JPS6233014Y2 - - Google Patents

Description

[Detailed Description of the Invention] (a) Technical Field of the Invention The present invention relates to a plasma processing apparatus, and particularly relates to improvement of a gate structure.

(b) Prior Art and Problems A conventional plasma processing apparatus, for example, a plasma vapor phase growth apparatus having a parallel plate structure is shown in FIG. In the same figure, a hollow flat plate-shaped upper electrode 4 having a reaction gas supply hole is arranged inside a chamber 3 installed on an aluminum chamber base 1 via a sealing gasket 2, and a sample electrode 4 which also serves as a lower electrode is disposed inside a chamber 3. Heater blocks 5 for heating are arranged opposite to each other. A sample 6, for example a semiconductor substrate, is placed on a susceptor 7 placed on the heater block 5. Further, an exhaust pipe 8 is attached to a part of the chamber base 1, and a gate (door) for introducing the sample 6 to the side wall of the chamber 3.
9 is provided via an O-ring 10. Note that a sample transport mechanism 11 is attached to the outside of the gate 9.

When performing vapor phase growth of a silicon nitride film on the semiconductor substrate 6 using such an apparatus, for example,
After evacuating through the exhaust pipe 8, the reaction gas, silane (SiH ₄ ) and ammonia (NH ₃ ) as a carrier, is supplied from the reaction gas supply hole of the upper electrode 4 so that the degree of vacuum in the chamber 3 becomes approximately 1 Torr. A mixed gas with nitrogen (N ₂ ) or argon (Ar) is introduced, and a high frequency voltage (13.56 MHz) is applied between the upper electrode 4 and the lower electrode 5 by the high frequency power supply 12 to turn the mixed gas into plasma. In the presence of plasma, a chemical reaction as shown in the following reaction formula occurs between the reactant gases, and a silicon nitride film (Si ₃ N ₄ ) is formed on the semiconductor substrate 6.

3SiH ₄ +4NH ₄ →Si ₃ N ₄ +12H _2In this case, most of the reaction gas becomes Si ₃ N ₄ due to the above chemical reaction and is deposited on the semiconductor substrate 6, and by-products are exhausted, but some unreacted gas remains. Gas and reaction by-products adhere as residue to low-temperature parts within the chamber, such as the inner wall of the chamber 3 and the inner wall of the gate 9. Some of these deposits are hydrolyzed by moisture in the air flowing into the chamber when the gate 9 is opened to take the semiconductor substrate 6 in and out, and are converted into oxides. Since this oxide has strong hygroscopicity, it causes problems such as making it difficult to exhaust the chamber during the next vapor phase growth, or adhering to the semiconductor substrate 6 and causing pinholes.

Therefore, in order to maintain the quality of the Si ₃ N ₄ film over many times of vapor phase growth, the above-mentioned deposits must be removed frequently. This removal method (cleaning) is carried out by Freon (CF ₄ ) plasma etching, but frequent removal operations corrode the O-ring for sealing, causing leakage.
Ring needs to be replaced.

However, the transport mechanism 11 is located on the side of the gate 9.
O for sealing gate 9 as it is attached with
It takes a long time to replace the ring 10, which causes a decrease in productivity.

(c) Purpose of the invention The purpose of the invention is to provide a plasma processing apparatus having a gate structure to prevent plasma corrosion of an O-ring used for gate sealing. be.

(d) Structure of the device In order to achieve the purpose, this device has a double seal structure for the O-ring of the sample feeding gate, and the inner O-ring
It is characterized by having a structure in which the ring is made of metal or metal-coated rubber.

(e) Embodiments of the invention Examples of the invention will be described below with reference to the drawings. Fig. 2 is a schematic diagram of a plasma processing apparatus according to an embodiment of the present invention, Fig. 3 is a plan view of the gate of the plasma processing apparatus, and Fig. 4 is an enlarged sectional view of the main part of the gate seal section. be. The same parts as in the previous figure are given the same reference numerals.

In Fig. 2, 20 is a sample feeding gate, 21
2 indicates an outer O-ring for sealing, and 22 indicates an inner O-ring.

As is clear from the figure, the particular difference from the conventional one is that the gate 20 has a double O-ring sealing structure as shown in Fig. 3, and the outer O-ring 21 is made of a material such as silicone rubber as before. Furthermore, an O-ring 22 made of metal, such as aluminum or aluminum coated rubber, which is not corroded by the above-mentioned Freon (CF ₄ ), is provided inside.

In this case, if the cross-sectional diameter d of the inner O-ring 22 is smaller than the cross-sectional diameter D of the outer O-ring 21 as shown in FIG. O-ring 22
shall be substantially adhered to the adhesion surface of the chamber 3, or may have a slight gap.

In such a gate structure, when cleaning deposits inside the chamber 3 described above, CF ₄ plasma is shielded by the inner O-ring 22 made of aluminum or aluminum coated rubber, and the outer O-ring 21 is shielded from the CF 4 plasma. Therefore, the O-ring 21 is not corroded and leakage within the chamber is prevented.

(f) Effect of the invention As explained above, according to the invention, the O-ring of the sample feeding gate has a double seal structure, and the inner O-ring is made of metal that will not be corroded by plasma gas.
Alternatively, by using metal-coated rubber, it is possible to prevent corrosion of the outer O-ring, which saves the effort of replacing the O-ring, which is effective in improving productivity.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram of a conventional plasma processing apparatus, FIG. 2 is a schematic diagram of a plasma processing apparatus according to an embodiment of the present invention, and FIG. 3 is a plan view of a gate of the plasma processing apparatus. , FIG. 4 is an enlarged cross-sectional view of the main part of the gate seal portion. In the figure, 3 is a chamber, 6 is a sample, 20 is a sample feeding gate, 21 is an outer O-ring, and 22 is an inner O-ring.

Claims (1)

[Scope of utility model registration request] A plasma processing apparatus characterized in that the O-ring of the sample feeding gate has a double seal structure, and the inner O-ring is made of metal or metal-coated rubber.