JPS60117711A - Forming apparatus of thin film - Google Patents

Abstract

PURPOSE:To enable the high-speed formation of a thin film excellent in film characteristics on a substrate set in a reaction chamber, by introducing rays of light into the reaction chamber together with an ECR plasma flow so as to decompose a material gas. CONSTITUTION:A reaction chamber 1 and a plasma generating chamber 4 are evacuated, and a substrate 3 is heated by a heater. Next, valves 9 and 11 being opened, a disilane gas is introduced into the reaction chamber 1 and an Ar gas into the plasma generating chamber 4. A microwave is generated by turning a microwave generator on, and simultaneously an Ar gas plasma is generated by forming a magnetic field by means of a magnetic coil 7. Next, a mercury lamp 13 being lighted, ultraviolet rays are introduced into the reaction chamber 1. In the reaction chamber 1, disilane molecules are brought into photochemical reaction by the ultraviolet rays, so that part of them is decomposed. This decomposition is further facilitated through the reaction thereof to Ar ions, Ar radical molecules or the decomposition product thereof taken out of the plasma generating chamber 4, and these decomposition products are transferred onto the substrate 3 and deposited as an a-Si film thereon.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a thin film forming apparatus that is effective in forming a desired thin film at high speed.

C Technical background of the invention and its problemsj Conventionally, CVD has been used to form thin films such as silicon oxide films, silicon nitride films, and amorphous silicon (a-8i) films.
method and plasma CVD method have been used. However, C.V.
Since method D requires a high substrate temperature (500 to 1000° C.), a substrate that cannot withstand 1 m [R] cannot be used. In plasma CVD method, the substrate temperature is 200~
/100℃, but the film formation rate is several 10 to 10
00 people/min, it has the disadvantage that a very long deposition time is required to obtain a film thickness of, for example, 10 to several tens of microns.

For this reason, there has been little research into equipment that can form films at low temperatures and at high speeds. One of them is a thin film forming method that utilizes plasma generated by electron cyclo-1 Heron resonance (ECR) using microwaves and a magnetic field. For example, a microwave of 2.45G)-17 is introduced into a plasma generation chamber using a rectangular waveguide, and a certain amount of scum introduced into the plasma generation chamber is turned into plasma, and then the plasma is discharged through a drawer window. A thin film is formed on the substrate by drawing the gas into the reaction chamber and interacting with the raw material gas introduced into the reaction chamber. According to this method, it is possible to form a silicon oxide film or a silicon nitride film without heating the substrate, but the film formation rate is at most several hundred people/minute, and a-31 The problem with films is that they do not necessarily have good properties such as photoconductivity.

[Object of the Invention] An object of the present invention is to provide a thin film forming apparatus capable of forming a thin film with good film characteristics at high speed.

[Summary of the Invention] The present invention utilizes decomposition of raw gas by ECR plasma and decomposition of source gas by light irradiation.

That is, an ECR plasma generation chamber is provided in communication with the reaction chamber, and a light source containing ultraviolet light is provided, and light is introduced into the reaction chamber at the same time as the ECR plasma flow to decompose the source gas and produce a substrate in the reaction chamber. A desired thin film is formed on top.

[Effects of the Invention] According to the present invention, the raw material gas is efficiently decomposed due to the synergistic effect of excitation by ECR plasma and excitation by light irradiation, and a high-quality thin film can be formed at high speed.

For example, the formation rate of the a-8t film obtained by the usual glow discharge decomposition method using disilane gas is 10 to 20 people/
seconds, whereas with the device of the invention a speed of 30-40 people/second can be obtained. However, the photoconductive properties and other properties of the A-81 film are in no way inferior to those produced by glow discharge.

[Embodiments of the Invention] The present invention will be described in detail below. FIG. 1 is a sectional view showing an embodiment of the apparatus. Reference numeral 1 denotes a reaction chamber that is reduced to a predetermined pressure, and a substrate mounting table 2 with a heater N is provided inside thereof, and a substrate 3 is placed on this. An ECR plasma generation chamber 4 is provided in the upper part of the reaction chamber 1 in communication with the reaction chamber 1 . A rectangular waveguide 6 is connected to the plasma generation chamber 4 through a microwave introduction window 5 made of quartz, and a magnetic coil 7 is installed around the rectangular waveguide 6. 8 is a raw material gas introduction pipe, 9 is a valve, 10 is a plasma generation gas introduction pipe, 1
1 is a valve. A light introduction window 12 made of quartz is provided on the side wall of the reaction chamber 1, and a 500 W low-pressure mercury lamp 13 is installed as a light source containing wavelength components of 2600 Å or less.
is provided. An inert gas such as nitrogen or argon is flowed into the lamp container 14 to prevent ozone generation due to ultraviolet light and to prevent a rise in temperature of the lamp.

The ECR conditions that must be met in the plasma generation chamber 4 are as follows:
When the frequency of the microwave generated by the microwave generator connected to the waveguide 6 is ω, it is given by ω−(e−B)/(m−c). m and e are the mass and charge of the electron, respectively, and C
is the speed of light, and B is the magnetic flux density.

A case in which a-S+S is formed using this apparatus will be specifically described as an example.

First, the inside of the reaction chamber 1 and the plasma generation chamber 4 are evacuated to about 2×10-” Torr using a diffusion pump and an oil rotary pump. At this time, the substrate 3 is
The temperature is 0℃. Next, valves 9 and 11 are opened, and disilane gas with a concentration of 100% is introduced into the reaction chamber 1, and Ar gas with a purity of 99°999% is introduced into the plasma generation chamber 4. At the same time, the exhaust system is connected to a diffusion pump and an oil rotor. Switch from pump system to mechanical booster pump and oil rotary pump system. Then, the flow rate of Ar gas is set to 508 CCM and the flow rate of disilane gas is set to 20 SCCM using the mass 70-controllers 1 to 0, and the pressure of the reaction chamber 1 is set to 0.05 Torr using the throttle valve.

In this state, turn on the microwave generator and set the frequency to 2.4.
A 5 GHz microwave of 300 watts is generated, and at the same time a magnetic field with a magnetic flux density of 875 Gauss is generated by the magnetic coil 7 to generate Ar gas plasma. Next, the mercury lamp 13 is turned on, and ultraviolet light having wavelengths of 1,850 and 2,537 people is introduced into the reaction chamber 1.

As a result, in the reaction chamber 1, the disilane molecules undergo a photochemical reaction due to the ultraviolet light, and a part of them is decomposed, and the disilane molecules drawn out from the plasma generation chamber 4 are exposed to r ions or Ar.
Radinol and disilane molecules or their decomposition products react to further promote decomposition, and they are transported onto the substrate 3 and deposited as an a-3i film.

In this example, film formation was performed for 1 hour in this state.

Then, close valves 9 and 11 to stop gas introduction.
The reaction chamber 1 and plasma generation chamber 4 are evacuated to 1Q' Torr level, the heater is turned off, and the substrate 3 is heated to ioo'
Take out this by holding it.

The thickness of the a-8t film thus formed was 12μ. In addition, when the photoconductive properties of this film were measured, the dark specific resistance was 1011Ω.
107Ω・cm for irradiation of 7A tons/ci・sec)
showed a specific resistance of As described above, according to this embodiment, EC
Due to the synergistic effect of R plasma and light irradiation, a thin film with good properties can be obtained at a fast film formation rate.

Further, according to the apparatus of this embodiment, the following incidental effects can be achieved. Since the light introduction window 12 is provided at a position further protruding from the side wall of the reaction chamber 1 away from the region through which the plasma flow flows, film formation on the light introduction window 12 is extremely small. The a-3 film usually has a low transmittance to irradiated light, which causes problems when it is formed on the light introduction window, but this can be effectively prevented in the apparatus of this embodiment. In particular, in the case of this embodiment, since the light introduction window 12 is provided at a position where the side wall protrudes to the outside, an air curtain is created by flowing an inert gas to the reaction chamber side of the light introduction window 12.
Film formation on the light introduction window 12 can be more effectively prevented. Furthermore, in this embodiment, the irradiated light is parallel to the substrate 3 and is not directly irradiated onto the substrate 3, so that the substrate 3 is not damaged by the irradiated light. This is particularly significant when a laser with high energy density is used as the light source.

Note that the present invention is not limited to the above embodiments. For example, although one light source is used in the embodiment, a small number of light sources may be provided around the reaction chamber 1. Figure 2 shows reaction chamber 1.
Three light introduction windows 12a to 12C at 120 degree intervals around the
This is an example in which three mercury lamps 138 to 13C@ are provided. In this way, when the substrate area is large or when films are formed on multiple substrates at the same time, variations in film characteristics within a substrate or between substrates can be reduced. Also a-8
iIl! The 81 compound gas as a raw material gas for forming is not limited to disilane, but may be other higher order silane gas or monosilane gas. Further, these raw material gases may be diluted with inert gas or hydrogen gas.

In addition to Ar, gases for plasma generation include He, Ne, and X.
An inert gas such as e or hydrogen gas can be used. Further, when forming a silicon oxide film, oxygen gas or nitrogen oxide gas may be used, and when forming a silicon nitride film, nitrogen gas or ammonia gas may be used.

Furthermore, it is also effective to use a mercury sensitization method in order to further increase the effect of photochemical reactions using ultraviolet light.

In this case, it is sufficient to simply mix mercury vapor with the introduced gas.

Further, when forming an a-8i film, a film with controlled valence electrons is often required, but in this case, a doping gas such as diborane or phosphine may be mixed with the raw material gas.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing a thin film forming apparatus according to one embodiment of the present invention, and FIG. 2 is a diagram showing a light source arrangement of a thin film forming apparatus according to another embodiment. 1... Reaction chamber, 2... Substrate mounting table, 3... Substrate,
4... Blasma generation, death... microwave introduction window, 6
... Rectangular waveguide, 7... Magnetic coil, 8... Raw material gas introduction pipe, 10... Gas introduction pipe for plasma generation, 9
, 11... Bulb, 12, 12a-12c... Light introduction window, 13° 13a-13c... Low-pressure mercury lamp, 1
4...Lamp container. Applicant's agent Patent attorney Takehiko Suzue

Claims (4)

[Claims] (1) a reaction chamber in which the substrate is placed and the pressure is reduced to a predetermined pressure;
A plasma generation chamber is provided in communication with the reaction chamber, and includes a plasma generation chamber that generates plasma by electron cyclotron resonance using microwaves and a magnetic field, and a light source containing an ultraviolet light component, and a source gas is introduced into the reaction chamber. A thin film forming apparatus characterized in that a thin film is formed on the substrate by introducing a plasma flow from the plasma generation chamber and light from the light source. (2) The thin film forming apparatus according to claim 1, wherein the light from the light source is 11T including a wavelength component of 2600 Å or less. (3) The thin film according to claim 1, wherein the light source is installed outside the reaction chamber, and the illumination light is introduced into the reaction chamber through a quartz window provided on a side wall of the reaction chamber. Forming device. (4) The thin film forming apparatus according to claim 1, wherein the light source is installed on multiple sides outside the reaction chamber.