JP2002124515A - Silicon dioxide conversion film and method of forming patterned silicon dioxide conversion film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a novel means for simply and quickly obtaining a more high-purity silicon dioxide film from a polysilazan coat. SOLUTION: The silicon dioxide converted film is prepared by exposing a polysilazan coat to short-wavelength UV rays having wavelength of 100-280 nm in the presence of oxygen molecules enough to photooxidize it. The method of patterning the converted film comprises a step for laying a pattern mask in the presence of air over the ordinal pressure on a surface of polysilazan applied to a base surface, exposing it to short-wavelength UV rays having wavelengths of 100-280 nm, and dissolving and removing unexposed portions by an developing solution.

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 silicon dioxide conversion film and a pattern-like silicon dioxide conversion film obtained by photooxidizing and decomposing polysilazane directly into a silicon dioxide film. This is expected to be effectively used in various fields as a high quality cured ceramic film.

[0002]

2. Description of the Related Art Silicon oxide-based ceramics films are used in various applications because of their excellent properties (heat resistance, corrosion resistance, abrasion resistance, transparency, electrical insulation, etc.). In particular, it is often used in the field of electronic devices (eg, semiconductor devices, liquid crystal display devices, printed circuit boards, etc.). Incidentally, the silicon oxide-based ceramics film is generally formed by using silicon dioxide or an organic silicon compound as a raw material and using a generally known thin film forming means (a physical method such as sputtering or a chemical method by CVD). However, in recent years, a method of forming a silicon dioxide film by chemically treating polysilazane as a raw material (in the presence of air, moisture, a catalyst, and heat) has been developed and has become a hot topic.
This is because the silicon dioxide film made of this polysilazane has higher adhesion to a substrate, higher film purity (hard and dense), and the like.

On the other hand, as a means for patterning the silicon dioxide film with the polysilazane, a method of imparting photosensitivity to the silazane, pattern masking, exposing to ultraviolet light, and then developing an unexposed portion ( (Hereinafter referred to as photoengraving method) (for example, JP-A-11-92666, JP-A-2000-2000)
A method of obtaining the polysilazane by the photoengraving method in an oxidizing atmosphere is known (for example, disclosed in JP-A-5-88373).

[0004]

DISCLOSURE OF THE INVENTION The present invention has been attained by finding a new special means as a result of intensive studies on means for directly converting polysilazane to silicon dioxide. It is the next means.

[0005]

According to the present invention, a polysilazane coating film is exposed to short-wavelength ultraviolet light having a wavelength of 100 to 280 nm in the presence of oxygen molecules. This is a silicon dioxide conversion film obtained by decomposition.

According to a second aspect of the present invention, as a more effective means, the short-wavelength ultraviolet light of the first aspect is used at 140 to 160 nm.
And a silicon dioxide conversion film having a peak wavelength of between 240 and 260 nm.

[0007] Further, the present invention provides a third aspect that it is effective to use a low-pressure mercury lamp as the short-wavelength ultraviolet light source in the second aspect.

The present invention also provides a method for forming a patterned silicon dioxide conversion film. That is, according to the present invention, a pattern mask is placed on the polysilazane surface coated on the substrate surface in the presence of air at normal pressure or higher,
After exposing to short wavelength ultraviolet light having a wavelength of 0 nm, the unexposed portion is dissolved and removed with a developing solvent.

According to a fourth aspect of the present invention, the polysilazane surface coated on the substrate surface is preliminarily exposed to short-wave ultraviolet light having a wavelength of 100 to 280 nm in the presence of air, and It is also provided that the coating film surface is dried and solidified by oxidative decomposition of the coating film.

[0010] Further, according to claims 6 and 7, the short-wavelength ultraviolet light has a wavelength of 140 to 160 nm and a wavelength of 240 to 2 nm.
It also provides that the maximum peak wavelength is 60 nm, and a low-pressure mercury lamp is preferable as a light source of this wavelength. Hereinafter, the present invention will be described in detail in the following embodiments.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The invention will be described from the first aspect. First, polysilazane (hereinafter, abbreviated as Psn), which is a starting material for forming the silicon dioxide film of the present invention, generally contains Si-N represented by the following chemical formula 1 as disclosed in many patent application publications. It is a silicon nitride polymer used as a repeating unit.

[0012]

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Here, R ₁ , R ₂ and R ₃ are a hydrogen atom, an organic group such as an alkyl group such as methyl and ethyl, and an aryl group such as phenyl. The appropriate molecular weight (eg, number average molecular weight) of the polymer is determined by the minimum strength required as a film (strength as a Psn coating film and a silicon dioxide film) and the solubility of Psn in an organic solvent. It is appropriately selected in the range of about 500 to 2500. And R ₁ ,
Particularly, when R ₂ and R ₃ are all hydrogen atoms, perhydropolysilazane (hereinafter abbreviated as H · Psn) is used, and when R ₂ and R ₃ are organic groups, organoperhydropolysilazane (hereinafter O · Ps) is used.
In the present invention, any of them is effectively oxidized and decomposed to change to a silicon dioxide film. Of course, Psn which is a mixture of both may be used. Psn is basically a linear polymer represented by the general formula, but may have a crosslinked structure in the molecule. However, this cross-linking is not desirable if the cross-linking density is too high to be insoluble in an organic solvent.

The Psn is placed in a coating state on a certain substrate surface before the photooxidative decomposition is performed. In forming the coating film, first, a predetermined amount of the Psn is dissolved in a generally known organic solvent (a substance containing moisture or easily absorbing moisture is avoided). Here, the solvent is, for example, an aromatic hydrocarbon such as xylene, or a linear or cyclic ether such as dibutyl ether or dioxane. The concentration of the Psn solution varies depending on the desired thickness of the silicon dioxide film, the accuracy of the coating, the coating means, and the like. However, according to the method of the present invention, even a thicker coating film is easily changed to a silicon dioxide film, and is not so affected by the coating film thickness. Further, the certain substrate is the coating film support, but its shape, transparency, etc. do not matter at all. However, a material which decomposes at least during exposure to the short-wavelength ultraviolet light of the present invention to reduce the strength must be avoided. The coating means is, for example, a method such as roll coating, gravure coating, spray coating, spin coating, dip coating, etc. Good. This is P
This is because sn itself is easily hydrolyzed by moisture.

After the Psn solution has been applied to the substrate, it is necessary to first dry (normal temperature or heating) to evaporate and remove the organic solvent. This operation is dried by exposure to the short-wavelength ultraviolet light, and the main exposure for oxidative decomposition may be continuously performed as it is, or a separate drying step is provided before the exposure, and dried and solidified in advance. Is also good. In addition, this drying step is generally performed by air drying (normal temperature or heating), but drying can be performed by, for example, exposure to the short-wavelength ultraviolet rays (simple preliminary exposure for drying and solidifying). This pre-exposure is a pre-operation for removing the adhesiveness of the coating film surface particularly when the molecular weight of Psn is small. Therefore, the exposure time in this pre-exposure is short (generally on the order of seconds), and there should be no substantial conversion of Psn to silicon dioxide.
Such a non-adhesive surface is effective, for example, when stacking and storing sheet-like substrates or when storing roll-like substrates by rolling them. It is.

Next, the Psn coating is exposed to short-wave ultraviolet light having a wavelength of 100 to 280 nm, especially in the presence of oxygen molecules. By this exposure, Psn is immediately photo-oxidized and decomposed into silicon dioxide to form a silicon dioxide film. Here, the presence of at least oxygen molecules (and thus may be air) is always essential during exposure. This oxygen molecule is used to form silicon dioxide, but it is considered that the oxygen molecule does not bond with the silicon atom as it is, but is once converted into an active oxygen atom and participates in the reaction. Thus, in an environment free of molecular oxygen, there is substantially no conversion to silicon dioxide.

The participation of the oxygen molecule in the reaction is preferably 100 to
It is performed only by exposing with short wavelength ultraviolet light having a wavelength of 280 nm. Therefore, regardless of the presence or absence of oxygen molecules, long-wavelength light exceeding 280 nm and 300 nm or more does not act to photooxidize and decompose into silicon dioxide. In addition, light having a wavelength shorter than 100 nm has a too high light energy, and does not smoothly convert to silicon dioxide to form a high-purity silicon dioxide film. Of course 2
This does not mean that ultraviolet rays having a wavelength longer than 80 nm must not be present at all. This is not to say that the presence of the wavelength has an adverse effect, but that it does not substantially contribute to the above-mentioned effects according to the present invention.

The reaction mechanism under the above two conditions is considered as follows. First, when the exposure starts, 100 to 28
At a wavelength of 0 nm, in particular, a wavelength energy of 100 to 200 nm excites oxygen molecules to change into an active oxygen atom atmosphere. On the other hand, particularly, wavelength energy of 200 to 280 nm
Is the Si—N bond, Si—H bond or Si—C of Psn.
Breaking the bond creates active (reactive) Si. It is presumed that active oxygen atoms are immediately chemically bonded to this active Si and converted to silicon dioxide.

More specifically, the wavelength of 100 to 200 nm has a peak wavelength of, for example, 140 to 160 nm, and the wavelength of 200 to 280 nm has a peak wavelength of 240 to 260 n.
m has a peak wavelength (Claim 2), and the light source is preferably a low-pressure mercury lamp (Claim 3).

The operational conditions under the above exposure conditions are as follows:
In general, exposure is performed for a predetermined time in the presence of (normal pressure) air. At this time, an environment in which the atmospheric concentration of oxygen molecules is reduced, for example, a vacuum state or the presence of an inert gas,
It is necessary not to perform in an environment such as in a closed container. Here, the exposure time depends on the thickness of the Psn coating film, but it is mainly determined by the exposure amount (mj / cm ² ) of the short-wavelength ultraviolet ray (output of the light source lamp and exposure distance). It is better to set it specifically by a preliminary test.

The silicon dioxide film formed as described above can be effectively used as a material for coating (protecting) various substrates and as a material for producing electronic parts due to its excellent properties. When used as a material for producing electronic parts, the silicon dioxide film is often used after being patterned into any shape. Therefore, in the present invention, a method of forming the silicon dioxide film when the silicon dioxide film is used in the form of a pattern is provided according to claims 4 to 7. Hereinafter, this pattern forming method will be described.

First, as described above, an organic solvent solution of Psn is applied to a substrate such as a metal substrate, a glass substrate, a plastic substrate, a semiconductor substrate (such as a silicon wafer), a liquid crystal substrate with a transparent conductive film, and a printed circuit board with a metal thin film. It is applied to the body surface with a predetermined thickness. The application method is as described above. However, when it is desired to apply with higher precision, the spin coating method is generally preferable.

When the coating is completed, drying is performed to evaporate and remove at least the organic solvent to form a solid coating. Drying (as described above) is generally performed by air drying at room temperature or by heating, but in the present invention, this drying can also be performed by the method provided in claim 5. In particular, when this drying and solidifying method is employed, the phenomenon is that the coating film has no tackiness,
It becomes a smooth surface. On such a coating film surface, the mask does not come into close contact with a pattern mask (for example, in the case of a mask using synthetic quartz glass as a substrate) placed on the coating film surface in the next step. Can be mounted with a slight clearance. This is effective for interposition of oxygen molecules required for oxidative decomposition of Psn. Of course, as described above, when the substrate to be used is a roll-shaped film, there is an effect that blocking does not occur even when rolled. When the pattern mask is a metal mask without a substrate (as will be described later), it may be better to have a certain degree of tackiness.
This is because, in the case of the mask, the mask adheres well because of the adhesiveness. This is because short-wavelength ultraviolet rays do not leak to the mask portion (the portion developed by the light-opaque portion), and the pattern reproduction accuracy is increased.

However, the condition described in claim 5 is merely drying and solidification. That is, this is achieved because the oxidative decomposition of Psn to silicon dioxide is minimal and not substantially converted. Specifically, it is determined whether or not the Psn coating film is dissolved in 3 to 10 seconds after immersion (normal temperature) in, for example, an aqueous solution of sodium hydroxide (for example, a dilute aqueous solution of 3 to 5% by weight). If dissolved, it is judged that it is simply proper drying and solidification without stickiness.

Next, a pattern was applied to the surface of the obtained Psn coating film.
Place the mask. Here, the mask is 100-
A desired pattern (eg, lattice, line, halftone dot) is formed by a material which is not substantially affected by 280 nm short-wave ultraviolet rays (such as being decomposed or absorbed by the ultraviolet rays). Therefore, the mask is composed of the ultraviolet light transmitting portion and the ultraviolet light non-transmitting portion. Specifically, a metal sheet is used as the material, and a halftone pattern is perforated in the metal sheet. A mask without a substrate generally called a metal mask or a synthetic quartz plate of about 1 mm or less is used. An example is a mask having a substrate on which a pattern is formed of chromium on one side. Here, in a mask without a substrate such as a metal mask, oxygen molecules are always present (the part transmitting the ultraviolet rays) even when the mask is mounted, but in a mask with a substrate such as the quartz plate mask, oxygen molecules are always present. In the mounted state, an exposure environment in which oxygen molecules are blocked easily occurs. Therefore, when such a mask is used, it is better to use a mask that is as light as possible and take measures such as that the Psn coating surface is not tacky as described above.

When the pattern mask is mounted, exposure is performed. At this time, the environment is in the presence of air at normal pressure or higher. This is because it is more preferable that the air at normal pressure or higher has more oxygen molecules. Therefore, even under a vacuum in which the concentration of oxygen molecules is low, or even if the pressure is higher than normal pressure, the oxygen concentration is low (for example, nitrogen gas is mixed).
Such an environment must be avoided. Even if you pressurize,
A pressure corresponding to maintaining the concentration required for the oxidation reaction at least within the exposure time is sufficient. Too much is not preferred (especially for those patterns with a substrate such as the glass mask pattern). Generally, it is performed at normal pressure. The ambient temperature at this time is generally room temperature, but may be under heating. However, the temperature also affects the temperature of the light source itself, which will be described later. If the temperature is too high, the output of the light source is reduced. It is better not to exceed 40 ° C.

Exposure is performed by short-wave ultraviolet light having a wavelength of 100 to 280 nm, preferably 140 to 160 nm, from above the pattern mask placed on the Psn coating surface under the above conditions.
The irradiation is performed by irradiating the ultraviolet light having the maximum peak wavelength in the range of 240 to 260 nm. The reason is as described above. Specifically, a light source that effectively generates the light beam is a low-pressure mercury lamp (a sealed mercury vapor pressure is low).
High-pressure mercury lamps mainly having a long wavelength of 0 nm or more are out of scope.

The conversion time to the silicon dioxide film is determined by the exposure time (proportional) and the exposure distance (inversely proportional to the square) if the light source output and the Psn coating thickness are constant. Specifically, a preliminary test is performed to determine this. For example, in the test, an output of 1 W was applied to a Psn coating thickness of 60 nm.
/ Cm low-pressure mercury lamp with an exposure surface distance of 100 mm
After irradiation for 2 seconds, it was almost completely converted to silicon dioxide. It is better to avoid exposure for a longer time than necessary as much as possible, in order to convert the silicon dioxide to silicon dioxide more completely. This is different from the general exposure under vacuum (for perfect adhesion of the pattern mask and exclusion of oxygen).
This is because the pattern mask is not completely adhered, so that light is likely to leak to the non-exposed portion. still,
In order to prevent this light leakage, it is preferable to use a linear beam as much as possible. For this purpose, for example, it is possible to improve the situation by arranging a honeycomb-shaped transmission plate between the placed pattern mask and the light source. .

Next, when the exposure is completed, the unexposed portions are dissolved and removed with a developing solvent (development processing). Here, examples of the solvent include an aqueous solution of an inorganic alkali such as sodium hydroxide or potassium hydroxide (generally, a dilute solution of 3 to 5% by weight), toluene, xylene, dibutyl ether, dioxane, or an organic solvent of a mixture thereof. . In this developing treatment, the unexposed portion is dissolved and removed by contacting the developing solvent at a temperature of generally about 20 to 50 ° C. The contacting is performed simply by contacting with the solvent, spraying, brushing, or the like, and an efficient method may be appropriately selected. After development, the surface is appropriately washed and dried. As described above, the desired silicon dioxide pattern is firmly formed on the substrate. If the initial purpose can be achieved only by this formation, the entire process is completed. If it is to be manufactured, an etching step is required. Needless to say, in this case, a substrate in which a conductor is laminated on an insulating substrate is used.

[0030]

The present invention will be described in more detail with reference to the following examples together with comparative examples. Example 1 First, an H · Psn solution (molecular weight: 700, organic solvent: xylene, solid content: 5% by weight) was added to 100
It was applied to a mm-square PET film (pre-treated by corona discharge after degreasing and washing) under the following conditions and dried. That is, the PET film is fixed on a rotating table of a spin coater, and the H.Psn solution is dropped almost over the entire surface to start rotation. The rotation gradually increased in speed, and when it reached 1500 rpm, the rotation was continued at that speed for 20 seconds. After finishing the rotation, it was dried at about 110 ° C. for 10 minutes. Although the surface was slightly tacky, the solvent was removed and the H.Psn coating was firmly formed.

Next, H. on the PET film obtained above was used.
The entire surface of the Psn coating film was exposed under the following conditions. A low-pressure mercury lamp having an output of 1 W / cm (having a maximum wavelength at 185 nm and 254 nm) is used as a light source.
The coating film was set at a distance of 0 mm (distance between exposed surfaces). Then, the entire surface was exposed under air at normal temperature and normal pressure for 70 seconds. The surface of the obtained coating film was glassy and hard, and the film thickness was 60 nm.

Then, the PET film obtained by the exposure was cut in half, and the following test was performed.
Conversion of the n film to a silicon dioxide film was confirmed. In one test, one PET film was immersed in a 5% by weight aqueous sodium hydroxide solution at room temperature for 5 minutes, washed with water, and dried. Observing the surface condition with a magnifying microscope,
No dissolution or erosion was observed at all, and the film thickness was measured, but it was the same as the initial value of 60 nm. As another test, the remaining PET film was IR
Infrared spectrum analysis was performed using an analyzer. From the obtained infrared spectrum chart, the absorption wavelength derived from H · Psn (N−H at 3400 cm −1, 2200 cm −1)
Of Si—H, 830 cm −1 of Si—N) and the absorption wavelength derived from silicon dioxide conversion (1080 cm −1 of Si—N).
0) was checked. As a result, all of the absorption wavelengths derived from H · Psn disappear, and 1080 cm −1 of Si-0
Was observed only. As is clear from the above test, the present invention is very easy to operate in a short time,
It can be seen that a high-purity silicon dioxide film can be obtained.

Example 2 First, an O.Psn solution (molecular weight: 900, having a methyl group at the terminal), an organic solvent: dibutyl ether, solid content: 4% by weight) was used, and
As in Example 1, spin coating was performed on two pieces of PET film (square mm) (after degreasing and washing and pretreatment of corona discharge), followed by drying. Although the surface was slightly tacky, the solvent was removed and the O.Psn coating film was firmly formed.

Next, preliminary exposure was carried out under the following conditions in order to obtain the tackiness of the O.Psn coating on the PET film obtained above. That is, under the exposure conditions used in Example 1, the exposure time was set to 8 seconds. The tackiness of the obtained O.Psn coating surface disappeared and became slippery. O here
-The Psn coating thickness was 62 nm. A part of the film was cut and immersed in a 5% by weight aqueous sodium hydroxide solution at room temperature for 7 seconds. As a result, since the coating film surface was completely dissolved and removed, it was also confirmed that this preliminary exposure was a preliminary treatment for properly removing tackiness.

Then, using one of the films, main exposure was performed under the following conditions. That is, the entire surface was exposed under the same conditions except that the exposure time in Example 1 was set to 60 seconds. The obtained coating film surface was glassy and hard. And also about 5% by weight similarly to Example 1.
A immersion test in an aqueous sodium hydroxide solution and identification analysis with an IR analyzer were performed. In the immersion test, no erosion or the like was observed in the same manner as in Example 1. Further, in the IR spectrum, only absorption at 1080 cm −1 based on silicon dioxide was observed, and no other absorption was observed.

(Comparative Example 1) In Example 1, the same conditions as in Example 1 were used except that N ₂ gas was continuously flowed between the light source and the H · Psn coated PET film, and the exposure was performed for 5 minutes. Exposure was performed from the coating film formation. The obtained product is added to a 5% by weight aqueous solution of sodium hydroxide at room temperature for 4 hours.
It was immersed for 0 second and pulled up. One part of the coating was dissolved and 1
The part was peeled off in the state of a film, and easily collapsed when a fingertip touched the film. In other words, this means that oxidative decomposition to silicon dioxide was not performed because oxygen molecules were not substantially present.

Comparative Example 2 The remaining Psn coated PET film obtained by predrying in Example 2 was used and exposed under the following conditions. That is, in the main exposure performed in Example 2, exposure was performed under the same conditions except that the light source was changed to a high-pressure mercury lamp (output: 1 W / cm) and the exposure time was set to 3 minutes. Although the obtained coating film surface was in a hardened state,
The same two tests were performed as in Example 2 to determine if conversion to silicon dioxide had occurred.
Here, the film thickness was 63 nm.

First, in one immersion test using a 5% by weight aqueous solution of sodium hydroxide, the surface was eroded, and surface roughness was observed. The film thickness was measured to be 36 nm. In another IR spectrum analysis, Si-0
However, it was observed that the absorption of Si—N was largely present. The above results are 300 ~
A light source having a dominant wavelength at 400 nm proves that no substantial conversion of Psn to silicon dioxide occurs even in the presence of oxygen molecules.

Example 3 First, a glass plate with an ITO conductive film was prepared by sputtering ITO (indium tin oxide) on two 100 mm square glass plates, and this was used as a substrate.

Then, the same H.Psn solution (molecular weight: 700, organic solvent: xylene, solid content: 5% by weight) as in Example 1 was spin-coated on the glass substrate under the same conditions and applied. After drying, an H.Psn coating film was formed on the ITO conductive film surface.

Next, the surface of the obtained H.Psn coating film was slightly tacky as in Example 1. In order to obtain this tackiness, a preliminary treatment for 8 seconds was performed under the same conditions as in Example 1. Exposure was performed. The tack was completely removed and turned into a smooth surface. Hereinafter, this is referred to as a pre-dried glass plate.

Next, using the pre-dried glass plate, a patterned silicon dioxide conversion film was formed under the following conditions. As a pattern mask, a 20 μm-thick stainless steel foil with 50 μm diameter pores perforated at an equal pitch of 90 μm was placed on the H.Psn coating surface of the pre-dried glass plate,
This was placed 80 mm below the light source used in Example 1.
Then, a honeycomb-shaped transmission plate (thickness: 15 mm) was placed horizontally at a position 10 mm above the H · Psn coating film surface, and the light source was turned on under normal temperature and normal pressure air. The exposure time was 70 seconds. Then, the mask is removed, and 5% by weight of room temperature
Was sprayed for 3 minutes to complete the development.

When the developed surface was observed with a magnifying microscope, it was first confirmed that the circular pattern of the mask was firmly formed of a silicon dioxide film. And when the diameter was measured, it was 55 micrometers. It can be seen that the diameter of the circular pattern is slightly larger, but is reproduced almost one-to-one. After this development, if the non-circular portion (the portion undissolved and removed by exposure to light—the underlying ITO film portion) is further etched (for example, an aqueous solution of ferric chloride), the underlying I
The TO film is formed on the glass plate in a non-circular pattern.

[0044]

The present invention has the following effects by being configured as described above.

A higher purity silicon dioxide film can be easily, rapidly, and rapidly produced from a Psn coating film.

As described above, the production control becomes easy, and the manufacturing time is greatly reduced.

Continued on the front page F-term (reference) 2H025 AA10 AA13 AA14 AA20 AB15 AB16 AB20 AC01 AD01 BD48 BF30 BJ10 FA05 FA15 2H096 AA25 AA26 BA20 DA02 EA02 GA01 LA30 4G072 AA25 BB09 GG01 GG03 HH28 JJ03 NN30B01 BB30B01

Claims (7)

[Claims] A polysilazane coating film is formed in the presence of oxygen molecules.
A silicon dioxide conversion film formed by exposure to short wavelength ultraviolet light having a wavelength of 100 to 280 nm and photo-oxidative decomposition. 2. The method according to claim 1, wherein the short-wavelength ultraviolet light is 140
A silicon dioxide conversion film having a maximum peak wavelength between about 160 nm and 240 to 260 nm. 3. The silicon dioxide conversion film according to claim 2, wherein said short wavelength ultraviolet light is a low pressure mercury lamp. 4. A pattern mask is placed on the polysilazane surface coated on the substrate surface in the presence of air at normal pressure or higher, and exposed to short-wave ultraviolet light having a wavelength of 100 to 280 nm. Forming a patterned silicon dioxide conversion film by dissolving and removing unexposed portions with a developing solvent. 5. The polysilazane surface coated on the substrate surface is preliminarily exposed to short-wavelength ultraviolet light having a wavelength of 100 to 280 nm, and dried and solidified by a slight oxidative decomposition. 5. The method for forming a patterned silicon dioxide conversion film according to item 1. 6. The method according to claim 1, wherein the short-wavelength ultraviolet light is 140 to 160 nm.
5. The method for forming a patterned silicon dioxide conversion film according to claim 4, which has a maximum peak wavelength in the range of 240 to 260 nm. 7. The method for forming a patterned silicon dioxide conversion film according to claim 6, wherein said short wavelength ultraviolet light source is a low pressure mercury lamp.