JPS61212016A - Film forming method - Google Patents

Abstract

PURPOSE:To obtain a high purity and high quality deposition film of excellent adhesivity with a substrate in an excellent reproducible manner by a method wherein, after a beam of light to be used for cleaning of a substrate is made to irradiate on the substrate provided in a reaction chamber, raw gas is introduced into the reaction chamber, and the deposition film is formed by projecting a beam of light to the raw gas. CONSTITUTION:A substrate 6 is provided in a reaction chamber 3, and the reaction chamber 3 is decompressed. After the desired quantity of oxygen or oxygen containing gas is introduced into the reaction chamber 3 as occasion demands, a beam of light 1 is made to irradiate on the substrate 6 through a light transmitting window 2, and the cleaning work is performed on the substrate 6. After the reaction chamber 3 is brought into the desired pressure, the raw gas to be used for formation of a deposition film is introduced into the reaction tube 3 from a raw gas cylinder 9. Then, the raw gas in the reaction chamber 3 is decomposed or polymerized by projecting the light of desired wavelength, and a desired film is obtained on the substrate 6. The same light or different lights may be used for cleaning of the substrate and the decomposition or polymerization of the raw gas.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a film forming method for forming a deposited film such as a high-purity thin film using a photochemical reaction.

[Prior Art] In recent years, it has become possible to form deposited films such as amorphous silicon with various functions at low temperatures by using photochemical reactions.
law) is attracting attention.

A photochemical vapor deposition apparatus (hereinafter referred to as a photoCVD apparatus) used in such a photoCVD method generally includes a reaction vessel, a means for introducing a raw material gas into the reaction vessel, and a means for introducing light into the gas. A desired deposited film is formed on a substrate provided in the reaction vessel by utilizing a photochemical reaction.

The principle configuration diagram of a typical conventional optical CVD apparatus is shown in FIG. 2, where ■ is a luminous flux, 2 is a light transmission window, 3 is a reaction vessel,
Reference numeral 4 indicates a raw material gas introduction valve, 5 indicates a deposited film, 6 indicates a substrate, and 7 indicates an exhaust port.

In the conventional optical CVD method, a device such as the one described above is used, and after a substrate 6 cleaned with various cleaning solutions is placed in a reaction vessel 3, light is irradiated into the reaction vessel 3 through a light transmission window 2. l
decomposes the raw material gas introduced into the container 3 using
Generally, a desired deposited film 5 is formed on the substrate 60. For example, silane gas is introduced into the reaction vessel 3, and high-energy light such as an excimer laser is irradiated to form the desired deposited film 5 on the substrate 6. Examples are known in which a hydrogenated silicon film is formed.

However, in this type of photo-CVD method, the substrate is placed in a reaction vessel after cleaning, so it is inevitable that the cleaned substrate will be exposed to the atmosphere. Problems arise in that the substrate is contaminated by solvents or the like, or by organic substances adhering to tools such as tweezers and substrate holding jigs used when installing the substrate. In addition, such contaminated substrates may reduce the adhesion force with the deposited film that is formed, deteriorate the electrical properties of the film, or cause variations in film quality and reduce reproducibility. There was a problem as mentioned.

[Problems to be Solved by the Invention] The present invention has been made in view of the above-mentioned problems, and an object of the present invention is to solve the problems of the above-mentioned conventional example and to improve the relationship between the substrate and the substrate. It is an object of the present invention to provide a novel film forming method which is capable of depositing a deposited film with excellent adhesion, high purity, and high quality with good reproducibility.

[Means for Solving the Problems] The present invention achieves the above object by cleaning the substrate by irradiating the substrate provided in the reaction vessel with substrate cleaning light, and then cleaning the cleaned substrate. A deposited film using the raw material gas as a raw material is formed on the cleaned substrate by introducing the raw material gas into the reaction vessel while being held in the reaction vessel and irradiating the raw material gas with light. This is a film forming method.

[Embodiments of the Invention] The light used for substrate cleaning in the present invention may be light of any wavelength, including infrared, visible, and ultraviolet rays, as well as shorter wavelengths such as X-rays and γ-rays. Light belonging to the group can also be used. The source of these lights is not particularly limited, and light emitted from, for example, a mercury lamp, a xenon lamp, or various known laser light generating devices is preferably used.

Cleaning of the substrate can be carried out under any pressure condition, such as under pressure, normal pressure, or reduced pressure, or even in a gas atmosphere containing specific gases such as oxygen gas. It is preferable to carry out the reaction under a gas-containing atmosphere (including, of course, under reduced pressure).

Hereinafter, the present invention will be described in detail with reference to an example of an embodiment apparatus used in the method of the present invention shown in FIG.

In FIG. 1, 1 is a luminous flux, 2 is a light transmission window, 3 is a reaction vessel, 6 is a substrate, 7 is a gas exhaust port connected to an exhaust means (for example, a rotary pump, etc.) not shown, and 8 is a A gas cylinder 9 is filled with oxygen or a gas containing oxygen used for cleaning the substrate, and a source gas cylinder 9 is filled with a source gas for forming a deposited film.

First, the substrate 6 is placed in the reaction container 3, and the exhaust means (not shown) is operated to exhaust gas from the gas exhaust lower, thereby reducing the pressure in the reaction container 3. Next, a desired amount of oxygen or oxygen-containing gas is introduced into the reaction vessel 3 from the gas pump 8 as required. After the above operation is completed, the substrate 6 is irradiated with light 1 through the light transmission window 2 to clean the substrate 6. At this time, especially if the substrate material is easily oxidized and adversely affects the film properties, oxygen is introduced. It is sufficient to perform cleaning by only light irradiation under reduced pressure. Of course, before placing the substrate 6 in the reaction vessel 3, it is possible to clean the substrate with a conventional cleaning liquid or the like.

As described above, the substrate placed in the reaction vessel is contaminated with oils, organic solvents, etc. floating in the atmosphere, and contaminants such as organic substances contained in these are attached to the substrate.

When such contaminants on a substrate are irradiated with light, the C-N bonds and 0-0 bonds in these contaminants are broken by the energy of the light, and these contaminants change into volatile substances and are absorbed by the substrate. and cleaning of the substrate is performed. The energy of the irradiating light is the C-N bond (bond energy;
The wavelength of the irradiated light must be 365 nm or less in order to be sufficient to break the 0-0 bond (bonding energy; approximately 33.2 Kcal/got) and the 0-0 bond (about 87.9 Kcal/mat). is more preferable. 3f15n
Light with a wavelength smaller than m has even greater energy, and by using such high-energy light, we can form C-C bonds, C-H bonds, C=O bonds, N
It is possible to cut more types of bonds such as -H bonds, and the cleanliness of the substrate can be further improved.

Furthermore, when light of 240 nm or less is irradiated in an oxygen-containing atmosphere, 03 is generated in the reaction vessel by the following reaction.

hv 0□ −→0+0 02 + 0 → 03 It is well known that 03 produced in this way has a strong oxidizing effect and has excellent detergency. By performing substrate cleaning n1 under such 03 generation conditions, it is possible to further improve the cleanliness of the substrate, and the present invention can be made more effective.

A desired deposited film is formed on the substrate 6 while the substrate 6 having undergone the cleaning process as described above is held in the reaction vessel 3. Film formation can be performed without any particular difference from conventional methods. That is, after the substrate 6 that has undergone the cleaning process is held in the reaction vessel 3 and the pressure inside the vessel 3 is brought to a desired level, a raw material gas for forming a deposited film is introduced into the reaction vessel 3 from the raw material gas pump 9. Next, a light beam of a desired wavelength (11) is emitted to decompose or polymerize the raw material gas in the reaction vessel 3, thereby obtaining a desired deposited film on the substrate 6.

In the present invention, the light used for cleaning the substrate and the light used for decomposing or polymerizing the source gas may be the same or different.

[Effects of the Invention] According to the method of the present invention, it is possible to form a film without exposing the cleaned substrate to the atmosphere, and the deposited film can be formed on the cleaned substrate by the henchmen. Therefore, it is possible to deposit a high-purity, high-quality deposited film with excellent adhesion to the substrate with good reproducibility.

[Example] Examples are shown below.

[Example 1] Using the apparatus shown in FIG. 1, a hydrogenated amorphous silicon film (hereinafter referred to as a-9i:H film) was formed on a flat glass substrate.

First, after thoroughly cleaning the glass substrate using a neutral detergent and pure water (cleaning solution), the substrate was placed in a reaction vessel using a bottle set.Next, the reaction vessel in which the glass substrate was installed was After reducing the pressure to −7 Torr, the substrate was cleaned by irradiating light with a wavelength of 3e5 nm for 20 minutes.

After the above cleaning is completed, the pressure inside the reaction container is maintained at 0.5 Tart while the substrate is held in the reaction container, and Si2H6:
H2 = 80 Vol$: 20 Vol$ (7) After introducing the raw material gas into the reaction vessel at an inflow rate of 0.5 t/wr:n (1), light with a wavelength of 185 nm is irradiated to form a film on the substrate with a thickness of 0. A .5p a-3i:H film was formed. By repeating such operations, a-3i:HIII2
50 glass substrates were obtained.

[Example 2] The wavelength of light during cleaning of the glass substrate in the reaction vessel was set to 15
Same as Example 1 except that the thickness was 0 nm.

Fifty glass substrates on which a-Si:H films were formed were obtained.

[Comparative example]

Example 1 except that the glass substrate was not cleaned with light
In the same manner as above, 50 glass substrates on which a-9i:H films were formed were obtained.

For each of the glass substrates of Examples 1 to 2 and Comparative Example created in this way, the substrate and a-Si:HlQ
When the adhesion force of the a-3i:H film in the comparative example was evaluated by measuring the shear stress, the adhesion force to the glass substrate was 0.2X 10"dyn/crn' ~ +
, ox to'°dyn/cm'. On the other hand, the adhesion force of the a-9i:H film to the glass substrate in Examples 1 and 2 was 1.2X to" dyn/ctn
'' to 1.flX 10''dyn/crry', which was found to be extremely excellent.

[Brief explanation of the drawing]

FIG. 1 is a diagram illustrating an outline of an example apparatus used in the method of the present invention, and FIG. 2 is a diagram illustrating an outline of a conventional optical CVD apparatus. ■---Light flux 2-m-light transmission window 3--reaction container 5-m=deposited film 6-m=substrate 7--exhaust port 1
Figure 2

Claims (3)

[Claims] (1) After cleaning the substrate by irradiating the substrate provided in the reaction vessel with substrate cleaning light, the raw material gas is introduced into the reaction vessel while the cleaned substrate is held in the reaction vessel. . A film forming method, comprising: irradiating the source gas with light to form a deposited film using the source gas as a raw material on the cleaned substrate. (2) The film forming method according to claim 1, wherein the light for cleaning the substrate is light having a wavelength of 365 nm or less. (3) The film forming method according to claim 1, wherein the cleaning is performed in an oxygen-containing atmosphere.