradiated portion 6. Next
Then, the conductive film 7 on the surface of the glass film 3 is treated with oxygen plasma.
It was removed by dry etching.

In the colored pattern obtained in this example, the ultraviolet light transmittance of the non-colored portion was as high as about 80% near the i-line (365 nm). The coefficient of thermal expansion is almost the same as the coefficient of thermal expansion of quartz glass. When the obtained colored pattern was used for pattern transfer, the required pattern was obtained. Further, the optical density (OD) in the colored portion of the colored pattern obtained in this example was 1.8, and it could be used as a photomask.

(Comparative example) SiO ₂ 64 wt%, Na ₂ O
15wt%, ZnO 9wt%, TiO ₂ 7wt%, Cl
A uniform glass containing 0.8 wt% was melted, the melt was cast to obtain glass, and the glass substrate was formed by processing into a plate having a thickness of 3 mm. Next, this glass substrate was immersed in AgNO ₃ molten salt at 240 ° C. to perform ion exchange between Na ⁺ near the surface of the glass substrate and Ag ⁺ in the molten salt.

Next, the glass substrate after the ion exchange is washed,
After drying, carbon was vacuum-deposited on the surface of the glass substrate to form a conductive film. Further, an electron beam was selectively irradiated with an accelerating voltage of 15 kV using an electron beam irradiation device to color the electron beam irradiated portion. Next, the carbon on the surface of the glass substrate was removed by dry etching using oxygen plasma.

The colored pattern obtained in this comparative example is
The transmittance of ultraviolet light in the non-colored portion was as low as 60% or less near the i-line (wavelength = 365 nm) as shown in FIG. 2 (b). The coefficient of thermal expansion is 78 x 1
It is 0 ^-7 / ° C, which is more than 10 times that of quartz glass, and when the pattern transfer was performed using the obtained colored pattern, the position where the width and relative position of the pattern changed were observed, and the requested pattern was obtained. Was not obtained.

[0027]

According to the method for forming a colored pattern of the present invention, a glass film containing silver ions is formed on a transparent substrate having a high transmittance of ultraviolet light and a low coefficient of thermal expansion, and the glass film is selectively colored. Since a negative pattern can be obtained by converting the pattern into a non-colored part, the ultraviolet light transmittance of the non-colored part is high and the exposure efficiency is good, and the pattern width and relative position do not change due to heat generated during pattern transfer. It is possible to produce a patterned pattern.

[Brief description of drawings]

FIG. 1 is a process drawing showing a method for forming a colored pattern of the present invention.

FIG. 2 shows the transmittance of the non-colored portion of the coloring pattern of the present invention and the transmittance of the non-colored portion of the conventional coloring pattern.

[Explanation of symbols]

 1 Transparent Substrate with Glass Film 2 Transparent Substrate 3 Glass Film 4 Molten Salt Containing Silver Ion 5 Electron Beam 6 Electron Beam Irradiated Part 7 Conductive Film

Claims (3)

[Claims] 1. A coating solution containing a hydrolyzed solution of silicon alkoxide, an alkali metal ion and a chlorine ion is applied on a transparent substrate having a high transmittance of ultraviolet light, and the coating solution is dried and fired to be vitrified. A step of producing a transparent substrate with a glass film, the glass film being brought into contact with silver ions to ion-exchange the alkali metal ions and silver ions in the glass film, and the glass film containing a silver ion And a step of selectively irradiating the glass film containing silver ions with an electron beam. 2. A glass film containing alkali metal ions is dipped in a molten salt containing silver ions,
The alkali metal ion in the glass film and the silver ion in the molten salt are ion-exchanged with each other.
A method for forming a colored pattern as described. 3. A photomask obtained by the method for forming a colored pattern according to claim 1.