JPH05190503A - Method and device for plasma treatment - Google Patents

Abstract

PURPOSE:To easily detect the end point of dry etching in a highly precise manner using a simple spectrometry. CONSTITUTION:The material to be treated 3 is arranged between the upper electrode 2 and the lower electrode 4 in a reaction container 1, and plasma is generated by a high frequency power source 5. The first interference filter 8 and the second interference filter 9 are attached to the window of the reaction container 1, and the change in intensity of specific luminescence related to etching is detected by a photoelectric amplifier tube 6 and a DC amplifier 7.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a plasma processing method and an apparatus therefor, and more particularly to a method and apparatus for determining an etching end point for determining an etching end point of a sample to be dry-etched by optical emission spectroscopy.

[0002]

2. Description of the Related Art FIG. 6 is a schematic diagram showing the structure of a conventional etching end point detecting device. In the figure, 1 is a reaction vessel, 2 is an upper electrode, 3 is an object to be treated, 4 is a lower electrode, 5 is a high frequency power source, 6 is a photomultiplier tube, 7 is a DC amplifier, 10
Is a spectroscope.

FIG. 7 is a schematic view showing another structure of a conventional etching end point detecting device. In the figure, an interference filter 8 is used in place of the spectroscope 10 of FIG.

Next, the operation will be described. A spectroscopic analysis method is generally used in the end point detection method of dry etching used for manufacturing a semiconductor device. This is because plasma is generated by the high frequency power source 5 between the upper electrode 2 and the lower electrode 4 in the reaction vessel 1 to etch the object 3 to be processed,
The specific light emission from the plasma due to the etching was detected by the spectroscope 10 and the photomultiplier tube 6, amplified by the DC amplifier 7, and the change in the light emission intensity was detected.

Further, although the spectroscope 10 can variably measure the light emission of a specific wavelength, the interference filter 8 is used instead of the spectroscope 10 when detecting only the emission of a certain specific wavelength.

[0006]

Such a spectroscope 1
0, a photomultiplier tube 6 and a DC amplifier 7 can detect the emission of variable wavelength with high resolution, but the apparatus is expensive and large in size, and therefore is generally a spectroscope. The interference filter 8 is used instead of 10. However, although the interference filter 8 is inexpensive, it does not have high resolution (because the resolution of the filter is about 10 to 1/20 of the resolution of the spectroscope), a sufficient S / N ratio cannot be obtained, and the end point is not obtained. Sometimes it was difficult to judge.

Therefore, the present invention has been made to solve the above-mentioned conventional problems, and its purpose is to:
It is an object of the present invention to provide a plasma processing method and an apparatus thereof capable of accurately detecting the end point of dry etching by a simple spectroscopic measurement method.

[0008]

In order to achieve such an object, the present invention is designed so that a plurality of interference filters are superposed and the light emitted through these interference filters is detected by a photoelectric converter and an amplifier. It is a thing.

[0009]

In the present invention, by stacking a plurality of interference filters, the spectral characteristics of the interference filters are sharpened and high resolution is obtained.

[0010]

Embodiments of the present invention will be described in detail below with reference to the drawings. FIG. 1 is a diagram showing a configuration of a dry etching end point detecting device for explaining an embodiment of a plasma processing method and an apparatus thereof according to the present invention. In the figure, 1 is a reaction vessel, 2 is an upper electrode, 3 is an object to be treated, 4 is a lower electrode, 5 is a high frequency power source, 6 is a photomultiplier tube, 7 is a DC amplifier, and 8 is a window of the reaction vessel 1. The attached first interference filter 9 is a second interference filter attached to the outside of the first interference filter 8. That is, the first interference filter 8 and the second interference filter 9 are provided in the window of the reaction container 1.
Is attached, and the photomultiplier tube 6 and the DC amplifier 7 are connected.

Next, the operation will be described. In the etching end point detection (spectroscopic measurement) method, light emission of a specific wavelength whose intensity changes with time due to etching is used. For example, the specific light emission is indicated by A (center wavelength λ _m = 260 _n shown in FIG. 3).
m). When detecting this specific emission A with a spectroscope,
Since the spectroscope has high resolution (about 0.6 to 1.0 nm), almost the same light emission as the specific light emission A of FIG. 3 such as C shown in FIG. 4 can be detected.

As for the interference filter, generally, the spectral characteristic is about 10 to 20 times (about 10) times as much as the light emission A having a half-width of the specific wavelength around the specific wavelength λ _m as shown by D in FIG.
.About.20 nm), for example, when there is light emission B whose intensity does not change due to etching in the vicinity of the specific light emission A as shown in FIG. 3, one interference filter detects both light emission A and light emission B. Good end point detection cannot be performed.

Therefore, by stacking two sheets of the first interference filter 8 and the second interference filter 9 as shown in FIG. 1, the spectral characteristic D of one interference filter is two sheets as shown in FIG. Although the transmittance of the emission intensity is reduced as in the spectral characteristic E of the interference filter, the half width can be sharpened. In this case, the multiplication of the spectrum characteristics results in a drop in the transmittance. This can be solved by correcting the gain with the DC amplifier 7.

That is, the emission B near the specific emission A can be cut by stacking a plurality of the interference filters,
Only the specific light emission A related to the end point determination can be detected.

Further, by using the photodiode 11 of FIG. 2 instead of the photomultiplier tube 6 of the above-mentioned embodiment,
The same effect as that of the above-described embodiment can be obtained, and the first interference filter 8, the second interference filter 9, the photodiode 11 and the DC amplifier 7 are integrated, so that the configuration can be made smaller than that of the above-described embodiment. It will be possible.

[0016]

As described above, according to the present invention, it is possible to detect the etching end point easily and accurately because the spectral characteristic having the half-value width almost equal to the half-value width of the specific emission wavelength can be obtained. In addition, it has extremely excellent effects such as obtaining a compact and low-priced device.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing the configuration of a dry etching apparatus to which an embodiment of the present invention is applied.

FIG. 2 is a schematic diagram showing the configuration of a dry etching apparatus to which another embodiment of the present invention is applied.

FIG. 3 is a diagram showing a relationship between specific light emission (wavelength) and intensity according to an embodiment of the present invention.

FIG. 4 is a diagram showing a spectral sensitivity characteristic of specific light emission (wavelength) of a spectroscope.

FIG. 5 is a diagram showing a spectral sensitivity characteristic of specific light emission (wavelength) of an interference filter.

FIG. 6 is a diagram showing a configuration of a conventional etching end point detection device using a spectroscope.

FIG. 7 is a diagram showing a configuration of a conventional etching end point detection device using an interference filter.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Reaction container 2 Upper electrode 3 Object to be processed 4 Lower electrode 5 High frequency power supply 6 Photomultiplier tube 7 DC amplifier 8 First interference filter 9 Second interference filter 10 Spectroscope 11 Photodiode

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[Procedure amendment]

[Submission date] September 16, 1992

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Claims (2)

[Claims] 1. A plasma processing apparatus in which an object to be processed is housed in a reaction vessel, and plasma processing is performed while detecting a change in emission intensity of plasma generated in the reaction vessel at a specific wavelength. A plasma processing method, wherein the specific emission intensity is detected by passing through an interference filter in which a plurality of specific wavelengths of the plasma are stacked. 2. A plasma processing apparatus in which an object to be processed is housed in a reaction container and plasma processing is performed while detecting a change in emission intensity at a specific wavelength of plasma generated in the reaction container. A plurality of stacked interference filters that transmit a specific wavelength of plasma, a photoelectric converter that detects light emitted through the interference filter, and a DC amplifier that amplifies the output of the photoelectric converter, Plasma processing apparatus.