JPS59140524A - Temperature controller - Google Patents

Abstract

PURPOSE:To measure accurately the temperature in a desired position to control it, by controlling the temperature of an object such as a board or the like with detection of a spectrum of spectral diffraction of the Raman light, amplification, conversion to temperature information, and the control of a heating means. CONSTITUTION:A coherent laser light 7 is radiated from a laser light source 6 on the outside of a bell jar 1 to a board 2 in the film forming operation. The laser light 7 is reflected on the surface of an evaporation film and is led to the outside of the bell jar 1 as a reflected light 7' and is made incident to a spectroscope 9 through a mirror 8. The reflected light 7' is attained as the Raman light, and the spectroscope 9 measures the Raman light and makes its spectrum of spectral diffraction incident to a photodetector 10. An analog signal is attained from the detector 10 and has noise component suppress by a multichannel analyzer 11 and is amplified to attain a high-S/N output signal. This signal is converted to a digital signal by an A/D converter 12 and is converted to temperature information by a personal computer 13, and an SCR power source 17 of a heater 4 is controlled through a temperature controller 15 and a gate unit 16 to control the heating temperature to a set temperature.

Description

Detailed Description of the Invention 1. Industrial Application Field The present invention relates to temperature control devices, such as vapor deposition, CVD (chemical vapor deposition), VPB (vapor phase epitaxy), ion blating, MBE (molecular beam epitaxy), etc. The present invention relates to a device suitable for controlling substrate temperature in epitaxy and the like.

2. In conventional vapor deposition apparatuses, the temperature of the substrate on which a thin film is to be deposited is important in obtaining a high-quality product, and for this reason, a means for measuring the substrate temperature during film formation is provided.

As this type of temperature measuring means, one in which a thermocouple made of CA (chromel-alumel), copper constantan, or platinum rhodium is inserted near the back surface of the substrate is known. Although this method using thermocouples is good in that temperature can be measured accurately, it has various drawbacks as follows.

(1) Although it is possible to measure the temperature on the back side of the substrate, it is impossible to measure the surface temperature of the film deposited on the front side of the substrate during film formation, so it is possible to accurately measure the temperature at locations that directly affect film quality. cannot be detected.

(2) When operating by applying a high voltage to the substrate, the substrate is covered with an insulator or glass, which slows down the thermal response of the thermocouple.

(3) When operating by generating high frequency waves on or around the board, thermocouples cannot be used because they pick up noise caused by the high frequency waves.

(4) When forming a film while moving the substrate, it is structurally impossible to move the thermocouple together, making temperature measurement itself impossible.

On the other hand, as another temperature measuring means, there is a method of detecting infrared rays emitted from the surface side of the substrate during film formation. However,
In this case, a sensor sensitive to the infrared region is required.
Since the infrared rays themselves tend to pick up ambient noise, there are serious drawbacks in that the error in the detection signal by the sensor becomes large and the signal cannot be amplified.

3. OBJECTS OF THE INVENTION An object of the present invention is to provide an apparatus that can accurately measure and control the temperature of a desired location on an object such as the above-mentioned substrate.

4. Structure of the invention, that is, the present invention includes a light source that irradiates light (particularly laser light) onto an object whose temperature is to be controlled (for example, a substrate to be deposited);
A spectroscope that measures the Raman light from the target object, an amplification section (for example, a multi-channel analyzer) that amplifies the output signal of the spectroscopic light receiving section of this spectrometer, and a temperature A conversion unit (for example, a microcomputer that processes digital signals from an A/I' converter) that converts the information into information, and a control unit that controls the heating means for the object based on the temperature information from this conversion unit ( For example, the present invention relates to a temperature control device characterized by having a temperature controller and a thyristor whose output is controlled by the temperature controller.

5. Examples Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

FIG. 1 schematically shows an example in which the present invention is applied to a vacuum evaporation apparatus f.

According to this vapor deposition apparatus, a Pelger 1 forming a vacuum chamber
A substrate 2 to be evaporated is disposed inside, and an evaporation source 3 of silicon or the like is disposed opposite to this. While the substrate 2 is heated to a predetermined temperature by a heater 4 such as a resistance wire or a heater lamp,
The structure is such that ionized or activated components are effectively attracted to the substrate 2 by applying a negative DC bias voltage (particularly within -10 KV) 5. Although not shown,
A modifying gas such as hydrogen gas can be ionized or activated and introduced into the Pelger 1 and mixed into a deposited film of amorphous silicon or the like to improve film properties (for example, dark resistance, photosensitivity). The resulting deposited film can be formed of various materials, such as a general semiconductor film, a photoreceptor, a dielectric, a solar cell, or a thin film for an image sensor. In addition, the inside of the Pelger 1 is evacuated to 10-3 to 1O-7 Torr via an exhaust pipe by a vacuum pump (both not shown), the substrate 2 is heated to 250 to 500°C, and a bias of -10KV or less is applied. A voltage is applied, and the evaporation source 3 may be heated and evaporated using an electron gun heating method (not shown).

Next, temperature control of the substrate 2 in the above vapor deposition apparatus will be explained.

A laser light source 6 is disposed outside the Pelger 1, and a coherent laser light 7 is emitted from this laser light source toward the substrate 2 during the film forming operation.

This laser beam 7 is incident on the surface region of a vapor deposited film (for example, an amorphous silicon film) deposited on the substrate 2, and is absorbed by the surface region of the vapor deposited film according to the energy gap of the vapor deposited material depending on the selection of the wavelength range. , further emitted from there. That is, the laser beam 7 is substantially reflected on the surface of the vapor deposited film and is led out of the Pelger 1 as reflected light 7', and further passes through the mirror 8 and enters the spectrometer 9. The laser beam 7 is emitted in a chopped waveform as shown in FIG. 2(a), and the reflected light 7' from the deposited film is obtained as Raman light having a Raman spectrum distribution as shown in FIG. 2(b). This Raman light is composed of laser light and scattered light specific to the material of the deposited film, and the Stokes line (intensity IA) and anti-Stokes line (intensity IA) and anti-Stokes line ( Intensity IB) appears. Generally, the intensity of the Stokes line is greater than that of the anti-Stokes line, and the wavelength shift amount Δλ changes depending on the temperature of the deposited film. This laser Raman light has good monochromaticity and is emitted with sharp directivity in a direction inclined by a certain angle when viewed from the direction of the incident light 7. Usable laser light sources 6 include He-Nev laser, A
``There are lasers, N21 lasers, YAG lasers, semiconductor lasers (LDs), dye lasers, etc.

The spectrometer 9 measures the above-mentioned laser Raman light and causes its spectrum to enter the light receiving element 10 .

Since the optical spectrum has a pattern as shown in FIG. 2, the light receiving element 10 is configured so that it can simultaneously receive Stokes light and anti-Stokes light. This light-receiving element includes photomultiplier tubes, PIN
Diode array, CCD (Charge Couple)
pled Device) etc. can be used,
It is preferable to configure it as a line sensor.

From the light receiving element 10 as a photodetector, as shown in FIG.
An electrical analog signal as shown in C) is obtained, and this is amplified by the next-stage multi-channel analyzer 11, resulting in an S/N signal in which noise is suppressed and only the necessary signal is amplified, as shown in Fig. 2(d). Output signals with good ratio can be obtained. The multi-channel analyzer 11 is a device in which well-known boxcar integrators capable of obtaining a high S/N ratio are connected in parallel so that the spectrum in the wavelength range from the Stokes line to the anti-Stokes line can be instantaneously measured. Of course, a single boxcar integrator or lock-in amplifier may be used instead of this amplifier.

When using a lock-in amplifier, it is preferable to manually input a reference signal from the drive circuit of the laser light source 6 at the same time as shown by the dashed line in FIG.

This output signal is input to the A/D converter 12, where it is divided into, for example, 8-bit signals.

Therefore, from the A/D converter 12, for example, as shown in FIG.
As shown in e), each unit of digital signal corresponding to the signal waveform of FIG. 2(d) is obtained in units of 8 bits. For example, the signal in Fig. 2(d) can be divided into n gates as a whole, of which 8 digital signals are all "on" from the spectrum (GL) corresponding to the laser beam. However, from the spectrum of the anti-Stokes light or Stokes light (gate GS1 or G52), digital signals having different repeating patterns of 1-on' and 1-off are obtained corresponding to the respective intensities.

This digital signal is then inputted to a microprocessor 13 configured as, for example, a personal computer. This computer calculates the digital signal, and calculates the wavelength Δλ and the intensity ratio Em/IB of the Raman spectrum.
It has a function to calculate. This combiator is programmed with Δλ and M/Ie corresponding to each set temperature in advance, and samples the above-mentioned calculated values to obtain the corresponding temperature information T (i.e., the surface temperature of the deposited film). Output.

This temperature information further enters the D/A converter 14, where it is converted into an analog signal and then sent to the temperature controller 1.
5 is man-powered. The temperature controller 15 compares the temperature information with a preset temperature and supplies a necessary temperature control signal to the gate unit 16.

In response to this, the gate unit 16 turns on the heater 4.
A control signal is sent to the thyristor power supply 17 to control the power supplied by the thyristor power supply 17 until the heating temperature by the heater 4 reaches the desired set temperature. Note that the temperature controller 15 is a known PID (Proport
ional I-integral Derivat
In addition, a relay switch may be used in place of the gate unit 16 and the thyristor power supply 17.

In this way, the temperature control system described above allows the substrate 2 to
The temperature (specifically, the surface temperature of the deposited film) is constantly measured during the film forming operation and is accurately controlled to a desired set temperature.

From the above, it will be understood that the temperature control device according to this example exhibits the following remarkable effects that cannot be achieved with conventional devices.

(1) Since the surface temperature of the film being formed can be measured and controlled, a high-quality deposited film can be obtained.

(2) Even if high voltage or high frequency is applied to the board, there is no noise effect that is seen when using thermocouples.

(3) Temperature measurement is possible even if the film is formed while moving the substrate.

(4) Since laser Raman light is not affected by surrounding heat, no error occurs in the detection signal from the light receiving element.

(5) In the case of laser Raman light, a sensor sensitive in the visible range, such as a silicon sensor, can be used, making signal processing such as amplification easier.

FIG. 3 shows another embodiment of the invention.

This example is characterized in that the laser beam 7 from the laser light source 6 is scanned in the surface direction of the arc-shaped substrate 2 by means of a rotatable mirror. That is, depending on the deflection angle of the mirror, the course of the laser beam 7 is changed from the solid line position to the one-dot chain line position, and accordingly, the laser Raman light 7' also changes its course. When the mirror 8 is rotated in the direction of the arrow 21 in response to this course change (or in synchronization with the rotation of the mirror), since the substrate 2 is formed in an arc shape,
Laser Raman light from any arbitrary position can be made incident on the mirror 8 and guided from there to the spectroscope 9.

In this way, the laser Raman light from each position in the plane direction of the surface of the deposited film on the substrate 2 is sequentially processed in the same manner as shown in FIGS. 1 and 2, and the personal converter 13
Each converter 1
4a, 14b, 14c and temperature controllers 15a, 1
5b and 15c operate. This allows each gate &l
From L27 to 16a, 16b, 16c, the board 2
Three heaters that heat independently in a divided form 4
Each thyristor power supply 17a, 1 for driving a, 4b, 4C
Control signals for individually controlling 7b and 17C are obtained. Through this independent control, each heater 4a, 4b.

Since the power of 4C can be controlled individually, it is possible to eliminate variations in temperature in the surface direction of the substrate 2 and to always make the surface temperature of the deposited film uniform. Therefore, the film characteristics of the entire deposited film can be made uniform, and a higher quality product can be obtained.

Although the present invention has been illustrated above, the above-mentioned example can be further modified based on the technical idea of the present invention.

For example, the temperature control device according to the present invention is not limited to the above-mentioned vapor deposition device, but also includes CVD, VPE, ion blating, M
It can be applied to various film forming apparatuses such as BE, or apparatuses that perform heat treatment such as annealing. It also measures temperature,
The object to be controlled may be hydrogen.

6. Effects of the Invention As described above, the present invention controls the temperature of the target object by detecting the spectrum of Raman light, amplifying it, converting it to temperature information, and controlling the heating means. It is possible to achieve remarkable effects.

(1) Accurate temperature control is possible because the temperature can be measured and controlled by irradiating light onto a desired part of the object.

(2) Even if high voltage or high frequency is applied to the object, there is no effect of noise that is seen when using thermocouples.

(3) Temperature measurement is possible even if the film is formed while moving the object.

(4) In particular, since laser Raman light is not affected by ambient heat, no error occurs in the detection signal from the light receiving element.

(5) In the case of laser Raman light, a sensor sensitive in the visible range, such as a silicon sensor, can be used, making signal processing such as amplification easier.

[Brief explanation of drawings]

The drawings show an embodiment of the present invention, in which Fig. 1 is a schematic diagram of a vapor deposition apparatus equipped with a temperature control device, Fig. 2 is a diagram sequentially showing signal waveforms in each temperature control process, and Fig. 3 is a vapor deposition apparatus equipped with a temperature control device according to another example. In addition, in the symbols shown in the drawings, 2...Substrate 3...Evaporation sources 4.4a to 4C...Heater 6...Fist laser light source 7...Laser light 7'--... - Laser Raman light 8.20 - Mirror 9... Spectrometer 10... Light receiving element (photodetector) 11...
・Amplifier (multi-channel analyzer) 12.14.14a~14C...Converter 13...
・Microcomputer (PC) 15.15a-1
5c...Temperature controller 16.16a-16c...Gate unit 17.17a-17c...Thyristor power supply. Agent: Patent attorney Hiroshi Saka (1 other person) a powder @ 10 @ 21 (a) (L Tanomi Hatake (dn Sekigo)

Claims (1)

[Claims] 1. A light source that irradiates light onto an object whose temperature is to be controlled;
A spectroscope that measures the Raman light from the target object, a light receiving section that detects the spectrum of the spectrometer, an amplifying section that amplifies the output signal of the light receiving section, and an amplification section that calculates the amplified signal from the amplifying section. What is claimed is: 1. A temperature control device comprising: a converter that converts temperature information into temperature information; and a controller that controls a heating means for the object based on the temperature information from the converter.