JPH04274317A - Method and device for forming thin film - Google Patents

Abstract

PURPOSE:To prevent reduction in a light excitation efficiency due to adhesion of a raw material compound or a reaction product onto a light-irradiation window and enable a thin film with a high quality to be formed with an improved productivity when forming each kind of thin film by the chemical vapor growth (CVD) method utilizing a light excitation reaction. CONSTITUTION:Title items are the light CVD method which performs light excitation of a raw material compound which is introduced onto a substrate in a reaction film-forming chamber before reaching onto the substrate and causing a decomposition film-forming reaction to occur and a light CVD device with a means for performing light excitation by emitting a visible light and a light in ultraviolet rays region to a flow of the raw material compound at a pre-stage when the raw-material compound to be introduced reaches onto a substrate surface which is retained within the reaction film-forming chamber in the chemical vapor growth method for forming a thin film by a decomposition film-forming reaction accompanied by light excitation. Cloudiness of a light irradiation window for performing light excitation of the raw-material compound can be restricted and a high-quality thin film can be produced with an improved productivity and stably. Further, exchange and cleaning of the light- irradiation window can be performed individually, thus eliminating reduction in productivity of a thin film accompanied by atmospheric opening of the reaction film-forming chamber.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention relates to a method and apparatus for forming thin films using photoexcitation reactions, and is particularly suitable for forming various thin films by chemical vapor deposition (CVD) by irradiating a raw material compound with light. The present invention relates to a thin film forming method by optical CVD and an apparatus therefor.

0002

[Prior Art] In the conventional photo-CVD method, a substrate is held in a reaction film forming chamber, various raw material compounds containing thin film constituent elements are introduced onto the substrate, and a thin film is formed using a light source such as a lamp or laser. Thin films were formed by irradiating light from the top or side of the substrate through a light irradiation window installed in a reaction film-forming chamber to cause a decomposition film-forming reaction due to optical excitation [Japanese Journal of Applied Physics (Japanese Journal of Applied Physics)] Japanese J. App
l. Phys. ) Volume 28, No. 3 (March 1989) p.
pL346-L348].

[0003] In this conventional photo-CVD method, a light irradiation window (quartz window) is provided in the reaction deposition chamber in which the substrate is held, so that raw material compounds, reaction products, by-products, etc. During the film-forming reaction, the particles fly to the light irradiation window and adhere to it, clouding the light irradiation window, which prevents light irradiation such as ultraviolet light and reduces photoexcitation of the raw material compound, resulting in a decomposition film-forming reaction that forms a thin film. There was a problem of deterioration.

0004

[Problems to be Solved by the Invention] As mentioned above, in the conventional photoCVD method, light irradiation such as ultraviolet light is irradiated onto the substrate surface through the light irradiation window installed in the reaction film formation chamber. During the film reaction, raw material compounds, reaction products, by-products, etc. tend to adhere to the light irradiation window, which blocks light irradiation, degrades the photoexcitation reaction, and significantly reduces thin film productivity.

An object of the present invention is to solve the above-mentioned problems in the prior art, and when forming various thin films by the photo-CVD method that utilizes photoexcitation reactions, the source compound or the like is used in the window for light irradiation. A thin film produced by photo-CVD, which allows high-quality thin films to be formed with high productivity without adhesion of reaction products and the like, which prevents light irradiation, and which has an extremely simple structure and maintenance management of the film-forming equipment. The object of the present invention is to provide a forming method and an apparatus for implementing the same.

[0006]

[Means for Solving the Problems] In order to achieve the above-mentioned object of the present invention, in the photo-CVD method that forms various thin films on a predetermined substrate using a photoexcitation reaction, raw material compounds are used in the visible and ultraviolet regions. The photoexcited raw material compound is preliminarily excited by irradiation with light, and the photoexcited raw material compound is introduced onto the substrate held in the reaction film formation chamber to efficiently cause the decomposition film formation reaction, thereby increasing the productivity of thin film formation. It is intended to improve.

In the photoCVD method of the present invention, light irradiation is not performed on the substrate held in the reaction film forming chamber, but on the raw material compound before it is introduced onto the substrate in the reaction film forming chamber. It is characterized by the fact that Therefore, the light irradiation window of the thin film forming apparatus does not necessarily need to be installed in the reaction film formation chamber, and the light irradiation window may be attached to the raw material compound introduction tube, or the light irradiation window may be provided at the front stage of the reaction film formation chamber. A configuration may be adopted in which a photoexcitation chamber for the raw material compound is installed independently. Furthermore, the outflow end of the raw material compound of the introduction pipe that introduces the raw material compound to the substrate part in the reaction film forming chamber is intensively irradiated with well-paralleled light such as laser light, so that the raw material compound introduced onto the substrate is heated. It is also possible to optically excite it in advance.

In the thin film forming apparatus of the present invention, the light irradiation section for optically exciting the raw material compound can be configured at a position independent of the substrate held in the reaction film forming chamber. In the CVD method, it is easy to devise a configuration in which the window for light irradiation, which is essential, does not allow raw materials and reaction products to fly in and adhere to it, and it is also possible to configure a light excitation chamber that is independent of the reaction deposition chamber. Can be done. In this case, by providing an exhaust mechanism in the photoexcitation chamber that is independent of the reaction deposition chamber, it is possible to maintain a vacuum in the reaction deposition chamber even if the light irradiation window becomes dirty due to long-term use of the thin film deposition apparatus. Since the light excitation chamber can be left open to the atmosphere and the light transmission window can be cleaned or replaced, there is no negative effect on film formation, and it also eliminates problems such as reduced mass productivity caused by opening the reaction film deposition chamber to the atmosphere. can be avoided.

[0009]

EXAMPLES Examples of the present invention will be described below in more detail with reference to the drawings. <Example 1> FIG. 1 is a schematic diagram showing an example of the configuration of a thin film forming apparatus used in this example. A raw material compound 8 supplied from a raw material gas supply section (not shown) is supplied to a flow rate control valve 7. The light is introduced into the light excitation chamber 10 through the. Photoexcitation chamber 10
There is a light irradiation window (quartz window) that irradiates the raw material compound 8 in the photoexcitation chamber 10 with ultraviolet light generated from the lamp 5a.
3 is provided. Then, the raw material compound 8 that has been optically excited by the ultraviolet light irradiation 4 is introduced into the substrate (not shown) installed on the substrate holder (inside the heater) in the reaction deposition chamber 11 through the flow rate control valve 7a. Then, a decomposition film formation reaction is caused on the substrate to form a desired thin film. Each of the reaction film forming chamber 11 and the optical excitation chamber 10 is installed independently for evacuation via a vacuum valve (not shown). Further, it goes without saying that the light source used for the ultraviolet light irradiation 4 may be lamp light or laser light. For comparison, the conventionally used reaction deposition chamber 11
FIG. 4 shows an example of the configuration of a photo-CVD apparatus having a light irradiation window 3 at the top.

[0010] Using the photo-CVD apparatus of the present invention shown in FIG. The photo-CVD method of the present invention will be specifically explained using an example in which a titanium nitride (TiN) film is formed.

The raw material compound 8, which has been vaporized by heating the raw material container (not shown) filled with Cp2Ti(N3)2, is cooled in the raw material compound introduction pipe 9 to prevent it from condensing or solidifying. The compound introduction pipe 9 has a structure that is heated and kept warm. In the case of Cp2Ti(N3)2, 1
At a vacuum degree of about 0 Pa and a temperature of about 130 to 150° C., it sublimates and becomes a gas. This Cp2Ti(N3)2 gas can be used alone or in combination with a carrier gas such as argon or nitrogen gas. Cp2 as the above gas
A raw material compound 8 containing Ti(N3)2 is introduced into a photoexcitation chamber 10, and ultraviolet light irradiation 4 generated from a lamp 5a such as a high-pressure mercury lamp is applied through a light irradiation window 3 to photoexcite Cp2Ti.
(N3)2 gas to 100 to 50% in the reaction film forming chamber 11.
When introduced onto a silicon substrate placed in a substrate holder that can be heated to a temperature of 0°C, the temperature of the substrate was approximately 300°C, which is unimaginable with conventional CVD film formation methods for conductive films. Even when the film was formed at low temperature, a high quality titanium nitride film could be formed. This is thought to be due to the fact that when Cp2Ti(N3)2 is photoexcited by irradiating it with light in the visible and ultraviolet regions using a light source such as a high-pressure mercury lamp, a decomposition reaction different from a thermal decomposition reaction occurs and film formation is promoted. It will be done. Photo-CVD of the present invention shown in FIG.
When forming a thin film using a device, Cp2Ti(N3
)2 raw material compound 8 is first photoexcited in a photoexcitation chamber 10,
In order to maintain the life of the excited species until the reaction film formation chamber 11, a decomposition reaction occurs on the heated substrate held in the reaction film formation chamber 11, and a titanium nitride film is formed. In addition,
The light irradiation window 3 of the light excitation chamber 10 had almost no dirt attached to it, and no clouding occurred. For comparison, when a thin film was formed using the same raw material compound as above using the conventional photo-CVD apparatus shown in Figure 2, a high-quality titanium nitride film similar to that in the above example was obtained. was completed. This is a CV process using Cp2Ti(N3)2 as a raw material compound.
It is thought that the D reaction mechanism is that the raw material compound is first photoexcited, and then a decomposition film-forming reaction occurs. However, in the conventional photo-CVD apparatus, the substrate 2 in the reaction deposition chamber 11
Since the light irradiation window 3 is provided in the upper part, the light irradiation window 3 is easily contaminated by flying reaction products and becomes cloudy, and after about 10 to 12 hours, the light irradiation window 3 becomes cloudy due to dirt attached to it. This resulted in a decrease in film-forming efficiency. In contrast, in the photoCVD apparatus of the present invention shown in FIG. 1, there is almost no fogging on the light irradiation window 3 provided in the photoexcitation chamber 10.
If dirt adheres to the window, the light irradiation window can be easily replaced and cleaned, making it possible to form a thin film semi-permanently.

<Embodiment 2> FIG. 2 shows a photoexcitation chamber 1 of the present invention.
FIG. 2 is a schematic diagram showing an example of the structure of 0. In the figure, a part of the raw material compound introduction tube 9 is made of a light-transmissive quartz tube 9a, and a lamp 5a is provided so as to surround the quartz tube 9a. The efficiency of light irradiation can be increased by covering the quartz tube 9a surrounded by the lamp 5a with a cover 14 whose inner wall is mirror-finished. Note that although the photoexcitation chamber 10 shown in FIG. 2 is attached to the reaction film formation chamber via the flow rate control valve 7a, the raw material compound 8 is directly supplied to the reaction film formation chamber without going through the flow rate control valve 7a. Supply may be provided.

<Embodiment 3> FIG. 3 shows an example of another configuration of the optical CVD apparatus of the present invention. In the figure, starting compound 8
is introduced into the reaction film-forming chamber 11 through the raw material compound introduction pipe 9, and at the same time, the light excitation part 1 near the outflow end of the raw material compound 8 of the raw material compound introduction pipe 9 connected to the reaction film-forming chamber 11 is introduced.
0a is irradiated with focused light, and the raw material compound 8 is applied to the substrate 2.
A light introduction tube 12 is provided to perform optical excitation before the light reaches the target. The light source 5 of the photo-CVD apparatus in this embodiment may be a mercury lamp or the like, but it is better to use a light source 5 with good parallelism such as a laser beam, since the intensity of the irradiated light can be increased and the decomposition film formation reaction can be further enhanced. can be promoted. In this embodiment, a concave reflecting mirror 13 is installed at the bottom of the reaction film forming chamber 11 to improve light collection efficiency. As shown in this example, by optically exciting the raw material compound 8 at the tip of the raw material compound introduction tube 9, the excitation efficiency of the raw material compound can be improved, and the same high quality titanium nitride as in Example 1 can be produced. A film could be formed. Also, as shown in Figure 3,
The substrate 2 also controls the temperature of the light introduction tube 12, concave reflector 13, etc.
This can be done separately from heating, so by controlling these temperatures appropriately, the light irradiation window 3 provided in the light introduction tube 12, the concave reflecting mirror 13, etc. can also be heated to prevent the attachment of raw material compounds and reaction products. It is possible to suppress the contamination caused by oxidation, and it is possible to use it continuously for a long period of time as in the case of the first embodiment.

[0014]

[Effects of the Invention] As explained in detail above, the method for forming a thin film using the photoCVD method of the present invention involves photo-exciting the raw material compound containing the thin film constituent elements in advance and introducing it onto the substrate in the reaction film forming chamber. This method uses a conventional optical CV with a light irradiation window above the substrate.
Compared to the case of film formation using D equipment, there is no problem that raw material compounds or reaction products adhere to the light irradiation window, clouding it and interfering with light irradiation, so it is possible to produce a stable, high-quality thin film over a long period of time. can be manufactured with high productivity. In addition, the photo-CVD apparatus of the present invention has a reaction film forming chamber and a light excitation chamber having a light irradiation window independently provided, or has a light excitation part configured in a structure separated from the reaction film forming chamber. The light irradiation window can be replaced and cleaned without adversely affecting the reaction film forming chamber, and the problem of reduced mass productivity due to opening of the reaction film forming chamber to the atmosphere can also be solved.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram showing the configuration of a thin film forming apparatus exemplified in Example 1 of the present invention.

FIG. 2 is a schematic diagram showing the structure of a light excitation chamber of the thin film forming apparatus exemplified in Example 2 of the present invention.

FIG. 3 is a schematic diagram showing the configuration of a thin film forming apparatus exemplified in Example 3 of the present invention.

FIG. 4 is a schematic diagram showing the configuration of a conventional thin film forming apparatus.

[Explanation of symbols]

1... Board holder (heater interior) 2...Substrate 3...Light irradiation window (quartz window) 4...Ultraviolet light irradiation 5...Light source 5a...Lamp 6...Lens 7...Flow rate adjustment valve 7a...Flow rate adjustment valve 8... Raw material compound 9... Raw material compound introduction pipe 9a...Quartz tube 10...Photoexcitation chamber 10a...Photoexcitation part 11...Reaction deposition chamber 12...Light introduction tube 13...Concave reflector 14...Cover with mirror-finished inner wall 15…Joint part of quartz tube and metal tube

Claims (2)

[Claims] Claim 1: In a chemical vapor deposition method in which a raw material compound is introduced onto a substrate placed in a reaction film formation chamber and a thin film is formed by a decomposition film formation reaction accompanied by optical excitation, the substrate in the reaction film formation chamber is A method for forming a thin film, characterized in that optical excitation of a raw material compound introduced onto the substrate is performed before it reaches the substrate and causes a decomposition reaction. [Claim 2] In a chemical vapor deposition apparatus in which a raw material compound is introduced onto a substrate held in a reaction film forming chamber and a thin film is formed by a decomposition film forming reaction accompanied by optical excitation, the introduced raw material compound is used to form a thin film through a reaction film forming process. A thin film forming apparatus comprising means for optically exciting the flow of the raw material compound by irradiating it with light in the visible and ultraviolet regions before reaching the surface of the substrate held in the chamber.