JPS62259423A - Apparatus for manufacture of thin film - Google Patents

Abstract

PURPOSE:To prevent a reactive product thin film from forming on an ultraviolet light transmission window without coating oil or the like by applying a bias voltage of a direction for separating ion species that the product becomes solid from the window between a first electrode and a second electrode provided on the window. CONSTITUTION:A power source 11 is so provided as to apply a bias voltage to between a first electrode 4 and a second electrode 2 patterned in a pectinated or latticelike shape on an ultraviolet light transmission window 5. Ion species or active species slightly charged in which reactive product contained in reaction gas becomes solid is separated from the window 5 by a bias voltage applied to between the electrodes 4 and 2. Thus, film forming velocity and critical film thickness are improved, and since oil is not coated on the window 5 like a conventional apparatus, no impurity is mixed in the formed thin film to obtain the film of high quality.

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Field of Application of the Invention The present invention relates to an apparatus for producing a thin film of a photochemical vapor phase reaction product on a substrate.

(b) Prior art In recent years, photochemical vapor phase reaction (hereinafter referred to as photoCV
D method) is attracting attention.

The conventional apparatus used for thin film production using this photoCVD method places a film forming substrate in a reaction vessel having a window for transmitting ultraviolet light, and introduces a thin film production gas under reduced pressure.
Ultraviolet light introduced through the ultraviolet light transmission window causes a photochemical vapor phase reaction in the reaction vessel, and a thin film of the reaction product is deposited on the substrate. The ultraviolet light transmission window is made of a material that easily transmits ultraviolet light, such as quartz glass, lithium fluoride, and magnesium fluoride.

In addition, in order to increase the production rate of thin films, mercury sensitization method is used, in which mercury is added together with the gas for forming thin films in the reaction vessel, and in order to make it possible to form thin films over a large area, the pressure in the ultraviolet light source chamber is reduced. Also, efforts have been made to increase the size of the ultraviolet light transmitting window.

By the way, this photo-CVD method introduces ultraviolet light into the reaction vessel through an ultraviolet light transmission window, so a thin film is formed not only on the film forming substrate but also on the transmission window, so it is not sufficient immediately after the introduction of ultraviolet light. A large amount of ultraviolet light is irradiated onto the substrate through the window, but as a thin film is formed on the transmission window, the amount of ultraviolet light transmitted decreases, and eventually a thin film is formed on the substrate. The problem was that it would no longer be possible.

In addition, as a solution to this problem, it has been proposed to coat the reaction vessel side of the transmission window with oil, but oil components are incorporated into the film formed during the photochemical vapor phase reaction and deteriorate the film quality. There was a problem.

(c) Purpose of the invention The present invention solves these problems.

That is, the present invention provides an optical CVD apparatus that does not form a thin film of a reaction product on an ultraviolet light transmitting window without applying oil or the like.

(D) Structure of the Invention The present invention provides a reaction vessel having an ultraviolet light transmission window, a means for evacuating the reaction vessel to a reduced pressure state, a means for introducing a gas for forming a thin film into the reaction vessel, and a means for introducing the gas for thin film production into the reaction vessel. In a thin film production apparatus having an activating ultraviolet light source, between a first electrode provided on the ultraviolet light transmission window and a second electrode provided with a distance from the first electrode, This thin film fabrication device is characterized by having a means for applying a bias voltage in a direction that directs the ionic species whose reaction products become solids away from the ultraviolet transmission window.

That is, by applying a bias voltage between the first electrode and the second electrode, ionic species or slightly charged active species that cause the reaction product contained in the reaction gas to become solid are exposed to ultraviolet light. It is characterized by being kept away from the transparent window.

Naturally, this bias voltage is a value lower than the discharge start voltage at the pressure inside the reaction vessel during the photochemical vapor phase reaction.

The first electrode and the second electrode are made of aluminum, molybdenum, tungsten, stainless steel, platinum, copper, chromium, silver, magnesium, or nickel.

It is made of zinc, cobalt, iron, indium, a metal selected according to the reactive gas used, or an alloy thereof, and a grid-like or comb-like electrode with an aperture ratio of 90% or more is preferable. .

Examples are shown below.

Example 1゜ FIG. 1 shows an outline of the apparatus of the present invention.

A second electrode (2) provided in the reaction vessel (1) serves both as a heater for heating the substrate and as a substrate support.

A low-pressure mercury lamp (6) was used as the ultraviolet light source, and the ultraviolet light source chamber α was under reduced pressure and adjacent to the reaction chamber through a quartz glass plate (5) as an ultraviolet light transmission window.

The first electrode (4) on the ultraviolet light transmitting window is made of nickel,
After vapor deposition on the entire surface of the window, the material was patterned in a grid pattern so that the line width was 50 μm and the aperture ratio was 90%. The size of the window was 300 m x 300 mm, and the thickness was about 3 cranes. Further, an application power source aυ is provided between the first electrode (4) and the second electrode (2) so that a bias voltage can be applied. Naa', sentry+g7:'+a, quartz moga"y entered (r)
t'f;-7i+(at +il quasi-tt IJfa
t++3° Using this apparatus, an attempt was made to produce a silicon nitride thin film by the photo-CVD method. The conditions are shown below.

Gas flow rate 5izHa 10 SCCMN H
35005CCM Nt 500 SCCM Reaction pressure 400 Pa Substrate temperature 300°C At this time, the distance between the first electrode (4) and the second electrode (2) is approximately 5
At 0n, the bias voltage is set to negative polarity on the first electrode (4) side so that, for example, ionized Si does not approach the window side.
It was set to 0.30.60V. The relationship between the thickness of the thin film and the reaction time at that time is shown in FIG. Curve ■ is the result when the reaction time is OV, and the reaction time is about 1000 people in 60 minutes, and there is a tendency that the film becomes thicker and does not form after that time. This is an ultraviolet light transmitting window (
Since a film is also formed in 5), it is shown that the amount of ultraviolet light that is sufficient to fully decompose the reaction gas does not pass through.

On the other hand, the bias voltage of the present invention is 30V (curve α3), 6
When applying 0V (curve α0), the film formation rate tends to slow down over time, but compared to the curve @, it is possible to form a thicker film clearly faster, and the critical film thickness is also lower. In the case of curve C141, the number of people reaches 3,000, which is about three times that of OV (curve a2).

Furthermore, after forming these films, if a voltage higher than the discharge starting voltage is applied between the first and second electrodes and an etching gas is introduced into the reaction chamber, the inside of the reaction chamber will be cleaned.
The advantage is that it can be done independently.

Example 2 Next, using the same apparatus as in Example 1, an amorphous silicon film was manufactured.

He-based 10%S i z as thin film generation gas
The other experimental conditions were exactly the same as in Example 1 except that Hb was flowed at 20 SCCM. In this example, the bias voltage is 0■
I went with 25V. The results are shown in FIG. In the case of OV, the film thickness stopped increasing completely about 10 minutes after the start of the reaction as shown in curve α, but when a bias voltage of 25V was applied between the first and second electrodes as in the present invention, Song'aQ
As shown in *, the film thickness continued to increase even after 10 minutes, and 60
The number has reached about 1,000 people per minute.

Note that the present invention is not limited only to the examples.

Further, in Example 1.2, the second electrode also serves as a substrate support, but the structure is not particularly limited to this.

(e) Effects By adopting the configuration of the present invention, the film formation speed and critical film thickness are improved by about three times compared to conventional photo-CVD equipment.

In addition, unlike conventional equipment, oil etc. are not applied on the ultraviolet light transmitting window, so no impurities are mixed into the thin film formed.
Good film quality can be obtained.

Furthermore, when a voltage higher than the discharge starting voltage is applied between the first electrode and the second electrode and etching is used as the reaction gas, there is an advantage that the reaction chamber can be etched with the same equipment configuration.

[Brief explanation of drawings]

FIG. 1 shows the apparatus of the invention. FIGS. 2 and 3 show the relationship between the thickness of the thin film obtained by the present invention and the reaction time. 1... Reaction chamber 2... Second electrode (substrate support) 4... First electrode 5... Ultraviolet light transmission window 6... Ultraviolet light source 0 /θ 2ρ 〆θ Narino face r5 electric (secondary

Claims (1)

[Scope of Claims] 1. A reaction vessel having an ultraviolet light transmission window, means for evacuating the reaction vessel to a reduced pressure state, means for introducing a gas for forming a thin film into the reaction vessel, and activating the gas. In a thin film production apparatus having an ultraviolet light source, a bias voltage is applied between a first electrode provided on the ultraviolet light transmission window and a second electrode provided with a space between the first electrode and the first electrode. 1. A thin film production apparatus characterized by having a means for producing a thin film. 2. In claim 1, the first electrode provided on the ultraviolet light transmitting window has an aperture ratio of 90% or more and is patterned in a comb shape or a lattice shape. thin film fabrication equipment. 3. In claim 2, the patterned first electrode is made of aluminum, molybdenum, tungsten, stainless steel, platinum, copper, chromium, silver, magnesium, nickel, zinc, cobalt, iron, or indium. 1. A thin film production device characterized by being made of a metal or an alloy thereof selected depending on the reactive gas to be used. 4. The thin film manufacturing apparatus according to claim 1, wherein the second electrode is a support for a substrate on which a thin film is deposited. 5. The thin film according to claim 1, wherein the bias voltage applied between the first electrode and the second electrode is equal to or lower than the discharge breakdown voltage at the pressure inside the reaction vessel during thin film production. Fabrication equipment.