JPH076063B2 - Light detection method and device - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a photodetection method and apparatus for detecting light in a thin film forming method in a vacuum which utilizes light or which secondarily emits light. It is a thing.

2. Description of the Related Art When a thin film is formed using light or accompanied by secondary light emission, the wavelength of this light is unique to atoms, molecules, ions, radicals, etc. of the thin film forming material. There is a correlation with the amount of atoms, molecules, ions, radicals, etc. of the forming material existing in the space. Therefore, this light is detected for the purpose of checking whether the thin film formation state has changed. However, at the time of forming the thin film, the thin film forming material adheres to a window (hereinafter, referred to as a light detection window) through which the detection light passes and becomes cloudy. Conventionally, various measures have been taken to reduce the fogging of the light detection window. For example, a shutter is provided on the optical path of the detection light to prevent the light detection window from being fogged, the shutter is opened only during measurement, the light detection window is moved away from the light source, and the detection light that is thin up to the light detection window is used. There was also an introduction path for people. Further, although the output value was corrected by detecting the amount of fog in the light detection window (Japanese Patent Application No. 61-12085), there was a limit to the continuous light detection. The method of removing the fog by spattering the window for light detection was also taken.

Problems to be Solved by the Invention Conventionally, measures have been taken to reduce the fogging of the light detection window, but in reality, the amount of fogging of the light detection window increases with the thin film formation time. Further, a thin film cannot be formed during the operation of removing the thin film forming material attached to the light detection window. Therefore, there are problems in long-time continuous thin film formation and light detection,
It was not suitable for mass production.

In consideration of the above problems, the present invention reproduces a light detection window without clouding when a thin film is formed on a transparent substrate using light or in a vacuum accompanied by secondary light emission. The purpose is to obtain a precise and accurate light detection amount continuously for a long time.

Means for Solving the Problems In order to solve the above problems, the present invention detects a light used at the time of forming a thin film or a light secondarily generated at a position where the light is received through a transparent substrate forming the thin film. A window is installed.

Action With this configuration, the thin film forming material does not adhere to the light detection window.

Also, during mass production, a thin film is formed with the same specifications, and
Since the transparent substrate is replaced with a new one after the thin film is formed, the variation in the detection value of the photodetector is very small among the substrates. Therefore, a reproducible and accurate light detection value can always be obtained.

First Embodiment FIG. 1 is a block diagram showing the configuration of a first embodiment of the photodetector of the present invention. In FIG. 1, reference numeral 1 is a thin film forming apparatus, and a DC sputtering apparatus is shown as an example. The thin film forming apparatus 1 has a target 11 and an anode 12, and glow discharge occurs when a high voltage is applied between them under vacuum. Due to this glow discharge, the gas introduced into the discharge space becomes plasma 14 state. Generally, argon is used as a gas, and positive ions are generated in the plasma 14 to collide with the target surface. The sputtered particles then form the anode 12
A thin film is formed by depositing on the transparent substrate 13 arranged above.

A part of the detection light 2 of the plasma 14 passes through the transparent substrate 13 and the light detection window 16 to reach the photodetector 3. Here, an anti-adhesion cover 17 is provided so that the light detection window 16 does not become cloudy.
It is preferable that the deposition-inhibiting cover 17 has a smaller gap with the anode 12 supporting the transparent substrate 13. The photodetector 3 includes a spectroscope 31, a phototube 32, and a current amplifier 33. The spectroscope 31 includes a diffraction grating, a prism, a lens, and a slit, and separates lights having different wavelengths. After separation, the energy of the light of the wavelength to be detected is converted into a current value by the phototube 32, and the current amplifier 33
It is amplified by and output.

In the present invention, since the detection light is received through the transparent substrate, there is no fear that the thin film forming material will adhere to the light detection window and become cloudy. In addition, when an opaque thin film is formed on a transparent substrate, the light detection value decreases as the thin film is formed, but when mass-producing the same specifications, it is possible to sufficiently confirm the presence or absence of abnormalities by comparing each substrate.

Further, although the optical path of the detection light 2 is not changed in FIG. 1, it is possible to change the optical path by using a reflecting mirror.
Therefore, the position of the photodetector 3 can be freely changed. Also, the first
Although there is no mechanism to rotate the transparent substrate 13 in the figure,
13 may be rotated. In this case, the support portion of the transparent substrate 13 may be partially connected to form a donut-shaped hole.

If the thin film forming material flies from one direction such as sputtering, a transparent substrate 13 can be replaced without erasing the plasma 14 by providing a shutter between the transparent substrate 13 and the target 11 so as not to block the anode 12 and the target 11. To be This is effective in mass production because the time required to generate the plasma 14 and the time required for the vacuum pressure to become constant can be omitted. In this case, a vacuum chamber for supplying the transparent substrate 13 is required adjacent to the thin film forming apparatus 1. In the case of thin film formation using a chemical reaction such as photo CVD, it is necessary to stop the inflowing gas or turn off the light in order to stop the chemical reaction, and it takes time to reach a steady state each time the transparent substrate 13 is replaced. However, the time cannot be shortened as described above.

FIG. 2 is a constitutional block diagram showing a second embodiment of the photodetector of the present invention. In FIG. 2, a part of the detection light 2 of the plasma 14 passes through the transparent substrate 13, only the detection wavelength light passes through the filter 34, is condensed by the condenser lens 35, is guided by the optical fiber 36, and is condensed by the condenser lens 37. Is collimated and guided to the detector 3. In the photodetector 3, the phototube 32 converts light energy into a current value, which is amplified by the current amplifier 33 and output.

Since the detection light is guided by the optical fiber 36 in the second embodiment, there is an advantage that the position of the photodetector 3 can be freely selected.
Although the filter 34 is placed before the optical fiber 36 in this embodiment, it may be provided after the optical fiber 36. Further, in the present embodiment, the filter 34 is used for the purpose of detecting the light of the same wavelength only, so that the spectroscope 31 in the photodetector 3 is eliminated and simplified. Of course, the spectroscope 31 may be inserted except for the filter 34.

In the case of this configuration, it is not the light detection window that is prevented from being fogged but the optical fiber or the like that is a light guide material for the detection light.

FIG. 3 is a configuration block diagram showing a third embodiment of the photodetector of the present invention. In FIG. 3, compared with FIG.
A film thickness detector 4 and a correction coefficient calculation circuit 5 are added.
The film thickness detector 4 is a device for measuring the film thickness formed on the transparent substrate 13, and there is, for example, one using a crystal oscillator.
On the basis of the output from the film thickness detector 4, the correction coefficient calculation circuit 5 amplifies the current amplifier 33 in the photodetector 3 so that the photodetection output value is obtained when the thin film is not formed on the transparent substrate 13. It is to correct the rate.

The film thickness detector 4 is used for general thin film formation control, and the output value thereof is used, so that the present embodiment can be easily executed.

According to the present invention, it is possible to obtain reproducible and accurate light detection values continuously for a long time without the light detection window always being fogged.

FIG. 4 is a constitutional block diagram showing a fourth embodiment of the photodetector of the present invention. In FIG. 4, compared with FIG.
A reflectance detector 6, a current amplifier 7, and a correction coefficient calculation circuit 5 are added. The reflectance detector 6 is a device for measuring the reflectance when a thin film is formed on the transparent substrate 13. The output from the reflectance detector 6 is amplified by the current amplifier 7 and corrected based on this output value. The coefficient calculation circuit 5 corrects the amplification factor of the current amplifier 33 in the photodetector 3 so that the photodetection output value is obtained when the thin film is not formed on the transparent substrate 13.

It is necessary to make the wavelength of the light used for the reflectance detector 6 different from the wavelength of the light accompanying the thin film formation to eliminate interference. Further, it is preferable to insert a filter between the reflectance 6 and the transparent substrate 13 to cut off the wavelength of light accompanying the thin film formation.

The reflectance detector 6 is generally used for thin film formation control, and the output value thereof is used, so that the present embodiment can be easily executed. According to the present invention, it is possible to obtain reproducible and accurate light detection values continuously for a long time without the light detection window always being fogged.

Although the current amplifier is used in the above embodiments, the voltage amplifier may be used when the output is a voltage.

According to the present invention, the thin film forming material does not adhere to the photodetector. Also, after forming a thin film, it is replaced with a new transparent substrate,
If a thin film is formed on a transparent substrate with the same specifications, the variation between the substrates is very small, so that a reproducible light detection value can always be obtained.

Therefore, no special means for eliminating the fogging of the light detection window is required, which is economical, and continuous detection can be performed for a long time, which is suitable for mass production.

[Brief description of drawings]

FIG. 1 to FIG. 4 are principle views of the photo-detecting device in the first to fourth embodiments of the present invention. 1 ... Thin film forming apparatus, 2 ... Detection light, 3 ... Optical monitor, 4 ... Film thickness monitor, 5 ... Correction coefficient calculation circuit, 6 ...
… Reflectance monitor, 7 …… Current amplifier, 11 …… Target (cathode), 12 …… Anode, 13 …… Transparent substrate, 14 …… Plasma, 15 …… Supporting part, 16 …… Light detection window, 17 …… Anti-adhesive cover, 31 …… Spectroscope, 32 …… Phototube, 33 …… Current amplifier,
34 …… filter, 35 …… condenser lens, 36 …… optical fiber, 37 …… condenser lens.

Claims (6)

[Claims] 1. A method for detecting light used for forming a thin film on a transparent substrate or light generated secondarily, the amount of the light being detected through the transparent substrate. A light detection method characterized by: 2. The light detection method according to claim 1, wherein the detection output value of the light quantity is corrected by the film thickness detection output obtained by detecting the film thickness of the thin film formed on the transparent substrate. . 3. The detection output value of the light amount is corrected by detecting the reflectance from the transparent substrate at the same time when the thin film is formed, and correcting the reflectance by the reflectance detection output. Light detection method. 4. In a system for detecting light used for forming a thin film on a transparent substrate or light generated secondarily, a surface of the transparent substrate opposite to the light source. A photo-detecting device, characterized in that a means for extracting the light is provided. 5. The output of the means for extracting light is provided with means for detecting the film thickness of a thin film formed on a transparent substrate and means for performing correction based on the film thickness. The photodetector according to claim 4. 6. A means for measuring the reflectance from a transparent substrate with light having a wavelength different from the light emitted when forming a thin film, and the light emitted when forming a thin film is received based on this reflectance. 5. The photodetection device according to claim 4, further comprising means for correcting the output value from the means for performing.