JPH0444225A - Coaxial plasma processing device - Google Patents

Abstract

PURPOSE:To block a gap through which ions and charged particles enter a coaxial plasma processing device so as to reduce a damage caused by charge-up by forming the entire shape of the internal electrode of the device to a bottomed cylinder, with the front end opening of the cylinder being closed with a blind plate or perforated plate. CONSTITUTION:A cylindrical chamber 1 made of a synthetic quartz Pyrex(R) glass, etc., is fixed to the main body of this coaxial plasma processing device and the upper end opening of the chamber 1 is closed with a chamber plate 1, with the bottom end opening being closed with another chamber plate 3. Especially, the chamber plate 3 is composed of an outside and inside sections 3a and 3b, with the section 3b being constituted in an ascending/descending free state, and a holding body 4 for holding numerous wafers W is provided on the plate 3. In addition, the chamber 1 is surrounded with an external plate electrode connected to a high-frequency oscillator 5 and an internal electrode 7 is put inside the chamber 1 in a coaxial state with the external electrode 6. In addition, the electrode 7 is composed of a punched metal or wire gauze with numerous small holes 8,..., with its base section being fitted to the upper surface of the outside section 3a of the chamber plate 3 and front end opening being closed with a blind plate 9.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a coaxial plasma processing apparatus used for ashing a resist film on the surface of a semiconductor wafer.

(Prior art) Japanese Patent Publication No. 53-334 was developed as a plasma processing device in which an external electrode and an internal electrode are arranged coaxially with a cylindrical chamber in between.
There is a device disclosed in Japanese Patent No. 71.

As shown in FIG. 3, the general structure of a coaxial plasma processing apparatus is that a cylindrical chamber 100 made of synthetic quartz or the like has openings at both ends closed with chamber plates 101 and 102.
A plate-shaped external electrode 104 connected to a high-frequency oscillator 103 is provided on the outside of the cylindrical chamber 100, and an internal electrode 105 electrically insulated from the external electrode 104 is provided on the inside of the cylindrical chamber 100.

The internal electrode 105 is made of punched metal, wire mesh, etc., and damage caused by plasma generated between the external electrode 104 and the internal electrode 105 can be applied to the wafer 10 supported by the holder 106 inside the internal electrode 105.
I'm trying not to reach 7.

(Problems to be Solved by the Invention) In the conventional coaxial plasma processing apparatus described above, damage caused by charge-up cannot be sufficiently prevented. That is, the base end of the internal electrode 105 is supported by one chamber plate 101, and there is a gap 10 between the other chamber plate 102 and the tip of the internal electrode 105.
I try to form 8. (If this is not done, the chamber plate 102 will cause the cylindrical chamber 100 to
The opening cannot be tightly closed. ) If there is a gap 108, the plasma generated between the external electrode 104 and the internal electrode 105 will enter the interior through this gap 108, and charge will accumulate on the wafer 107 near the gap 108, causing damage due to charge-up. occurs.

(Means for Solving the Problems) In order to solve the above problems, the present invention arranges an external electrode connected to a high frequency oscillator on the outside of a cylindrical chamber, and electrically insulates it from the external electrode inside the cylindrical chamber. The proximal end of the internal electrode is supported on a chamber plate that closes one opening of a cylindrical chamber of a plasma processing apparatus in which an internal electrode with a large number of small holes is disposed coaxially.
The opening of the internal electrode facing the other chamber plate was closed with a blind plate or a perforated plate.

(Function) Ions and charged particles in the plasma generated in the space between the external electrode and the internal electrode are prevented from entering by the internal electrode, and only radicals that are effective for the reaction pass through the small holes in the internal electrode to the wafer. reach.

(Example) Embodiments of the present invention will be described below based on the accompanying drawings.

FIG. 1 is a longitudinal sectional view of a coaxial plasma processing apparatus according to the present invention, and FIG. 2 is a longitudinal sectional view of the coaxial plasma processing apparatus.

A coaxial plasma processing device has a cylindrical chamber 1 made of synthetic quartz, Pyrex glass, etc. fixed to the device body, etc.
The upper end opening of this cylindrical chamber 1 is closed by a chamber plate 2, and the lower end opening is closed by a chamber plate 3. These chamber plates 2.3 are made of a metal material with excellent thermal conductivity such as aluminum or copper and are grounded.In particular, the chamber plate 3 consists of an outer part 3a and an inner part 3b, and the inner part 3b can be raised and lowered. A holder 4 for holding a large number of wafers W is provided on its upper surface.

Further, a plate-shaped external electrode 6 connected to a high-frequency oscillator 5 is arranged on the outer periphery of the cylindrical chamber 1, and an internal electrode 7 is arranged coaxially with the external electrode 6 inside the cylindrical chamber 1. There is. Here, "coaxial" means not only that the centers of the external electrode 6 and the internal electrode 7 are completely coincident, but also that they are slightly deviated from each other.

Further, the internal electrode 7 is made of punching metal or wire mesh and has a large number of small holes 8, the base end of which is attached to the upper surface of the outer part 3a of the chamber plate 3, and the first
In the figure, the tip opening is closed with a blind plate 9.

Further, a reaction gas introduction pipe 11 connected to a gas cylinder or the like and an exhaust pipe 12 connected to a vacuum pump are exposed to the plasma generation space 10 formed between the external electrode 6 and the internal electrode 7.

In the above process, a reaction gas is introduced from the gas introduction pipe 11 while the pressure inside the chamber 1 is reduced through the exhaust pipe 12, and high frequency waves are applied to the external electrode 6. Then, plasma is generated in the plasma generation space 10 between the external electrode 6 and the internal electrode 7, ions and charged particles in this plasma are removed, and effective radicals pass through the small holes 8 of the internal electrode 7 and reach the internal electrode. It enters the reaction space surrounded by 7, reacts with the resist film on the surface of the wafer W, and removes the resist film.

FIG. 2 is a sectional view similar to FIG. 1 showing another embodiment,
In this embodiment, instead of the blind plate 9, a perforated plate 13 similar to that of the internal electrode 7 is used to close the tip opening of the internal electrode 7.

(Effects) As explained above, according to the present invention, the overall shape of the internal electrode of the coaxial plasma processing apparatus is made into a bottomed cylindrical shape with the tip opening closed with a blind plate or a perforated plate. , it closes the gaps through which ions and charged particles in the plasma enter, reducing damage caused by charge-up.

[Brief explanation of drawings]

FIG. 1 is a longitudinal sectional view of a coaxial plasma processing apparatus according to the present invention, FIG. 2 is a longitudinal sectional view showing another embodiment, and FIG. 3 is a longitudinal sectional view of a conventional example. In the drawing, 1 is a cylindrical chamber, 2 and 3 are chamber plates, 5 is a high frequency oscillator, 6 is an external electrode, 7 is an internal electrode, 9 is a blind plate, 10 is a plasma generation space, and 13 is a perforated plate. applicant

Claims (1)

[Claims] A plasma in which an external electrode connected to a high-frequency oscillator is arranged outside a cylindrical chamber, and an internal electrode coaxially arranged inside the cylindrical chamber, which is electrically insulated from the external electrode and has many small holes. In the processing apparatus, the openings at both ends of the cylindrical chamber are closed by chamber plates, the proximal end of the internal electrode is supported by the chamber plate that closes one opening of the cylindrical chamber, and the internal electrode faces the other chamber plate. A coaxial plasma processing apparatus characterized in that an opening of an electrode is closed with a blind plate or a perforated plate.