JPH036204A - Method for forming plasma polymerization film - Google Patents

Abstract

PURPOSE:To obtain the subject film wherein the skeleton of a starting gas is kept intact by decomposing the starting gas with a plasma which has been transferred from the site of electric discharge to the site of starting gas decomposition and depositing the decomposition product on a base. CONSTITUTION:A vacuum chamber 1 is evacuated and a base heater 10 is energized by a heating power supply 17 to heat a base 2 placed on a support 8. While keeping this state, an electric discharge gas (a) is introduced into the chamber 1 from an electric discharge gas source 4 and an electric discharge voltage is applied to an electric discharge induction coil 6 from an RF power supply 3 to generate a plasma. The plasma is transferred from the site of electric discharge to the site of starting gas (b) decomposition in a period of time which is longer than the time taken for the afterglow of the plasma to disappear and mixed with the gas (b) supplied from a monomer source 5 to decompose the gas (b), and the decomposition product is deposited on the base 2 to give the subject film.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a method for producing a plasma polymerized film in which the skeleton of a raw material gas is retained.

(Technical Technology) The conventional method for forming a plasma polymerized film is to evacuate the vacuum chamber A as shown in Fig. 4, and place M! A discharge gas a is introduced from the gas TMB, and then a discharge voltage is applied to the discharge induction coil E1.1 from the RF power source to generate plasma, and a raw material gas b is introduced into the vacuum chamber A from the monomer supply source F. The raw material gas b and the plasma are mixed at a location G away from the plasma discharge location to decompose the raw material gas, and the decomposition products are placed on a support H in the vacuum chamber A. Further, the plasma polymerized film was deposited on the substrate J heated by the heater I to form a plasma polymerized film on the open substrate J.

Note that K is a power supply for the heater, and L is a vacuum exhaust system.

(Problems to be Solved by the Invention) In the conventional plasma polymerization film forming method, when raw material gas is decomposed by plasma, there is insufficient effort to control the energy of electrons in the plasma and the excited species in the plasma. As a result, the decomposition control of the raw material gas by plasma is insufficient, and the skeleton of the raw material gas is gently destroyed by the plasma, and the resulting plasma polymerized film retains the skeleton of the raw material gas. I was told that it had not been done.

If the skeleton of the raw material gas is destroyed, for example, when making a conductive film, the conductivity will be interrupted at the location where the skeleton is destroyed, so the film will not become conductive.

For example, when forming a film on an optical device, light is disrupted at locations where the skeleton is broken, resulting in poor optical transmission efficiency.

For this reason, it has conventionally been thought that film forming methods using plasma polymerization are not suitable as a method for producing films in which the skeleton of the raw material gas is not destroyed.

(Object of the Invention) An object of the present invention is to provide a method for forming a shiso film by plasma polymerization, which enables the production of a film in which the skeleton of the raw material gas is not destroyed.

(Means for solving the problem) The method for forming a plasma polymerized film of the present invention involves generating discharge plasma in the vacuum chamber 1 shown in FIG. The raw material gas is decomposed by mixing it with gas at a location away from the discharge location,
In a method for forming a plasma polymerized film in which the decomposition products are deposited on a substrate 2 installed in the vacuum chamber 1 to generate a plasma polymerized film on the substrate 2, plasma decomposes raw material gas from a discharge location. The time required for the discharge plasma to travel from the discharge location to the decomposition location is made longer than the time required for the afterglow of the discharge plasma to dissipate, thereby significantly destroying the skeleton of raw gas molecules present in the plasma while traveling from the plasma discharge location to the decomposition location. A method characterized by relaxing high-energy excited species and high-energy electrons to be destroyed and mixing this energy-relaxed plasma with raw material gas to form a plasma-polymerized film in which the skeleton of raw material gas molecules is maintained. It is.

FIG. 1 shows an example of a film forming apparatus used in the plasma polymerized film forming method of the present invention.

In the figure, l is a vacuum chamber and 2 is a substrate.

3 is an RF power source, 4 is a discharge gas source, 5 is a monomer supply source,
6 is an induction coil for discharge, and 7 is a vacuum exhaust system.

8 is a substrate support stand, 9 is an RF electric field shielding plate, 10 is a heater for heating the substrate, 11 is a gas flow meter, 12 is a pressure gauge, 13 is a capacitive vacuum gauge, 14 is a discharge gas introduction tube, 15 is a discharge gas A support part for the introduction pipe, 16 is an O-ring for preventing leakage, and 17 is a heater power source.

The RF electric field shielding plate 9 prevents the RF electric field from leaking near the substrate 2, causing glow discharge, etc. near the substrate 2, and generating new high-energy excited species and high-energy electrons that destroy the skeleton of raw material gas molecules near the substrate 2. This is to prevent it from being generated.

Adjust the height of the discharge gas introduction tube 14 with the support part 15, and
The distance between the electric power station and the decomposition site at the raw material gas supply position can be adjusted.

In order to form a polymer film using the film forming apparatus shown in FIG.
is placed on the substrate support stand 8 in the vacuum chamber 1, the chamber 1 is evacuated, and power is supplied from the heater power source 17 to the substrate heating heater 10 to heat the substrate 2. It is desirable that the temperature of the substrate 2 is normally between room temperature and 400°C. In this state, discharge gas a is introduced into the vacuum chamber 1 from the discharge gas source 4, and the internal pressure of the vacuum chamber 1 is set to 0.1 to
Adjust the gas flow rate so that it is below rr. discharge gas a
For this purpose, a rare gas such as Ar, or an inert gas such as hydrogen or nitrogen which cannot form a film by itself is used.

After introducing the discharge gas, the RF power source 3 applies a discharge voltage to the discharge induction coil 6 to generate plasma. In the film forming apparatus shown in FIG. 1, plasma is generated by an induced RF discharge, but the plasma generation method is not limited to this; for example, a parallel plate type RF discharge may be used.
The discharge may be performed at any frequency from C to microwave.

At this time, a raw material gas b different from the electric gas a 7a is introduced into the vacuum chamber 1 from the monomer supply source 5. The raw material gas b may be either organic or inorganic.

In the present invention, while the plasma moves from the plasma discharge location to the decomposition location, the skeleton of the raw material gas molecules present in the plasma is destroyed. It relaxes high-energy excited species and high-energy electrons that break down. The time required for high-energy excited species and high-energy electrons to relax in the plasma can be evaluated by the time required for the afterglow of the discharge plasma to disappear, so the plasma moves from the discharge location to the decomposition location of the raw material gas. The time required for this to occur is longer than the time required for the afterglow of the /ffl electric plasma to disappear.

Therefore, in the present invention, the distance between the plasma discharge location and the raw material gas decomposition location is adjusted so that the time required for the discharge plasma to travel from the discharge location to the raw material gas decomposition location is longer than the distance.

At this time, the possible value of L is the internal pressure of 100 mt.

In the pressure range below rr, it is given by the following equation.

L. + = 1f760 + Pot F) /
f60・P・sl X v <LF Discharge gas flow rate (S
CCM) I], the internal pressure of the vacuum chamber (torr) S: the cross-sectional area of the discharge gas introduction tube (cm"), the time required for the afterglow of the discharge plasma to disappear (sec) Po: the gas internal pressure of the discharge gas supply source The value of the (torr) distance mL must be larger than the value of L inf, but if it is too large, the plasma will diffuse or the energy will become extremely low, which will significantly reduce the efficiency of plasma polymerization. Even if the distance is large, L inf is 100
It is desirable that it be less than twice that.

(Function) The plasma polymerized film forming method of the present invention makes the time required for the plasma to move from the discharge location to the decomposition location of the raw material gas longer than the time required for the afterglow of the discharge plasma to disappear. , the time it takes for the plasma to move from its discharge location to its decomposition location is increased, and during that time, high-energy excited species and high-energy electrons that destroy the skeleton of raw gas molecules present in the plasma are removed or annihilated and relaxed. . For this reason, the destruction of the skeleton of raw material gas molecules by these excited species and high-energy electrons is suppressed.

A plasma polymerized film is produced that retains the skeleton of the raw material gas.

(Example 1) Using the plasma polymerized film forming apparatus shown in FIG. 1, toluene was used as the raw material gas, argon was used as the discharge gas a, the discharge gas flow rate was 11005 cc, and the discharge gas partial pressure was 20 m t o.
r r, internal pressure of vacuum chamber 1 21 mtorr, r
ll The cross-sectional area of the electric gas introduction pipe 14 is 0.2 cm2. Discharge gas supply source 1! A plasma polymerized film was formed at a gas pressure of 1140 torr.

Under these conditions, the time required for the afterglow of the discharge plasma to disappear is 5 usec, and the value of Lint' is 2.4 cm. Film formation was performed with a distance of 5 cm. The film forming time was 60 minutes, and the temperature of the substrate 2 was 150°C. The substrate 2 used was a glass slide with gold vapor-deposited on its surface.

When the infrared absorption spectrum of the polymer film obtained in this example was measured, the spectrum shown in FIG. 2 was obtained. This spectrum is in good agreement with that of polystyrene. This shows that the methyl groups of toluene are partially and selectively split and polymerized, and that the toluene skeleton is thereby retained even in the plasma polymerized film.

(Comparative Example 1) For comparison with Example I, an experiment was conducted with the distance m+- being 1 cm. Other conditions were the same as in Example 1.

When the infrared absorption spectrum of the polymer film obtained in Comparative Example 1 was measured, the spectrum shown in FIG. 3 was obtained. This spectrum is significantly different from that of polystyrene, indicating that the skeleton of the raw material gas is not retained in the plasma polymerized film.

(Comparative Example 2) For comparison with Example 1, an experiment was conducted with the distance fiL set to 20 cm. Other conditions are the same as in Example 1. The infrared absorption spectrum of the polymer film obtained in Comparative Example 2 was measured. The spectrum is similar to that of polystyrene, but it can be seen that the spectral intensity has weakened due to the plasma dispersion along the way.

(Example 2) In order to change the value of L inf in Example 1, an experiment was conducted by changing the value of the discharge gas flow rate as follows.

Discharge gas flow ffi: 200SCCM, discharge gas partial pressure 1
0 mtorr, internal pressure of vacuum chamber 1 = 21 mtorr
The cross-sectional area of the r, H electric gas introduction tube is 10 m2. Under these conditions, the time required for the afterglow of the discharge plasma to disappear is 5 μsec, and the value of Linf is 0.1 cm. Film formation was performed with a distance of 5 cm. The infrared absorption spectrum of the film obtained in this example is consistent with that of pus obtained in Example 1, indicating that the skeleton of the raw material gas is retained even in the plasma polymerized film.

(Comparative example 3) Film formation was carried out in Example 2 except that the distance was changed to 15 cm.

In this case, no plasma polymerized film was obtained on the substrate 2.

(Example 3) In Example 1, a plasma polymerized film was formed using aniline as the raw material gas. As a result of constant infrared absorption spectra of the polymerized film thus obtained, it was found that there was a large amount of aniline skeleton in the film, and that the skeleton of the raw material gas was retained in the plasma polymerized film.

(Example 4) In Example 1, a plasma 1 composite film was formed using PNA (paranitroaniline) as the raw material gas. As a result of measuring the infrared absorption spectrum of the polymerized film thus obtained, it was found that a large amount of PNA skeleton was present in the film, and that the skeleton of the raw material gas was retained even in the plasma polymerized film.

(Example 5) In Example 1, a plasma polymerized film was formed using ethylamine as the raw material gas. As a result of measuring the infrared absorption spectrum of the polymer film thus obtained, it was found that the film contained C-H, C-N,
There are many N-H bonds, but C=C, C=N, C=N
It was found that there were almost no bonds and that the destruction of ethylamine by the plasma was very low.

(Example 6) In Example 1, hexamethyldisiloxane, S
i (CH313-0=S i ((j1313
A plasma polymerized film was formed using the following method. As a result of measuring the infrared absorption spectrum of the resulting polymer film, it was found that there were many 5i-0-5i, 5i-C, and 5i-CF13 bonds in the film, and the destruction of hexamethyldisiloxane by plasma It was found that there were very few.

(Effects of the Invention) The method for forming a plasma polymerized film of the present invention has the following effects.

(2) This has been considered difficult with conventional plasma polymerization. It is possible to create a polymer film that retains the skeleton of the raw material gas.

(2) Since the skeleton of the raw material gas is not destroyed, it is possible to produce, for example, conductive films with good conductivity or films for optical devices with good transmission efficiency.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram showing an example of a film forming apparatus used in the plasma polymerized film forming method of the present invention, FIG. 2 is an infrared absorption spectrum diagram of the polymerized film obtained in Example 1, and FIG. The figure is an infrared absorption spectrum diagram of the plasma polymerized film obtained in Comparative Example 1, and FIG. 4 is an explanatory diagram of a film forming apparatus used in the conventional method for forming a plasma polymerized film. 1 is a vacuum chamber 2 is a base

Claims (1)

[Claims] A discharge plasma is generated in the vacuum chamber 1, and the plasma and the raw material gas supplied into the vacuum chamber 1 are mixed at a place away from the discharge location to decompose the raw material gas, and the decomposition products are removed from the vacuum chamber 1. In a method for forming a plasma polymerized film in which the plasma polymerized film is deposited on a substrate 2 installed in a chamber 1 to generate a plasma polymerized film on the substrate 2, the time required for the plasma to move from the discharge location to the decomposition location of the raw material gas is The time is longer than the time required for the afterglow of the discharge plasma to dissipate, and the high energy excited species and high A method for forming a plasma polymerized film, characterized by relaxing energetic electrons and mixing this energy-relaxed plasma with a raw material gas.