JPH0247851B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Technical Field of the Invention The present invention relates to improvements in microwave plasma processing equipment.

(b) Prior art and problems When conventional plasma processing is performed, it is necessary to avoid damaging samples such as silicon substrates and to ensure uniformity of sample processing. A microwave plasma processing apparatus is used in which a processing chamber is separated by a shielding plate having predetermined plasma ejection holes (shield holes).

That is, in the same figure, the sample processing chamber 1 has an exhaust port 2.
The sample processing chamber 1 is evacuated to a vacuum via the plasma chamber 1, and a plasma generation chamber 4, which is a part of the waveguide 3, is provided in the upper part of the sample processing chamber 1. A shielding plate 5 (part of a waveguide) interposed between the plasma generation chamber 4 and the sample processing chamber 1
serves as a partition wall for separating the two chambers, and a plurality of predetermined plasma ejection holes 6 (shield holes) are provided in the shielding plate 5 to communicate the two chambers. A sample stage 8 on which a sample 7 is placed is provided within the sample processing chamber 1 . Further, the plasma generation chamber 4, which is a part of the waveguide, has a gas inlet 9 in a part thereof.
is provided, and the JIS
The waveguide 3 and the microwave oscillator 11 having standard dimensions are connected as shown. The microwave transmission window 10 is vacuum sealed with an O-ring 12 as shown in the figure in order to maintain a vacuum in the plasma generation chamber 4, and is generally made of a material such as quartz or alumina.

When the sample 7 is subjected to plasma processing using the microwave plasma processing apparatus configured as described above, the sample 7 is placed on the sample stage 8, evacuated through the exhaust port 2, and the desired amount is extracted through the gas inlet 9. A processing gas is introduced to adjust the inside of the plasma generation chamber 4 and the sample processing chamber 1 to a predetermined degree of vacuum. Next, the microwave oscillator 11 is activated to apply microwaves of 2.45 GHg to the processing gas in the plasma generation chamber 4 through the waveguide (JIS standard) and the transmission window 10 to generate plasma, which mainly consists of radicals. The plasma etching gas is introduced into the sample processing chamber 1 through the plasma jet hole 6, and the sample 7 is etched.

In this case, a standing wave A is generated in the plasma generation chamber, which is a part of the waveguide, as shown in the figure, but in the conventional device, this standing wave A and the position where the microwave transmission window 10 is provided are particularly limited. This was not taken into consideration, and as a result, heat generation due to standing waves in the transmission window 10 was a problem. That is, when a processing gas such as carbon tetrafluoride (CF ₄ ) is used due to heat generated by the transmission window 10, etching of the transmission window made of quartz or the like is accelerated, resulting in problems such as shortening of the life of the device. , and a transparent window 1 made of alumina material.
At 0, etching is not caused by the processing gas, but the amount of microwave absorption is large and the temperature rises, causing problems such as burning of the O-ring 12 for vacuum sealing.

(c) Purpose of the Invention The purpose of the present invention was made in view of the above-mentioned problems, and by creating a structure that can minimize the heat generation of the microwave transmission window, it is possible to provide a long-distance processing device that can be processed more stably than conventional devices. Our goal is to provide microwave plasma processing equipment with a long service life.

(d) Structure of the Invention In order to achieve the object, the present invention includes a microwave generator, a waveguide extending from the microwave generator, and a microwave transmitting device that is a part of the waveguide and that is transparent to microwaves. It comprises a plasma generation chamber provided with a window, and a sample processing chamber that is in contact with the plasma generation chamber and communicates with it through the plasma ejection hole, and the microwave transmission window is arranged so that the amplitude of the electric field of the standing wave is minimized. It is characterized by being installed in a position where

(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 microwave plasma processing apparatus according to an embodiment of the present invention.

In the figure, 21 is a sample processing chamber, 22 is an exhaust port, 23 is a waveguide having JIS standard dimensions, 24 is a plasma generation chamber which is a part of the waveguide, 25 is a shielding plate, and 26 is a plasma ejection hole ( shield hole), 27
is the sample, 28 is the sample mounting table, 29 is the gas inlet,
30 is a microwave transmission window, 31 is a microwave generator, and 32 is an O-ring.

The difference between the microwave plasma processing apparatus according to the embodiment of the present invention and the conventional one is that, as shown in the figure, the microwave transmission window 30 is provided at a position where the amplitude of the electric field of the standing wave B generated in the plasma generation chamber 24 is minimized. It is at the point where That is, since the plasma generation chamber has a waveguide shape, the phase of the microwave standing wave can be calculated, so the microwave transmission window 30 is placed where the electric field amplitude is theoretically 0 (assuming complete reflection).
By providing this, it has become possible to significantly reduce heat generation due to microwaves compared to conventional devices. As a result, a microwave transmitting window 3 made of a quartz plate
The etching rate of 0 is reduced, making it possible to extend the life of the device, and the microwave transmission window made of alumina prevents problems such as seizure of the O-ring 32 due to temperature rise, allowing stable etching of sample 2.
7 plasma processing is now possible.

(f) Effects of the Invention As explained above, according to the present invention, by providing the microwave transmission window at a position where the amplitude of the electric field of the standing wave is minimized, damage to the transmission window due to heat generation is reduced compared to conventional devices. This makes it possible to perform stable sample processing and extend the life of the product, which is effective in reducing equipment maintenance costs and at the same time improving the quality of processed samples.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram of a conventional device, and FIG. 2 is a schematic diagram of an embodiment of the present invention. In the figure, 1 and 21 are sample processing chambers, 3 and 23
is a waveguide, 4, 24 is a plasma generation chamber, 6, 26
is a plasma ejection hole, 7 and 27 are samples, 9 and 29 are gas inlet ports, 10 and 30 are microwave transmission windows, 3
1 is a microwave generator, 12 and 32 are O-rings, and B is a standing wave.

Claims (1)

[Claims] 1. A microwave generator, a waveguide extending from the microwave generator, a plasma generation chamber that forms part of the waveguide and is provided with a microwave transmission window, and the plasma generation chamber. and a sample processing chamber that is in contact with and communicates with through the plasma ejection hole, and wherein the microwave transmission window is provided at a position where the amplitude of the electric field of the standing wave is minimized. Plasma processing equipment.