JPS60220848A - Apparatus for utilizing plasma - Google Patents

Abstract

PURPOSE:To enable exact detection of the light emitting condition of plasma by measuring the light from a standard light source provided on the outside of an apparatus body via an observing window, the inside of the apparatus body and the 2nd observing window and correcting the quantity of the light emitted by the chemical species of the specified object on the basis of the change rate of the measured quantity of light. CONSTITUTION:High-frequency electric power source is applied between power sources 10 and 11 from a high-frequency power source 12 by using SiH4 and N2 at 1:9 mixing ratio as a gaseous raw material in the case of determining exactly the quantity of the light emitted by N2 in SixNy plasma. A thin Si3N4 film is thereby formed on an Si wafer in the apparatus body 1 for utilizing plasma as a plasma CVD apparatus. The light of the specific wavelength from filters 14, 15 are converted respectively by photodiodes 16, 17 to electrical signals which are fed to a calculator 4. The detected quantity of the light emitted by N2 is corrected by the quantity of the light emitted by Hg and the correct quantity of the light emitted by N2 is obtd. in the calculator 4. Said quantity is displayed.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to a plasma utilization device configured so that the amount of light emitted by a specific luminescent chemical species generated in plasma can be accurately grasped from the outside. It is something.

[Background of the invention]

Up to now, in plasma utilization devices, plasma monitoring has been carried out by measuring the amount of light emitted by specific luminescent chemical species generated in the plasma inside the device body outside the device body. However, since the measurement is carried out through the observation window, the observation window may be contaminated by K such as plasma reactants, and light absorption by the observation window material may occur.
There is a problem in that changes in the amount of light emitted by a particular luminescent chemical species cannot be accurately determined due to scattering, interference, and the like.

[Purpose of the invention]

Therefore, the purpose of the present invention is to improve the luminescence state of plasma! The purpose of the present invention is to provide a plasma utilization device that can be accurately grasped.

[Summary of the invention]

For this purpose, the present invention measures light from a standard light source provided outside the device main body through a first observation window, inside the device main body, and a second observation window, and detects a specific target based on the amount of change in light intensity. It is designed to correct the amount of light emitted by the luminescent chemical species. . The first light source is dirty to the same extent as the change in the amount of light from the standard light source. The degree of contamination of the second observation window is known, and the apparent amount of light emitted by the luminescent chemical species can be corrected to the correct amount of light depending on the degree of contamination.

[Embodiments of the invention]

The present invention will be explained below with reference to FIGS. 1 to 3.

First, the general configuration of the plasma utilization apparatus according to the present invention will be explained. FIG. 1 shows its configuration. According to this, there is a pair of electrodes 10 inside the plasma utilization device main body 1.
, 11 are provided, but if the high frequency power supply 12 applies a staining force between the electrodes 10 and 11 in a state where the raw material gas is sealed, the raw material gas will be ionized between the electrodes 10 and 11. As a result, plasma 5 is generated. The light 7 from the plasma 5 is separated by an observation window 8 as a measurement window, and light of a specific wavelength is separated and detected by the light detection mechanism 3. On the other hand, an observation window 9 for introducing standard light is provided in the part of the plasma utilization apparatus main body 1 facing the observation window 8, and the light 6 from the standard light source 2 is transmitted through the observation window 9, inside the plasma utilization apparatus main body 1, and into the observation window 8. The light detection mechanism 3 serves as a detector. When the observation window 8 is contaminated with plasma reactants or the like or when the amount of light emitted from the plasma 5 changes, when correcting the amount of Wako, the light 6 from the standard light source 2 and the light 7 from the plasma 5 are used. is simultaneously detected by the photodetection mechanism 3. light 6゜7
is converted into an electrical signal corresponding to the amount of light 7t and then fed to the computing unit 4. However, the intensity of the light 6 is measured in advance by the computing unit 4 before plasma generation, with the observation window 8 not contaminated. The rate of change in the amount of light can be seen between the amount of light 6 and the amount of light 6. Assuming that observation windows 8 and 9 are in the same state of contamination, the rate of change is the light 6 at observation window 8,
The state of the plasma 5 can be accurately grasped by knowing the light attenuation rate of 7 and correcting the detected amount of light 7 (light due to the target luminescent species) using this light attenuation rate. The standard light source 2 is a light source with a wavelength of 200 nm, such as a No. 10 gun lamp, a mercury lamp, a tungsten lamp, or an infrared lamp.
It is said that it can emit light of ~2000 nm. Also,
The light detection mechanism 3 may include a diffraction grating, a prism, etc. that uses an optical fiber for spectroscopy or transmission of detected light.
Spectroscopic means such as beam splitters, interference filters, and slits, and photodetection means such as photomultiplier tubes, optical sensors (photodiodes, etc.), infrared detectors, and semiconductor detectors are matched to the wavelength of the chemical species to be measured. It is considered to be a combination. Furthermore, the passage position of the light 6 from the standard light source 2 within the main body of the plasma utilization apparatus 1 may be any arbitrary position as long as the light 6 can reach at least the observation window 8, and does not necessarily need to be passed through the plasma 5.

Next, as shown in FIG. 2, the emission of N2 i! in SiχNy plasma using the plasma utilizing apparatus according to the present invention! A case in which it is set accurately will be explained in detail. In this example, 81H4 and Nt with a mixing ratio of 1:9 are used as the raw material gas, and the frequency is 13.5.
6MHz high frequency power is supplied from the high frequency power source 12 to the electrode.
, it is now given between it. As a result, plasma C
Inside the main body 1 of the plasma utilization device as a VD device, 81. N, a thin film is formed.

By the way, when an Hg rung is used as the standard light source 2, the light 6 from Hg and the light 7 from the plasma 5 are mixed and sent to the beam splitter 1 within the photodetection mechanism 3, if necessary.
It is divided into 92 parts by 3 and filters 14 and 15 respectively.
It is designed to be guided by.

The filter 14 selectively transmits only light with a wavelength of 336 nm, which is the wavelength of the N2 emission peak, and the filter 15 selectively transmits only light with a wavelength of 436 nm, which is the wavelength of the Hg emission peak. . Filter 1
The lights of specific wavelengths from 4 and 15 are each converted into electric signals by photodiodes 16 and 17 as photodetectors and sent to the calculator 4, where the detected N2 emission t is converted into Hg. By correcting the amount of light emission, the correct amount of light emission of Nt is obtained and this is displayed.

Through this, it is possible to know the plasma 50 emission state, and Zolazma 5
It is possible to some extent to control the condition in a good condition. Plasma CV
If it is not used as a D device, it can be expected to improve the yield in semiconductor manufacturing.

FIG. 3 shows the change over time in the amount of N2 light actually detected. Even if the amount of light emitted from N2 does not actually change, the amount of light that is actually detected will apparently decrease as shown by characteristic A due to dirt on the observation window. However, the plasma utilization device according to the present invention? When used, the amount of light actually detected can be correctly corrected and becomes as shown in characteristic B.

〔Effect of the invention〕

As explained above, in the case of the present invention, the degree of dirt on the observation window can be determined using the standard light source, and the amount of light emitted by the specific luminescent chemical species from the plasma can be corrected based on this information, so that the luminescence state of the plasma can be accurately grasped. There is an effect.

[Brief explanation of the drawing]

Fig. 1 is a diagram showing a general configuration of a plasma utilization device according to the present invention, and Fig. 2 is a diagram showing a specific example of a photodetection mechanism in the configuration, and accurately determining the amount of light emitted by a specific luminescent chemical species. FIG. 3, which is a diagram for explaining the method, is a diagram showing changes over time in the amount of luminescence of N2 as a specific luminescent chemical species that is actually detected. 1... Plasma utilization device main body, 2... Standard light source, 3
...Light detection mechanism, 4...Arithmetic unit, 8.9...Observation window. Representative Patent Attorney Tadashi Akimoto %N Figure 2 Figure 3

Claims (1)

[Claims] The plasma utilization device has an observation window for extracting light from plasma generated inside the device body to the outside of the device body, and an observation window for introducing standard light is added to the part of the device body facing the observation window. A window is provided, and a standard light source is provided near the observation window side, and the light from the standard light source and the light from the plasma are taken out through the observation window to the outside of the device main body, and each is spectrally detected by a spectroscopic detection means. In addition, the calculation means performs spectral detection from the spectral detection means based on the amount of light from the standard light source related to the spectral detection and the amount of light from the standard light source when the observation window is not contaminated, which has been spectrally detected in advance. A plasma utilization device characterized by a configuration for correcting the amount of light from an fCf plasma.