JPS60241220A - Formation of accumulated film - Google Patents

Abstract

PURPOSE:To form an accumulated film which contains silicon atoms at a high speed with thermal energy of low level while maintaining high quality by employing a silicon compound having at least one azide group bonded directly with silicon atom as row material gas. CONSTITUTION:A heater 4 is provided in an accumulation chamber 1, and a support 2 and a supporting base 3 are heated by the heater 4 to 150-300 deg.C. Raw material gas and carrier gas for forming a-Si are respectively stored in gas supply sources 9-12. Gas of silicon compound having at least one azide group bonded directly with silicon atom is fed to the chamber 1. The gas is heated by the surface of the support 2 to form an accumulated film on the surface of the support 2.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a deposited Mi film forming method that uses heat as excitation energy to form a photoconductive film, a semiconductor film, or an insulating film on a predetermined support. By applying energy, the raw material gas is excited and decomposed, and amorphous silicon (hereinafter referred to as a
-5i)).

Conventionally, glow discharge deposition and thermal energy deposition using SiH4 or 5i2-H6 as a raw material are known as methods for forming a-5i deposited films. That is, these deposition methods use 5i)(4 or 5i2) as the raw material gas.
This is a method in which HB is decomposed using electrical energy or thermal energy (excitation energy) to form a deposited film of A-3i on a support. It is used as a film for various purposes.

However, in the glow discharge deposition method, in which the deposited film is formed under high-power discharge, it is difficult to control reproducible and stable conditions, such as not always achieving a uniform discharge distribution state, and furthermore, the film formation The effects of high-power discharge on the film inside are severe, making it difficult to ensure the uniformity of electrical and optical properties and quality stability of the formed film, resulting in disturbance of the film surface during deposition and damage to the deposited film. internal defects are likely to occur. In particular, it has been extremely difficult to form a thick deposited film with uniform electrical and optical properties using this method.

On the other hand, the thermal energy deposition method also requires high temperatures, typically 400°C or higher, which limits the support materials that can be used. This increases the probability of failure, making it difficult to obtain desired characteristics.

Therefore, one way to solve these problems is to
A-3i low heat energy deposition method (thermal CVD) using silicon compounds other than SiH4 and Si2H6 as raw materials
is attracting attention.

This low-heat thermal energy deposition method uses low-temperature heating instead of the glow discharge or high-temperature heating in the above-mentioned methods as excitation energy, and allows the production of a-5I deposited films at low energy levels. It is something that makes it possible.

In addition, the lower the temperature, the easier it is to uniformly heat the raw material gas, and the energy consumption is lower than that of the above-mentioned deposition method.
It is possible to form a high-quality film that maintains uniformity, it is easy to control manufacturing conditions, and stable reproducibility can be obtained, there is no need to heat the support to high temperatures, and there is good selectivity to the support. There is also the advantage of expanding.

The present invention has been made in view of the above points, and uses low-level thermal energy as excitation energy to form a deposited film containing silicon atoms at a high deposition rate while maintaining high quality at a low energy level. The object of the present invention is to provide a thermal energy deposition method that can be used.

Another object of the present invention is to form a high-quality deposited film that ensures uniformity of electrical and optical properties and stable quality even in the formation of a large-area, thick deposited film. The goal is to provide a method that can be used.

As a result of intensive studies, the present invention was completed after discovering that these objects can be achieved by using a silicon compound having at least one azide group that directly bonds with a silicon atom as a raw material gas that is decomposed by thermal energy. It is what was done.

In other words, in the deposition method of the present invention, a gaseous silicon compound having at least one azide group directly bonded to a silicon atom is introduced into a deposition chamber in which a support is placed, and thermal energy is applied to the compound. and forming a deposited film containing silicon atoms on the support.

The raw materials for forming a deposited film used in the method of the present invention are:
It is a silicon compound that has at least one azide group that is directly bonded to a silicon atom, and is characterized by being easily excited and decomposed by thermal energy. Representative examples include those shown by the structural formula below. I can do it.

In the above formula, R1, R2, R3, and R4 each independently represent hydrogen, halogen, or an alkyl group having 1 to 4 carbon atoms, an aryl group, or an alkoxy group.
Note that the alkyl group, aryl group, or alkoxy group having 1 to 4 carbon atoms may be substituted with other substituents, and R1 to R4 do not need to be different from each other, for example, all of R1 to R4 are methyl groups. In some cases.

Among these compounds, preferred are compounds represented by the following structural formulas.

N3 N3 In the method of the present invention, such a silicon compound is introduced into the deposition chamber so that it becomes gaseous at least within the deposition chamber, and thermal energy is applied to it to excite and decompose it.

A deposit M (a-S j film) containing silicon atoms is formed on a support placed in a deposition chamber.

Next, heat treatment and energy application to the silicon compound gas introduced into the deposition chamber are performed using a Joule heat generating element, high frequency heating means, and the like.

Examples of the Joule heat generating element include heaters such as heating wires and heating plates, and examples of the high frequency heating means include induction heating and dielectric heating.

To explain the embodiment using the Joule heat generating element, the heater is brought into contact with or close to the back surface of the support to conductively heat the surface of the support, thermally excite and decompose the raw material gas near the surface, and the decomposition products are transferred to the surface of the support. to be deposited.

Alternatively, it is also possible to place the heater near the surface of the support.

Hereinafter, the method of the present invention will be explained in detail with reference to FIG.

FIG. 1 is a schematic diagram of a deposited film forming apparatus for forming a functional film such as a photoconductive film, a semiconductor film, or an insulating film made of a-5i on a support.

Formation of the deposited film takes place inside the deposition chamber l. Deposition chamber l
Reference numeral 3 placed inside is a support stand on which the support body is placed.

Reference numeral 4 denotes a heater for heating the support, and power is supplied to the heater 4 through a conductive wire 5. The inside of the gas introduction pipe for introducing the raw material gas of a-3i and gases such as carrier gas used as needed into the deposition chamber 1 is connected to the deposition chamber 1.

The other end of this gas introduction pipe 17 is connected to gas supply sources 9, 10, 11, 12 for supplying the raw material gas and gases such as carrier gas used as necessary. Gas supply source9. to.

In order to measure the flow rate of each gas flowing out from 11.12 toward the deposition chamber 1, a corresponding flow meter 15-1.
15-2.15-3.15-4 is provided in the middle of the corresponding branched gas introduction pipe 17-1°17-2.17-3.17-4. Valve 1 is installed before and after each flow meter.
4-1.14-2.14-3.14-4゜16-1.1
6-2.16-3.16-4 are provided, and by adjusting these valves a predetermined flow rate of gas can be supplied. 13-1°13-2.13-3.13-4. is a pressure meter, and is used to measure the pressure on the high pressure side of the corresponding flow meter. The gases that have passed through the flowmeter are mixed and introduced into the deposition chamber 1 under reduced pressure by an exhaust device (not shown). In addition, the pressure meter 18 measures the total pressure in the case of mixed gas.

A gas exhaust pipe 20 is connected to the deposition chamber 1 in order to reduce the pressure inside the deposition chamber 1 and to exhaust the introduced gas.

The other end of the gas exhaust pipe is connected to an exhaust device (not shown).

In the present invention, the number of gas supply sources 9, 10, 11, 12 can be increased or decreased as appropriate.

That is, when using a single raw material gas, one gas supply source is sufficient. However, when two types of raw material gases are mixed and used, or when a single gas (catalyst gas, carrier gas, etc.) is mixed, two or more gases are required.

Note that some raw materials do not turn into gas at room temperature and remain liquid, so when using liquid raw materials, a vaporizer (not shown) is installed. There are two types of vaporizers: those that utilize heating and boiling, and those that pass a carrier gas through a liquid raw material. The source gas obtained by vaporization is introduced into the deposition chamber 1 through a flow meter.

By using the apparatus shown in the first factor and using the method of the present invention, a deposited film consisting of a-3i can be formed in the following manner.

First, the support body 2 is set on the support stand 3 in the deposition chamber l.

Various types of supports 2 can be used depending on the purpose of the deposited film formed. Examples of materials that can form the conductive support include N1CfL, Stare L/S, Al, and Cr.

Mo, Au, Nb, Ta, V, Ti, Pt.

Metals such as Pd or alloys thereof; semiconducting supports include semiconductors such as Si and Ge; electrically insulating supports include
Polyester, polyethylene, polycarbonate, cellulose acetate, polypropylene, polyvinyl chloride,
Examples include synthetic resins such as polyvinylidene chloride, polystyrene, and polyamide, glass, ceramics, and paper. The shape and size ti of the support 2 are appropriately determined depending on the intended use.

In particular, in the method of the present invention, the temperature of the support is 150°C.
Because it can be used at a relatively low temperature of ~300″C, it is difficult to apply to conventional glow discharge deposition methods or conventional thermal energy deposition methods among the materials for forming the support. It has now become possible to use supports made of materials with low heat resistance.

After the support 2 is placed on the support stand 3 in the deposition chamber 1 in this way, the air in the deposition chamber is exhausted through the gas exhaust pipe 20 by an exhaust device (not shown) to reduce the pressure. The atmospheric pressure inside the deposition chamber under reduced pressure is 5X10-5 Torr or more, preferably 1O-
It is preferable to use less than 11iTorr.

When an electric heater 4 is used as the thermal energy imparting means, the heater 4 is energized to heat the support 3 to a predetermined temperature after the inside of the deposition chamber 1 has been reduced in pressure. The temperature of the support at this time is 150 to 300°C, preferably 200 to 300°C.
The temperature is assumed to be 250°C.

In this way, in the method of the present invention, the support temperature is relatively low, so it is possible to use the glow discharge deposition method or the 5fH4,5t
This saves time and required energy consumption, since there is no need to heat the support to high temperatures as in thermal energy deposition methods using 2H6 as a raw material.

Next, each of the valves 14-1 and 16-1 of the supply source 9 storing gases of the raw material compound for forming the a-3i film as mentioned above is opened, and the raw material gases are released. Deposition chamber l
Send it inside.

At this time, the flow rate is adjusted while being measured by the corresponding flow meter 15-1. Usually, the flow rate of the raw material gas is 10 to 11
0003CC, preferably in the range of 20 to 5'003CCM.

The pressure of the source gas in the deposition chamber 1 is 1O-2 to 100 Torr.
r, preferably maintained in the range of 10-2-tTorr.

In this way, thermal energy is imparted to the raw material gas flowing near the surface of the support 2, promoting thermal excitation and thermal decomposition, and a-3t, which is a product, is deposited on the support.

As mentioned above, the raw material gas used in the method of the present invention is easily excited and decomposed by thermal energy.
A high film formation rate of about 5 to 50 people/sec can be obtained. Decomposition products other than a-3t and undecomposed surplus raw material gas are discharged through the gas exhaust pipe 20, while new raw material gas is continuously supplied through the gas introduction pipe 17.

In the method of the present invention, thermal energy is used as excitation energy, but since the application is not a high amount of heat but a low amount of heat, the energy is always applied uniformly to a predetermined space occupied by the raw material gas to be provided. can.

The deposited film in the process of being formed is not affected by high-power discharge as observed in the glow discharge deposition method, and uniformity is maintained without disturbing the film surface or causing defects within the deposited film during deposition. The formation of the deposited film continues.

In this way, an a-3t film is formed on the support 2, and a
When the desired film thickness of -5t is obtained, the application of thermal energy from the heater 4 is stopped, and further the valve 14-1.
16-1 is closed and the supply of raw material gas is stopped. a-3t
The thickness of the film is appropriately selected depending on the intended use of the formed a''5ifi.

Next, after the gas in the deposition chamber is removed by driving an exhaust device (not shown), the valve 21 is opened when the support and the deposited film reach room temperature, and atmospheric air is gradually introduced into the deposition chamber.
The inside of the deposition chamber is returned to normal pressure, and the support on which the a-3i film is formed is taken out.

The a-3i film thus formed on the support by the method of the present invention is an a-3t film with excellent uniformity of electrical and optical properties and stability of quality.

In the example of the method of the present invention described above, the deposited film was formed under reduced pressure, but the present invention is not limited to this, and the method of the present invention can be formed under normal pressure or under pressure as desired. It can also be carried out under pressure.

According to the method of the present invention as described above, a low amount of thermal energy is used as excitation energy, and a raw material gas that is easily excited and decomposed by the thermal energy is used, thereby achieving a high film formation rate. It has become possible to form an a-5i deposited film at a low energy level, and it has become possible to form an a-3t deposited film with excellent uniformity of electrical and optical properties and stability of quality.

Therefore, in the method of the present invention, supports made of materials with low heat resistance that cannot be applied to conventional glow discharge deposition methods or conventional thermal energy deposition methods can also be used. It has become possible to save energy consumption required for high-temperature heating.

Hereinafter, the method of the present invention will be explained in more detail according to examples.

Example 1 Using the apparatus shown in FIG. 1 and using silicon compound No. 1 listed in Table 1 as a starting material for forming a deposited film,
The a-3i (Amol 77-Si) film was formed as follows.

First, a support (trade name: Corning #70597', transparent conductive film (polyester base, manufactured by Dow Corning)) is set on the support stand 3 in the deposition chamber 1, and the gas exhaust pipe 20 is passed through the exhaust device (not shown). ) by deposition chamber l
The internal pressure is reduced to 1O-6 Torr, and the heater 4 is energized to raise the support temperature to 200'C! and then the valve 14-1 of the raw material supply source 9 filled with silicon compound No. 1.
．． 16-1 was opened, and the raw material gas was introduced into the deposition chamber 1.

At this time, the gas flow rate was adjusted to 1503 CCM while measuring with the corresponding flow meter 15-1. Next, the pressure inside the deposition chamber was reduced to 0. Keep ITorr, thickness tooo person a-
The 3i film was deposited on support 2 at a deposition rate of 20 people/sec.

Table 1 Note that thermal energy was uniformly applied to the gas flowing near the entire surface of the support 2 disposed in the deposition chamber 1. At this time, decomposition products other than a-3i and surplus raw material gases that were not decomposed were discharged through the gas exhaust pipe 20, while new raw material gas was continuously supplied through the gas introduction pipe 17.

Thus formed by the method of the present invention. a-3
Evaluation of the i film was performed by adding a comb-shaped AI gap electrode (length 2
50JLrt15mm), the photocurrent (light irradiation intensity AMI: approximately 100 mW/0m2) and dark current were measured, and the ratio of the photoconductivity σP and dark conductivity σd (σP/
σd).

Note that the gap electrode is a
-3i film is placed in a deposition tank, and the tank is heated once to 10-6T o
After reducing the pressure to a vacuum level of r r, the vacuum level is reduced to 1O-5T.
orr, and the deposition rate was 20 people/sec.
Al was vapor-deposited on the a-3i film to a thickness of 1,500 yen, and this was etched using a pattern mask having a predetermined shape to form a pattern mask.

Table 2 shows the obtained P values and σP/σd ratios.

Examples 2 to 4 Using each of silicon compounds No., 2 to No. 4 (Examples 2 to 4) listed in Table 1 as starting materials for forming a deposited film, a-3i films were formed. It was formed in the same manner as in Example 1, and the obtained a-S i li was evaluated in the same manner as in Example 1. The evaluation results are shown in Table 2.

Comparative Example 1 An a-3i film was formed in the same manner as in Example 1 except that S i 2H6 was used as the raw material for supplying a-3i, and the σd of the obtained a-3illi was determined in the same manner as in Example 1. It was measured. The measurement results are shown in Table 2.

Examples 5 to 8 Each of silicon compounds No. 1 to No. 7 (Examples 8 to 14) listed in Table 1 was used individually as a triggering substance for forming a deposited film, and the support temperature was set at 250°C. An a-5i film was deposited in the same manner as in Example 1 except that the setting was made as follows.

The obtained &-3i film was evaluated in the same manner as in Example 1.

The evaluation results are shown in Table 3.

Comparative Example 2 An a-3t film was formed in the same manner as in Example 8 except that S i 2H6 was used as the raw material for supplying a-3i, and the σd of the obtained a-3i film was set in the same manner as in Example 8. It was measured using The measurement results are shown in Table 3.

To summarize the results of Examples 1 to 8 and Comparative Example 1.2 above, as shown in the evaluation results in Tables 2 and 3, the film formation rate was as follows when the support temperature was 200°C. The film formation rate in Comparative Example 1 was 10 persons/sec, whereas the film formation speed in Example 1.4 of the present invention was 2.
0 inputs/see, and when the support temperature was 250°C, the t and H speeds in Comparative Example 2 were 12 people/s.
In Example 5.8 of the present invention, a good film forming rate of 23 to 25 people/sec was obtained, whereas in any of Examples 1 to 8 of the present invention, Even in the case where the photoconductivity σP is 2.3XIO-5 to 1.2X10
Masu, Mata σP/σd is 4. l X I O3~8X1
It showed a good value of 04.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram of an example of a deposited film forming apparatus used in the method of the present invention. 1: Deposition chamber 2: Support 3: Support 4: Heater 5: Conductor 6-1.6-2゜6-3 = Gas flow 9, 10, 11゜12: Gas supply source 13-
1.13-2゜13-3.13-4.18: Pressure meter 16-1.16-2.16-3.16-4゜21: Valve 15-1.15-2,15 to 5 17- 1.17
-2.17-3.17-4: Gas introduction pipe 2 t-2
0: Gas exhaust pipe

Claims (1)

[Claims] Introducing a silicon compound having at least one azide group directly bonding to a silicon atom in a gaseous state into a deposition chamber in which a support is disposed, applying thermal energy to the compound,
A method for forming a deposited film, comprising forming a deposited film containing silicon atoms on the support.