JP4003851B2 - Thin film forming apparatus and plasma source thereof - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a thin film forming apparatus for forming a thin film such as an oxide film or a nitride film, and a plasma source applied to the apparatus .
[0002]
[Prior art]
Conventionally, an evaporation source that heats and evaporates a solid metal film-forming material into a vacuum chamber that is evacuated, and oxygen and nitrogen reactive gases that react with the evaporated film-forming material are subjected to high-frequency, etc. 2. Description of the Related Art There is known a thin film forming apparatus provided with a plasma source that is converted into a plasma by being excited with a gas and ejected into the vacuum chamber, and a substrate on which a thin film of a film forming material that reacts with the reaction gas is formed. In this apparatus, a vapor of a film-forming substance is supplied toward the substrate, and a thin film such as an oxide is formed by reacting with a reactive gas plasma on the substrate.
[0003]
An example of this plasma source is as shown in FIG. 1, and a gas inlet c for introducing a reactive gas such as oxygen or nitrogen gas is provided below a crucible b made of an insulator surrounded by a metal shield plate a. A high-frequency coil d provided around the crucible b excites the reaction gas in the crucible b into plasma, and the plasma is ejected from a jet outlet f formed in the crucible lid e toward the substrate in the vacuum chamber. The nozzle f has a small diameter of about 0.5 to 2.5 mm, and the pressure in the crucible b is kept at a high vacuum of 10 ⁻⁶ Torr or more in order to form a high-quality thin film in the vacuum chamber. Can be maintained at a low vacuum of 10 ⁻² to 10 ⁻³ Torr required for discharge.
[0004]
[Problems to be solved by the invention]
In the conventional plasma source, the jet port f is provided in the crucible lid e, and once the plasma source is attached to the thin film forming apparatus, the diameter, that is, the opening area of the jet port f cannot be changed. In the plasma source, it is necessary to increase the pressure in the crucible to about 10 ⁻¹ to 10 ⁻² Torr at the start of plasma discharge, compared with the normal discharge, and accordingly the pressure in the vacuum chamber is 10 ⁻³ to 10 ^{−. As a result} , it increased to ⁴ Torr, and the substrate that had been cleaned in a high vacuum was contaminated again, making it impossible to produce a high-quality thin film. Further, since the diameter of the nozzle f is constant, the pressure in the crucible b and the pressure in the vacuum chamber are uniquely determined. For example, the plasma chamber, that is, the pressure in the crucible b is maintained constant. It was impossible to produce a thin film by greatly changing the pressure parameter in the vacuum chamber, such as controlling the pressure of the vacuum chamber. In order to adjust the pressure in the vacuum chamber independently from the pressure in the crucible, the vacuum chamber must be exposed to the atmosphere, the crucible lid e of the plasma source removed from the crucible b, and replaced with one having a different area of the jet outlet f. In other words, the replacement work is complicated and the operation efficiency of the apparatus is deteriorated.
[0005]
An object of the present invention is to provide a plasma source in which the inside of a vacuum chamber of a thin film forming apparatus can be easily controlled independently from the pressure of the plasma source without being exposed to the atmosphere.
[0006]
【The invention's effect】
As described above, according to the present invention, since the adjustment means for adjusting the opening area is provided at the plasma outlet of the plasma source of the apparatus for forming a thin film , the area of the plasma outlet can be reduced without exposing the vacuum chamber to the atmosphere. Even if the plasma source is set to a low vacuum to start discharge, the vacuum chamber can be maintained at a high vacuum so that the substrate in the vacuum chamber is not contaminated, and the opening area can be adjusted relatively easily. Therefore, the configuration of claim 2 has an effect that the adjusting means can be manufactured easily and inexpensively.
[0007]
DETAILED DESCRIPTION OF THE INVENTION
An embodiment of the present invention will be described with reference to the drawings. In FIG. 2, reference numeral 1 denotes a vacuum chamber having a vacuum exhaust port 2 connected to a vacuum pump, 3 denotes a substrate holder provided in the vacuum chamber 1, The evaporation source 5 and the plasma source 6 are attached to the vacuum chamber 1 so that the vapor of the deposition material and the plasma of the reaction gas reach the substrate 4 detachably held on the substrate holder 3 with the plate surface facing downward. . The evaporation source 5 is a well-known one having a container to be heated therein, and vapor generated by heating a solid metal accommodated in the container is evaporated toward the substrate 4. A thin film is formed by vapor deposition on the plate surface. When a plasma of a reactive gas such as oxygen or nitrogen is ejected from the plasma source 6 toward the substrate 4 during the vapor deposition, the thin film deposited on the substrate 4 undergoes an oxidation or nitridation reaction, and an oxide film or a nitride. Become a film.
[0008]
For example, as shown in FIG. 3, the plasma source 6 is provided with a gas introduction port 8 for introducing a reactive gas such as oxygen or nitrogen gas at the lower part, and an insulating crucible 7 whose upper part is closed with a crucible lid 10. A high-frequency coil 9 is provided around the reaction gas, and the reaction gas inside the crucible 7 is excited by the high-frequency coil 9 to be turned into plasma, and is ejected toward the substrate 4 from a plasma outlet 11 formed in the crucible lid 10. However, this configuration is substantially the same as the conventional one. However, in order to eliminate the disadvantage that the substrate 4 is contaminated by raising the pressure of the plasma source 6 at the start of discharge as described above, An adjusting means 12 for adjusting the opening area of the jet outlet 11 is provided.
[0009]
For example, as shown in FIG. 4, the adjusting means 12 is configured so that a shutter 12 a having three openings 13 having different areas can be moved along the front surface of the crucible lid 10 by an operating shaft 14. By rotating 14 directly or indirectly from the outside of the vacuum chamber 1, the opening area of the ejection port 11 is controlled to the area of each opening 13. In this case, each opening 13 is formed in an area smaller than the ejection port 11. The shutter 12a may be configured by a plate without an opening, and a variable throttle may be configured to gradually close the ejection port 11 at the side edge of the plate when the operating shaft 14 is turned.
[0010]
When the diameter of the ejection port 11 is 2 mm, round holes having a diameter of 1 mm, 0.5 mm, and 0.2 mm are formed in the shutter 12a, and the vacuum chamber 1 is in a high vacuum of 10 ⁻⁶ Torr level. By closing the nozzle 11 with an opening 13 having a smaller area than that of the nozzle, the crucible 7 can have a low vacuum of 10 ⁻² to 10 ⁻³ Torr at the start of discharge. A high vacuum in the vacuum chamber was maintained, and a compound thin film could be formed on this without contaminating the substrate 4. Prior to the start of discharge, the evaporation source 5 is operated to introduce the vapor of the film forming material into the vacuum chamber.
[0011]
【The invention's effect】
As described above, according to the present invention, since the adjusting means for adjusting the opening area is provided at the plasma outlet of the plasma source of the apparatus for producing the compound thin film, the area of the plasma outlet without exposing the vacuum chamber to the atmosphere. Even if the plasma source is set to a low vacuum to start discharge, the vacuum chamber can be maintained at a high vacuum so that the substrate in the vacuum chamber is not contaminated, and the opening area can be adjusted relatively easily. There exists an effect, and it has the effect that the adjustment means can be manufactured simply and cheaply by setting it as the structure of Claim 2.
[Brief description of the drawings]
1 is a side view of a plasma source provided in a conventional thin film forming apparatus. FIG. 2 is a partially cutaway side view showing an embodiment of the present invention. FIG. 3 is a part of a main part of the plasma source in FIG. Cutaway enlarged cross-sectional view [Fig. 4] Plan view of the crucible lid of Fig. 3 [Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Vacuum chamber, 2 Vacuum exhaust port, 4 Substrate, 5 Evaporation source, 6 Plasma source, 8 Gas introduction port, 9 High frequency coil, 10 Crucible lid, 11 Plasma ejection port, 12 Control means, 12a Shutter, 13 opening, 14 Actuation axis,

Claims (2)

The vacuum chamber includes a deposition material evaporation source, a plasma source that emits plasma of a reactive gas that reacts with the deposition material, and a substrate on which a thin film of the deposition material that reacts with the reactive gas is formed. in the thin-film forming apparatus, the plasma jet outlet of the plasma source, the thin-film forming apparatus characterized by comprising adjusting means for adjusting an opening area of該噴outlet. In the plasma source provided in the vacuum chamber of the thin film forming apparatus, an adjusting means for adjusting the opening area of the jet outlet is provided at the plasma jet outlet of the plasma source, and the adjusting means is provided along the front surface of the jet outlet. A plasma source for a thin film forming apparatus, comprising: a shutter having a plurality of apertures that move and have different aperture areas.

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