JPH11170428A - Gas adsorption inhibiting base material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the adsorption of gas molecules, and allow gas molecules adsorbed to be removed easily by forming a gas adsorption inhibiting film made by converting polysilazane or a polysilazane-containing composition into ceramics, having as main component silicon dioxide on at least the gas adsorption inhibiting surface of a base material. SOLUTION: A solution formed by dissolving polysilazane or a polysilazane- containing composition with a solvent is applied on at least the gas adsorption inhibiting surface of a base material consisting of metal such as stainless steel, plastics, and the like. Then, the solvent is converted into ceramics by hydrolysis, oxidation decomposition, thermal decomposition, and so on by heat hardening, ordinary temperature hardening, moisture heat hardening, and the like in order to form a gas adsorption inhibitory film consisting mainly of silicon dioxide and containing nitrogen. Thus, a gas adsorption inhibiting film can be obtained easily effectively, can prevent the adsorption of gas molecules and allow gas molecules to leave easily even when gas molecules adsorb thereto.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is used to suppress the adsorption of gas, and in particular, to various vacuum structures such as vacuum insulation tubes and vacuum vessels, and various gas supply systems such as pipes, valves and joints. The present invention relates to a gas adsorption suppressing base material suitable for use in piping equipment.

[0002]

2. Description of the Related Art Generally, in metals such as stainless steel, gas molecules are adsorbed on a metal surface, then the gas molecules are dissociated into atoms, and the atoms move and dissolve (absorb) into the metal (in particular, H). Dissolution of ₂ is remarkable.). In the process of desorption of gas molecules, after the desorption of the physisorbed gas molecules on the metal surface, contrary to the above process, the atoms dissolved in the metal are adsorbed to each other and to the metal surface Or recombine with an atom to form C _m H _n , H ₂ , CO,
It is released as desorbed gas such as N ₂ and H ₂ O. Gas molecules are adsorbed on the metal surface because of the presence of the physical adsorption layer on the gas molecules with high bonding force accompanied by electronic bonding or the chemical adsorption layer between atoms and metal surface atoms. Separation is difficult.

[0003] In the case of a metal base material such as stainless steel used for a vacuum system, in order to improve the pumping speed, the ultimate vacuum degree and / or maintain the vacuum degree in a sealed vacuum system, It is necessary to remove the gas molecules adsorbed on the surface of the metal substrate by subjecting the metal substrate to high-temperature, long-time vacuum degassing under heating. For example, in a vacuum chamber of an analyzer that requires a high vacuum atmosphere, a piping member and a vacuum vessel of an evacuation system, a vacuum insulated thermos that needs to maintain a degree of vacuum for a long time, an analyzer, or a manufacturing apparatus. Heat vacuum degassing is performed before startup and during the manufacturing process, the required time is long, and a large amount of energy due to high-temperature heating is required, which is not efficient.

In a stainless steel base material used for a gas supply system member for a semiconductor manufacturing apparatus, as a general method for maintaining the purity of a supply gas, a gas contact surface is mechanically polished, electrolytic polished, or electrolytically polished. Smoothing is performed by polishing and chemical polishing, and a passivation treatment is performed for stabilization. The base material itself is made of a vacuum double or triple dissolution material from which impurities are eliminated as much as possible. When the equipment is started, baking is performed by vacuum degassing under heating or an inert gas flow to remove gas molecules adsorbed on the surface of the base material, preventing the intrusion of impurity gases into the process to the utmost. doing.

[0005] As another method for reducing the gas release rate of stainless steel materials, vacuum furnace baking is used. However, since this processing method requires heating at a high temperature of about 1050 ° C., a large energy cost is required particularly when processing a large vacuum vessel or the like. Further, since heating is performed at a high temperature of 1050 ° C., there is a problem that a metal seal portion such as a flange or a joint hardened by burnishing or the like is softened.

Therefore, conventionally, as described in, for example, Japanese Patent Application Laid-Open No. 4-157149, after vacuum-cleaning a stainless steel vacuum device, pure oxygen is introduced at a predetermined temperature to obtain a dense surface. Oxide film
Methods have been proposed to reduce the release of hydrogen. Further, as described in JP-A-4-183846,
The electrolytically polished stainless steel is heated in an inert gas having an oxygen partial pressure of 4 Pa or less, or in a vacuum, at a temperature of 900 ° C. to 1200 ° C.
A method has been proposed in which an oxide film having a predetermined thickness and a Cr content is formed by performing a heat treatment at a temperature of not more than ℃ to reduce the amount of water released from the surface. In addition, 3-2
As described in JP-A-8515, the surface of a strength-imparting metal vacuum component made of an Al alloy or the like is coated by thermal spraying, hot-dip plating, or the like to form a surface of a high-purity Al layer, and a dense surface is formed on the surface. A method has been proposed in which an oxide film is formed to prevent adsorption of a substance having a reduced degree of vacuum and to suppress formation of a hydrated oxide film.

[0007]

However, among the above conventional examples, the methods described in JP-A-4-157149 and JP-A-4-183846 are all stable and thin on the surface of the base material. By forming a dense oxide film, it is intended to prevent adsorption and chemical bonding of gas molecules in the atmosphere, but an extremely clean and smooth surface is required as a surface state before forming an oxide film. ,
In addition, precise control of the atmosphere during the formation of the oxide film is required, and the processing temperature is often quite high. This complicates the production process, lowers productivity and results in higher costs. In addition, the method described in Japanese Patent Publication No. 3-28515 discloses a method in which a dense oxide film layer can be formed on the surface of a high-purity Al layer even before the high-purity Al layer is formed. An extremely clean and smooth surface is required as the surface state. Also, formation of a high-purity Al layer,
The formation of the oxide film and the manufacturing process are complicated, the productivity is poor, and the cost is not satisfactory.

According to the present invention and the like, as a result of various studies, it has been found that a covalent bond substance such as silicon dioxide does not dissociate gas molecules into atoms, and gas molecules (atoms) are compared with metal materials.
Is less dissolved, that is, the adsorption of gas molecules is physical adsorption mainly without electron binding, so that the adsorbed gas molecules are easily desorbed, and the desorbed gas components are extremely low. Thus, it was found that the gas adsorption suppressing effect can be exhibited.

[0009] In general, polymer materials are structurally
Since very small pores are present, water molecules and the like enter the small pores, and their desorption is difficult. Also, even once desorbed, by being exposed to the atmosphere,
Again, water molecules and the like are adsorbed and penetrate into the pores. Therefore, polymer materials do not have very desirable characteristics for use in vacuum systems and high-purity gas supply systems. However, by coating the surface of the polymer material with a covalent bonding substance such as the above-mentioned silicon dioxide, it is possible to prevent desorption of water molecules and the like from the pores and to prevent gas adsorption when exposed to the atmosphere. Can be controlled, and
Although it varies depending on the type of the polymer material, it has been found that hydrogen bonding to a functional group such as an alkyl group or Coulomb force bonding can be prevented.

[0010] The present inventors have found that among the above-mentioned covalent bonding substances,
Attention was paid to silicon dioxide, which has excellent mechanical strength and electrical insulation. Conventionally, as a method for coating the silicon dioxide on a substrate such as a metal, there are a vapor phase growth method such as a CVD method and a sputtering method, and a sol-gel method. However, in the vapor phase growth method, not only is it difficult to coat a substrate having a complicated shape, but also because the coating layer is extremely thin, fine irregularities on the substrate cannot be flattened. It can not be said that it can be produced at low cost. Further, it is difficult to form a strong glass coating by the sol-gel method, and the resulting coating has low density.

Therefore, the present inventors applied ceramics by applying polysilazane or a polysilazane-containing composition to various substrates made of various metals such as stainless steel, aluminum and carbon steel, and various plastics. The main component is silicon dioxide, which can prevent gas molecules from being adsorbed, and can easily and inexpensively form a gas adsorption suppression film capable of easily desorbing the adsorbed gas molecules, It has been found that the number of post-processing steps such as vacuum degassing and baking can be reduced, and the present invention is based on this finding.

[0012]

According to the present invention, there is provided a gas adsorption suppressing substrate according to the present invention, wherein at least a gas adsorption suppressing surface of a substrate is formed by converting a polysilazane or a polysilazane-containing composition into a ceramic, The main component is a gas adsorption suppressing film formed.

In the above structure, it is preferable that the nitrogen content in the gas adsorption suppressing film is selected in the range of 0.005% to 5% in atomic percentage, and the thickness of the gas adsorption suppressing film is 0.05 μm. Preferably, it is selected in the range of 10 to 10 μm.

Further, the base material is selected from metal or plastic, and can be used for a vacuum structure or a high-purity gas supply system piping device.

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the gas adsorption suppressing substrate of the present invention will be described. At least a gas adsorption suppressing surface of a substrate made of metal such as stainless steel, plastic, etc. In some cases, one or both surfaces thereof, and when the base material is a tubular material, one or both of the inner peripheral surface and the outer peripheral surface thereof)
Alternatively, a solution obtained by dissolving a polysilazane-containing composition in a solvent is applied, and the solution is subjected to hydrolysis (reaction with OH), oxidative decomposition (reaction with O ₂ ), thermal decomposition by heat curing, room temperature curing, or heat curing in moisture. It is decomposed into ceramics by decomposition or the like to form a gas adsorption suppressing film containing silicon dioxide (SiO ₂ ) as a main component and containing nitrogen (N).

The above-mentioned substrate for suppressing gas adsorption can be applied to various shapes and structures such as a plate material and a tube material. Specifically, a vacuum heat insulating pipe, a vacuum heat insulating tank, a vacuum heat insulating chamber, a vacuum heat insulating container, It can be applied to vacuum structures such as vacuum insulated thermos, analytical vacuum chamber, vacuum piping member, etc.It can also be applied to high-purity gas supply piping equipment such as gas piping, various valves and fittings. .

The polysilazane is represented by the following general formula:

[0018]

Embedded image

(In the above formula, R ¹ , R ² , and R ³ each independently represent a hydrogen atom, an alkyl group, an alkenyl group, a cycloalkyl group, an aryl group, or a group other than these groups directly bonded to silicon. Is a carbon atom, an alkylsilyl group, an alkylamino group or an alkoxy group, provided that at least one of R ¹ , R ² and R ³ is a hydrogen atom.) Polysilazane having a number average molecular weight of 100 to 50,000 can be used.

Alternatively, a modified polysilazane obtained by reacting a polysilazane of the above general formula with a boron compound, a modified polysilazane containing a metal such as nickel, titanium, platinum, iron, or aluminum in the polysilazane of the above general formula; Al ₂ O ₃ , Si
A polysilazane composition containing an inorganic filler such as O ₂ , ZrO ₂ , and MgO can be used. In short, as the polysilazane or the polysilazane-containing composition of the present invention, it is possible to use various kinds of materials that can be formed into a ceramic to form a gas adsorption suppressing film containing silicon dioxide as a main component by being applied to a substrate. it can.

Xylene, benzene, toluene, alkane, n-heptane, decane, ketone, ester, glycol ether and the like can be used as a solvent capable of forming a solution by dissolving polysilazane or a polysilazane-containing composition. These can be selected appropriately according to the polysilazane or the polysilazane-containing composition. These solvents can be appropriately selected depending on the polysilazane used, or the average molecular weight of the polysilazane-containing composition, the molecular weight distribution, and the structure so that the workability of application to the base material is improved. 1 in concentration
It can be mixed in the range of -50% by weight, preferably in the range of 5-30% by weight.

As a method for applying the above solution to a substrate,
There are a spin coating method, a dip coating method, a spray coating method, a flow coating method and the like. Which of these coating methods is to be adopted is selected in consideration of the shape of the base material, control of the film thickness, liquid concentration, and the like. Compared with the above-mentioned various film forming methods, large equipment is not required, it is easy to apply to a substrate having a simple and complicated shape, and the surface is easily flattened.

In the method of forming a gas adsorption suppressing film by heat curing, a solution in which a polysilazane or a polysilazane-containing composition is dissolved in a solvent such as xylene is heated to disperse the solvent, thereby taking in oxygen in the air. To form a gas adsorption suppressing film, and when heated to 400 ° C. or more, it is completely ceramicized. The method of forming the gas adsorption suppressing film by curing at room temperature involves curing by taking in oxygen in the air or oxygen from the moisture in the air in addition to volatilization of the solvent at room temperature, which is quite difficult for ceramics formation. Although it takes a long time, a gas adsorption suppressing film having a pencil hardness of 9H or more can be formed. The method for forming the gas adsorption suppressing film by heat curing in moisture is to accelerate the curing by applying moisture at about 100 ° C., and it is preferable that the humidity sufficient for the curing is about 80%.

The above-mentioned gas adsorption suppressing film necessarily contains nitrogen by using polysilazane, but it is difficult to make nitrogen less than 0.005% in atomic percentage, while nitrogen is in atomic percentage. If it exceeds 5%, silicon dioxide becomes insufficient, and the desired hardness and the like cannot be obtained. Therefore, nitrogen is added in an atomic percentage of 0.005% to 5%.
%, Preferably in the range of 0.005% to 3%. This can be obtained by appropriately adjusting the amount of the solvent used.

When the thickness of the gas adsorption suppressing film is less than 0.05 μm when it does not contain an inorganic filler, it is difficult to completely cover the surface of the substrate having fine irregularities with a substantially uniform thickness. The effect of suppressing gas adsorption may not be expected, and if it exceeds 5 μm, cracks may occur when ceramics is formed, and peeling may occur, so the range of 0.05 μm to 5 μm More preferably, it is selected in the range of 0.1 μm to 2 μm. When the inorganic filler is contained, if the particle size of the inorganic filler is smaller than 0.1 μm, the inorganic filler is easily aggregated in the solution, is difficult to be uniformly dispersed, and is required to obtain a dense film without voids. It is preferable to use an inorganic filler having a particle size of about 1 μm, and therefore a film thickness of 0.1 μm or more is preferable. Also, by containing an inorganic filler, volume shrinkage during film formation is eased and cracks are less likely to occur, so that a thick film up to about 10 μm can be obtained.
However, if the film thickness exceeds 10 μm, pores are likely to be generated,
It is difficult to obtain a uniform film. Therefore, a film thickness of 10 μm or less is preferable. As described above, the thickness of the gas adsorption suppression film is selected to be a desired thickness in the range of 0.05 μm to 10 μm including both the case where the inorganic filler is not contained and the case where the inorganic filler is contained. Is preferred. The thickness of the gas adsorption suppressing film can be arbitrarily set by adjusting the solid concentration of the polysilazane solution.

According to the gas adsorption suppressing substrate having the above structure,
Since the gas adsorption suppressing film containing silicon dioxide as a main component hardens by taking in oxygen as described above, there are no air bubbles at the interface between the base material and the gas adsorption suppressing film, and the gas adsorption suppressing film is not cured when the film is cured. Gas molecules (H ₂
O, O ₂ ) is taken into the film, so that the substrate surface and its interface after the formation of the gas adsorption suppressing film are extremely clean,
The desorbed gas molecules do not pass through the gas adsorption suppressing film and are released from the substrate surface and the interface. Further, since the gas adsorption suppressing film is stable and dense and has a low gas molecule adsorption energy, the gas molecule adsorption can be prevented efficiently, and the adsorbed gas molecules can be easily desorbed. it can. Therefore, when the baking process is performed in the same time as the conventional case, the temperature may be low, and when the baking process is performed in the same high temperature as the conventional case, the time may be short, and the baking process or the vacuum degassing process may be reduced. Can be achieved. The gas adsorption suppressing film can be easily and inexpensively obtained by a coating method.

As an example of the gas adsorption suppressing vacuum structure using the gas adsorption suppressing base material of the present invention applied to a vacuum heat insulating pipe, for example, an inner pipe, an outer pipe, and an annular pipe made of stainless steel will be described. An end plate is used, the inner tube is inserted into the outer tube, both ends of the outer tube and the inner tube are sealed with the annular end plates, and a vacuum heat insulating layer is provided between the outer tube and the inner tube. In such a vacuum insulated pipe, the above-mentioned gas adsorption suppressing base material is used as an inner pipe, an outer pipe, and an annular end plate. That is, a gas adsorption suppression film is formed on at least the outer peripheral surface of the inner tube, which is a gas adsorption suppression surface, the outer peripheral surface, which is at least the gas adsorption suppression surface of the outer tube, and the inner surface of the annular end plate, which is at least the gas adsorption suppression surface. Is formed.

Such a vacuum insulated tube is manufactured by forming a gas adsorption suppressing film on the outer peripheral surface of the inner tube, the inner peripheral surface of the outer tube, and the inner surfaces of the annular end plates at both ends. Even when the outer peripheral surface of the inner tube, the inner peripheral surface of the outer tube, and the inner surface of the annular end plate sometimes come into contact with the atmosphere, the adsorption of gas molecules is small. In addition, when the vacuum heat insulating layer is formed by evacuation, even if the gas molecules are adsorbed on the outer peripheral surface of the inner tube, the inner peripheral surface of the outer tube, and the inner surface of the annular end plate, a small amount of the gas molecules is reduced to 100%. It is easily desorbed by baking at about ℃ or heating vacuum degassing, so a heat insulating layer with a high degree of vacuum is formed without baking or heating vacuum degassing requiring a lot of energy and a long time. The degree of vacuum can be maintained for a long time even after the layer is sealed, and a vacuum heat insulating tube having a high vacuum heat insulating effect and a stable heat insulating effect for a long time can be manufactured efficiently and at low cost.

In particular, in the case of a vacuum insulated pipe made of carbon steel or the like, when the fluid flowing inside the inner pipe is high-temperature steam, hydrogen gas penetrates the inner pipe and penetrates into the vacuum layer, and the degree of vacuum increases. However, by coating the inner peripheral surface of the inner tube with a gas adsorption suppressing film, it is possible to prevent hydrogen gas molecules from entering the vacuum layer. Therefore, a decrease in the degree of vacuum of the vacuum layer can be prevented, and the heat insulating effect of the vacuum heat insulating layer is not hindered.

In a piping device for a high-purity gas supply system for semiconductor production or the like using the above-mentioned substrate for suppressing gas adsorption of the present invention, for example, a gas adsorption suppressing film is formed on the gas contact surface of a substrate made of stainless steel. By doing so, adsorption of gas molecules of ultra-high purity gas flowing on the gas contact surface of the piping equipment is prevented, and even if the gas molecules are adsorbed, they are easily desorbed and the gas contact surface is always in a clean state. . Therefore, it is possible to improve the contact resistance of the gas supply system piping base material through which the corrosive gas flows, and to adsorb on the gas contact surface of the gas supply system piping equipment when starting up a semiconductor manufacturing apparatus or the like. 8 gas molecules
By baking at a low temperature around 0 ° C,
Conventionally, it has been restricted by the thermal properties of the sheet and the packing by applying a polymer material such as PCTFE or fluorine-based rubber to the sheet or the packing because the valve can be easily removed. 100
Baking treatment of a metal material such as stainless steel can be easily performed in a short time even at a temperature of about ° C. This allows
Since the purity of gas to be supplied to semiconductor manufacturing equipment can be stably supplied to a predetermined purity in a short time, the start-up time can be greatly reduced, and the equipment can be manufactured at low cost. Can be. Further, in the high-purity gas supply system, the quality of the supplied high-purity gas can be ensured, and the reliability of the high-purity gas supply system for semiconductor production or the like can be improved.

[0031]

Next, specific examples of the substrate for suppressing gas adsorption according to the present invention will be described. (Example 1) 150 mm in length provided with flanges at both ends,
Stainless steel pipe with inner diameter of 10.77 mm and outer diameter of 12.7 mm (Sumikin stainless steel pipe: SUS316L TP-
SCBA), and one flange was connected to a flange of a closing plate with a drain port and a valve. And first,
The above-mentioned flanged pipe was set vertically so that the valve side was located on the lower side. Next, a 10% xylene solution of perhydropolysilazane (having hydrogen atoms at R ¹ , R ² and R ³ in the general formula of Chemical Formula ¹ ) (product name: HERVIC standard type, manufactured by NE Chemcat) was flanged. The pipe was filled by pouring from its upper opening. Next, open the valve and open the drain port
The solution was discharged at a speed of 0 cm / min. After discharging, the obstruction plate and the like were removed from the flanged pipe, and the flanged pipe was dried in a drying furnace at 80 ° C. for 10 minutes. Subsequently, after performing a heat curing treatment at 400 ° C. for 3 hours in a heating furnace, the mixture was naturally cooled in the air to form a gas adsorption suppressing film on the inner peripheral surface of the pipe with the flange.

Example 2 1 of perhydropolysilazane
A gas adsorption suppressing film was formed on the inner peripheral surface of the flanged pipe in the same manner as in Example 1 except that a 5% xylene solution was used.

Example 3 2 of perhydropolysilazane
A gas adsorption suppressing film was formed on the inner peripheral surface of the flanged pipe in the same manner as in Example 1 except that a 0% xylene solution was used.

When the gas adsorption suppressing films of Examples 1 to 3 were observed with a scanning electron microscope (SEM), it was confirmed that the gas adsorption suppressing films were formed in a good condition without cracks or the like. Was. In addition, the composition distribution on the surface of the gas adsorption suppressing film is determined by an energy dispersive X-ray analyzer (EDX).
As a result, it was confirmed that the obtained gas adsorption suppression film was a uniformly uniform nitrogen-containing silicon dioxide film, and its purity was 99.5% as an average value of the analyzed area. When the thickness of the coating film was roughly measured from the SEM image of the cross section of the sample, the average film thickness was 0.3 μm in Example 1.
m, 0.8 μm in Example 2, and 1.5 μm in Example 3.
Met. In addition, the density of any of the gas adsorption suppressing films in Examples 1 to 3 was about 2.2 (g / cm ³ ), lower than 2.4 (g / cm ³ ) of quartz glass, and 1.0 (g / cm ³ ) of alkali glass. 9 (g / cm ³ ), and the compactness is
The etching rate (nm / min) is about 80, and the commercial sol-gel coating (fired at 450 ° C.) is 35.
0, which is extremely higher than that of the thermally oxidized silicon dioxide film, and has a surface hardness of 9H or more in pencil hardness.

Emission gas velocity of the samples of Examples 1, 2 and 3 under vacuum (the sum of the velocity of the desorption gas from the substrate surface and the velocity of the emission gas from inside the substrate is referred to as the emission gas velocity Evaluation). In this evaluation, comparison was made with a comparative sample having no gas adsorption suppressing film.

(Evaluation 1) First, in order to keep the state of all the samples as same as possible, each sample was conditioned at a humidity of 30% and a temperature of 2%.
Stored in a dry box adjusted to 5 ° C for 24 hours,
Gas molecules were sufficiently adsorbed and absorbed on the surface of each sample. Thereafter, each sample was taken out of the dry box, a vacuum pump was connected to one end of each sample via a valve, and an absolute pressure gauge was connected to the other end to make a sealed state. Was. That is, while opening the valve and driving the vacuum pump to evacuate each sample, 5
The sample was heated to 350 ° C. at a rate of temperature rise of 350 ° C./min, and subjected to a heating vacuum degassing process at 350 ° C. for 1 hour. Thereafter, the cooling time was set to 2 hours from the start of cooling, and the system was cooled to 25 ° C. After cooling, the valves were closed to make each sample side a closed system, and the pressure change in the system was measured in a time series with an absolute pressure gauge. FIG.
Shows the results of pressure as a function of time.

FIG. 1 shows that the pressure rise of the samples of Examples 1, 2 and 3 of the present invention coated with the gas adsorption suppressing film was obviously slower than that of the comparative sample not coated with the gas adsorption suppressing film. This can be confirmed, which means that the amount of gas emitted from the sample is smaller. As apparent from Table 1, the samples of Examples 1, 2, and 3 having a coating were 5.3 × 10 ⁻¹¹ and 3, respectively, as apparent from Table 1.
2 × 10 ⁻¹¹ , 1.9 × 10 ⁻¹¹ , whereas the comparative sample without the coating has 8.8 × 10 ⁻¹⁰ ,
It was confirmed that Examples 1, 2, and 3 of the present invention were superior to Comparative Examples by one order of magnitude or more.

[0038]

[Table 1]

(Evaluation 2) Using a quadrupole mass spectrometer (QMS), the intensity (ion current value) of gas molecules emitted from the samples of Examples 1, 2, and 3 of the present invention and the sample of Comparative Example was measured with temperature. It was measured every time. As in the case of the evaluation 1, first, in order to keep all the samples in the same condition as much as possible, the humidity of each sample was set to 30%.
%, And stored for 24 hours in a dry box adjusted to a temperature of 25 ° C. to sufficiently adsorb and absorb gas molecules on the surface.
Thereafter, each sample taken out of the dry box was connected to QMS via a pressure adjustment valve, and the pressure in each sample was reduced to 1%.
5 ° C./min while keeping constant at × 10 ⁻⁴ Torr
While heating up to 350 ° C. at the temperature rising rate, gas molecules emitted from each sample at each temperature at that time were measured. FIG. 2 shows the results of the samples of Examples 1, 2, and 3 of the present invention (measurement results are almost the same in each of Examples 1, 2, and 3; therefore, representative examples are shown), and FIG. The measurement results of the comparative sample are shown. 2 and 3, the vertical axis represents the ion current, and the horizontal axis represents the temperature.

2 and 3 that the main desorbed gas components are H ₂ O, H ₂ , CO ₂ irrespective of the presence or absence of the coating.
/ N ₂ , O ₂ , and CO ₂ , and most of them are H ₂ O
It turns out that it is. However, although there is no difference in the desorbed gas components, it can be confirmed that the release behavior with respect to temperature greatly differs depending on the presence or absence of the coating. The amount of desorbed H ₂ O in the coated samples of Examples 1, 2 and 3 of the present invention rapidly increased with increasing temperature, but gradually decreased around 70 ° C. On the other hand, in the comparative sample without the coating, the temperature gradually rises up to about 200 ° C. as the temperature rises, and the tendency is to release more from around 200 ° C. Similarly, the release amount of H ₂ was also rapidly increased around 200 ° C., and the release amount was similar to that of Example 1 of the present invention.
It is overwhelmingly large compared to a few samples. On the other hand, O ₂ tends to decrease from around 170 ° C. in the comparative sample. This is a behavior that appeared due to the accelerated oxidation of the stainless steel material, and was not particularly observed in the samples of Examples 1, 2, and 3 of the present invention having a coating.
Therefore, it can be understood that the silicon dioxide-based coating film on the surface is very stable and dense.

When the evaluation 1 is verified from the evaluation 2, the samples of Examples 1, 2 and 3 having a coating show that the desorption of H ₂ O which is a dominant factor of the released gas component is 100 ° C.
It can be performed easily at low temperatures below, as compared with Comparative Sample uncoated require high temperature (200 ° C. or higher) to elimination of H ₂ O, H ₂ O sufficient elimination possible As a result, it can be determined that the released gas amount at 25 ° C. after the degassing was smaller than that of the comparative example without the coating. From this, the silicon dioxide coating film has a very low adsorption energy with gas molecules, which can easily desorb molecules adsorbed on the surface with low energy, typically H ₂ O molecules which are the main components of degassing factors. Can be determined to have a characteristic of being extremely small.

[0042]

In summary, according to the present invention, the adsorption of gas molecules can be effectively prevented, and even if the gas molecules are adsorbed, the gas molecules can be easily desorbed. The suppression film can be obtained easily and efficiently, so that the vacuum degassing process, the baking process, and the like can be reduced, and the manufacturing cost can be reduced.

[Brief description of the drawings]

FIG. 1 is a diagram showing Examples 1 and 2 of a substrate for suppressing gas adsorption according to the present invention.
3 is a graph showing the relationship between the pressure and the released gas velocity under vacuum in Comparative Example 3 and Comparative Example.

FIG. 2 is a graph showing measurement results of gas molecules emitted from each embodiment of the present invention at each temperature.

FIG. 3 is a graph showing measurement results of gas molecules emitted from a comparative example at each temperature.

Claims (4)

[Claims] 1. A gas adsorption-suppressed substrate in which polysilazane or a polysilazane-containing composition is ceramicized on at least a gas adsorption-suppressing surface of the substrate, and a gas adsorption-suppressing film containing silicon dioxide as a main component is formed. 2. The gas adsorption suppressing substrate according to claim 1, wherein the nitrogen content in the gas adsorption suppressing film is selected in the range of 0.005% to 5% by atomic percentage. 3. The thickness of the gas adsorption suppressing film is 0.05 μm or more.
The gas adsorption suppressing base material according to claim 1, wherein the base material is selected in a range of 10 μm. 4. The gas adsorption suppressing group according to claim 1, wherein the base material is selected from metal or plastic, and the base material is used for a vacuum structure or piping equipment for a high-purity gas supply system. Wood.