JPS63178517A - Photo excitation reaction apparatus - Google Patents

Abstract

PURPOSE:To execute surface treatment of substrate by forming a plasma, as a light source, by applying a microwave power and magnetic field higher than the electron cyclotron resonance (ECR) condition, providing an optical reflector and decomposing the second gas with optical excitation. CONSTITUTION:The microwave and magnetic field higher than the ECR condition are applied with a coil 4 into the apparatus 1. A second gas inlet port 8 and a substrate 3 are arranged within the same case as that forming the plasma of ECR discharge. A first gas is kept at 10<-6>-10<-4> Torr and is then introduced 2 and the sufficient vacuum ultraviolet beam is obtained from the plasma of ECR discharge and the substrate 3 is irradiated with such beam by selecting the waveform and reflecting 9 the beam with a concave mirror or diffraction grating. A second gas which does not react with the first gas is introduced 8, a CVD thin film is formed on the substrate 3 or the etching is carried out. Since the vacuum ultraviolet beam is not caused to pass through the phototransmitting window, the beam effectively excites the second gas.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a photoexcitation reaction device that utilizes light to form a thin film on a substrate or perform surface treatment such as etching.

2. Prior Art Conventional photoexcitation reaction devices include 1, for example, JP-A-60-2
It is shown in the No. 02928 publication. Thin film formation will be described below.

FIG. 3 shows a cross-sectional view of a conventional photoexcitation reaction device, where 3 is a substrate and 4 is a magnetic field coil.

5 is a substrate 4 by exciting the second gas with light energy.
This is a reaction chamber in which a thin film is formed on top. Reference numeral 6 denotes a light emitting unit that uses plasma formed by microwaves and a magnetic field generated by a magnetic field coil as a light source of optical energy. Reference numeral 7 denotes a light transmitting window that transmits the light energy obtained from the light emitting section 6 into the reaction chamber 5. Light transmittance 7 is an alkaline earth metal that allows vacuum ultraviolet light to pass through.

Using an alkali metal fluoride.

In the light emitting section 6, the first gas is excited by microwave power and a magnetic field, particularly a magnetic field that satisfies electron cyclotron resonance (hereinafter abbreviated as TEGR), and the highly excited E of the first gas is excited.
A CR discharge plasma is formed. A thin film is formed on the substrate 4 by exciting the second gas introduced into one reaction chamber 5 using the plasma as a light source. Since the CVD gas and etching gas used to form a thin film are excited by vacuum ultraviolet light of 18 Qnm or less, the first light emitting section 6 uses plasma from a KCR discharge that generates vacuum ultraviolet light. When forming an amorphous silicon film using monosilane gas, xenon is used as the first gas.

Monosilane gas was used as the second gas, the gas pressure of the first gas was 10-1 to 1σ'TOrr, and the substrate temperature was 200°C.
℃, a high quality amorphous silicon film was formed on the substrate 3.

However, in the above configuration, the vacuum ultraviolet light generated in the light emitting section 6 causes a reaction on the surface of the light transmission window 7 facing the reaction chamber 6, resulting in the formation of a thin film. As a result, the vacuum ultraviolet light obtained from the generating section 6 is absorbed by the light transmission window 7.

There was a problem in that the vacuum ultraviolet light did not reach the substrate 3.

In view of these points, the present invention has the following features: 1! :C1 (The object of the present invention is to provide a photoexcitation reaction device that uses plasma generated by discharge as a light source, efficiently uses the light energy generated by the light source to excite gas, and performs surface treatment of a substrate using the excited gas.

Means for Solving the Problems The present invention applies microwave power and a magnetic field higher than the EOR condition to cause ECR discharge of the first gas.

ECR discharge is used as a light source, a substrate and a second gas inlet are provided in the same container as the light source, and a light reflector is provided to change the optical path of the light emitted from the light source. This is a photoexcited reaction device with ~1 o-”rorr iC.

Effect of the present invention is to form an EOR plasma of a first gas by applying microwaves and a magnetic field equal to or higher than the [R condition, use this ECR plasma as a light source, particularly a vacuum ultraviolet light source, and place a substrate in the same container as this ECR plasma. and a second gas inlet. first.

As an example of the generation of vacuum ultraviolet light by ECR plasma, we can look at the Lyman series emission of hydrogen atoms (91, 2-122.
5 nm), the absorption cross section σ of self-absorption where the hydrogen atom itself absorbs Lyman series light emission at a hydrogen atom number of 10110-1 degrees is as large as 1×10-12 cril.

Therefore, the Lyman series vacuum ultraviolet light generated even in ECR discharge at 1o-1 to 1σ' Torr has an absorption coefficient of 3.
Since it is large at ~3 x 103 cM-', most of it is absorbed. Therefore, in order to obtain the vacuum ultraviolet light necessary for thin film formation, it is necessary to provide a large-diameter, large-capacity discharge space separately from the reaction chamber. Furthermore, a light transmitting window is also required that separates the discharge space from the reaction chamber and allows vacuum ultraviolet light to pass therethrough.

However, according to experiments conducted by the present inventors, when the gas pressure of hydrogen gas as the first gas is 10-6 to 1σ' Torr, the absorption coefficient becomes 3 to 3 It was possible to obtain ultraviolet light.This made it possible to provide the substrate and the second gas inlet in the same container.

Embodiment FIG. 1 shows a schematic diagram of an apparatus according to an embodiment of the present invention. 1 is a main body of the apparatus, 2 is a first gas inlet, 3 is a substrate, 4 is a magnetic field coil, 8 is a second gas inlet, and 9 is a light reflector.

Microwave (2,45Gl(z) and ECl
A magnetic field equal to or higher than the R condition (in the case of microwave frequency f0 = 2.45 GIIZ, magnetic field strength B = 0.0875 T) was applied by the magnetic field coil 4. The second gas inlet 8 and the substrate 3 were arranged in the device 1 in the same container as the container in which plasma of ECR discharge is formed.

and by a light reflector 9 which changes the optical path of the light energy emitted from the plasma of the ECR discharge.

Optical energy was made incident on the substrate 3 by changing the optical path.

With the above configuration, hydrogen gas is introduced from the first gas inlet 2 to cause KCR discharge and the hydrogen gas pressure is 1o-6.
FIG. 2 shows the amount of Lyman series vacuum ultraviolet light (121 nm) when changing it to ~1σ' Torr.

In this way, the gas pressure of the first gas is
'Torr J:, it is enough to obtain Z vacuum ultraviolet light. The formation of an amorphous silicon film using this vacuum ultraviolet light will be described below.

Deuterium (D2) was used as the first gas, and monosilane gas (SiH4) containing hydrogen (H2) was used as the second gas.

The gas pressure of deuterium gas was 5×10-5 Torr, the gas pressure of monosilane gas was 2×10'Torr, and the microwave power was 200W. In this way, an amorphous silicon film was formed on the substrate 3 without heating the substrate. The deposition rate was about 250 people/min.

Table 1 shows a comparison between the conventional example and this example.

Table 1 The apparatus of the present invention made it possible to form a thin film without heating the light transmission window 7 or the substrate.

In the example, an alurous silicon film was formed, but the substrate surface may be etched using at least one kind of etching gas as the second gas. Surface treatment may be performed using gas from multiple plates using two or more inlets. Furthermore, although deuterium gas is used here as the first gas, any gas may be used as long as it does not react with the second gas and can excite vacuum ultraviolet light by ECR discharge. Although a magnetic field coil is used as a means for generating a magnetic field higher than the ECU conditions, a magnet or the like may also be used. Further, the magnetic field distribution may be of a mirror type or a cusp type, and any magnetic field distribution that satisfies the ECR condition or more may be used.

Note that the light reflector may be of any shape and material as long as it can reflect vacuum ultraviolet light. Further, even when the light reflector is a concave mirror, the shape and material may be any shape as long as it can condense vacuum ultraviolet light onto the substrate. The same applies when a diffraction grating is used as a light reflector.

Furthermore, when multiple diffraction gratings are used as a light reflector.

It also includes introducing a plurality of types of gases through the second gas inlet to efficiently excite each gas.

Further, by having a mechanism that can reflect the light in the direction opposite to the direction from the KCR plasma to the substrate, vacuum ultraviolet light can be used more effectively.

Effects of the Invention As described above, the present invention uses ECR plasma as a light source of vacuum ultraviolet light, arranges a substrate and a gas inlet in the same container as IcR plasma, changes the optical path of vacuum ultraviolet light, and emits vacuum ultraviolet light onto the substrate. By being equipped with a light reflector that allows light to enter, E
The vacuum ultraviolet light obtained by CR plasma is absorbed and excited by the introduced gas without a light transmission window, and has an excellent effect of processing the substrate surface. Additionally, by light reflectors.

The industrial value of the present invention is high because it has the effect of eliminating damage to the substrate surface caused by ions from the KCR plasma.

[Brief explanation of the drawing]

FIG. 1 is a schematic cross-sectional view of an apparatus according to an embodiment of the present invention, FIG. 2 is a diagram showing the relationship between hydrogen gas pressure and light amount, and FIG. 3 is a schematic cross-sectional view of a conventional photoexcitation reaction apparatus. DESCRIPTION OF SYMBOLS 1...Device body, 2...First gas inlet, 3...Substrate, 4...Magnetic field coil, 5
...Reaction chamber, 6...Light emitting section, 7...
...Light transmission window, 8...Second gas inlet. Name of agent: Patent attorney Toshio Nakao and one other person J-
Basic Sales 4- Monthly 1 hot water carp 2 Part 1 Figure 8- Box for your respect Part 2
Figure Hydrogen Curse Pressure (Tbdr) Figure 3

Claims (7)

[Claims] (1) Form a plasma of at least one type of first gas by applying a magnetic field greater than or equal to the magnetic field intensity that satisfies the electron cyclotron resonance (ECR) conditions determined by the microwave power and the frequency of the microwave, and generate the pre-plasma light. using energy as a light source, providing an inlet for introducing the substrate and at least one type of second gas into the same container as the light source, and providing at least one light reflector for changing the optical path of the light emitted from the light source; A photoexcitation reaction device characterized in that the second gas is photoexcited and decomposed by the light energy to perform surface treatment of the substrate. (2) Set the gas pressure of the first gas to 10^-^6 to 10^-^4
2. The photoexcitation reaction device according to claim 1, wherein the photoexcitation reaction device is set to Torr. (3) The photoexcitation reaction device according to claim 1, wherein a CVD gas is used as the second gas, and the surface treatment of the substrate is performed to form a thin film on the substrate. (4) The photoexcitation reaction device according to claim 1, wherein the surface treatment of the substrate is performed by etching the substrate by using an etching gas as the second gas. (5) The photoexcitation reaction device according to claim 1, wherein a gas that does not react with the second gas is used as the first gas. (6) The photoexcitation reaction device according to claim 2, characterized in that a concave mirror is used as the light reflector. (7) The photoexcitation reaction device according to claim 2, characterized in that the wavelength of the light source can be selected by using a diffraction grating for the light reflector.