JPS61170572A - Deposited film forming device - Google Patents

Abstract

PURPOSE:To form an amorphous Si film having a high grade by preventing sticking of Si to a window for transmission of high energy light in the stage of passing gaseous raw materials in a vessel in which a base is disposed and forming the amorphous Si film by a photo CVD method on the base. CONSTITUTION:The base 3 to be treated is placed in the vessel 1 and is heated to 50-150 deg.C by a heater 4. The inside of the vessel 1 is evacuated to a reduced pressure and thereafter a gaseous hydrogenated silicon compd. such as SiH4 or Si2H6 is mixed with a carrier gas, gaseous halogen, etc. 6-9 and is introduced through an introducing pipe 10 into the vessel. The high energy light 18 of a mercury lamp 17, etc. is irradiated through the window 19 for transmission of light of the vessel 1 to excite and decompose the gas such as SiH4 by which the amorphous Si(alpha-Si) is deposited on the surface of the base 3. Light energy 23 such as UV rays is at the same time focused by a lens 2 onto the window 19 and is scanned to decompose the alpha-Si sticking to the window 19 by which the transmittability of the light energy 18 is improved and the decrease in the forming speed of the alpha-Si film is prevented.

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention relates to amorphous silicon (hereinafter referred to as a-5i) useful as a deposited film containing silicon, a photoconductive film, a semiconductor film, or an insulating film. The present invention relates to a deposited film forming apparatus suitable for forming a deposited film of polycrystalline silicon or the like.

[Conventional technology]

Conventionally, glow discharge deposition and thermal energy deposition have been known as methods for forming deposited films using silicon hydride compounds such as Si& and Si2H6 as raw materials. In these deposition methods, silicon hydride compounds are excited and decomposed using electrical energy or thermal energy, and a-9
This is a method of forming a deposited film of i. The deposited film thus obtained is used for various purposes.

However, in the glow discharge deposition method, under high power, the influence of discharge energy on the a-9i film being deposited is large;
It becomes difficult to control reproducible and stable conditions. This is particularly noticeable when forming a thick deposited film over a wide area.

In addition, the thermal energy deposition method requires high temperatures, which limits the types of supports that can be used, and increases the probability that useful bonded hydrogen atoms in the a-9i film will be desorbed due to high temperatures. It is difficult to obtain a deposited film with these characteristics.

In this way, when forming a deposited film using glow discharge deposition or thermal energy deposition, it is difficult to ensure uniform electrical and optical properties and quality stability, and furthermore, the film surface is disturbed during deposition. At present, there still remain problems such as the tendency for defects to occur in the deposited film.

In recent years, in order to solve these problems, a method of depositing an a-9i deposited film using light energy (photo-CVD method) has been proposed and is attracting attention. According to this photo-CVD method, the above-mentioned problems can be significantly improved due to the advantage that the a-9i deposited film can be produced at a low temperature and by an ion-free reaction.

[Problems to be Solved by the Invention] However, in the photoCVD method, the a-9i deposited film is also formed on the light transmission window of the deposited film forming device, and this reduces the transmittance of the incident light into the reaction vessel. A new problem has arisen in which the rate of formation of a deposited film on the support is reduced by lowering the thickness.

In order to avoid this difficulty, a method of applying vacuum pump oil to the inner surface of the light-transmitting window has generally been adopted. However, bringing organic substances such as oil into the reaction vessel leads to the introduction of impurities such as oil molecules into the deposited film that is formed.

There was a problem in that the high quality of the film, which is a characteristic of the photo-CVD method, was impaired.

The present invention has been made to solve the above-mentioned problems in the photo-CVD method.

The purpose of the present invention is to form a deposited film for a photo-CVD method that can produce a high quality silicon film while keeping the film deposition rate constant on a support by preventing deposition on a light-transmitting window. The goal is to provide equipment.

[Means for solving problems]

That is, the deposited film forming apparatus of the present invention includes a reaction vessel, a means for introducing a raw material gas into the reaction vessel, and a high-energy light applied to the raw material gas through a light transmission window provided in the reaction vessel. In a deposited film forming apparatus for decomposing the source gas using a photochemical reaction and forming a deposited film on a support carried into the reaction vessel, It is characterized by being provided with a light energy generating device and an optical system for condensing the light emitted from the light energy generating device onto the light transmission window.

〔Example〕

DESCRIPTION OF THE PREFERRED EMBODIMENTS The deposited film forming apparatus of the present invention will be described in detail below with reference to FIG. 1 showing one embodiment.

The deposited film forming apparatus of the present invention basically includes a reaction vessel 1, a source gas introduction means, and a high energy light generation device W17.
, a light energy generating device 21 , and an optical system 22 .

In FIG. 1, the reaction vessel 1 has a partition wall 15 that can be opened and closed.
An antechamber 14 is attached which is separated from the reaction vessel l.

The desired support 3 on which the deposited film is to be formed is introduced and placed on the support 2 in the reaction vessel 1 through the antechamber 14 using suitable means. The support 3 may be any conductive, semiconductive or electrically insulating support, for example,
As electrically insulating supports, films or sheets of synthetic resins such as polyester, polyethylene, polycarbonate, cellulose acetate, polypropylene, polyvinyl chloride, polyvinylidene chloride, polystyrene, polyamide, glass, ceramics, paper, etc. are usually used. Ru. Moreover, an electrode layer, another silicon layer, etc. may be laminated on the support 3 in advance.

A heater 4 for heating the support is disposed at the bottom of the support base 2, and is supplied with power through a conductor 5 to generate heat.0 Temperature of the support when forming a deposited film using the apparatus of the present invention is not particularly limited, but is preferably 50 to 150°C, more preferably 100 to 150°C.

The raw material gas supply sources are indicated by 6 to 9, and when a liquid silicon hydride compound is used, an appropriate vaporizer is provided. There are two types of vaporizers, such as a type that uses heating boiling, and a type that allows carrier gas to pass through during liquid measurement. Types of silicon compounds.

In the case of using a halogen gas, a carrier gas, a diluent gas, a catalyst gas, etc., they are appropriately selected depending on whether or not they are premixed with the silicon hydride compound that is the raw material gas. For the raw material gas supply sources 6 to 9, the suffix a indicates a branch pipe, the suffix b indicates a flow meter, and the suffix C indicates a valve for opening/closing each gas flow and adjusting the flow rate. be.

Raw material gases and the like supplied from each gas supply source are mixed in the middle of the gas introduction pipe 10 and introduced into the reaction vessel 1 .
11 is a pressure gauge for measuring the pressure of the gas introduced into the reaction vessel l. Further, 12 is a gas exhaust pipe, which includes valve IB or 16゛ and reculator valve 1.
3, it is connected to an exhaust device (not shown) for reducing the pressure inside the reaction vessel 1 or the front chamber 14 and forcibly exhausting the introduced gas.

When forming a deposited film by the photoCVD method using the deposited film forming apparatus of the present invention, it is preferable that the inside of the reaction vessel l be placed under reduced pressure, but the deposited film can also be formed under normal pressure or under pressure. be able to.

When forming a deposited film by photo-CVD under reduced pressure,
Before introducing raw material gas etc., the inside of the reaction vessel 1 is evacuated, and the pressure inside the reaction vessel 1 is preferably 5×10″5 Torr.
Hereinafter, it is more preferably less than l x 1G' Torr. Further, the pressure inside the reaction vessel 1 when introducing the raw material gas etc. is preferably txto4 to 100 Torr,
More preferably l x 10-2 to l Tarr.

As the high-energy light generating device 17, for example, a mercury lamp, a xeno lamp, a carbon dioxide laser, an argon ion laser, a nitrogen laser, an excimer laser, etc. are used. Note that the light energy used in the present invention is not limited to ultraviolet rays, but can be used to excite and decompose raw material gas,
As long as the decomposition products can be deposited on the support, the wavelength range does not differ, and the light energy is absorbed by the raw material gas or the support and converted into thermal energy, and the thermal energy is The source gas is excited by
The light 18 directed from the high-energy light generating device 17 to the support 3, which does not exclude the case where a deposited film is formed by decomposition, is transmitted through a light-transmitting window 18 provided in the reaction vessel 1.
is irradiated with the raw material gas etc. flowing in the direction of the arrow 20 through the support 3 to excite and decompose the raw material gas etc. to form a deposited film of a-Si on the entire surface or a desired portion of the support 3. If a suitable optical system is attached to the high-energy light generating device 17, it is possible to irradiate the entire surface of the support 3 to form a deposited film, or selectively control and irradiate only the desired portion to form a partial film. A deposited film can also be formed. The photo-CVD method also has the convenience of being able to form a deposited film by irradiating only a predetermined graphical portion using a resist or the like.

When a hydrogen-silicon compound as a raw material gas introduced into the reaction vessel 1 is excited and decomposed to form an a-Si deposited film, gaseous hydrogen and halogen compounds (
For example, F2 gas, CI2 gas, gasified Br2,
It is desirable to introduce halogen (I2, etc.). By introducing these, a radical generation reaction occurs between Si and H1/\halogen atoms, promoting the formation of a deposited film, and It is expected that atoms will be incorporated, reduce structural defects, and also act as a terminator to bond to dangling bonds of Si, forming a high-quality silicon film. The halogen to be introduced may be radicalized in advance, and two or more types of silicon hydride compounds may be used in combination, but in this case, the expected film properties of each compound should be averaged. , or synergistically improved properties are obtained.

In this way, a desired a-Si deposited film is formed on the support 3, but as described above, during the deposition, the light transmitting window 18
An a-9i deposited film similar to that on the surface of the support 3 was also deposited on the wall surface of the reaction chamber, which lowered the daily light transmittance of the light transmission window 18 and reduced the rate of formation of the deposited film on the support 3. let Therefore, in the deposited film forming apparatus of the present invention, a light energy generating device 21 and a light beam 2 emitted from the device 21 are used.
3 on the light-transmitting window 19, preferably on the wall surface of the reaction chamber of the window 19.
lens) is installed. Light energy generator 21
Examples include mercury lamps, xeno lamps, carbon dioxide lasers, argon ion lasers, and nitrogen lasers.

An excimer laser or the like is used. Although not shown in the figure, the optical system 22 is configured to scan the entire surface of the light transmission window 19 with the light beam 23. This light beam 23 serves to decompose the film deposited on the inner wall surface of the light transmitting window 18 by using light energy, thereby keeping the transmittance of the light 18 constant. Since the light beam 23 is focused on the light transmission window 13 by the optical system 22, the a-Si deposited film being deposited on the support 3 is
It has almost no effect.

When forming a deposited film on the support 3 using the deposited film forming apparatus of the present invention, the optical energy generator 17 is operated to form the deposited film on the support 3, and at the same time the optical energy generator 21 is activated. One method is to prevent film deposition on the light transmission window 18 by operating the scanning optical system.

On the other hand, first, the optical energy generator 17 is activated to form a deposited film on the support 3, and when the film becomes noticeably deposited on the light transmission window 19, the support 3 is temporarily moved to the front chamber 1.
4, the optical energy generator 21 and its scanning optical system 22 are activated to decompose the deposited film on the light transmission window 18, and then the support 3 is moved to the reaction vessel again to prevent the formation of the deposited film. You can also do it.

The embodiment shown here is only an example of the configuration of the present invention, and for example, the support body 3 is vertically erected and the light 18 is irradiated horizontally from the side, or the light beam 2 is irradiated horizontally from the side.
3 irradiates perpendicularly to the light transmission window 19, etc.
It goes without saying that it is included in the present invention.

〔Effect of the invention〕

As explained above, the deposited film forming apparatus of the present invention uses optical energy to prevent the film from being deposited on the light-transmitting window, thereby maintaining a constant film deposition rate on the support while maintaining high quality. An a-9i deposited film can be produced.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram showing an example of a deposited film forming apparatus of the present invention. 1-m-reaction container 2-m-support support 3--
-Support 4--Heater 5-m=conducting wire 6-9-m-Gas supply source 10-m-Gas introduction pipe 11-m-Pressure gauge 12--
-Gas exhaust pipe

Claims (1)

[Claims] 1) Irradiating high-energy light to the raw material gas through a reaction vessel, means for introducing the raw material gas into the reaction vessel, and a light transmission window provided in the reaction vessel. In a deposited film forming apparatus for decomposing the raw material gas using a photochemical reaction and forming a deposited film on a support carried into the reaction vessel, a generator;
A deposited film forming apparatus comprising: an optical system for condensing light emitted from the optical energy generating device onto the light transmission window. 2) The deposition according to claim 1, wherein the optical system functions to scan light emitted from a light energy generating device and focused on the light transmission window over the light transmission window. Film forming device.