JPS63118075A - Coating method by glow discharge - Google Patents

Abstract

PURPOSE:To form a high-purity coated film having excellent characteristics by introducing the vaporized gas of a metal halide and a treating gas into a vessel, generating glow discharge, and periodically and intermittently supplying the vaporized gas while keeping the discharge. CONSTITUTION:An article 2 to be treated is arranged in the closed vessel 1 kept at <=10<-1>Torr by an evacuation system 6. The halide of a metal or semimetal component element to be used for the desired coated film such as TiCl4 contained in a vessel 15 is vaporized by a carrier gas 12 such as gaseous H2, gaseous Ar, or their mixture, and the vaporized gas is introduced into the closed vessel 1. A gaseous diluent 12b such as gaseous H2 or gaseous Ar and a gaseous reactant 12c such as hydrocarbons, N2, etc., are simultaneously introduced. Glow discharge is generated by a DC power source 4 in the vicinity of the article 2 to be treated, hence the gases are excited and dissociated, and the film of TiC, TiN, etc., is deposited on the surface of the article 2 to be treated. In this case, the vaporized gas is periodically and intermittently supplied while keeping the glow discharge.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a method for surface treatment of members by glow discharge,
In particular, the present invention relates to a coating method using glow discharge that can reduce impurities mixed into a coating formed on the surface of an object to be treated and obtain a highly pure treated layer.

[Conventional technology]

The CVD method is being actively developed as a surface treatment method using glow discharge. Among these CVD methods, the DC plasma CVD method is common, and the metal surface is coated with TIC or TI.
It is used to coat N, etc.

FIG. 2 is a schematic diagram of a DC7' lasma CVD apparatus.

Two examples of TIC or TIN i coating will be described using conventional DC plasma CVD technology.

A member to be processed 2 is placed in a sealed container 1, with the member to be processed 2 serving as a cathode and the sealed container itself serving as an anode.

The inside of the sealed container is maintained at a vacuum level of 10-" Torr or less using the vacuum evacuation system 6. Inside the sealed container, a carrier gas (hydrogen, argon, or a mixture thereof) is pumped into the 12Al octalogonide storage container 15. to vaporize the halide and introduce it into the sealed container 1 together with a diluent gas (hydrogen, alcohol, or a mixture thereof) 12b.When coating the entire TIC or TIN, the halide is.

TIC14 etc. are used. First, as a reaction gas, hydrocarbon gas for TIC, nitrogen or ammonia gas for TIN is introduced into the sealed container 1, and direct current pressure is applied by the power source 4 to generate glow emission, and the target to be treated is TIC or t'! on the surface of member 2. TkN'i micoating. Since the plasma CVD method utilizes the excitation and dissociation effects of atoms and molecules in plasma, it is possible to form a film at a lower temperature than the normal thermal CVD method.

Halogen tends to remain in a film produced by the DC plasma CVD method. As a result, the purity of the film decreases, causing problems such as uneven gloss or cloudiness on the film surface, and a decline in functional properties such as adhesion at the interface with the substrate, film hardness, and corrosion resistance. there were.

As a technology to reduce halogen contamination in membranes by 1tt.

A method using hydrogen is shown, for example, in JP-A-58-1068. In this method, after the halogen gold mixed in the film is formed, hydrogen is reacted with hydrogen by glow discharge in a hydrogen atmosphere and removed as hydrogen halide. In this method, the halogen remaining on the very surface of the membrane is reduced or removed by hydrogen ion bubbling, thereby cleaning the membrane, and over time a beautiful glossy surface can be obtained. However, if the film is thick.

Reduction reactions within the membrane are difficult to occur, and halogen remains. This is because the atomic radius of halogen is large,
This is because it is difficult to diffuse within the membrane and leave. It is possible to raise the temperature to a high temperature in order to completely diffuse the halogen inside the film, but although this would make it possible to remove the halogen inside the film, the film would be damaged by heating and the P# characteristic of plasma CVD, which is formed at a low temperature, would be reduced. is selected.

In addition, CV'D in which film formation is performed at, for example, 700 to 1200°C
A method is also considered, but it has the problem that the discharge pressure becomes high and the discharge becomes non-uniform, making it more likely that the surface treatment cannot be uniformly applied to the workpiece due to the temperature difference. ing.

As a solution, there are, for example, a method of performing ion treatment in a conventional vacuum heat treatment furnace, or a method of performing ion treatment while applying high frequency heating from the outside. However, in the former case, the workpiece is heated by a heater such as carbon fiber, which requires high output from the side heating power source.
Since heating by ions is reduced, the amount of ions reaching the surface of the processed item is also reduced compared to conventional treatment using only ions. Therefore, the structure of the grooves in the device is complicated, the control is complicated, the overall energy consumption is large, and the concentration of atoms involved in the cleaning action of ions and the processing of atoms captured on the surface is also reduced.

In the latter case, if many parts are installed in the furnace, the heated temperature will vary depending on the distance from the high-frequency coil, and as in the former case, the heated temperature will vary depending on the distance from the high-frequency coil. 1! Controlling the output of the source becomes complicated. In addition, a large amount of energy is required for the treatment, and there is also a drawback in terms of ion cleaning action and control of the ion concentration on the surface.

Another conventional technique for reducing halogen in films is disclosed in Japanese Patent Application Laid-open No. 1983
-70767. For example, this method involves arranging multiple cathodes at regular intervals apart from the cathode that surrounds the object to be processed inside a vacuum container around the outer periphery of the object to be processed. metal halides,
Introducing hydrogen, methane or nitrogen gas to increase the gas pressure,
By generating glow discharge by controlling the gap between the cathodes and the power output, etc., a hollow cathode discharge with a high density is generated between the cathode and the object to be treated, and the surface to be treated is heated and maintained at a high temperature. This process forms a film. In this treatment, as shown in FIGS. 3 and 4, an auxiliary electrode 5 for completely forming a hollow cathode discharge is placed separately from the cathode 2 to be treated 8. FIG. 5 is a perspective view of the arrangement of the supply pipe and the workpieces shown in FIG. 4. In such a method, 1! of reactive species are generated near the treated area! Since the packing density can be increased, a high-quality coating can be uniformly formed over the entire surface at high speed compared to the method using only glow discharge described above. However, as the gap between the auxiliary electric tank and the workpiece becomes smaller, the supply of new gas into that space becomes less luminous, and the residence time of the reactive gas, that is, hydrogen halide, in that space becomes shorter. As a result, the purity of the halogen remaining in the film may decrease.

Another prior art technique for reducing halogen in membranes is shown in Japanese Patent Application Laid-Open No. 61-56273.

That is, a part has a structure in which the reaction gas substance/it is decomposed and excited and activated by plasma in a space that does not directly reach the surface of the workpiece in a reduced pressure reaction chamber, and a part that guides the activated gas to the surface of the workpiece. By being fully equipped with this, activated reactive species can be supplied at a high concentration near the surface of any workpiece, and new reactive gas can also be constantly supplied to the space to be activated, so that the activated reactive species can be By uniformly distributing the particles, a high-purity, high-quality, and homogeneous film can be formed at high speed. Such processing is
This can be done by arranging the processing apparatus shown in FIG. 6 and the electrodes having the structure shown in FIG. However, even in this method, the reactive species is activated within the electrode with a very high concentration.

The reaction product gas, such as hydrogen halide, is adsorbed onto the surface of the member to be treated.

May remain in the coating. In order to reduce this phenomenon, increasing the distance between the electrode and the workpiece will reduce the residual t, but this will also reduce the amount of activated reactive species reaching the workpiece, resulting in a decrease in the film formation rate. There is a tendency to

[Problem that the invention seeks to solve]

As described above, the plasma CVD method uses glow radiation t' to generate low-temperature plasma gold, and this plasma activates all reactive species to form a film at a relatively low temperature and at high speed.

In all conventional technologies, reaction products remain in the membrane.

In particular, insufficient consideration was given to reducing halo R7.

There is a problem that the properties of the resulting film are insufficient or highly variable.

The purpose of the present invention is to provide a high-purity film with excellent characteristics, with less contamination of reaction product impurities, especially halogen, in the formed film in the plasma CVD method including not only the DC plasma CC method but also the RF plasma CVD method. An object of the present invention is to provide a coating method for forming a gold coating.

[Means to solve the problem]

The above object is achieved in the plasma CVD method by periodically intermittent supply of vaporized gas of metal or metalloid metal or metalloid while maintaining glow discharge.

The above plasma CVD method includes D, C, plasma CVD methods and 'R, F, plasma C■ methods.
DC plasma CVD with an auxiliary electrode described in the "Prior Art" section or the "Example" section, auxiliary 1tffl
and DC plasma CVD with a gas introduction tube and a metal counter electrode,
Parallel plate type RF plasma CVD and hexode fJAR
This includes F plasma CvD.

[Effect]

By intermittent supply of the halide vaporized gas, the concentration of the gas near the object to be treated is periodically reduced. For this reason, the film formation rate is periodically reduced or the bottom film is stopped.

- By maintaining a glow discharge, the surface of the coating is sputter-cleaned to remove reaction products, mainly halogens, that are incorporated into the coating.

Therefore, films containing less reaction products can be sequentially deposited.

There are also concerns about continuing the supply of hydrogen gas.

Since the reaction product incorporated into the film reacts with hydrogen and is removed, films containing even less one reaction product can be sequentially deposited.

〔Example〕

Example 1 The apparatus used was a DC7'' plasma CVD apparatus shown in FIG. 4 having an auxiliary TV/I and gas supply means shown in FIG. 9.

FIG. 4 shows the CVD apparatus used in Example 1.

In this figure, 1 is a furnace body, and an upper cover and a lower cover are fixed to the upper and lower openings of a hollow cylindrical body via backings, and are in a sealed state. Reference numeral 2 denotes an article to be processed which becomes a cathode, and is held by a rotating holding member 3 connected to a rotating cathode terminal 8. The other end of this rotating cathode terminal 8 is connected to one pole of the t source 4 by a rotating power supply mechanism 9. 17t, the rotation holding member 3 is rotated by the rotary electric motor 21, and A
Ru. Inner and outer cylindrical auxiliary electrodes 5 a s 5 b are arranged near the object 2 to be processed, one end of which is connected to the cathode side.

A gas supply pipe 17 for processing gas is also arranged within this auxiliary electrode. FIG. 5 shows the detailed structure of the article to be processed 2, the auxiliary electrodes 5m and 5b, and the gas supply pipe 17. An electrode structure in which cylindrical auxiliary electrodes 5m, 5b'i are arranged facing each other while sandwiching the object 2 to be processed, and the object 2 to be processed and the auxiliary electrodes 5m, 5b'
A gas supply pipe 17 is disposed so as to be located on the circumference between. The cylindrical auxiliary electrode 5a + -5b is
The inner circumferential surface of the auxiliary electrode 5a and the outer circumferential surface of the auxiliary electrode 5b face each other in a concentric circle, and a pin-shaped workpiece 2 is placed on the concentric circle in between.
are arranged, and furthermore, the inner peripheral surface of the auxiliary electrode 5a and the workpiece 2,
A plurality of branched gas supply pipes 17 are arranged on a circle between the outer peripheral surface of the auxiliary electrode 5b and the object to be processed.

The object to be processed 2 and one end of the auxiliary electrodes 5m+5b are connected to the cathode of the power source. Processing gas is supplied to the gas supply pipe 17 from the fourth
It is supplied by the mechanism shown in the figure. In addition, the gas supply pipe 17
is provided with a plurality of gas ejection ports 22, from which processing gas is ejected toward the workpiece 2.

In order to uniformly form a film with a target composition, it is necessary to uniformly distribute the processing gas. For this purpose, the object to be processed, or both of them, is completely moved across the processing gas supply pipe. For example, the position is changed intermittently or continuously by rotating or reciprocating the processing gas supply pipe. Similarly, when both the article to be treated and the processing gas supply pipe are completely moved, the article to be treated is also relatively moved. It is also preferable to consider the size of the gas jet ports and their distribution state.

By creating such a gas distribution state.

A film with the desired composition is formed with uniform distribution.

In addition, by adjusting the appropriate equivalence ratio and supplying nine reactive gases to the space between the object to be treated and the auxiliary electrode, or the space between the auxiliary electrodes through a gas supply pipe, a glow discharge with high ionization density is generated. , increasing the bottom membrane velocity.

Here, the processing gas supply/control system is shown in FIG. 4. The carrier gas 121 is supplied by the flow rate controller 13 &, and the gas inlet side and outlet side flow rate controllers 13 d and 13@ of the halide vaporized gas ogonide storage container 15 are supplied. Control. This is used when bypassing the carrier gas to the flow rate controller 13f, and by closing the gas inlet side flow rate controller 13d and the outlet side flow rate controller 13 of the container 15, the flow rate of the carrier gas that does not contain halide is increased. It is something to control. The flow rate controller 13b is a gas that reacts with a halide (hereinafter referred to as reaction gas) 12b'i, flow! The controller 13c controls the dilution gas 12c.

In Example 1, the carrier gas 12a and the diluent gas 12a
Hydrogen gas as hydrogen gas, TiCl2 total as halide,
Nitrogen gas was used as the reaction gas 12b.

The flow rate-controlled t''L treatment gas is introduced into the gas supply pipe 17 in the furnace body 1 through the entire gas rotation supply mechanism 16 which is electrically insulated by an insulating layer 18.

Next, the gas concentration control cycle will be explained. 1st
The figure shows changes in gas concentration and treatment temperature over time. The concentrations of the carrier gas and diluent gas maintain constant values after the initial discharge stabilizes, as shown by curve a. The carrier gas 12m closes the flow rate controllers 13d and 13e, and the pi/? By controlling the gas flow rate controller 13f to keep the gas constantly flowing, it is possible to supply and maintain the gas concentration without large fluctuations. The diluent gas 12b is maintained at a constant level by a flow rate controller 13b. - 10,000, the halide gas concentration is determined by intermittent supply of halide gas periodically as shown in the curve. That is, the film forming step A and the film cleaning step B are repeated. The film forming step A'''C is a period in which all processing gases are supplied to form a film.In the film cleaning step B, the supply of halide gas is stopped and hydrogen gas is supplied to clean the inside of the film. The reaction gas 12c may be kept constant by the flow rate controller 13e, or may be supplied only to the film forming step A to increase the gas concentration.

The flow rate controller 1'3 for halide is used only in film forming process A.
The carrier gas 12m is supplied while being controlled by d and 13e, and the gas concentration is maintained at a high level. At this time, the flow rate controller 13f is closed. By controlling the gas concentration in this way, a reaction gas is supplied depending on the halide and purpose in the film forming step A, and a film is formed. In the film cleaning process, a carrier gas and a diluent gas, or in some cases a reaction gas, are supplied, and these gases are used to perform cleaning by cleaning or degassing and reduction reaction with hydrogen gas, and the reaction products of halide are removed. A film is formed in which no or only a very small amount of is mixed.

It should be noted that since the halogens incorporated into the film deposited in each film forming process A are removed in the film cleaning process B that immediately follows, the thickness of the deposited film must be such that it can be cleaned. Depending on the process conditions, the total time for each film forming process must be determined. In other words, if the processing time of the film forming step A becomes longer and the film becomes thicker, the sputter cleaning, degassing, and reduction reaction will occur only on the surface of the film, and the reaction products of the halide will remain inside the film. It's a good thing. Note that each film cleaning step needs to be sufficiently long.

This is because even if the supply of halide gas is stopped, the halide gas remains in the gas piping or around the object to be treated for a certain period of time, and the gas concentration immediately becomes 0 (!). In Example 1, the coating The processing times of the forming step A and film cleaning step B were 1 minute and 3 minutes, respectively, and these steps were repeated 20 times.

As described above, by repeatedly forming an ultra-thin film that is cleaned in the film cleaning step B to form a film of the desired thickness, a film that does not leave any reaction products of halide etc. can be formed. Can be done.

The part to be processed (- is a pin for aluminum die-casting mold made of JIS standard SKD 61 hot die steel 61 type (diameter Lo)
A stepped structure with a height of 120 m was used.

The auxiliary electrodes 5a and 5b in FIG. 5 have a height of 150 m, the inner diameter of the auxiliary electrode 5a is 340 m, and the outer diameter of the auxiliary electrode 5b is 250 m, and both are made of mild steel with a thickness of 5 mm. A bin for the workpiece 2 is placed on a circumference of 295 m in diameter, which is the middle of the inner diameter of the auxiliary electrode 5a and the outer diameter of the auxiliary electrode 5b. Approximately 5
12 trees were installed at intervals of 0 gardens. A total of 12 gas supply pipes 17 were provided, two each at an angle divided into six equal parts in the space between the auxiliary electrodes 5a, 5b and the bottle of the object to be processed 2. This gas supply pipe is provided with a large number of gas jet ports 22 each having a diameter of 0.8 to 1.5 mm and increasing in size toward the end within a range of the end 130xm.

The coating process was performed by evacuating the inside of the furnace body 1 to a vacuum level of 5×10 Torr or less using the vacuum pump 6, and then introducing the processing gas whose flow rate was adjusted as described above.
A DC voltage of ~900 V was applied to generate high ionization density plasma in the space between the workpiece 2 and the auxiliary electrodes 5a, 5b. The treatment temperature was 900°C. As a result, TIN
A coating film is formed with a thickness of about 4 μm, and T
The ratio of the chemical composition of I and N was close to 1. Also, E
PMA (Electron Probe Micro
Analyzer) showed that no chlorine was detected. The surface hardness is about Hv2200 in terms of Vickers hardness.
, indicating a sufficiently hard value. Therefore, the coating contains HCj and NH4C, which have an adverse effect on properties such as hardness.
It is clear that a highly pure TIN film was formed, with no contamination of l, or even if there was, the amount was so small that it could not be detected. In addition, HCl.

NT (4Ct) is a reaction product of TlC44, N2 and N2.

On the other hand, the 7'l-TIN coating formed by the conventional method had a Vickers hardness of about 900 Hv, which was a low value. ``f 7'h According to EPMA, a Ct peak is recognized, and the ratio of Ct to the detected intensity of T1 is 0,
It was 06. Therefore, it is clear that impurities remain in the HC7 or NH4C6 state in the film formed by the conventional method.

As described above, it is clearly confirmed that according to this example, a TIN film with less contamination of impurities can be formed.

Also regarding the devices shown in Figures 1'c, g2 and 3.

As a result of the same treatment, HCl, NH2C
A highly pure TiN film containing no 1 was obtained.

Example 2 A DC plasma CVD apparatus shown in FIG. 6 was used.

Using the electrode structure with the gas supply port shown in Fig. 7, the processing gas concentration will be as shown in the curve shown in Fig. 1.
N coating was performed. 4 fiWc as a processed member
-Co-based cemented carbide tips (15x15x5t) were used. The object to be treated 2 is installed in a jig insulated from the cathode and anode, and facing the electrode 5', which also has a gas supply port, the distance from the gas supply port of all electrodes to the object to be processed 21 is 20 m. Arranged. Note that the pole 5' has a structure as shown in Figure 7. A large number of gas supply ports 22 each having a diameter of 0.5 W are arranged on the side of the electrode 5' facing the member 2 to be processed.
A plurality of plates 24 made of SUS 304 with a height of 15 cm and a thickness of 2 cm are arranged at intervals of 4 m+ in the longitudinal direction surrounding the board.

In the coating process, the pressure inside the furnace body 1 is reduced to 10 Torr or less using a vacuum bomb 7°6, and the diluent gas 12
c using hydrogen gas and controlling it with the flow rate controller 13c.
A glow discharge is generated on the electrode 6 by applying DC pressure of ~100 OV, and a high electric current Rq! ! Degree release 1! All occurred. At this time, no glow discharge occurs in the member to be processed 2, and the electrode 5'
It is heated and maintained at 900°C by radiant heat from.

Next, Bc entered Denbe as a B source halide.
t, the gas was kept at a temperature of 20° C. and was vaporized while being controlled by a gas flow rate controller, and ammonia gas was supplied as the reaction gas 12b while being controlled by a flow rate controller 13b. In addition, B.C.
Since l3 has a high vapor pressure, no carrier gas was used in this example.

The concentration cycle of these processing gases was such that the processing time of the film forming step A was 30 seconds and the film cleaning step B' was 2 minutes, and these steps were performed 30 times. Note that the reaction gas 12b
The ammonia gas was not supplied in film cleaning step B, and the same gas concentration was maintained during the curve. In this way,
A BN coating process was performed at 900° C. for a total film formation time of 15 minutes and a film cleaning time of 60 minutes.

-1' for comparison, the conventional method was also treated by supplying BCl3, ammonia and hydrogen gas for 15 minutes.

As a result, according to the method of the present invention, a BN coating film with a thickness of 3 μm was formed, and the crystal structure was determined by X-ray diffraction.
It was h-BN because it is exagonal.

In addition, in X@diffraction, this h'-BN and W of the processed member
Only the diffraction lines of the e-Co cemented carbide were identified, and the diffraction lines of impurities such as NI (4C4) were not identified. Even in the surface analysis results using E-Habutsu, no Ct peak was observed. Therefore, the method of the present invention It is clear that a high purity BN film has already been formed.

On the other hand, the BN film formed by the conventional method is prone to peeling and
A C4 peak was also observed in the PMA analysis, and the ratio of the C2 peak height to Tl was 0.04. In this way, it is thought that the film formed by the conventional method is likely to peel off because the reaction product of (logonide) remains as an impurity. - In this example, it is possible to form a high-purity film with few residual impurities and a film with good E adhesion.

Example 3 Parallel plate type R, F, plasma CVD shown in Fig. 8 (1)
Using the same equipment as in Examples 1 and 2, the same treatment as in Examples 1 and 2 was carried out to obtain a coating with high purity. By appropriately selecting the bias voltage, it is possible to adjust the time ratio of hollow cathode discharge to n-density even during the film forming process, and the purity distribution in the film thickness direction can be made more uniform.

Hexode type R, F, plasma Cv shown in Figure 8(b)
The TiN film and BN film were exploded using D equipment.

A highly pure membrane was obtained.

〔Effect of the invention〕

According to the present invention, it is possible to produce a membrane with good purity and excellent properties, with a low concentration of halogens that are harmful to the membrane properties. In particular, since it is possible to make the rhodan concentration distribution uniform and low in the film thickness direction, it is suitable for producing thick films with excellent properties.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing the processing gas concentration and processing temperature in the present invention, FIG. 2 is a schematic diagram of a typical C plasma CVD apparatus, FIG. 3 is a schematic diagram of a DC plasma CVD apparatus having an auxiliary electrode, and FIG. The figure shows D with auxiliary electrode and gas supply pipe.
A schematic diagram of the C plasma CVD apparatus, Figure 5 is an auxiliary diagram of Figure 4! Layout diagram of poles, gas supply pipes and processed items, No. 6
In the figure, the product to be processed is electrically neutral, and D is equipped with all counter electrodes.
A schematic diagram of the C plasma CV'D apparatus, FIG. 7 is a perspective view of the counter electrode in FIG. 6, and FIGS. 8(a) and (b) are R
It is a schematic diagram of an F7' lasma CVD apparatus. 1...Furnace body, 2...Product to be processed, 3.
...Rotation holding member, 4...DC power supply, 5a *
sb... Auxiliary electrode, 5'... Special pole, 6... Vacuum exhaust system, 7... Anode terminal, 8... Rotating cathode terminal, 9... Rotating power supply mechanism, 11. ...Vacuum probe, 121L, 12b, 12e...Carrier, reaction, diluent gas, 13...Gas flow control system, 13a*13b+13as13d, 13e*13f -
...Flow rate controller, 15...Halide storage container, 16...Gas rotation supply mechanism, 17...Gas supply pipe, 21...Electric motor. 22...Gas outlet, 24...8US 30
4 board. 25...High frequency power supply.

Claims (1)

[Claims] 1. A processing gas whose main components are a vaporized gas of a halide of the metal or metalloid component element of the target film, hydrogen gas, an inert gas, or a mixture thereof is introduced into the container, and a glow is generated near the object to be processed. A method of generating a discharge to excite and dissociate the gas to deposit a film on the surface of the object to be treated, characterized in that the supply of the vaporized halide gas is periodically interrupted while maintaining the glow discharge. Coating method using glow discharge.