JPH06104097A - Plasma generation method and apparatus - Google Patents

Abstract

PURPOSE:To provide a method and device for plasma generation having high energy efficiency for the treatment of a semiconductor base and capable of uniform treatment. CONSTITUTION:In a method and device for plasma generation for guiding a microwave into a magnetic field and generating a plasma to treat a base 14, the position for generating ECR is set in a part having a strong electric field by the reflected wave of the microwave in the base 14. Thus, energy efficiency is high, and uniform plasma treatment can be performed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a microwave plasma generation method and apparatus, which is suitable for enhancing the energy efficiency of processing a substrate such as a semiconductor substrate and is excellent in the uniformity of processing. And the device.

[0002]

2. Description of the Related Art Conventional microwave generation techniques are, for example,
Semiconductor plasma process technology (written by Sugano, publishing industry books,
As described in p. 139), a discharge tube made of quartz is provided in the waveguide for propagating microwaves, and plasma is generated in the discharge tube by the action of the external magnetic field and the microwave electric field. Then, the semiconductor wafer is processed using the plasma.

[0003]

In the above-mentioned prior art, there is an unstable region when the microwave power is increased to increase the plasma density, and a large amount of microwave power is exceeded to reach the stable region. However, there is a problem that it is not efficient. An object of the present invention is to provide a highly efficient plasma generation method and apparatus for generating such high density plasma with less microwave power.

[0004]

In order to achieve the above object, the position where ECR occurs is set at a portion where the electric field due to the reflected wave of the microwave on the substrate is strong.

[0005]

When the ECR point is set to a place where the resonance width of the standing wave is large, this electric field also contributes to plasma generation at low density, so that the reflection is kept small when the microwave power is increased. As it is, it is absorbed by the plasma and shifts to high-density plasma. Therefore, high-density plasma can be generated with high efficiency.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described with reference to the magnetic field type microwave plasma processing apparatus of FIG. Reference numeral 1 is a magnetron, which is a microwave oscillation source. Reference numerals 3 to 6 are waveguides. Here, 3 is a rectangular waveguide, 4 is a circular rectangular waveguide, 5 is a circular waveguide, and 6 is a circular expansion tube. The discharge chamber 7 is made of, for example, highly pure Al,
It also functions as a waveguide. 8 is a vacuum chamber. Reference numeral 9 is a quartz plate for supplying microwaves to the discharge chamber 7. 1
Reference numerals 0 and 11 denote solenoid coils that apply a magnetic field to the discharge chamber 7. 12 is a semiconductor element substrate (hereinafter abbreviated as a wafer)
The sample table on which 14 is mounted and the bias power source R
The F power source 13 is connected. Reference numeral 15 is a gas supply system for supplying a gas for performing processing such as etching and film formation into the discharge chamber 7. Reference numeral 16 denotes a vacuum pump system for evacuating the discharge chamber 7 and the vacuum chamber 8 under reduced pressure.

Here, the circular waveguide 6, the discharge tube 7, and the sample stage 12 (wafer 14) constitute a microwave waveguide portion having a resonance structure. FIG. 2 shows a result obtained by examining the unstable region of plasma by changing the output power of the magnetron 1 and arranging by the height of the ECR point in the etching apparatus configured as described above. As a result, when the ECR height is near a certain height H, the unstable region is small, and when the ECR height deviates from it, the unstable region becomes large.
The reflected wave is also large.

FIG. 3 shows the distribution of the microwave electric field strength on the central axis in the axial direction when the magnetic field is set to the ECR height where the unstable region is generated. The solid line indicates that the microwave power is small. When the microwave electric field has a peak between the ECR point and the substrate, the dashed-dotted line has a high microwave power, and when the ECR point is exceeded, the microwave electric field between the substrate and the microwave decreases significantly. Is shown. From the results of FIG. 2 and FIG. 3, it is considered that one cause is that electric field distributions of two modes occur near the ECR point when the microwave power is increased in the unstable region. Therefore, when the ECR height is set in the vicinity of the position H where the electric field of the stationary source is large, the ECR height smoothly transitions from low density to high density, instability is small, and the density can be efficiently shifted to high density.

In the stable region to the left of the unstable region in FIG. 2, that is, the stable region at low microwave power, the plasma is in a sufficiently uniform state by the self-adjusting function. Therefore, if the ECR height is set to near H and the high density plasma is efficiently transferred, other E will be generated even in the high density plasma.
It was found that a more uniform plasma was obtained as compared with the CR height, and the uniformity of treatment was also improved.

[0010]

As described above, according to the present invention, E
By setting the CR point to a place where the resonance width of the standing wave is large, it is possible to efficiently transfer to a high density, and it is possible to provide a plasma generation method and apparatus excellent in the uniformity of high density plasma. There is an effect.

[Brief description of drawings]

FIG. 1 is a configuration diagram of a magnetic field type microwave plasma processing apparatus showing an embodiment of the present invention.

FIG. 2 is a diagram showing an example of an observation result regarding a stable range of plasma.

FIG. 3 is a diagram showing an example of measurement results of microwave electric field strength in plasma.

[Explanation of symbols]

1 ... Magnetron, 7 ... Processing chamber, 9 ... Quartz plate, 10, 1
1 ... Solenoid coil, 12 ... Sample stand, 13 ... RF power supply, 14 ... Wafer (substrate).

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Yoshifumi Ogawa 794 Azuma Higashitoyo, Shimomatsu City, Yamaguchi Prefecture Stock company Hitachi Kasado Factory (72) Inventor Seiichi Watanabe 502 Kandachicho, Tsuchiura City, Ibaraki Japan Co., Ltd. (72) Inventor, Muneo Furuse, 502 Kintatecho, Tsuchiura City, Ibaraki Prefecture

Claims (2)

[Claims] 1. A plasma generation method for introducing a microwave into a magnetic field to generate plasma to process a substrate,
A plasma generation method characterized in that a position where CR occurs is set to a portion where an electric field is strong due to a reflected wave of a microwave on the substrate. 2. A plasma generation apparatus for processing a substrate by generating a plasma by introducing a microwave into a magnetic field, wherein a microwave is introduced so as to form a resonance structure between the waveguide for introducing the microwave and the substrate. A plasma generating apparatus comprising: a wave waveguide portion; and a magnetic field configured so that a position where ECR is generated can be set in a portion where an electric field of a reflected wave on the substrate is strong.