JPH0627333B2 - Deposition method - Google Patents

Description

The present invention relates to a film forming method using a photochemical reaction.

In the conventional photochemical reaction, for example, in the photo CVD method of amorphous silicon whose main raw material is silane gas, the silane gas is sufficiently photolyzed only by ultraviolet rays having a wavelength of 160 nm or less, and ultraviolet rays of this wavelength are irradiated. Mercury catalyzed mercury-sensitized photochemical reactions have been used because no suitable light source is available.

However, this method has a problem that mercury used as a catalyst is mixed in the film, which adversely affects the film. Further, the decomposition product adheres to the ultraviolet transmitting window and is deposited, and the light energy is absorbed by the decomposition product, so that a sufficient deposition rate and film thickness cannot be obtained.

On the other hand, when a higher-order silane such as disilane is used, photolysis can be directly performed by light from a low-pressure mercury lamp or the like without using the mercury sensitization reaction, and the adverse effect of mercury can be eliminated.
The film forming rate is about 0.025 nm / sec, which is still insufficient in terms of practicality.

Then, a film forming method of decomposing and depositing silane by using high frequency power of 13.56 MHz is generally performed. However, there is a problem that a deposited film is damaged by charged particles or impurities are mixed into the film. There was a point.

Therefore, an object of the present invention is to provide a film forming method having a deposition rate which is sufficiently fast and can be put to practical use for a high quality and uniform thin film free from the adverse effects of mercury and free from impurities and charge damage.

The structure is such that in a film forming method in which a plasma region formed by gas discharge and a region in which a substrate for film formation is arranged are contained in one container, plasma is formed by noble gas or hydrogen or deuterium. Alternatively, it is performed by supplying high-frequency power to an electrode provided in the vicinity of a region to which a gas for ultraviolet radiation selected from a mixed gas containing these is supplied or by supplying microwaves from a waveguide, while, The photoreactive gas, which is a raw material for film formation, is characterized in that it is discharged near the substrate from a pipe structure which is arranged between the plasma region and the substrate and also serves as an electrode for applying a voltage.

Embodiments of the present invention will be specifically described below with reference to the drawings.

In FIG. 1, the electrode 1 above the inside of the container 5 has a hollow disk shape and is arranged substantially parallel to the substrate holder 3 arranged below the container 5. Then, a large number of ejection holes are formed on the lower surface and communicate with the introduction holes 9 for the ultraviolet radiation gas G ₁ . Therefore, the ultraviolet irradiation gas G ₁ is applied to the electrode 1
And is ejected downward from the ejection port on the lower surface. The other electrode is also used by the substrate holder 3, and the electrode 1
High-frequency power is applied between the substrate holder 3 and the substrate holder 3. Therefore, the plasma P is formed, and light emitted from the plasma P and containing ultraviolet rays having a wavelength of 160 nm or less is irradiated downward.

Next, the pipe structure 2 assembled in a mesh shape is arranged between the electrode 1 and the substrate holder 3, and the photochemically reactive gas G, which is a raw material for film formation, is ejected from the ejection holes formed in the pipe structure 2.
₂ is discharged to the vicinity of the substrate 4 placed on the substrate holder 3. Therefore, the photochemically reactive gas G ₂ is directly decomposed by the light including the ultraviolet rays having a wavelength of 160 nm or less, and the thin film becomes the substrate 4.
A film is deposited and deposited on top.

Then, a voltage is applied to the pipe structure 2 and the electrode 1
Substrate 4 of charged particles in the plasmola P between the pipe structure 2 and the pipe structure 2
It is designed to prevent diffusion in the direction. Therefore,
Even though the plasma P region and the substrate 4 are in the same container 5, the thin film is not damaged by the charged particles in the plasma P, and impurities are less mixed. Further, in this embodiment, since the electrode 1 and the substrate 4 are parallel to each other, ultraviolet rays are emitted from the substrate 4
The photochemically reactive gas G ₂ emitted evenly on the top and ejected from the pipe structure ₂ is directly decomposed without unevenness, and a high quality thin film can be obtained.

As described above, since the radiated light from the plasma P is directly radiated to the substrate 4, there is no light absorption on the way as in the conventional photo-CVD method, and further short wavelength ultraviolet rays can be generated, and the photosensitization reaction by mercury can be performed. It is possible to obtain a sufficiently high film formation rate without depending on
Pollution by mercury is not a problem. Further, the discharge by the high frequency power has good uniformity even in a large area, and in this respect, there is an advantage over the conventional method.

In addition, the other electrode is replaced with the substrate holter 3 and the pipe structure 2
High frequency power may be applied between the electrode 1 and the pipe structure 2 or the pair of electrodes 1, 1 may be provided above the container 5.
1 may be arranged so as to face each other, and plasma may be generated between the pair of electrodes 1, 1. Further, it is obvious that the plasma may be generated by using the microwave from the waveguide instead of the high frequency power.

In this embodiment, in order to effectively act the plasma P as a light source, a rare gas, hydrogen, deuterium, or a mixed gas containing these is used as a film forming raw material in the plasma P region as the ultraviolet radiation gas G _1. Is selected according to the type of the photochemically reactive gas G ₂ .

On the other hand, the photochemically reactive gas G ₂ is supplied to the vicinity of the substrate 4 and is directly decomposed and efficiently deposited on the substrate 4. For example, when amorphous silicon is deposited, the photochemically reactive gas G ₂ is silane. If so, silane directly absorbs UV rays of 160 nm or less, and photolyzes and deposits it.
Argon, krypton, xenon or the like is selected as the ultraviolet ray emitting gas G ₁ that effectively emits ultraviolet rays of 60 nm or less. The emission wavelength of argon is 104.8n.
m, 106.7 nm, krypton is 123.6 nm, 1
16.5 nm, xenon 147.0 nm, 129.6 nm
nm.

Next, as an example of film formation, the high frequency power has a frequency of 13.
56MHz, power 10-15W, container pressure 0.5
When a thin film of amorphous silicon is deposited under the condition of Thor, the ultraviolet radiation gas G ₁ is argon, the flow rate is 100 SCCM, and the photochemically reactive gas G ₂ is silane.
When the flow rate was 10 to 20 SCCM, a film could be formed on the 3-inch substrate 4 at a deposition rate of 0.5 to 0.8 nm / sec.

As for the metal thin film, for example, the photoreactive gas _{G 2} Al (CH _{3) 3} is the absorption edge 260 nm, the maximum absorption wavelength is approximately 200 nm, the ultraviolet radiation gas _{G 1} is in the vicinity of 170nm Using a gas in which nitrogen having a strong emission line and argon having a short wavelength of around 104 nm and having discharge stability at a ratio of 10: 1 are used, the flow rate of the photoreactive gas G ₂ is 10 to 20 SCCM, and in the container. Pressure is 0.2
It was possible to deposit an aluminum thin film having a film thickness of 1 μm or more under the conditions of a high frequency power of 8 to 16 W.

As described above, according to the film forming method of the present invention, the plasma is formed by supplying high-frequency power to the electrodes provided in the vicinity of the region to which the gas for ultraviolet radiation is supplied or by microwaves from the waveguide. , While the photoreactive gas is
Since it is designed to emit in the vicinity of the substrate from the pipe structure that is placed between the plasma region and the substrate and also serves as an electrode that ignites voltage, mercury is used as a high-quality and uniform thin film that is free from impurities and charge damage. It is possible to provide a film forming method capable of forming a film at a sufficiently high deposition rate that enables practical use.

[Brief description of drawings]

FIG. 1 is an explanatory diagram of an apparatus used in an embodiment of the present invention. 1 ... Electrode, 2 ... Pipe structure 3 ... Substrate holder, 4 ... Substrate 5 ... Container, 9 ... Introduction hole P ... Plasma

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Katsumi Aota 840 Takeno, Shimotomi, Tokorozawa, Saitama Prefecture, CITIZEN WATCH CO., LTD.Technical Research Laboratory Address Ushio Electric Co., Ltd. (56) Reference JP-A-59-145778 (JP, A) JP-A-59-145779 (JP, A)

Claims (1)

[Claims] 1. A film forming method comprising a plasma region formed by gas discharge and a region in which a substrate for film formation is arranged in one container, wherein the plasma is formed by a rare gas, hydrogen or deuterium. Alternatively, it is performed by supplying high-frequency power to an electrode provided in the vicinity of a region to which a gas for ultraviolet radiation selected from a mixed gas containing these is supplied, or by supplying microwaves from a waveguide. The film forming method, wherein the photoreactive gas that is a raw material for film formation is discharged in the vicinity of the substrate from a pipe structure that is disposed between the plasma region and the substrate and also serves as an electrode for applying a voltage.