JPS63124514A - Plasma cvd equipment - Google Patents

Abstract

PURPOSE:To form a thin film having an excellent property over a long time by using a discharge electrode also as a heater for heating a substrate to facilitate the temperature control of a substrate film forming surface. CONSTITUTION:Since it has a substrate holder 3 for holding a substrate 2 for forming a thin film and a discharge electrode 4 disposed oppositely to the holder 3 and used also as a heater for heating the substrate, the electrode 4 itself is heated to the temperature near the substrate temperature. Thus, since material gas decomposed by a glow discharge does not become powder on the electrode 4 but becomes a dense thin film to be adhered, the discharge and the generation of a plasma are stabilized to form a thin film having excellent property. A frequency cleaning is not necessary, and the film formation for a long time and the repetition of the film formation can be performed. Further, since the electrode 4 near the substrate 2 oppositely to the film forming surface is used also as the substrate heater, the film forming surface of the substrate 2 can be directly heated to properly and easily control the temperature of the film forming surface.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a plasma CVD apparatus for forming thin films of semiconductors, insulators, etc.

[Conventional technology]

Thin films such as amorphous silicon used in solar cells, photoreceptors, image sensors, etc. are produced using Plus T CV D, which decomposes raw material gas such as silane by glow discharge and deposits the thin film on a substrate heated to an appropriate temperature. (Chem
It is usually formed by the icaj vapor deposition method.

An apparatus for carrying out this method generally includes a substrate holder 3 that holds a substrate 2 for forming a thin film in a film forming chamber 1, and a substrate holder 3, as shown in FIG.
This is a parallel plate type plasma CVD apparatus equipped with a discharge electrode 4 placed opposite to the substrate holder 3, and a heater 5 for heating the substrate is provided on the opposite side of the discharge electrode 4 away from the substrate holder 3. After holding the substrate 2 on the substrate holder 3, raw material gas is introduced at a constant flow rate from the raw material gas supply port 6 into the evacuated film forming chamber 1, and a shower portion 7 is formed on the discharge electrode 4.
The liquid is uniformly supplied to the surface of the substrate 2 through the wafer. High frequency waves are applied from a high frequency power source 9 to a discharge Nt electrode 4 electrically insulated from the film forming chamber 1 by an insulator 8 to induce glow discharge plasma between the electrodes 3 and 4, which is then heated by a substrate heating heater 5. A thin film of amorphous silicon or the like is formed on the substrate 2.

However, the decomposed raw material gas is deposited in the film forming chamber 1 other than the heated substrate 2, and is particularly likely to be deposited on the discharge electrode 4 near the substrate 2. Moreover, since the discharge electrode 4 is not heated, it is at a low temperature of about 100 C or less, so that the deposits on the discharge electrode 4 do not form a thin film but are deposited in the form of powder. This powdery deposit impeded discharge at the discharge electrode 4 and made plasma generation unstable, making it impossible to form a film for a long time. Furthermore, in order to remove powdery deposits, it is necessary to stop the equipment and clean it frequently, which is a major cause of reduced efficiency. Furthermore, powdery deposits may scatter and adhere to the substrate 2, adversely affecting the quality of the formed thin film.In addition, in conventional plasma CVD apparatuses, as shown in FIG. 5 is placed on the opposite side of the substrate 2 with the substrate holder 3 in between, which has the disadvantage that temperature control on the film-forming surface of the substrate 2 becomes inaccurate.

[Problem that the invention seeks to solve]

The present invention provides a parallel plate type plasma CVD apparatus that allows easy temperature control of the substrate film-forming surface, eliminates powder deposits on discharge electrodes, and can form thin films with excellent film quality over a long period of time. [Means for solving the problems] The plasma CVD apparatus of the present invention includes a substrate holder for holding a substrate for forming a thin pancreas, a discharge electrode disposed opposite to the substrate holder, and a discharge electrode arranged opposite to the substrate holder. The discharge electrode is characterized in that the discharge electrode also serves as a heater for heating the substrate.

A specific example of the device of the present invention will be explained with reference to FIG. Inside the film forming chamber 1, there is a substrate holder 3 that holds a substrate 2 for forming a thin film, and a substrate 2 is placed opposite the substrate holder 3.
The Nt emitter pole 4 is installed so as to face the radiator. The discharge electrode 4 is electrically insulated from the film forming chamber 1 by an insulator 8,
It is connected to a high frequency power source 9. Further, the surface of the discharge electrode 4 facing the substrate holder 3 is a shower part 7 for supplying raw material gas.
and communicates with the raw material gas supply port 6.

The plate of the shower part 7 of the discharge electrode 4 has a sheath heater 10 for heating the substrate on the inside, that is, on the raw gas supply port 6 side.
This is provided. Therefore, in the apparatus of the present invention, there is no need to separately provide a heater for heating the substrate on the side of the substrate holder 3 opposite to the substrate 2, unlike the conventional apparatus, and the entire apparatus is made smaller.

[Effect]

In the device of the present invention, since the discharge electrode 4 also serves as a heater for heating the substrate, the discharge electrode 4 itself is heated to a temperature close to the substrate temperature. As a result, the raw material gas decomposed by the glow discharge does not become powdery but adheres to the discharge electrode 4 as a dense thin film, so that the discharge and plasma generation are stabilized, and a thin film with excellent film quality can be formed. Further, there is no need for frequent cleaning, and it is possible to form a film over a long period of time or repeatedly.

Further, a discharge electrode 4 close to the substrate 2 and facing the film-forming surface thereof
Since the heater 2 also serves as the heater 2 for heating the substrate, the film forming surface of the substrate 2 can be directly heated, and the temperature of the film forming surface can be appropriately and easily controlled.

〔Example〕

An amorphous silicon thin film was formed on a substrate using the plasma CVD apparatus shown in FIG. The film forming conditions were: pressure inside the film forming chamber: 0.5 torr, source gas: 100% S
iH, raw material gas flow rate 200 sccm SRF power-4
00 W, and the substrate temperature was 200C. In addition, by heating with a sheath heater and setting the group NN pole to 350C, it was possible to heat the substrate temperature to 2000C.

In the device of the present invention, even when an amorphous silicon thin film with a thickness of 50 μm is formed on the substrate, only an amorphous silicon thin film with a thickness of several tens of μm is formed on the discharge electrode.
Unlike conventional methods, there was no adhesion of powdery deposits, and stable film formation was possible.

In addition, in the conventional apparatus shown in Fig. 2, a large amount of powdery deposits adhered to the discharge electrode when an amorphous silicon thin film of approximately 10 μm was deposited on the substrate under the same film-forming conditions as above. , it was no longer possible to continue film formation.

〔Effect of the invention〕

According to the present invention, it is easy to control the temperature of the film forming surface of the substrate, and there is no adhesion of powdery deposits to the emission electrode, so it is possible to form a thin film with excellent film quality over a long period of time. A parallel plate type plasma CVD apparatus can be provided.

[Brief explanation of the drawing]

FIG. 1 is a schematic sectional view of a plasma 0VD apparatus of the present invention, and FIG. 2 is a schematic sectional view of a conventional plasma CVD apparatus. 1. Film formation chamber 2. Substrate 3. Substrate holder 4. Discharge electrode 5. Heater for heating the substrate 6. Raw material gas supply lower.
・Shower part 8・・Insulator 9・・High frequency power supply 10・・Sheath heater Fig. 1 Fig. 2

Claims (2)

[Claims] (1) In a parallel plate type plasma CVD apparatus equipped with a substrate holder that holds a substrate for forming a thin film and a discharge electrode placed opposite to the substrate holder, the discharge electrode serves as a heater for heating the substrate. A plasma CVD device that is characterized by having double functions. (2) Claim (1) characterized in that the surface of the discharge electrode facing the substrate holder serves as a shower section for supplying raw material gas, and a heater for heating the substrate is provided inside the shower section. ) The plasma CVD apparatus described in item 1.