JPH05186871A - Formation of sin film - Google Patents

Abstract

PURPOSE:To obtain a thin film with the progress of oxidation retarded in the formed film by supplying a process gas capable of being excited by a laser beam and used as an N source in the final film forming stage, irradiating the atmospheric gas contg. excess N with a laser beam and forming the film. CONSTITUTION:The vicinity of a substrate 4 is heated and held by a heater 7a provided to a substrate holder 7. The Si2H6 and NH3 as the gaseous materials (g) are supplied from a gaseous material feed line 2. The gaseous materials (g) are diffused and supplied on the upper region of the substrate 4, the gaseous materials (g) are decomposed and excited by the heating of the heater 7a and the supply of the energy of a laser beam 9, and an SiN film is grown on the substrate 4. The synthesized film is then enriched with nitrogen. In this case, a process gas gt capable of being excited by a laser beam and used as the N source is supplied to a thin film forming chamber 1a to produce an atmospheric gas contg. an excess N source close to the substrate 4, and the N content on the film surface is increased utilizing the N source. Consequently, the film has a stable SiN structure, and the oxidation resistance is improved.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention provides a CVD method for supplying a first material gas serving as a Si source and a second material gas serving as an N source in a mixed state to a substrate to form a SiN film on the substrate. The present invention relates to a method for forming a SiN film in a device.

[0002]

2. Description of the Related Art In such a SiN film forming method, SiH ₄ , Si ₂ H ₆ or the like is used as the first material gas, NH ₃ or the like is used as the second material gas, and the film forming portion is kept at an appropriate temperature. The SiN film is formed in the region (350 ° C. or lower when using the laser CVD system, 700 to 800 ° C. when using the thermal CVD system).

[0003]

However, when the SiN film is formed by utilizing such a process, not only the Si substrate which has been conventionally used as a substrate but also a plastic substrate, for example, should be used. Is also currently proposed. A major problem in adopting such a material is that if the film is formed at a relatively low temperature (for example, 150 ° C. or lower in laser CVD), SiN
The film does not have a composition suitable for the stoichiometric composition, and the composition ratio of nitrogen is small. Then, in a film having such a composition, if the thin film is left in the atmosphere, the film is oxidized with the lapse of time after film formation, and in the worst case, a film that should have the composition SiN is Composition SiO ₂
There is a problem that the film is denatured. That is, this factor has been a major obstacle in performing film formation at a low temperature. Therefore, an object of the present invention is, for example, when a SiN film is formed at a relatively low temperature and a thin film in which N is insufficient with respect to the stoichiometric ratio is formed, the thin film is oxidized over time. It is to obtain a method for forming a SiN film capable of forming a stable SiN film that rarely occurs.

[0004]

A characteristic constitution according to the present invention for attaining this object is to provide a laser irradiation means, and to supply a processing gas which can be excited by a laser and becomes an N source in a final stage of film formation. In addition, there is a nitrogen enrichment treatment step of forming a film by irradiating a laser beam from a laser irradiating means to an atmosphere gas in which the N component is in excess of that in the film forming step in the previous stage. Is the street.

[0005]

When this method is employed, the nitrogen enrichment treatment is performed on the film surface after the thin film is formed or at the final stage. That is, in this process, a process gas that can be excited by a laser and serves as an N source is supplied near the film formation surface of the substrate, and the atmosphere near the substrate is in an excessive N source state. Then, the processing gas is excited by the laser irradiation means and injected into the film. As a result, the film treated in this state has a composition ratio of the outermost surface of the film sufficiently close to the original stoichiometric ratio with respect to N. Therefore, after film formation,
Even when left in the air for a long period of time, a thin film that is hard to oxidize can be obtained.

[0006]

Since the thin film formed by the above method is excellent in oxidation resistance, for example, a plastic substrate is used as the substrate and the film formation is carried out at a low temperature of 150 ° C. or lower by a laser CVD apparatus. In this case (in this case, a thin film in which N is deficient with respect to the stoichiometric ratio is easily formed), it is possible to form a thin film that is not oxidized and denatured in the atmosphere.

[0007]

Embodiments of the present application will be described with reference to the drawings. FIG. 1 shows the structure of a CVD thin film forming apparatus 1 having a substrate holder 7. The CVD thin film forming apparatus 1 is a so-called laser CVD thin film forming apparatus, which decomposes / excites / forms a material gas by thermal energy supplied by a heating body and light energy supplied by laser light. .. This laser CVD thin film forming apparatus is
Since a thin film can be formed at a lower temperature than a conventional simple CVD thin film forming apparatus, it has an advantage that a substrate or the like is not thermally damaged and a good film can be formed. The case where the thin film layer 6 which is a SiN film is formed on the semiconductor (IC, LSI, etc.) substrate 4 will be described below as an example. Here, the substrate 4 is a silicon substrate as an example, and the SiN thin film 6 as an insulating film or a protective film is formed on the substrate 4.

First, the structure of the device 1 will be described.
This apparatus 1 is provided with a thin film forming chamber 1a whose internal pressure can be adjusted, and is provided with a material gas supply passage 2 and a material gas discharge passage 3. Further, the thin film forming chamber 1a
A substrate holder 7 on which a substrate 4 to be a thin film is to be placed is provided in the central portion 1c. This substrate holder 7
A heater 7a for supplying heat necessary for film formation is provided inside the. Further, a laser beam irradiation window 10 for introducing a laser beam 9 for exciting the material gas g on the substrate is introduced into the thin film forming chamber, and an excimer laser 11 as a laser irradiation means for oscillating the laser beam 9.
Are provided on the side of the device 1. Also, laser light 9
However, the laser light exit window 1 is led out of the thin film forming chamber 1a.
2 is also provided.

The case of forming the thin film 6 on the substrate 4 using the apparatus 1 of the present application will be described below. The vicinity of the substrate (particularly the upper region) is heated by a heater 7a provided on the substrate holder 7 and is maintained in a temperature range of about 350 ° C., and Si ₂ H ₆ as a material gas g is supplied from the material gas supply passage 2.
(This is to be a source of Si in the thin film is referred to as a first material gas g1.) And NH ₃ (which is to be a N source in the thin film is referred to as a second material gas g2.) Is supplied It This material gas g is diffused and supplied to the upper region of the substrate. Here, the material gas g (g1, g2) is
It is decomposed and excited by the above-mentioned heating by the heater 7a and the supply of light energy by the laser beam 9, and as a result, it grows as a SiN film on the substrate 4. In this way, the film formation on the substrate 4 is performed. The specific conditions for forming the SiN film are shown below. (SiN film synthesis conditions) First material gas (g1) supply amount Si ₂ H ₆ = 1.5 cc / min Second material gas (g2) supply amount NH ₃ = 30 cc / min Auxiliary gas supply amount N ₂ = 40 cc / min Substrate temperature 350 ° C. Reaction pressure 10 torr Laser 40 mJ × 100 Hz

Further, following the above-mentioned film synthesis, in the method of forming the SiN film of the present application, nitrogen enrichment treatment is performed. This process can be excited by a laser into the thin film forming chamber 1a, and a process gas (gt) serving as an N source is supplied to make the atmosphere near the substrate excessive in N sources. The composition ratio in is to have a high N ratio. Specifically, ammonia as the second material gas (g2) is supplied as the processing gas (gt). The processing conditions are shown below.

(Nitrogen Enrichment Treatment Conditions) First Material Gas (g1) Supply Amount Si ₂ H ₆ = 0 cc / min Second Material Gas (g2) Supply Amount NH ₃ = 30 cc / min Auxiliary Gas Supply Amount N ₂ = 40 cc / Min Substrate temperature 350 ° C. Reaction pressure 40 torr Laser 40 mJ × 100 Hz By performing this treatment, N was injected to the surface layer number of about 10 Å to supplement the above-mentioned deficiency, and the stoichiometric composition was approached, and a stable film was obtained. Is obtained. Table 1 shows the results of comparison of changes with time between those subjected to the above-mentioned nitrogen enrichment treatment and those not.

[0012]

[Table 1]

From the result table, the composition of the outermost surface of the film is greatly different between the treated product and the untreated product immediately after the reaction, and the amount of N in the nitrogen-enriched product is about 1.8 times that of the untreated product. There is a large amount of N, and the nitrogen-rich treated product also has more N in the inside of the film. In the film composition after standing in the air for 240 hours, N was decreased and O was increased in the untreated product compared with the composition immediately after the reaction, but the N was slightly decreased in the treated product. However, the amount of O did not change. As a result,
It can be seen that N taken up in the film by the nitrogen enrichment treatment is bonded to Si to form a stable SiN structure, which improves the oxidation resistance.

[Other Embodiments] Other embodiments of the present application are listed below. (A) In the above embodiment, an example in which the method of the present invention is adopted in a laser CVD apparatus using the laser beam 9 as a material gas decomposition / excitation means is shown. It does not matter what the conditions are, and it can be applied to any material for forming a thin film by exciting a material gas or the like. That is, this process may be performed after the film formation is completed or at the completion stage. Further, the method of the present application can also be applied to film formation using a simple thermal CVD apparatus. (B) Further, in the above embodiment, when ammonia is used as the second material gas, an example of using this ammonia in the nitrogen enrichment treatment is shown, but hydrazine or the like is also used in addition to ammonia. Is possible
Any process gas that can be excited by a laser and serves as an N source may be used.

It should be noted that reference numerals are given in the claims for convenience of comparison with the drawings, but the present invention is not limited to the configurations of the accompanying drawings by the entry.

[Brief description of drawings]

FIG. 1 is a diagram showing a configuration of a CVD thin film forming apparatus of the present application.

[Explanation of symbols]

 4 substrate 6 SiN film 11 laser irradiation means g1 first material gas g2 second material gas gt processing gas

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Shigeru Morikawa Inventor Shigeru-ku, Kyoto City, Kyoto Prefecture 17 Chudo-dera Minami-cho 17 Stock Company, Kansai Institute of New Technology (72) Inventor, Takashi Kobayashi 17 Naka-doji Minami-cho, Shimogyo-ku, Kyoto City, Kyoto Prefecture Kansai New Technology Research Center

Claims (2)

[Claims] 1. A first material gas (g1) serving as a Si source and N
The second source material gas (g2) as a source is supplied to the thin film forming chamber (1
A method for forming a SiN film in a CVD device (1) for supplying a mixed state to a) and forming a SiN film (6) on a substrate (4) in the thin film forming chamber (1a), comprising: laser irradiation means (11) is provided, and in the final stage of film formation, a process gas (gt) that can be excited by a laser and serves as an N source is supplied, and the laser is added to the atmosphere gas in which the N component is in excess of that in the film formation process in the previous stage. A method for forming a SiN film, comprising a nitrogen enrichment treatment step of forming a film by irradiating a laser beam from an irradiation means (11). 2. The method for forming a SiN film according to claim 1, wherein the processing gas (gt) is the second material gas (g2).