JPH0660410B2 - Thin film forming method and thin film forming apparatus - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a thin film forming method and a thin film forming apparatus, and more specifically, semiconductors such as IC and LSI, semiconductor devices, solar cells, optical fibers; fine ceramics; optics. Thin film forming method and thin film useful for forming a thin film of metal, metalloid or its alloy or ceramics on the surface of a substrate such as equipment parts, precision machine parts, general machine parts, special glass such as heat ray reflective glass Forming apparatus

INDUSTRIAL APPLICABILITY The method and apparatus of the present invention are applicable not only to CVD (chemical deposition method-pyrolysis method, hydrogen reduction method, sealed tube method, etc.) but also to PVD (physical deposition method-vacuum deposition method, sputtering method, ion plating method). Etc.), plasma CVD, plasma PVD,
This is useful when forming a thin film by MOCVD (organic metal CVD). The thin film formed in the present invention includes any atomically arranged thin film such as an epitaxial film with a well-arranged atomic arrangement, an amorphous film with a disordered atomic arrangement, or a film positioned in between.

[Prior Art] For example, semiconductor devices called LSIs and VLSIs are currently playing a leading role in the remarkable development of the electronics field. In addition to general-purpose gases, rare gases such as argon and helium, corrosive gases such as hydrogen chloride and chlorine, and special gases such as silane, arsine, and borane gas are used. Further, at present, the semiconductor device manufacturing process is rapidly progressing toward higher integration (ultra-miniaturization).

As the degree of integration of LSI rises and the current 256 Kbit is increased to 1 Mbit and 4 Mbit, the line width of minute patterns becomes smaller and smaller, and even fine particles, which have not been a problem so far, will affect the yield. It came out.

Therefore, the gases related to the semiconductor manufacturing described above are also used, for example, for silicon wafers that will be LSI substrates, for epitaxial use in device manufacturing processes, for doping, for etching,
Gases for cleaning and the like are required to have a purity of 4 to 5 nines or more, and in addition, a dryness with a water content of 1 ppm or less and no suspended dust is required.

Moisture in these gases causes various obstacles as shown below, and therefore must be strictly controlled.

Corrosion of metal parts such as piping, valves, and flow meters in the semiconductor manufacturing process occurs, and fine metal impurities and fine particles are generated. (For example, corrosive gas such as KCl gas) H ₂ and O ₂ are generated by the decomposition of water in the manufacturing furnace.
O ₂ causes unexpected oxidation impurities.

A chemical reaction occurs between the gas itself and water to produce by-product impurities.

The above-mentioned problem of the high degree of drying of gas becomes an important problem when a metal or ceramic thin film is formed on the surface of a base material such as optical mechanical parts and precision mechanical parts. That is, the purity of the gas used in the CVD method and the PVD method has a great influence on the structure and physical properties of the thin film, and the higher the purity of this gas, the better the quality of the thin film.

Currently, for example, an adsorption method using a molecular sieve is partially used for drying gas in a semiconductor device manufacturing process. Molecular sieves are desiccants with the ability to adsorb phosphorus pentoxide, and it is relatively easy to highly dry common gases.

Further, this desiccant is widely used because it has an advantage as a physical desiccant which does not cause troubles such as deliquescent and swelling. However, the drawback is that the heating regeneration that is generally performed is 200-40
A high temperature of 0 ° C is required, and suspended dust is generated by repeated use of heating and regeneration.

Further, the molecular sieve may be crushed by an acid gas such as hydrochloric acid gas.

There are acid-resistant grades, but the generation of suspended dust cannot be ignored, and a dust filter must be installed. It is also impossible to regenerate the molecular sieve.

On the other hand, a method of using a polymer film as a gas drying method is described in US Pat. No. 3,735,558 and JP-A-53-60563. Unlike the adsorption method using molecular sieves, these membrane permeation methods do not require regeneration and can be used continuously for a long time, which is an excellent method.

For the former, a polymer having a fluorinated sulfonic acid group is used, and it can also be used for corrosive gases.
However, neither of them has a high degree of dryness that can be used in a semiconductor manufacturing process.

[Problems to be Solved by the Invention] The disposable molecular sieve adsorption method has a high running cost and may generate dust. In the absence of a desiccant, the quality of the gas that comes out of the gas cylinder may change over time, making it difficult to control the process, and thus adversely affecting the quality of the semiconductor wafers, semiconductor devices, and intermediate products that are products. Is. Furthermore, in the conventional manufacturing process without a desiccant, not only the quality and yield, but even if a small amount of water is mixed in the gas, metallic pipes and metallic gas flow rate regulators that guide the gas from the gas cylinder to the reactor. Cause corrosion, and if replaced every six months to at least every two years, become a source of heavy metal and dust scattering due to metal corrosion. At the same time, this cost is also a large factor in cost increase.

Therefore, the method of obtaining a highly dry gas, which has a low running cost, does not generate dust and impurities, and has a strong need for development in the widespread semiconductor market, has been a strong technology.

[Means and Actions for Solving Problems] According to the present invention, there is provided a method for forming a thin film on a substrate under a reduced pressure or normal pressure atmosphere, which comprises forming a thin film in a reduced pressure or normal pressure system. Introducing a gas for forming a thin film on the surface of the substrate, the gas for forming a thin film is brought into contact with one side of the fluorinated copolymer film having a cation exchange group and the other side. A thin film forming method, characterized in that a dry purge gas is brought into contact with or a gas for forming a thin film, which is dehumidified by depressurizing the other side, is used.
And a film forming chamber capable of reducing the pressure to normal pressure, a gas inlet for introducing a gas into the film forming chamber from a gas supply source, and a source pressure means for sucking the gas in the film forming chamber, A thin film forming apparatus comprising a water separation means between a gas inlet and a gas supply source, wherein the water separation means has a large number of hollow fiber membranes made of a fluorinated copolymer having a cation exchange group casing. A thin film forming apparatus is provided, which is inserted into a hollow fiber membrane, is fixed at both ends with a resin, and is formed so that another kind of gas can pass through the inside and outside of the hollow fiber membrane.

As the fluorinated copolymer having a cation exchange group used in the thin film forming method and the thin film forming apparatus of the present invention, those having a cation exchange group such as a sulfonic acid group, a carboxylic acid group and a phosphoric acid group are preferable. The use of a fluorinated copolymer having a sulfonic acid group is the best in terms of easiness of production, high water content of the membrane, and thermal stability.

There are various structures of the fluorine-based copolymer having a sulfonic acid group, and among them, the general formula (In the formula, m = 0 or 1, n = an integer of 2 to 5) A fluorine-based copolymer containing a repeating unit is preferable.

Tetrafluoroethylene as the fluorine-based copolymer,
Fluorinated olefins such as trifluoroethylene, perfluorovinyl ether, vinylidene fluoride, vinyl fluoride and the general formula (II) Those obtained by copolymerizing the perfluorovinyl ether monomer represented by (m = 0 or 1, n = integer of 2 to 5) are preferable.

The sulfonic acid group of the above-mentioned fluorine-based copolymer has an ion exchange capacity of 0.5 to 2.5 meq / g H in the copolymer.
It is preferably introduced in such an amount that it becomes a mold dry resin. When the ion exchange capacity of the fluorine-based copolymer is within the range of 0.5 to 2.5 meq / g H-type dry resin, the water vapor permeation rate is not significantly reduced, and
The melting point of the copolymer does not become too high, the polymer thin film is easily manufactured, and the physical strength of the polymer thin film is maintained without lowering the physical strength. Ion exchange capacity is 0.
More preferably, it is 8-1.8 meq / g H-type dry resin.

Metal salts as salt of a sulfonic acid group of the fluorine-based copolymer used in the present invention, it is possible to use the ammonia salt form, SO ₃ H type most permeation rate of the water content is high water vapor is large, It has sufficient thermal stability and is preferable.

The thinner the hollow fiber, the higher the water vapor permeability and the better the performance, which is preferable, but it is limited by the moldability and pressure resistance. Inner diameter 400 ~ depending on the diameter of hollow fiber
The thickness of 500 μm is preferably 40 to 60 μm.

The shape of the fluorine-based copolymer may be any of a flat membrane, a tubular shape and a hollow fiber membrane, but a hollow fiber membrane having a large membrane area per unit volume and a high treatment capacity is particularly preferable. For example, in order to achieve a high degree of dryness with a water content of 10 ppm or less, particularly a water content of 5 ppm or less, the airtightness of the device is important, and the hollow fiber membrane is preferable from that point.

The film of the fluorinated copolymer having a cation exchange group used in the present invention is preferably a film of the fluorinated copolymer containing the repeating unit represented by the general formula (I), which has been pretreated by heating. . The heating pretreatment of this film means that after forming a thin film of a fluorine-based copolymer obtained by copolymerizing a monomer represented by the general formula (II) and a fluorinated olefin,
That is, the terminal group SO ₂ F is converted to SO ₃ H by hydrolyzing with an alkali and treating with a strong acid, and then the polymer is heat treated.

The heat treatment can be carried out, if necessary, while purging a dry gas such as nitrogen gas having a water content of 5 ppm or less, or under reduced pressure. A heat treatment temperature of 70 to 250 ° C is suitable. If the temperature is too high, the ion-exchange group may be eliminated and the performance may be deteriorated. The heat treatment temperature is particularly preferably 70 to 200 ° C.

The heat treatment causes the copolymer to shrink by several tens of percent, and the water absorption rate is also reduced.

A film obtained by heat-treating a film of a fluorocopolymer containing a repeating unit represented by the general formula (I) has a relationship between the water absorption rate W and the ion exchange capacity Q of the formula (III) 1.20Q-1.964 < log W <1.20Q-1.742 (III) It has excellent properties, and particularly exhibits excellent performance in highly drying gas.

The heat-treated film having the relationship of the formula (III) enables a high degree of dehumidification with a water content of 1 ppm or less at room temperature. Therefore, if the conditions are set as necessary, the water content is 10 ppm.
Of course, it is naturally possible to dehumidify to any value such as 5 ppm or less. In actual thin film formation, 10ppm or less may be sufficient, 5ppm or less, and further 3ppm or less or 1
The present invention is applicable to any of these cases, although it may be useless if it is not lower than ppm.

In the case of a flat membrane among the above-mentioned heat-treated membranes, it can be easily determined whether or not it is produced by the heat treatment by measuring the water absorption.

However, if the membrane is a thin hollow fiber, the water absorption rate is difficult to measure, so that the determination can be made by measuring the heat shrinkage start temperature described below.

Attach a light weight (sufficient to straighten the thread but not enough to stretch it) to the hollow fiber membrane and hang it in the air tank. In that state, the temperature of the air tank is gradually raised and the change in the yarn length is read and measured with a telescope. Fig. 5 shows an example of the measurement results in a graph with temperature on the horizontal axis and length on the vertical axis. L ₂₅ is a length of 25 ° C. and L _t is a length at a temperature of t ° C. In FIG. 5, the temperature indicated by the arrow, that is, the maximum temperature at which there is no dimensional change due to temperature rise is defined as the "maximum temperature at which there is no heat shrinkage." Several hollow fibers with different heat treatment temperatures (t) were prepared, and their "maximum temperature (T) without heat shrinkage"
Was measured and the results were plotted on a graph, as shown in FIG. That is, T = t (1), and the heat treatment temperature (t) of the hollow fiber membrane can be known by measuring the maximum temperature (T) without heat shrinkage.

In the method of the present invention, the gas to be dried is usually a gas filled in a cylinder, which is generally obtained on the market, and a gas whose water vapor concentration is not so high. The gas filled in the cylinder is usually about several tens of ppm, but in some cases, it is 100 ppm or more. It is possible to obtain the target dehumidification level by changing the membrane area of the water separator or making it in multiple stages according to the concentration of the target gas.

In the present invention, the gas for forming a thin film includes a source gas, a carrier gas, a sputtering gas such as an argon gas used in sputtering, a reactive gas such as an oxygen gas used in reactive sputtering, and a replacement gas. It means a gas such as gas or balance gas that is introduced into a system under reduced pressure or normal pressure and that directly or indirectly participates in the thin film formation.

An epitaxial gas is used as the gas used in the present invention. Epitaxial gases include HCl, PH ₃ , B ₂ H ₆ ,
SiCl ₄ , SiH ₂ Cl ₂ , SiHCl ₃ , SiH ₄ , Si ₂ H ₆ , SiI ₄ , SiI ₂ , S
iF ₄ , SnCl ₄ , SbCl ₅ , GeH ₄ , GeCl ₄ , GeI ₄ , GeI ₂ , TeH ₂ ,
_{BBr 3, BCl 3, PCl 3} , AlCl 3, AsCl 3, (CH 3) 3 Al, (C 2 H 5) 3 A
_{l, (CH 3) 3 Sb} , (C 2 H 5) 3 Sb, (CH 3) 3 Ga, (C 2 H 5) 3 Ga, (CH 3)
₃ As, (C ₂ H ₅ ) ₃ As, (CH ₃ ) ₂ Hg, (C ₂ H ₅ ) ₂ Hg, (CH ₃ ) ₃ P, (C ₂ H
₅ ) ₃ P, etc., or a mixed gas thereof, etc., among which hydrogen chloride gas, phosphine gas, diborane gas, tetrachlorosilane gas, trichlorosilane gas, dichlorosilane gas, or a mixed gas thereof is generally often used. .

AsH ₃ , AsCl ₃ , PCl ₃ , PH ₃ , HCl, H ₂ , N ₂ , H ₂ Se, H for thin film growth and impurity diffusion in metalorganic vapor phase epitaxy.
₂ S, H ₂ Te, (CH ₃ ) ₃ Ga, (C ₂ H ₅ ) ₃ Ga, (C ₂ H ₅ ) ₂ GaCl, (CH ₃ ) _{3
Al, (C 2 H 5)} 3 Al, (CH 3) 3 In, (C 2 H 5) 3 In, (C 2 H 5) 2 Zn, (CH
₃ ) ₂ Zn, (CH ₃ ) ₂ Cd, (C ₂ H ₅ ) ₂ Cd, (CH ₃ ) ₂ Hg, (CH ₃ ) ₄ Sn, (C
₂ H ₅ ) ₄ Sn, (CH ₃ ) ₄ Pb, SbH _3, etc., or a mixed gas thereof is used.

In the CVD method among the methods for forming a thin film on a substrate, a source gas (source) carrier gas or the like is used.

If an example of a thin film coated on the surface of the base material in the CVD method is shown together with the source gas (source) and the carrier gas, the above TiC, T
In addition to iN, BeC (source: BeCl ₃ + C ₆ H ₅ CH ₃ , carrier gas: H ₂ ), SiC (source: SiCl ₄ + CH ₄ , carrier gas:
H ₂ ), ZrC (source: ZrCl ₄ + C ₆ H ₆ , carrier gas:
H ₂ ), B ₄ C (source: BCl ₃ + C ₆ H ₅ CH ₃ , carrier gas:
H ₂ ), WC (source: WCl ₆ + C ₆ H ₅ CH ₃ , carrier gas: H ₂ )
Carbides such as BN (source: BCl ₃ , carrier gas: N ₂ +
H ₂ ), TiN (source: TiCl ₄ , carrier gas: N ₂ + H ₂ ),
ZrN (source: ZrCl ₄ , carrier gas: N ₂ + H ₂ ), HfN
(Source: HfCl ₄ , carrier gas: N ₂ + H ₂ ), VN (Source: VCl ₄ , carrier gas: N ₂ + H ₂ ), TaN (source: Ta
Cl ₅ , carrier gas: N ₂ + H ₂ ), Be ₃ N ₂ (source: BeCl ₃ ,
Nitriding of carrier gas: N ₂ + H ₂ ), AlN (source: AlCl ₃ , HCl, carrier gas: N ₂ + H ₂ ), Th ₃ N ₄ (source: ThCl ₄ , carrier gas: N ₂ + H ₂ ), etc. Material: AlB (source: AlCl ₃ + BCl ₃ , carrier gas: H ₂ ), SiB (source: SiCl ₃ + BCl ₃ , carrier gas: H ₂ ), TiB ₂ (source: TiCl ₄ + BBr, carrier gas:
H ₂ ), ZrB ₂ (source: ZrCl ₄ + BBr ₃ , carrier gas: H ₂ ),
HfB ₂ (source: HfCl ₄ + BBr ₃ , carrier gas: H ₂ ), VB ₂
(Source: VCl ₄ + BBr ₃ , carrier gas: H ₂ ), TaB (Source: TaCl ₅ + BBr ₃ , carrier gas: H ₂ ), WB (Source: WCl
Borides such as ₆ + BBr ₃ , carrier gas: H ₂ ; MoSi (source: MoCl ₅ + SiCl ₄ , carrier gas: H ₂ ), TiSi (source: Ti
Cl ₄ + SiCl ₄ , carrier gas: H ₂ ), ZrSi (source: ZrCl ₄ + SiC
L ₄ ), VSi (source: VCl ₃ + SiCl ₄ , carrier gas: H ₂ ) and other silicides; Al ₂ O ₃ (source: AlCl ₄ , HCl, carrier gas: H ₂ + CO), SiO ₂ (source) : SiCl ₄ , SiH ₄ + O ₂ , carrier gas: H ₂ + CO), Fe ₂ O ₃ (source: Fe (CO) ₅ , carrier gas:
H ₂ + CO), ZrO ₂ (source: ZrCl ₄ , carrier gas: H ₂ + CO)
And oxides thereof.

In addition, a thin film of a single metal or alloy may be formed on the surface of the base material for the purpose slightly different from the above.

Examples of the single metal thin film are Cu (source: CuCl ₃ , carrier gas: H ₂ or Ar), Be (source: BeCl ₃ , carrier gas: H ₂ ), Al (source: AlCl ₃ , carrier gas: H _2). Or Ar), Ti (source: TiCl ₄ , carrier gas: H ₂ or A)
r), Zr (source: ZrCl ₄ , carrier gas: H ₂ or A
r), Ge (source: GeI ₂ , carrier gas: H ₂ or A
r), Mo (source: MoCl ₅ , carrier gas: H ₂ ), W
(Source: WCl ₆ , carrier gas: H ₂ ), Si (Source: Si
Cl ₄ , SiH ₂ Cl ₂ , carrier gas: H ₂ ), B (source: BCl ₃ ,
Carrier gas: H _2), Pt _{(Source: (PtCl 2) 2 (CO} ) 3, carrier gas: Ar or He), Pb _{(Source: Pb (C 2 H 5)} 4,
Carrier gas: Ar or He) and the like.

As an example of the alloy thin film, Ta-Tb (source: TaCl ₅ + NbCl ₅ ,
Carrier gas: Ar or He), Ti-Ta (Source: TiCl ₄ +
TaCl, carrier gas: Ar or He), Mo-W (source:
MoCl ₆ + WCl ₆ , carrier gas: Ar or He), Cr—Al (source: CrCl ₃ + AlCl ₃ , carrier gas: Ar or He) and the like.

Among the methods of forming a thin film on a substrate, the gases used in the PVD method are Ar, O ₂ , N ₂ , CH ₄ , C ₂ H ₂ , CO, H ₂ S, S.
Examples thereof include iH ₄ , PH _{3 and the} like, or a mixed gas thereof, and among them, Ar gas is generally used in many cases.

In the present invention, a typical example of the semiconductor wafer is a silicon wafer. Examples of compound semiconductors include semiconductors composed of Group II elements and Group VI elements of the Periodic Table, as well as semiconductors composed of Group III elements and Group V elements of the Periodic Table. Currently, compound semiconductors are group III-IV to III
-Developing into GaAs and GaAlAs using -V group. There are 16 binary compounds of group III B, Al, Ga, In and group V N, P, As, Sb, none of which is effective in group IV simple semiconductors such as Si and Ge. It has certain physical properties.
It is also possible to synthesize multi-component compounds such as ternary and quaternary compounds of the groups III and V. Although there are many types, their characteristics depend on the composition. Among the III-V group compound semiconductors, some of the binary compounds can be obtained as crystals grown from their melts, but the crystals often show impurities and lattice defects, which is also most suitable for industrialization of semiconductor devices. The vapor phase epitaxial growth method is considered to be an important technology in the future.

The semiconductor device means all devices such as IC and LSI made of the above semiconductors, and the compound semiconductor device means all devices such as IC and LSI made of the above compound semiconductors. In addition, the intermediate product means a semi-finished product obtained in an intermediate process up to the final semiconductor device.

Note that the semiconductor device in the present invention also includes a solar cell. A solar cell is a doping of n-type impurities such as P (phosphorus) and As (arsenic) into a silicon wafer. B is a p-type impurity into an n-doped wafer.
Doping of surface layer of (boron) etc. Vapor deposition of metal such as Au, Ni, Sn etc. on p-type region, heat alloying It is manufactured through processes such as vapor deposition of antireflection film such as SiO 2 provided on the light receiving surface.

In the CVD method of the thin film forming method of the present invention, for example, in the case of forming a titanium carbide (TiC) film on the surface of a steel substrate, when methane gas is used as a carbon source and hydrogen is used as a carrier gas, The reaction proceeds like.

TiCl ₄ + CH ₄ + H ₂ → TiC + 4HCl + H ₂ (1) CH ₄ C + 2H ₂ (2) TiCl ₄ + 2Fe + C → TiC + 2FeCl ₂ (3) TiCl ₄ + C (solid solution) + 2H ₂ → TiC + 4HCl (4) The temperature is usually around 1000 ° C, and the coating time is several hours. When coating with TiN, TiCl ₄ , N ₂ and H ₂ are used.

In the present invention, the thin film coating on the substrate is performed under a reduced pressure or normal pressure atmosphere. The reaction pressure can be said to be an important factor in the CVD reaction. The higher the reaction pressure, the higher the precipitation rate, but the coarser the crystal grains occur. In order to obtain a high quality thin film of fine-grained polycrystal, it is preferable to carry out the CVD process under a reduced pressure atmosphere.

The nature of the substrate also has a large effect on the thin film. When coating a TiC thin film on steel, it is required to have a high carbon content, high core hardness by heat treatment, and little heat treatment deformation.

As an application example of coating with TiC or TiN, SKH as a base material
Example of using 9, SKH 55, SKH 57, cemented carbide for punches, dies, etc. in the field of cold forging; SKD as a base material
1, SKD 11, SKH 9, Cemented Carbide and applied to piercing punches, dies and shearing dies in the field of sheet metal processing; SKD 1 and SKD 11 as base materials, powder compacting in general, core loading Example of application to reamers, taps, cutting tools, drills and cutters in the field of cutting using SKH 9, SKH 55 and SKH 57 as base materials; in the field of plastic molding using SKD 1 and SKD 11 as base materials Example of applying to extrusion screw, torpedo, ring, nozzle; SKS 2,3, SK2 as base material
Example of applying 2,3,4, SUJ 1,2,3 to yarn paths, yarn guides and cutters in the textile field; SKD as a base material
1, SKD 22 can be applied to guide bushes for drills and plug gauges in the field of auxiliary tools.

The thin film forming method is also advantageous when forming a diamond thin film on a substrate. The diamond thin film can be formed by, for example, an electron beam CVD method. In this method, hydrocarbons are decomposed with an electron beam, and the resulting carbon is deposited to have a diamond crystal structure.
Since methane (CH ₄ ) has a tetrahedral structure as a hydrocarbon raw material, there is a high possibility that crystal growth can proceed while maintaining a tetrahedral structure, which is preferable. If the hydrocarbon is used here in a highly dried state, a high performance diamond thin film can be obtained.

Further, according to the present invention, high quality amorphous silicon
It becomes possible to form an (a-Si) thin film. Electrophotographic photoreceptors and solar cells are known as devices using a-Si thin films. There are glow discharge method, CVD method, etc. as a method for forming an a-Si thin film, and by using the raw material gas, carrier gas or atmosphere gas in these methods to be highly dried by the method of the present invention, a A Si thin film can be obtained.

For example, in the glow discharge method, SiH ₄ is decomposed in plasma generated by glow discharge to form an a-Si film. Also,
The SiF ₄ as a raw material used with hydrogen or SiH _4, amorphous silicon - fluorine-hydrogen alloy (a-Si: F:
H) A film can be obtained. With the CVD method, the pressure is 400
A-Si by pyrolyzing SiH ₄ at a temperature of 700 ℃
A film is deposited, but a treatment in hydrogen plasma is performed in order to sufficiently bond hydrogen to Si.

The thin film forming method of the present invention can be preferably used also when an optical fiber preform is manufactured by an internal CVD method (internal chemical vapor deposition method). In the internal CVD method, the raw material gas (vapor-phase glass raw material, vapor-phase doping material) and O ₂ gas in the quartz glass pipe are supplied, and oxyhydrogen reciprocates along the outer circumference of the pipe. The inside of the glass pipe is heated by a heat source such as a flame burner, and by the oxidation reaction of the raw material gas and the transparent vitrification of the reaction product performed by this, a glass layer is deposited and formed in the glass pipe, By drying and using this raw material gas according to the present invention, a deposited layer having excellent physical properties can be obtained in the silica glass pipe.

The vapor-phase glass raw material supplied into the glass pipe is Si
Cl ₂ and typical vapor-phase dopants are GeCl ₄ and POCl ₃ .

A single movement of the burner forms a synthetic glass film having a thickness of 10 μm in a quartz glass tube, and this is repeated many times to form a glass film for a core having a predetermined thickness (100 to 300 μm). An optical fiber preform can be obtained by welding a hollow quartz glass tube having a glass film for core formed thereon by heating according to a conventional method.

Next, applications of the thin film forming material obtained by the method of the present invention will be described.

An oxide film materials Al ₂ O _3, MgO, none of the ZrO ₂ such as heat resistance (1,700-2,200 ° C.) and strength (2000kg / cm, 1200
C.), it is suitably used for coating cutting tools.

In addition, carbides such as SiC, WC, B ₄ C, and TiC (which were mentioned above) have high melting points (2100 to 3100 ° C) and high hardness (25
00 to 2800kg / mm ² ), high thermal conductivity (0.04 to 0.10 cal / cm ・ se)
c ・ ° C) and wear resistance make it suitable for mechanical seal cemented carbide tools. Further, by forming a TiC thin film on the carbon fiber, the strength and resistance can be dramatically increased.

Nitride thin films such as Si ₃ N ₄ , AlN, and BN have high resistance and hardness, and are extremely resistant to corrosion and thermal shock, so they are used for the same applications as the above-mentioned carbides.

Boride thin films such as TiB ₂ , ZrB ₂ and CrB ₂ have high melting points (2760〜30
40 ° C), high hardness (1700-3400kg / mm ² ), excellent mechanical strength and corrosion resistance, high electrical conductivity, and remarkable metallicity, so it is a coating for molten metal containers and high-temperature electronic materials. Suitable for

In addition, a boron fiber can be obtained by using a tungsten core wire as a base material and performing boron coating by a CVD method using boron chloride and hydrogen gas. In this case, carbon fiber may be used for the core wire. By depositing a thin film of silicon carbide on the surface of boron fibers by CVD, bolusic fibers that prevent reaction with metals can be obtained. A series of these
By highly drying the raw material gas and the carrier gas used in the CVD method by the method of the present invention, a fiber having high strength and high heat resistance can be obtained.

In addition to the above, the thin film forming method of the present invention can be applied to all coatings of base materials by the CVD method, and can be used for various equipments in nuclear power generation, optical products, abrasives, aircraft / cars, trains / trains.
It is useful for coating ship parts, turbine parts, reactors, catalyst electrodes, etc.

Next, the PVD method among the thin film forming methods of the present invention will be described.

The PVD methods are roughly classified into vacuum vapor deposition method, sputtering method, ion plating method and the like, and each method has many variations. In each case, the same material as the thin film to be produced is formed in vacuum. Is a technique of evaporating and adhering it on the opposing substrate. Further, in the case of an alloy, a method of evaporating the alloy itself, or evaporating a single substance separately and alloying it when adhering may be used. Also, in the sputtering method,
Ions such as argon that collide at high speed cause target atoms to fly out and adhere to the substrate on the counter electrode. Although there are many variations in the sputtering method, basically, the sputtering phenomenon of the target material by argon ions is used. In reactive sputtering, a gas such as oxygen or nitrogen is introduced into the system, and a silicon material is used as a target to form an insulating film on the substrate by one kind of chemical reaction. Further, as the PVD technology in the semiconductor process, an electron beam evaporation method which is one of the vacuum evaporation methods and a magnetron sputtering method which is one of the sputtering methods are often used.

In the thin film forming method of the present invention, a film having a particularly excellent dehumidifying ability is used to form a film on a substrate by using a highly dehumidified gas. The film formation is performed by introducing the highly dehumidified gas in the PVD device.

For example, among sputtering methods, the thin film formed by reactive sputtering is a method in which a reactive gas is mixed into a discharge gas for sputtering. By this method, a compound thin film can be formed on a substrate. That is, when attempting to apply a TiC thin film to an Al alloy, first, without directly applying TiC, a Ti thin film is applied to the Ti target using only the discharge gas Ar, and then CH _{4 is} gradually added. This is because when Ti is mixed into Ar to form a TiC thin film, the TiC thin film surely adheres to the Al alloy. It is considered that Ti plays an adhesive role between the Al alloy and TiC. It is believed that this type of graded composition lends itself to mechanical utilization of thin films. Thin films formed by reactive sputtering include metals, semiconductor oxides, nitrides, carbides, silicides and phosphorus compounds. The target materials to be targeted are almost all metals and semiconductors, and oxides of Ag, Au, and Pt are also made. The reactive gases used are O _{2 and the} like for oxides, N ₂ and NH ₃ for nitrides, and CH ₄ and C for carbides.
₂ H ₂ , CO, etc., H ₂ S etc. for sulfides, SiH for silicide
₄ etc. PH ₃ etc. are used for phosphorus compounds. These gases are not used alone, but are often mixed and used in Ar gas.

Compound thin films formed by reactive sputtering include the following.

Oxides: Al ₂ O ₃ , Cr ₂ O ₃ , In ₂ O ₃ , SiO ₂ , SnO ₂ , Ta ₂ O ₂ , Ti
O ₂ , VO ₂ , WO ₃ , ZnO, In ₂ O ₃ · SnO ₂ Nitride: AlN, NbN, Si ₃ H ₄ , TaN, TiN, ZrN Carbide: FeC, SiC, TaC, TiC, VC, WC Sulfide : CdS, CuS, MoS ₂ , PbS silicide: Cr-Si, Fe-Si, Mo-Si, Ta-Si, Ti-Si, WS
i Phosphorus compound: A technique for producing a solar cell or an electrophotographic photoreceptor by forming an amorphous silicon (a-Si) film by an InP reactive sputtering method or an ion plating method is attracting attention. It is also applicable to. That is, when forming the a-Si film,
In the reactive sputtering method, electric power is applied between electrodes placed in a low-pressure argon gas (which is dried and used according to the present invention) to generate a discharge, and a crystalline silicon plate (target) is placed on one electrode. When depositing a silicon film on the substrate placed on the opposite electrode side by sputtering, H ₂ or SiF ₄ (either gas is used by drying according to the present invention) is mixed into the argon gas, and further impurities are added. To add an element, B ₂ H ₂ or PH ₃ is mixed and sputtering is performed. In the ion plating method, solid silicon is evaporated by an electron beam in a vacuum, and this is introduced into a plasma formed in a vacuum container to be ionized, and at the same time, a reaction with hydrogen (used by drying according to the present invention) is caused. Form an a-Si film. Here, the ionized particles are accelerated by the DC voltage applied between the evaporation source and the substrate and are deposited toward the substrate. Both a method using a direct current electric field and a method using a high frequency electric field can be adopted for forming plasma.

[Effects of the Invention] The effects of the present invention can be summarized as follows.

In the thin film forming method and the thin film forming apparatus of the present invention, a fluorine-based copolymer film having a cation exchange group is used to dry the gas for forming the thin film. It can be highly dried and its drying performance can be connected for a long time. In addition, since the film is dried, no suspended dust is generated during the drying. Further, this membrane is not easily corroded when exposed to acidic gas, does not require regeneration unlike molecular sieves, and can be continuously used for a long time.

Gases such as semiconductor material manufacturing process gas, semiconductor device manufacturing gas, new material manufacturing process gas, etc. are highly dried, and in order to perform thin film formation using this gas, semiconductor wafers, semiconductor devices or intermediates thereof. The yield of products and new materials increases, and the quality improves.

Because of the membrane separation, dust is not mixed in the gas and the product yield
Quality is improved together.

Piping corrosion is prevented due to the reduction of water content in the gas,
No fine metal impurities are generated.

Prevents corrosion of metal equipment such as piping, valves, and flow meters,
The life of the device / appliance is greatly extended, resulting in cost reduction.

The decomposition of water produces H ₂ and O ₂ , which can prevent the unexpected generation of oxidative impurities by O ₂ .

It can prevent the gas from chemically reacting with water and defeating the intended purpose. (When the water in the gas remains in very small gaps in the reactor, if the next gas, such as SiCl ₄ or SiHCl ₃ , enters, it causes a chemical reaction with this water, and has the intended purpose. The result is not obtained.) [Examples] The present invention will be described in more detail with reference to Examples. The moisture content of the gases of the examples and comparative examples was measured by a dew point meter or a moisture meter, and depending on the gas, Karl Fischer.

Production example Tetrafluoroethylene, And ion-exchange capacity of 0.94 meq / g H
A mold dry resin was obtained.

A film of 500 μm is formed from the obtained resin at a molding temperature of 250 ° C, and after hydrolyzing this film with an alkaline alcohol solution, ion exchange is performed with an aqueous solution of hydrochloric acid to make the end of the side chain sulfonic acid type (H type) and air dry. did. The obtained membrane was subjected to dry temperature treatment in vacuum, and the equilibrium water absorption was determined at 25 ° C. (First
(Refer to the figure) As shown in Fig. 1, the water absorption rate drastically decreased when the dry heat treatment temperature was about 70 ° C or higher. The water absorption was almost constant even at higher temperatures.

Similarly, as shown in Table-A, the monomer species were changed to prepare a semipermeable membrane having an ion exchange capacity of 0.8 to 1.1 meq / g, and a membrane having the water absorption rate shown in Table-A was prepared.

From the results of Table-A, the relationship between the ion exchange capacity and the water absorption rate of the membrane of the present invention is shown by the shaded area in FIG.

Reference example with tetrafluoroethylene Was copolymerized to obtain an H-type dry resin having an ion exchange capacity of 0.90 meq / g. The obtained resin was melt-spun at a spinning temperature of 250 ° C. and a spinning speed of 88 mm with a molding machine equipped with a hollow fiber manufacturing die to obtain a hollow fiber membrane having an inner diameter of 500 μm and a thickness of 60 μm.

After the hollow fiber was hydrolyzed with an alkaline alcohol solution, ion exchange was performed with a hydrochloric acid aqueous solution to make the end of the side chain a sulfonic acid type (H type) and air dried. 40 cm length of the obtained thread
We bundled 400 pieces of the above-mentioned products and fixed them to a separator made of SUS with epoxy resin at both ends to make a water separator as shown in Fig. 1. N ₂ gas adjusted to a water content of 1 ppm (dew point −76 ° C.) or less was pressurized to 5 kg / cm ² G in the water separator, and 0.5 l / min
(The flow rate is converted to atmospheric pressure, the same applies below.) The flow rate was set to the inside of the hollow fiber.

The N ₂ gas also adjusted to the following water content 1 ppm (dew point -76 ° C.) in the outer shed 0.75 l / min. This was placed in a constant temperature bath at 70 ° C, and after heat treatment for 3 hours, the water separator was returned to room temperature, the water content rate was 31 ppm (dew point -52 ° C), and the pressure was 5 kg / cm ² G.
Flowing N ₂ gas was adjusted to the inside of 0.5 l / min hollow fiber, the outside of the hollow fiber dew point adjustment N ₂ gas was flowed 0.75 l / min to -76 ° C. or less (hereinafter moisture content 1 ppm) . The separator N ₂
When the gas outlet dew point was measured, it was −76 ° C. or lower (water content rate 1 ppm or lower). Operates continuously as it is, and gas outlet dew point is -76 ° C or less (water content is 1ppm or less) even after 24 hours.
It remained.

On the other hand, with respect to the purge gas on the outside of the hollow fiber, the dew point at the outlet of the water separator was measured after 24 hours, and it was -66 ° C (water content rate 4.6 ppm). After that, the N ₂ gas outlet dew point after operating continuously for approximately 1000 hours under the same conditions was −76 ° C. or less (water content 1
(ppm) and the ratio of the amount of water reduced in the moisture separator of the sampling gas and the amount of water increased in the moisture separator of the purge gas was 1.2: 1, which were almost in agreement within the measurement error.

The same results as those of the reference example were obtained for the other films of the present invention as shown in Table-A.

Comparative Reference Example N ₂ gas and purge gas were measured in the same conditions as in the Reference Example without the heating pretreatment in the same apparatus as the Reference Example. 44
After ₂ hours, the dew point of N ₂ gas did not reach to -60 ° C (water content rate 10.6 ppm).

Examples 1, 2, 3 (i) The following chemical structural formulas having a sulfonic acid group A hollow fiber membrane (inner diameter 500 μm, wall thickness 60 μm) of a polytetrafluoroethylene copolymer (ion exchange capacity 0.94 meq / H type dry resin) having a repeating unit of was prepared. 400 pieces of the hollow fiber cut into a length of 40 cm were inserted into a spring and SUS casing, both ends were fixed with an epoxy resin, and otherwise a water separator was produced in the same manner as in the reference example. The pressure of the sample gas and the purge gas are changed under the same conditions by using this moisture separator, the type of sample gas and the moisture content are changed, and the moisture content after the treatment is performed by the moisture separator in the same manner as in the reference example using the depressurization method. The rate was measured and the results shown in Table 1 below were obtained. In addition, using these low moisture content gases,
When semiconductor wafers, semiconductor devices and intermediate products thereof were manufactured using the epitaxial reactor as shown in the figure, the yield was improved by about 5%.

(Ii) again Almost the same results were obtained for the hollow fiber membrane of the polytetrafluoroethylene copolymer having the repeating unit of (ion exchange capacity 0.90 meq / H type dry resin).

Example 4 The following structural formula having a sulfonic acid group A hollow fiber membrane (inner diameter: 500 μ, thickness: 60 μ) of a polytetrafluoroethylene copolymer (ion exchange capacity = 0.90 meq / g H-type dry resin) having a repeating unit of was prepared. 400 pieces made by cutting this hollow fiber into a length of 40 cm are spring-loaded and inserted into a SUS casing as shown in Fig. 3, both ends are fixed with epoxy resin, and a water separator as shown in Fig. 3 is attached. I made it. Moisture content of 1 ppm or less (moisture content measured by dew point measurement method or Karl Fischer method depending on gas) in the separator, 0.5 l / min of nitrogen gas pressurized to a pressure of 5 kg / cm ² G, inside the hollow fiber Shed to. A dry nitrogen gas (purge gas) having a water content of 1 ppm or less was flowed outside at 0.75 l / min at atmospheric pressure. This was placed in a room temperature bath of 70, preheated for 3 hours, then returned to room temperature, the inside of the hollow fiber was adjusted to a water content of 18 ppm, and a pressure of 5 kg / cm ² G was applied to arsine gas (sample gas) 0.5 l / The water content of the sample gas at the outlet of the separator was measured and found to be 1 ppm or less. As it was, after 24 hours of continuous operation, the outlet water content of the sample gas remained below 1 ppm. Under the same conditions as above, the water content at the outlet of the sample gas after about 170 hours remained below 1 ppm.

Examples 5 and 6 Using the same separation apparatus as in Example 1, the pressures of the sample gas and purge gas were changed under the same conditions, the type of sample gas and the water content were changed, and the depressurization method was used as in Example 4. The water content after the treatment was measured with a separator, and the results shown in Table 1 below were obtained. Furthermore, when a compound semiconductor wafer, a compound semiconductor device, and an intermediate product thereof were manufactured using the reactor (epitaxial reaction apparatus) shown in FIG. 4 using these gases having a low water content, the yield was about 3%.
% Improvement has been realized.

Example 7 (i) Nitrogen gas pressurized to a moisture content of 1 ppm or less and a pressure of 5 kg / cm ² G was flown inside the hollow fiber in the same moisture separator as in Example 4 at a pressure of 5 kg / cm ² G. . Dry nitrogen gas (purge gas) at atmospheric pressure with moisture content below 1ppm
0.75 l / divided. Put this in a constant temperature bath at 70 ° C, preheat for 3 hours, return to room temperature, and then set the moisture content inside the hollow fiber.
Was adjusted to 50 ppm, the pressurized CH ₄ gas pressure 5 kg / cm ² G
When the water content at the outlet of the water separator of the switching gas at 0.5 l / min was measured, it was 1 ppm or less.

Similarly, H ₂ gas was dehumidified to a water content of 1 ppm or less.

Next, using TiCl ₄ gas and CH ₄ gas and H ₂ gas after treatment with a water separator, using a CVD apparatus as shown in FIG.
The (SKH 11) punch was coated with a TiC thin film.

The resulting TiC thin film was very dense and had small crystals. Also, TiCl ₄ and CH ₄ (water content 30
ppm) and H ₂ (23ppm) gas, the same punch as above was CVD treated and TiC coated. When the gas was not dried, the one with a life of 50,000 times dried the gas as described above. After that, the TiC-coated product improved to 250,000 times.

(Ii) again Almost the same results were obtained for the hollow fiber membrane of the polytetrafluoroethylene copolymer having the repeating unit of (ion exchange capacity 0.90 meq / H type dry resin).

Example 8 (i) The following chemical structural formula having a sulfonic acid group A hollow fiber membrane (inner diameter 500 μm, wall thickness 60 μm) of a polytetrafluoroethylene copolymer (ion exchange capacity = 0.90 meq / g H-type dry resin) having a repeating unit of was prepared. 400 pieces of the hollow fiber cut into a length of 40 cm were spring-loaded, inserted into a SUS casing, and both ends were fixed with epoxy resin to manufacture a water separator as shown in FIG. Nitrogen gas pressurized to a moisture content of 1 ppm or less and a pressure of 5 kg / cm ² G was flown into the moisture separator inside the hollow fiber at 0.5 l / min. A dry nitrogen gas (purge gas) having a water content of 1 ppm or less was flowed outside at 0.75 l / min at atmospheric pressure. This was placed in a constant temperature bath at 70 ° C, preheated for 3 hours, then returned to room temperature, the inside of the hollow fiber was adjusted to a water content of 50 ppm, and 0.5 l of CH ₄ gas pressurized to a pressure of 5 kg / cm ² G was adjusted. When the gas content at the outlet of the moisture separator was measured after switching to / min, it was 1 ppm or less.

Similarly, Ar gas was dehumidified to a water content of 1 ppm or less.

Next, using the Ar gas and CH ₄ gas obtained above, a steel (SKH 11) punch was coated with a TiC thin film using a PVD apparatus as shown in FIG. The formed film had very small crystals, was uniform, and had no defects such as pinholes. In addition, Ar (water content 20ppm), CH
₄ Compared to the TiC thin film formed by sputtering the same punch as above using a gas (water content: 30 ppm), if the gas is not dried, the one with a life of 50,000 times is
It has improved to over 200,000 times.

(Ii) again The same results as above were obtained for the hollow fiber membrane of the polytetrafluoroethylene copolymer having the repeating unit of (ion exchange capacity = 0.94 meq / g H type dry resin).

Example 9 (i) Disc-shaped aluminum-magnesium alloy (AA 508
6) was used as a substrate, and while gradually raising the temperature to 220 to 260 ° C., the moisture content was adjusted to 1 ppm by the moisture separator assembled in Example 8 using chromium as a target and a thin film forming apparatus. In dehumidified Ar gas atmosphere (10 ^-2 Tor
r) A substrate with an underlayer was prepared by performing magnetron sputtering for 1.5 minutes. A Co ₈₀ Ni ₂₀ magnetic layer with a thickness of 0.06 μm was formed on this chromium layer by magnetron sputtering (in the same equipment and atmosphere as above).
A carbon protective film layer having a thickness of 0.02 μm was provided.

Using the magnetic disk thus obtained, CS
S test (contact start stop test, this is a magnetic disk mounted on Winchester drive,
This is a test that measures the output reduction rate (%) by repeating start, operation, and stop. ) Was done. The results are as follows. CSS output reduction rate (%) 10,000 0 20,000 0 30,000 0 40,000 1 50,000 4 (ii) Almost the same results were obtained for the hollow fiber membrane of the polytetrafluoroethylene copolymer having the repeating unit of (ion exchange capacity 0.94 meq / g H type dry resin).

Comparative Example 1 A magnetic disk was manufactured in the same manner as in Example 9 except that the magnetron sputtering in Example 19 was performed in an Ar gas atmosphere having a water content of 20 ppm. The same CSS test as above was performed on this magnetic disk. The results are as follows. CSS output reduction rate (%) 10,000 0 20,000 0 30,000 4 40,000 7 50,000 12

[Brief description of drawings]

FIG. 1 is a graph showing the relationship between the dry heat treatment temperature and the equilibrium water absorption of the polymer semipermeable membrane obtained in the production example, and FIG. 2 is the production example.
Ion exchange capacity 0.8-
A graph showing the relationship between the polymer water absorption rate (W) and the ion exchange capacity (Q) of the polymer semipermeable membrane of 1.1, FIG. 3 is a conceptual diagram of a water separator used for carrying out the method of the present invention, Figure 4 is CV
A conceptual diagram showing the position where the water separator is used in the D device or PVD device, Fig. 5 is a graph for obtaining the maximum temperature without heat shrinkage of the hollow fiber membrane, where the horizontal axis is temperature and the vertical axis is It is the ratio of the length (L _t ) of the hollow fiber membrane at t ° C. to the length (L ₂₅ ) at a temperature of 25 ° C. FIG. 6 is a graph showing the relationship between the heat treatment temperature (t) of the hollow fiber membrane and the maximum temperature without heat shrinkage. The heat treatment temperature can be determined from this graph. FIG. 7 is a schematic explanatory view showing the PVD device. 1 ... Hollow fiber membrane, 2 ... Sample gas inlet 3 ... Sample gas outlet 4 ... Purge gas inlet (closed when decompressing) 5 ... Purge gas outlet (decompressing when reducing pressure) 6 ... Cell, 7 ...... Separator, 8 ...... Moisture separator 9 ...... CVD or PVD device 10 …… Various cylinders, 11 …… Cock (valve) 12 …… Target (cathode), 13 …… Substrate (anode) 14 …… Substrate stand 15 …… Gas outlet (to vacuum pump) 16 …… Film forming chamber, 17 …… Gas inlet 18 …… PVD equipment

 ─────────────────────────────────────────────────── ─── Continuation of the front page (31) Priority claim number Japanese Patent Application Sho 60-168624 (32) Priority date Sho 60 (1985) August 1 (33) Priority claim country Japan (JP)

Claims (2)

[Claims] 1. A method of forming a thin film on a base material placed under a reduced pressure or normal pressure atmosphere, wherein a gas for forming a thin film is introduced into a system of reduced pressure or normal pressure to form a thin film on the surface of the base material. In coating with, the gas for forming a thin film is brought into contact with one side of the fluorinated copolymer film having a cation exchange group, and the dry purge gas is brought into contact with the other side, or the other side is brought into contact. A method for forming a thin film, which comprises using a gas for forming a thin film, which is dehumidified by reducing the pressure. 2. A film forming chamber capable of reducing pressure to normal pressure, a gas inlet for introducing gas into the film forming chamber from a gas supply source, and a pressure reducing means for sucking gas in the film forming chamber, In addition, the thin film forming apparatus is provided with a water separation means between the gas inlet and the gas supply source, wherein the water separation means has a large number of hollow fiber membranes made of a fluorinated copolymer having a cation exchange group. A thin film forming apparatus, characterized in that the thin film forming apparatus is inserted into the main casing, fixed at both ends with a resin, and formed so that another kind of gas can pass through the inside and outside of the hollow fiber membrane.