JPS60242614A - Deposition film forming method - Google Patents

Abstract

PURPOSE:To enable to form a thick deposition film of large area by a method wherein excitation energy is formed using a specific annular silicon compound as raw meterial, and a deposition film containing silicon atoms is formed using low level heat energy. CONSTITUTION:In the method wherein the excitation and decompositional condition of raw gas are formed by giving heat evergy and, especially, an amorphous silicon (a-Si) deposition film is formed on a specific supporting member, the silicon compound gaseous atmosphere indicated by a general formula (provided that R<1> and R<2> indicate H or the alkyl radical of 1-3C, m indicates the integral number of 3-7, and n indicates the integral number of 1-11) is formed as the raw gas to be decomposed by heat energy. By exciting and decomposing said compound utlizing the heat energy, an a-Si deposition film of low energy level can be formed at a high film forming speed, and the a-Si deposition film which is excellent in electrical and optical characteristics and the stability in quality can be formed. The deposition film is formed in a deposition chamber 1.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a deposited film forming method for forming a photoconductive film, a semiconductor film, or an insulating film on a predetermined support using heat as excitation energy. , by applying thermal energy to excite and decompose the raw material gas,
The present invention particularly relates to a method of forming a deposited film of amorphous silicon (hereinafter abbreviated as a-3i) on a predetermined support.

Conventionally, glow discharge deposition and thermal energy deposition using SiH4 or Si286 as a raw material are known as methods for forming a-Si deposited films. That is, these deposition methods use SiH4 or Si2 as a raw material gas.
This is a method of decomposing H6 using electrical energy or thermal energy (excitation energy) to form a deposited film of a-3i on a support, and the deposited film formed can be a photoconductive film, a semiconductor film, an insulating film, etc. It is used 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 high-power discharge has a large effect on the film inside the film, making it difficult to ensure the uniformity of electrical and optical properties and quality stability of the formed film, causing disturbances on the film surface during deposition, and damage to the inside of the deposited film. 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 a high temperature of 400°C or higher, which limits the support materials that can be used, and in addition, useful bonded hydrogen atoms in the desired a-Si are separated. Since the probability increases, it is difficult to obtain desired characteristics.

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

This low-calorie 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-3T deposited films at a low energy level. It is something that makes it possible. In addition, the lower the temperature, the easier it is to uniformly heat the raw material gas, making it possible to form a high-quality film that maintains uniformity with lower energy consumption than the above-mentioned deposition method. It is easy to control and stable reproducibility can be obtained, and there is also the advantage that there is no need to heat the support to a high temperature and that selectivity to the support is widened.

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 characteristics and stability of quality even in the formation of a large-area, thick deposited film. The goal is to provide a way to do so.

As a result of intensive studies, the present invention was completed after discovering that these objects can be achieved by using a compound having a cyclic structure composed of silicon atoms and carbon atoms as a raw material gas that is decomposed by thermal energy. It is what was done.

That is, in the deposited film forming method C of the present invention, in the deposition chamber in which the donor is placed, the following general formula;
2 each independently represents H or an alkyl group having 1 to 3 carbon atoms, mζ±3 to 7 integer, n represents an integer from 1 to 11) forming a gaseous atmosphere of a silicon compound; Exciting the compound using thermal energy,
A deposited film containing silicon atoms is formed on the support by decomposition. The raw material for forming the deposited film used in the method of the present invention is composed of silicon atoms and carbon atoms. It is a silicon compound having a cyclic structure, and is characterized by being easily excited and decomposed by thermal energy, and is represented by the general formula above.

Among such compounds, in the above formula, m is 3 to
It is preferably an integer of 7, more preferably 3 to 6.
, is optimally an integer from 3 to 5. That is, when the number of silicon atoms in the compound is 3 or more, the bond between adjacent silicon atoms, especially the bond between a silicon atom sandwiched between two silicon atoms and another silicon atom bonded to the atom, It becomes unstable due to relatively low excitation energy and decomposes into radicals. On the other hand, as the number of directly bonded silicon atoms in a compound increases, it becomes easier to undergo radical decomposition due to excitation energy (lower).
If the number of directly bonded silicon atoms is 8 or more, the quality of the formed a-Si film will deteriorate, which is not preferable.

Therefore, in order to efficiently excite and decompose and deposit a high-quality a-3i film, the number of silicon atoms in the compound is preferably 3 to 7 degrees, more preferably 3 to 6 degrees, and most preferably It is desirable that it is 3-5.

In addition, the number of carbon atoms to achieve the cyclic structure consisting of silicon atoms and carbon atoms in the above formula is from 1 to 11, which is easy to synthesize, easily gasifies, and has high decomposition efficiency with thermal energy. Therefore, it is suitable for use in the method of the present invention.

Typical silicon compounds used in the method of the present invention include the following compounds.

2 2 H2H2 2 2 H2H2 2 H2H2 2 (CH3)2 (CH3)2 (CH3)2 (CH3)2 H2 CCH3)2 (CH3)2 (CH3)2 (CH3)2 (CH3)2 In the method of the present invention In this case, such a silicon compound was introduced into the deposition chamber so as to be at least gaseous within the deposition chamber, thermal energy was given to it, it was thermally excited and thermally decomposed, and the silicon compound was placed in the deposition chamber. A deposited film (a-5i film) containing silicon atoms is formed on the support.

Next, imparting thermal energy to the silicon compound gas introduced into the deposition chamber includes a Joule heat generating element;
This is carried out using high frequency heating means or 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 describe an embodiment using a Joule heat generating element, a heater is placed in contact with or close to the back surface of the support to conductively heat the surface of the support, thermally excite and thermally decompose the raw material gas near the surface, and transfer the decomposition products to the support. Deposit on the surface. 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-5T on a support.

Formation of the deposited film takes place inside the deposition chamber 1.

Reference numeral 3 placed inside the deposition chamber 1 is a support base on which a support is placed.

This is a heater for heating the 44-piece support, and power is supplied to the heater 4 through a conductive wire 5. A gas introduction pipe for introducing a-3t raw material gas and gases such as a carrier gas used as necessary 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, and 13-4 are pressure meters, which are used to measure the pressure on the high pressure side of the corresponding flow meter.

The gases that have passed through the flow meters 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, gas supply source 9. The number of to, 11° and 12 may 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 raw material gas (catalyst gas, carrier gas, etc.) is mixed, two or more 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 raw material gas obtained by vaporization is introduced into the deposition chamber 1 through a flow meter.

Using the apparatus shown in FIG. 1 and 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 1.

Various types of supports 2 can be used depending on the purpose of the deposited film formed. Materials that can form the support include, for example, NiO2, ST7less, An, and Cr for the conductive support.

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

Metals such as Pd or alloys thereof, and semiconductive supports include 1. Semiconductors such as St and Ge, and electrically insulating supports include synthetic resins such as polyester, polyethylene, polycarbonate, cellulose acetate, polypropylene, polyvinyl chloride, polyvinylidene chloride, polystyrene, polyamide, glass, ceramics, paper, etc. can be mentioned. The shape and size of the support 2 are determined as appropriate depending on the intended use.

In particular, in the method of the present invention, the temperature of the support is 150°C.
Since the temperature can be relatively low at around 300°C, it is possible to use materials with low heat resistance that cannot be applied to conventional glow discharge deposition methods or thermal energy deposition methods. It is now possible to use other supports.

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 in the deposition chamber under reduced pressure is 5XLO-5 Torr or less, preferably 1O-
BTorr or less is desirable.

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

As described above, since the support temperature is relatively low in the method of the present invention, it is possible to use the glow discharge barrel stacking method or the SiH4,5
Since there is no need to heat the support to high temperatures as in thermal energy deposition methods using i2Hs as raw material, the energy consumption required for this purpose can be saved.

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-3T 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 lO~11
0003 cc, preferably in the range of 20 to 5003 CCM.

The pressure of the raw material gas in the deposition chamber 1 is 10-2 to 100 Torr.
r, preferably maintained in the range of to-2 to ITorr.

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-5i, 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 forming rate of about 5 to 50 pieces/SeC can be obtained. Decomposition products other than a-3i 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-Si film is formed on the support 2, and a
- When the desired film thickness of Si 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-3i
The film thickness of the film is appropriately selected depending on the intended use of the formed a-Si film.

Next, after the gas in the deposition chamber is removed by driving an exhaust device (not shown), when the support and the deposited film reach room temperature, the valve 21 is opened to gradually introduce atmospheric air 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-5i film thus formed on the support by the method of the present invention is an a-3i 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, thermal energy with a low calorific value is used as excitation energy, and a source gas that is easily excited and decomposed by the thermal energy is used, so that a high film formation rate can be achieved. It has become possible to form an a-3i deposited film at a high 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 the silicon compound No.
The formation of a -5i (7 mol 77 Si) film was performed as follows.

First, a support (trade name: Corning #7059) and a transparent conductive film (polyester base)) are 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) into the deposition chamber. The internal pressure was reduced to 1O-6 Torr, the heater 4 was energized to maintain the support temperature at 230°C, and then the valves 14-1 and 16-1 of the raw material supply source 9 filled with silicon compound No. 4 were turned on. It was opened, and the source gas was introduced into the deposition chamber 1.

At this time, the gas flow rate was adjusted to 150 secM while measuring with the corresponding flow meter 15-1. Next, the pressure inside the deposition chamber was reduced to 0. Keep ITorr, thickness 4000 people (7)
An a-Si film was deposited on support 2 at a deposition rate of 13 people/SeC.

Note that the 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 T film was performed by adding a comb-shaped AI gap electrode (length 2
50 color width 5mm) and photocurrent (light irradiation intensity AM
This was done by measuring the dark current (I: about 100 mW/cm2) and calculating the photoconductivity σP and the ratio of the photoconductivity σP to the dark conductivity σd (σP/σd).

Note that the gap electrode is a
-Put the 3T film into the vapor deposition tank, and add the nuclide once to 1 (lGTor).
After reducing the pressure to a vacuum level of r, the vacuum level is reduced to 1 (15 Torr).
The deposition rate was 20 people/sec, and the deposition rate was 150.
AI was deposited on the a-3i film to a film thickness of 0.05 mm, and this was etched to form a pattern using a pattern mask having a predetermined shape.

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

Examples 2 to 5 Silicon compounds listed in Table 1 were used as starting materials for forming deposited films: No. 6, No. 1 O, No.

Using each of No. 13, No. 20 (Examples 2 to 5) individually, an a-3t film was formed in the same manner as in Example 1, and the obtained a-3i film was formed in the same manner as in Example 1. It was evaluated as follows. The evaluation results are shown in the table below.

Comparative Example 1 An a-Si film was formed in the same manner as in Example 1 except that 5i2He was used as a raw material for supplying Si, and the obtained a-3i film was evaluated in the same manner as in Example 1. The evaluation results are shown in Table 1.

"' To summarize the results of Examples 1 to 5 and Comparative Example 1, as shown in the evaluation results in Table 1, when the support temperature was 230"C, the film formation rate was higher than that of Comparative Example. While the film formation rate in No. 1 was 6 people/sec,
Example 4 of the present invention A good film deposition rate of 17 to 27 people/sec was obtained in 5°C, and in any of Examples 1 to 5 of the present invention, , photoconductivity σ
P is 5X10-5 to 1.5X10-4, and σP/σd
is 1.0X104 to 1.0X105. ! -Showed good values.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram of an example of a deposition M film forming apparatus used in the method of the present invention. 1: Deposition chamber 2: Support 3: Support 4: Heater 5: Conductor 6-1.6-26-3 = Gas flow 9, 10, 11° 12: Gas supply source 13-1
．． 13-2゜13-3.13-4.18: Pressure meter 14-1.14-2.14-3.14-4. Ward 16-
1.16-2.16-3.16-4. ．． 17.17-
1.17-2.17-3゜17-4: Gas introduction pipe
Advantage: Corporate Strength 20: Gas Exhaust Pipe Applicant: Canon Co., Ltd.

Claims (1)

[Claims] (1) In the deposition chamber in which the support is placed, the following general formula; forming a gaseous atmosphere of a silicon compound represented by an integer of l-'t, n is an integer of t, and applying thermal energy to the compound to form a deposited film containing silicon atoms on the support. A method for forming a deposited film, characterized in that: