JPS60219730A - Forming method of deposited film - Google Patents

Abstract

PURPOSE:To uniformalize characteristics by a method wherein a deposited film is formed, exciting and decomposing by photo energy after forming gaseous atomsphere of cyclic silane compound and halogen compound. CONSTITUTION:A substrate 2 is placed on a supporting stand 3 inside a depositing chamber 1, and after decompressing inside the depositing chamber 1, the substrate 2 is heated by a heater 4. Secondly, valves 14-1, 16-1 of supply source 9 are opened and stock gas is sent into the depositing chamber 1. As the stock gas, cyclic silane compound is used. At the same time, valves 14-5, 16-5 are opened and halogen compound gas is introduced into the depositing chamber 1 from supply source 29. Consequently, a photo energy generator 7 is operated and irradiates the optical energy to the mixed gas, and then urges photo-excitation and photodecomposition. Thus, the amorphous Si which is formed is deposited on the substrate 2. As a result, a wide deposited film with good accuracy and good uniformity can be formed.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a deposited film forming method that uses light as excitation energy to form a photoconductive film, a semiconductor film, or an insulating film on a predetermined support -1-. In particular, by applying or using light and, if desired, heat, etc., the raw material gas is excited and decomposed, and placed on a predetermined support, in particular,
The present invention relates to a method for forming a deposited film of amorphous silicon (hereinafter abbreviated as a-9i).

Conventionally, methods for forming a-3i deposited films include SiH4,
Alternatively, a glow discharge deposition method and a thermal energy deposition method using Si2H6 as a raw material are known. That is, these deposition methods use 5iHa and 5i2H as source gases.
6 is electrical energy or thermal energy (excitation energy)
This is a method in which a deposited film of a-5i is formed on a support by decomposing the film, and the deposited film thus formed is used for various purposes such as a light guiding M film, a semiconductor or an insulating film, etc.

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 influence of high-power discharge on the film inside is large, and it is difficult to ensure the uniformity of the electrical and optical properties of the formed film.1 It is difficult to ensure the stability of the quality, and the film surface may be disturbed during deposition, resulting in a deposited film. In particular, it is difficult to form large-area or thick deposited films with uniform electrical and optical properties using this method. It was difficult for me.

-・For force and thermal energy deposition method, 1 usually 400'
Since a high temperature of C or higher is required, the number of support materials to be used is limited, and in addition, the desired i
Since the probability of detachment of a bonded hydrogen atom that is necessary increases, it is difficult to obtain desired characteristics.

Therefore, one way to solve these problems is to
The a-3i light energy Il+ planting method (photoCVD) using SiH4,5i7H6 as the raw material 4 has recently been attracting attention.

This optical energy deposition method uses light as the excitation energy instead of glow discharge or heat in the aforementioned methods, and allows the production of a-3i deposited films at low energy levels. Ta. In addition, it is easy to uniformly irradiate the source gas with light energy, resulting in high-quality film formation that maintains uniformity with lower energy consumption than the deposition methods described above. Furthermore, the production conditions can be easily controlled and stable reproducibility can be obtained.Furthermore, there is no need to heat the support to a high temperature, and the selectivity with respect to the support is widened.

However, with such optical energy deposition methods using SiH4 and Si2H6 as raw materials, there is a limit to how much efficient decomposition can be expected, and therefore the film formation speed cannot be improved, making it difficult to mass-produce. It has been pointed out that there is a problem.

The present invention was developed in view of these problems, and it is possible to form a deposited film containing silicon atoms at a low energy level at a high film formation rate while maintaining high quality by using light as excitation energy. An object of the present invention is to provide a light energy deposition method.

Another object of the present invention is to provide uniform electrical and optical characteristics even in the formation of a large-area, thick deposited film.

An object of the present invention is to provide a method capable of forming a high-quality deposited film that ensures quality stability.

The present invention has achieved these objectives as a result of intensive studies.

The raw material residue for forming a δ-3i film that is decomposed by light energy has the following general formula;
It was discovered and completed that this can be achieved by using a cyclic silane compound represented by (iH3) in a mixed state with a halokene compound.

That is, in the deposited film forming method of the present invention, in a deposition chamber in which a support is arranged, the following general formula;
By forming a gaseous atmosphere of a cyclic silane compound and a halogen compound represented by (iH3), and using light energy to excite and decompose these compounds, silicon raw f- is deposited on the support. It is characterized by forming a deposited film containing.

The raw material for forming the a-9i deposited film used in the method of the present invention has the following general formula: (However, in the above formula, n is 3.4 or 5, and B is H or C.
It is a cyclic silane compound represented by H3.

Examples of such cyclic silane compounds include the following.

However, with such cyclic silane compounds, when light energy is used as excitation energy, efficient excitation 11 decomposition cannot be obtained, and a good tlf film formation rate is not achieved. I can't get it.

Therefore, in the method of the present invention, a halogen compound is mixed with the cyclic silane compound in order to more efficiently promote the excitation and decomposition of the cyclic silane compound by light energy.

The halogen compound mixed with the cyclic silane compound in the method of the present invention is a compound containing combined halogen atoms, and can more efficiently promote excitation and decomposition of the cyclic silane compound by light energy. It is something. Such halogen compounds include CI2, B
r2, I2. Examples include halogen gas such as F2.

In the method of the present invention, the proportion of the halogen compound mixed in the raw material compound for forming the a-Si film or the amount of a used
-Varies depending on the type of raw material compound and halogen compound for Si film formation, but 0.01 Volt to °65 Volt
L bf t L < is 0. I VolL ~50Vo
Used within the range of 1X.

In addition, in the cyclic silane compound represented by the above general formula, n is 6.
The above substances, in a mixed state with a halogen compound,
It is expected that the desired deposited film can be obtained by easy decomposition and low-energy excitation, but contrary to expectations, the quality of the photoconductive film and semiconductor film is poor, and in addition, defects on the surface of the film and the deposited film It was found that there was a lot of turbulence within the film, resulting in an uneven film. Therefore, if such a cyclic silane compound is used, it is difficult to control the production of the deposited film. Further, when n in the above formula is 2, it is also considered as a cyclic silane compound, but this compound is unstable and therefore difficult to isolate at present.

Therefore, n in the above formula is preferably 3.4 or 5.

In the present invention, light energy refers to energy rays that can generate sufficient excitation energy when irradiated to the raw material gas, and excite and decompose the raw material gas.
Any material can be used regardless of wavelength range as long as it can deposit decomposition products.

Examples of such light energy include ultraviolet rays,
Examples include I-visual rays, X-rays, and γ-rays, and can be appropriately selected depending on compatibility with the raw material gas.

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-9i on a support.

Formation of the HE implant takes place inside the deposition chamber 1.

11 [3 placed inside the tail chamber 1 is a support stand on which a 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. A gas introduction pipe 17 for introducing the raw material gas for the a-Si removal into the deposition chamber l and gases such as a carrier gas used as necessary; Gas introduction pipe 3
0 is connected to the deposition chamber l. The other end of the waste introduction pipe 17 is a gas supply source 9°IQ for supplying waste such as carrier waste used as necessary for the a-Si film forming film forming raw material compound.11. +2, and the other end of the waste introduction pipe 30 is connected to a gas supply source 29 for supplying a halogen compound. l! tied together.

It is preferable that the nitride compound and the halogen compound for forming the a-3i film are introduced separately into the deposition chamber 1. This means that when a mixed state flows through the gas introduction pipe,
These compounds react at the same time as they are mixed, decomposition of the raw material for forming the a-3i film occurs, and this decomposition product is deposited in the gas introduction pipe, which is undesirable because it contaminates the inside of the gas introduction pipe.

In order to measure the flow rate of each gas flowing out towards the deposition chamber 1 from the gas supply sources 9.1O111, 12, 29, corresponding flow meters 15-1.15-2.15-3°!
5-4. Branched gas introduction pipe corresponding to 15-5 +7-
1゜17-2.17-3.17-4 and gas introduction pipe 30
It is located in the middle of. There are valves 14-1.14-2.14-3.14-4.14- before and after each flow meter.
5, 18-1. +8-2°+5-3. +5-4.
18-5 are provided, and by adjusting these pulps a predetermined flow rate of gas can be supplied. +3-1.1
3-2.13-3.13-4.13-5 is a pressure meter, which is used to measure the pressure on the high pressure side of the corresponding flow meter.

Each gas that has passed through the flow meter is introduced into the deposition chamber l under reduced pressure by an exhaust device (not shown). Note that the pressure meter 18 measures the total pressure when the mixed sludge flows inside the gas introduction pipe 17.

11, a waste 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. Is the other end of the waste exhaust pipe an exhaust system (not shown)? 1.

7 is a light energy generator.

+11 If the planting chamber l is not made of a transparent material such as quartz glass, a window for irradiating the light energy 8 may be provided.

In unexploded IJ1, gas supply source 9jO, ll, 12
．． The number of 29 may be increased or decreased as appropriate.

That is, when using a medium-sized raw material gas, one gas supply source from 9 to 12 is sufficient. However, when mixing and using two raw material gases, or when mixing raw material gases with a width of -, two or more are required.

Note that for Kawahara's a-SiljQ formation (some compounds and halogen compounds do not turn into gases at room temperature and remain liquids, if they are used as liquids, a vaporizer (not shown) must be installed. There are some vaporizers that utilize heating boiling, and others that allow a carrier gas to pass through the liquid.The raw liquid 1 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 8-81 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 for forming the support include 1fNicI, stainless steel, Cr, No, ^u, Nb, Ta, and V.
, metals such as Ti, Pt, and Pd, or alloys thereof; conductive supports include semiconductors such as Sl and Ge; and insulating supports include polyester, polyethylene, polycarbonate, cellulose, Acetate, polypropylene, polyvinyl chloride, polyvinylidene chloride,
Examples include synthetic resins such as polystyrene and polyamide, glass, ceramics, and paper. 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 set at 50 to
Since the temperature can be relatively low at around 150°C, it is a material with low heat resistance that cannot be applied to the conventional glow discharge deposition method or thermal energy deposition method among the materials for forming the support described in L. It has now become possible to use supports made of

After the support 2 is placed on the support stand 3 in the deposition chamber 1 in this manner, 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 5×10″5 Torr or less, l[/suitably 1
0” Tart or less is desirable.

When the pressure inside the deposition chamber 1 is reduced, the heater 4 is energized to heat the support 3 to a predetermined temperature. The temperature of the support at this time is preferably 50 to 150°C, preferably 50 to 100°C.

As described above, since the support temperature is relatively low in the method of the present invention, it is not necessary to heat the support to a high temperature as in glow discharge deposition method or thermal energy deposition method. The energy consumption required for this can be saved.

Next, the valve 1 of the supply source 9 in which the gas of the raw material compound for 91 supply for forming the a-3i film as mentioned above is stored.
4-1.Open 16-1 to feed the raw material gas into the deposition chamber 1. At the same time, open the valves +4-5 and 16-5 to feed the halogen compound gas from the supply source 29 into the deposition chamber 1. Introduce.

At this time, adjust the flow rate while measuring with the corresponding flow meter 15-1.15-5.Normally, the flow rate of the raw material gas is l.
O~10005CCM, preferably 20~5009CC
A range of M is desirable.

The pressure of the raw material gas for a-SiM formation in the deposition chamber 1 is 10-
2-100 Torr, preferably 10-2 to 1 Torr
It is desirable to maintain it within the range of r.

Once the raw material gas for forming the a-Si film and the halogen compound gas have been introduced into the deposition chamber 1, the optical energy generator 17 is driven to irradiate the mixed gas with optical energy.

As the light energy generating bag W7, for example, a mercury lamp,
A xenon lamp, carbon dioxide laser, argon ion laser, or excimer-1 can be used.

An optical system (not shown) is incorporated so that the desired light energy generated by driving the light energy generating device 7 irradiates the support 2 installed in the deposition chamber 1.

The light energy can be applied uniformly to the gas flowing in the vicinity of the support 2 arranged in the deposition chamber 1 or by selectively controlling the ljQ radiation portion.

In this way, optical energy is imparted to the mixed gas flowing near the surface of the support 2, and the photoexcitation and photodecomposition of the raw material compound for a-Silfi formation is promoted more efficiently, and the produced substance a-9i is The raw material gas used in the method of the present invention, which is deposited on a support at a high film formation rate, is more easily excited and decomposed by light energy due to the action of the halogen compound as described above. 5-100
A film formation rate of about A/sec can be obtained. Decomposition products other than a-Si and surplus raw material gas that has not been decomposed are discharged through the gas exhaust pipe 20, while new raw material gas and halogen compound gas are continuously supplied through the gas introduction pipe 17.30. Ru.

In the method of the present invention, light energy is used as excitation energy, and this light energy is used in such a way that it can always uniformly irradiate a predetermined space occupied by the gas to be irradiated, that is, the excitation energy It is easy to control using an optical system so as not to cause uneven distribution of the light energy itself.

There is no effect of high-power discharge on the deposited film during the formation process, as observed in the glow discharge deposition method, and uniformity is maintained without disturbing the film surface during deposition or causing defects within the deposit. The formation of the deposited film continues. In particular, since light energy can be irradiated uniformly over a wide range, it has become possible to uniformly form a deposited film over a large area with high precision.

Further, by selectively controlling the irradiated portion of the light energy, it is possible to limit the portion on the support where the deposited film is formed.

In addition, in the present invention, the excitation and decomposition of the raw material gas by light energy includes not only the case where the raw material gas is directly excited and decomposed by the light energy, but also the case where the light energy is absorbed by the raw material gas or the support and generates heat. This also includes cases where the light energy is converted into energy and the resulting thermal energy causes excitation and decomposition of the source gas, which is a derivative effect of light energy.

In this way, an a-3i film is formed on the support 2, and a
- When the desired film thickness of Si is obtained, the irradiation of light energy from the light energy generating bag M7 is stopped, and further the bulb +4-1.14-5. Close IB-1, 18-5,
Stop supply of raw material gas. The thickness of the a-Si film is appropriately selected depending on the intended use of the formed a-3i film.

Next, by driving an exhaust device (not shown), the gas in the deposition chamber is expelled, the heater 4 is turned off, and when the support and the deposited film reach room temperature, the valve 31 is opened to gradually introduce atmospheric air into the deposition chamber. Then, the inside of the deposition chamber is returned to normal pressure, and the support on which the a-Si film is formed is taken out.

The a-9ill thus formed on the support by the method of the present invention is the a-5illll which has 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 method is not limited to this, and the method of the present invention may be formed under normal pressure, under normal pressure, as desired. It can also be carried out under pressure.

According to the method of the present invention as described above, optical energy is used as excitation energy, and a halogen compound is mixed into the cyclic silane compound, which is a raw material for forming the a-Si film, to form a cyclic silane compound. is efficiently and easily excited by light energy.

The formation of a-3i deposited films at low energy levels due to the high deposition rate becomes rJ (reactive), forming a-5i deposited films with excellent uniformity of electrical and optical properties and stable quality. Now you can.

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 thermal energy deposition methods can be used, and the high temperature of the supports can also be used. It has become possible to save energy consumption required for heating. Furthermore, it is easy to control the light energy so that the energy is always uniformly irradiated to a predetermined space occupied by the gas to be irradiated, and thick deposited films can be formed uniformly with high precision. In particular, since uniform irradiation can be performed over a wide range, it has become possible to form a deposited film uniformly and accurately even over a large area.

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, the cyclic milan compound No. mentioned above was used as a raw material for forming the a-3i deposited film.

Using I, and further using I2 as a halogen compound, ■
Formation of an a-5i (amorphous-5i) film was carried out as follows. First, a support (polyethylene terephthalate) is set on the support stand 3 in the deposition chamber l,
The pressure inside the deposition chamber 1 was reduced to 10" Torr by an exhaust device (not shown) through the gas exhaust pipe 2o, and the support temperature was maintained at 50"0 by energizing the heater = 4. Next, cyclic silane compounds No. Valve 14- of raw material supply @9 filled with
1. Iθ and I2 filled source 29 valve +
4-5 and 16-5 were each opened, and the raw material gas and the halogen compound gas were introduced into the deposition chamber 1.

At this time, while measuring with the corresponding flow meter 15-1.15-5, the gas flow rate of cyclic silane compound No.
03CCM d, ■2 Nokasu flow rate wo 30SCCH d59
Adjustment.

Next, the pressure inside the deposition chamber was reduced to 0. While maintaining the temperature at I Torr, xenon light with a light intensity of 130 mW/crn' was generated from the optical energy generator W7 and irradiated perpendicularly to the support.
Thickness 5000A No.I type a-9iM, 50A/se
c+7) Deposited on support 2 at a deposition rate. Note that the light energy was uniformly applied to the gas flowing in the vicinity of the entire support 2 disposed in the deposition chamber 1. At this time, decomposition products other than a-3i and surplus raw material gas that has not been decomposed are discharged through the gas exhaust pipe 20, while new raw material gas and halogen compound gas are continuously supplied through the gas introduction pipe 17.30. was supplied to.

A-5 thus formed by the method of the present invention
Evaluation of the i film was performed by adding a comb-shaped AI gap electrode (length 2
50 pL, III 5 mm), the photocurrent (light irradiation intensity AMI, about 100 mW/crn') and dark current were measured, and the photoconductivity σp and the difference between the photoconductivity σp and the dark conductivity σd were determined. This was done by calculating the ratio (σp/σd).

Note that the gap electrode is made by placing the a-Si film formed as described in 2.
After reducing the pressure to a vacuum level of r, the vacuum level is reduced to 10' Torr.
1500 at a deposition rate of 20 A/sec.
A1 was deposited on the a-9i film to a thickness of A, and then etched into a predetermined shape using a pattern mask.

The obtained σρ values and σp/σd ratios are shown in Table 1.

Examples 2 and 3 As the halogen compound, Br2 (Example 2) or C
A type I a-9i film was formed in the same manner as in Example 1 except that 12 (Example 3) was used, and the obtained a-9i
The membrane was evaluated in the same manner as in Example 1. The evaluation results are shown in Table 1.

Examples 4 to 12 As the raw material and halogen compound for forming the a-Si deposited film, the cyclic silane compound No. 2 listed above was used. No.

Example 1 was carried out in the same manner as in Example 1, except that 3, 4, I2, Br2, and C12 were used in combination, and the support temperature and halogen gas flow rate were set as shown in Tables 1 and 2. Then, an a-3i film was deposited. The obtained a-3i film was evaluated in the same manner as in Example 1. The evaluation results are shown in Tables 1 and 2.

Comparative Examples 1 to 4 Cyclic silane compound No. 1 listed above as a raw material for forming the a-3i deposited film. A- Sil! was deposited. The obtained a-Si film was evaluated in the same manner as in Example 1. The evaluation results are shown in Tables 1 and 2.

To summarize the results of Examples 1-12 and Comparative Examples 1-4 above, the film formation rate was as shown in the evaluation results in Tables 1 and 2. When comparing the corresponding Examples and Comparative Examples, when a halogen compound was mixed, the film formation rate was about 2 to 8 times higher than when it was not mixed. The rate of acceleration of film formation rate depending on the type of halogen is generally CI2, B
The order of magnitude is r2, ■, and so on.

Furthermore, the a-9i film formed in this example is as follows.

All had good electrical characteristics as well.

Table 1 Attack 1 σP/σd: Ratio of photoconductivity and dark conductivity 2 σ
p: Photoconductivity (Ω・cm)' Table 2 Village σp/σd: Comparison between photoconductivity and dark conductivity 2 σp
: Photoconductivity (Ω・cm)'3r,t: Room temperature

[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 table 4: Heater 5: Conductor 8-1.6-2.8-3.8-4: Gas flow 7; Light energy generator 8: Light energy 8.10 .1+, 12, 2! ] :Gas supply source 13-1
．． 13-2.13-3.13-4.13-5.18: Pressure meter 14-1.14-2.14-3.14-4.
14-5゜1B-1, 18-2, 1ft-3, 16-4
, 16-5, 21: Valve 15-1.15-2.15-
3.15-4.15-5: Flow meter 17.17
-1.17-2.17-3.17-4,307 Gas inlet pipe 20: Gas exhaust pipe

Claims (1)

[Claims] (1) The following general formula is placed in the deposition chamber in which the support is placed. Form a gaseous atmosphere of a cyclic silane compound and a halogen compound represented by (11), in the above formula, n is 3.4 or 5. A method for forming a deposited film, characterized in that a deposited film containing silicon atoms is formed on the support -1- by excitation and decomposition.