JPH0341720A - Apparatus for forming semiconductor thin film - Google Patents

Abstract

PURPOSE:To control a thin film accurately in an apparatus wherein light is projected on a semiconductor substrate and a semiconductor thin film is selectively grown by measuring the thickness of the thin film which is partially grown on the substrate in an MOMBE apparatus at the same time of the growing. CONSTITUTION:One of first laser beams 5 is projected through each of windows 2 and 2' at the same point on a substrate 1 in a growing chamber 4. Under this state, metal arsenic, allicin, phosphine, triethylgallium, trimethylindium and the like are supplied, and growing is performed. Thus, a diffraction grating is selectively grown at a part where the first laser beam is projected. The first laser beam 5 is diffracted with the grown diffraction grating as the diffraction grating is being grown. Thus diffracted light 3 is obtained. The diffracted light is measured with an optical power meter 6 which is provided at the outside of the window 2'. The intensity of the diffracted light 3 which is diffracted through the selectively grown diffraction grating depends on the height of the selectively grown diffraction grating.

Description

Detailed Description of the Invention (Industrial Application Field) The present invention is a method of growing a semiconductor thin film by irradiating light onto a substrate to promote the thin film growth reaction. The present invention relates to a semiconductor thin film forming apparatus 0 for forming a semiconductor thin film that is grown only on the substrate.

(Prior Art) As semiconductor devices, including those for optoelectronics, become more sophisticated and functional, their manufacturing processes are becoming increasingly complex. In order to simplify the process, not only device structures but also semiconductor thin film manufacturing processes have been proposed. For example, Applied Physics Letters
) Vol. 54, No. 4 (1989), p. 335, when forming a semiconductor thin film, by partially irradiating light onto a semiconductor substrate in a metal organic molecular beam epitaxy (MOMBB) device, A technique has been developed to selectively form a semiconductor Fyi film on a portion of a substrate. For example, in this thin film growth method, a single laser beam is split into two using a beam splitter, and this is used to form a semiconductor film on a substrate. By irradiating one location, a pattern with a striped light intensity distribution can be obtained in the irradiated area. By growing the 'a film without irradiating this pattern, a diffraction grating grown on the substrate can be obtained.

(Problem to be solved by the invention) yi partially grown using this semiconductor thin film forming method
The thickness of the film was controlled by measuring the growth time. That is, since the thickness of the thin film grown per unit time is constant when the growth temperature and the amount of raw material supplied are constant, the relationship has been measured in advance and controlled by measuring the growth time. However, the selective growth rate was highly dependent on the growth temperature and varied greatly with fluctuations in the growth temperature. The selective growth rate also depended on the amount of raw material supplied, and fluctuated at the same rate as the rate of fluctuation in the supply amount. Therefore, in the conventional method, even if the growth time is constant, the thickness of the partially grown thin film fluctuates by about 10%.

(Object of the Invention) The present invention was proposed in order to improve the above-mentioned drawbacks, and its purpose is to provide an apparatus for selectively growing a semiconductor thin film while irradiating a semiconductor substrate with light. The purpose of this method is to accurately control the thickness of a YT film partially grown on a substrate by measuring it simultaneously with the growth.

(Means for Solving the Problems) In order to achieve the above object, the present invention provides an organometallic molecular beam epitaxy apparatus and a first laser optical system for irradiating a substrate in the organometallic molecular beam epitaxy apparatus. A semiconductor thin film forming apparatus comprising: a means for irradiating a substrate in the apparatus with a first laser beam irradiation part; and a means for measuring reflected light, and the first laser beam of the apparatus is diffracted. The gist of the invention is a semiconductor thin film forming apparatus, characterized in that a window is installed at a position where the light intensity is measured, and a means for measuring light intensity is installed outside the apparatus.

(Function) The present invention is a MOMBE apparatus that selectively grows a semiconductor thin film while irradiating a semiconductor substrate with light. By measuring the thickness of thin films simultaneously as they grow by measuring light or diffracted light,
The thickness can be precisely controlled.

(Example) Next, an example of the present invention will be described. It should be noted that the examples are merely illustrative, and within the scope of the spirit of the present invention,
It goes without saying that various changes and improvements can be made.

FIG. 1 shows a schematic diagram of an embodiment of the semiconductor thin film forming apparatus of the present invention.

In the figure, 1 is a substrate, 2 and 2' are windows, 3 is a diffracted light beam, 4 is a growth chamber, 5 is a first laser beam, and 6 is an optical power meter. At the same point on the substrate l in the growth chamber 4, there is a window 2.
．． Metal arsenic, allicine phosphine, triethyl gallium, trimethyl indium, etc. are supplied and grown while irradiating one first laser beam 5 from 2', thereby selecting the part irradiated with the first laser beam 5. The diffraction grating grows. As the first laser beam 5, for example, an argon ion laser (wavelength: 514.5 ns) is used. As the diffraction grating grows, the first laser beam 5 is diffracted by the grown diffraction grating to obtain diffracted light 3. The intensity of the diffracted light 3 diffracted by the selectively grown diffraction grating depends on the height of the selectively grown diffraction grating. do.

FIG. 2 shows the relationship between the height of the grown diffraction grating and the relative intensity of the diffracted light (relative to the total diffracted light intensity) when the first laser beam is diffracted by the diffraction grating.

By finishing the growth at the light intensity shown in FIG. 2, it is possible to obtain a diffraction grating of a desired height.

According to the apparatus shown in FIG. 1, the purpose can be achieved using only a detector (optical power meter) without requiring any other light source.

FIG. 3 shows a schematic diagram of another embodiment of the invention.

In the figure, l is the substrate, 2 and 2゛ are windows, 4 is a growth chamber, 5 is the first laser beam, 6 is an optical power meter, 7 is the second laser beam, 8 is the 0th order diffracted light, 9 is a half mirror. At the same point on the substrate 1 in the growth chamber 4, a window 2.
Metal arsenic, allicine, phosphine, triethyl gallium, trimethyl indium, etc. are supplied while irradiating with one first laser beam 5 from each of the laser beams 2 and 2 to perform growth.

As a result, a diffraction grating selectively grows in the area irradiated with the first laser beam 5. The first laser beam 5 is, for example, an argon ion laser (wavelength: 514.5 nm).
m) is used. A second laser beam 7 is irradiated onto this diffraction grating through the window 2. For example, a helium neon laser can be used as the second laser beam 7. As the grating grows, the second laser beam 7 is diffracted by the grown grating. Therefore, the intensity of the zero-order diffracted light 8 depends on the height of the selectively grown diffraction grating. If necessary, this diffracted light 8 is reflected by a half mirror 9 and measured by an optical power meter 6 installed outside the window 2.

Figure 4 shows the relationship between the height of the grown diffraction grating and the relative intensity of the 0th order diffracted light of the second laser beam diffracted by the diffraction grating (with respect to before the diffraction grating grows).
Since it can be seen that the growth is completed at the light intensity shown in the figure, it is possible to obtain a diffraction grating with a desired height.

According to the apparatus shown in Fig. 3, reflected light can be obtained at the same point regardless of the pinch of the diffraction grating being fabricated (with the apparatuses shown in Figs. 1 and 5, if the pitch of the diffraction grating is different, According to this device, the first. Approximately twice the change in light intensity can be obtained compared to the device shown in FIG.

FIG. 5 shows a schematic diagram of another embodiment of the invention.

In the figure, 1 is a substrate, 2 and 2゛ are windows, 4 is a growth chamber, 5 is a first laser beam, 6 is an optical power meter, 7 is a second laser beam, 10 is a diffracted light, and 11 is a laser light source. It is. Metal arsenic, allicin, phosphine, triethyl gallium,
Supply trimethylindium and perform growth. As a result, a diffraction grating selectively grows in the area irradiated with the first laser beam 5. As the first laser beam 5, for example, an argon ion laser (wavelength: 514.5 nm) is used. This diffraction grating is irradiated with a second laser beam 7 from a laser light source 11 installed in the growth chamber 4. As the light source of the second laser beam 7, for example, a GaAs semiconductor laser can be used. As the grating grows, the second laser beam 7 is diffracted by the grown grating. Therefore, the intensity of the diffracted light 10 depends on the height of the selectively grown diffraction grating. This diffracted light 10 is measured with an optical power meter 6 installed in the growth chamber.

FIG. 6 shows the relationship between the height of the grown diffraction grating and the relative intensity of the diffracted light (relative to the total diffracted light intensity) of the second laser beam diffracted by the diffraction grating.

By finishing the growth at the light intensity shown in FIG. 6, it is possible to obtain a diffraction grating of a desired height.

Furthermore, by using a photodiode array as the optical power meter 6, the position of the diffracted light can be measured, and the pitch of the diffraction grating can be measured without taking the substrate 1 out of the growth chamber 4.

According to the apparatus shown in FIG. 5, there is no need to provide an optical system for measurement outside the growth chamber, and it is suitable for producing a large number of identical diffraction gratings.

FIG. 7 shows a schematic diagram of another embodiment of the invention.

In the figure, 1 is a substrate, 2 and 2' are windows, 4 is a growth chamber, 5 is a first laser beam, 6 is an optical power meter, 12
is a chigoppa, and 13 is a lock-in amplifier. Growth room 4
Metallic arsenic, allicin, phosphine, triethyl gallium, trimethyl indium, etc. are supplied while irradiating the first laser beam 5 chopped by the laser beam 12 through the window 2 onto the substrate l in the middle, and growth is performed.
A thin film whose cross section has a Gaussian distribution is selectively grown in the region irradiated with the first laser beam 5 of 0n. As the first laser beam 5, for example, an argon ion laser (wavelength 5
14.5 nm). The first laser beam 5 is scattered by the grown thin film as the thin film grows.

This scattered light is measured by an optical power meter 6 installed outside the window 2.
is detected, amplified by a lock-in amplifier 13, and measured.

The intensity of the light scattered by the selectively grown region depends on the thickness of the selectively grown thin film. Figure 8 shows the relationship between the thickness of the grown thin film and the light intensity of the scattered first laser beam. By finishing the growth at the light intensity shown in Figure 8, a thin film of the desired thickness can be obtained. Is possible.

(Example Work) A GaAs diffraction grating was grown using the apparatus shown in FIG. As the first laser beam 5, an argon ion laser (wavelength: 514.5 nm) was used, and the incident angle was 32.4 degrees. Growth was performed while measuring the first-order diffracted light obtained in the 29 degree direction. , before the growth, the power of the laser beam reflected by the substrate 1 of the first laser beam 5 is measured, and the growth is stopped when the first-order diffracted light reaches 0.223% of this, and the diffraction at a height of 100 nm is performed. When the lattice was grown, the variation was within 3%.

(Example 2) An InP diffraction grating was grown using the apparatus shown in FIG.

The first laser beam 5 is an argon ion laser (
The wavelength was 488 nm), and the incident angle was 30.5 degrees. A helium-neon laser was applied perpendicularly to the substrate through the window 2, and growth was performed while measuring the zero-order diffracted light 8. Growth was stopped when the intensity of the 0th order reflected light 8 reached 99.544% of the intensity before the growth of the diffraction grating, and when a diffraction grating with a height of 1100 nm was grown, the variation was within 2.5%.

(Example 3) A GaAs diffraction grating was grown using the apparatus shown in FIG. As the first laser beam 5, an argon ion laser (wavelength: 514.5 nm) was used, and the incident angle was 32.4 degrees. A second laser beam 7 is incident on this at an incident angle of 53 degrees using an AlGaAs semiconductor laser installed in the growth chamber 4, and growth is performed while measuring the first-order diffracted light obtained in the direction of 54.4 degrees. went. Growth was stopped when the value obtained by multiplying the intensity of the second laser beam 7 by the reflectance of GaAs was 0.228%, and when a 100 nm diffraction grating was grown, the variation was within 3%.

(Example 4) A spot-shaped GaAs thin film was grown using the apparatus shown in FIG. As the first laser beam 5, an argon ion laser (wavelength: 514.5 nm) was used. Growth was performed while detecting the scattered light with a silicon photodetector. When selective growth was performed based on FIG. 8, the thickness of the thin film varied within 3%.

(Effects of the Invention) As explained above, in a MOMBE apparatus that selectively grows a semiconductor thin film while irradiating a semiconductor substrate with light, there is a means for irradiating a laser beam irradiated part onto a substrate in the apparatus, and a means for irradiating a laser beam irradiated part onto a substrate in the apparatus, and By providing a means to measure MOM
The thickness of the yI film can be measured in the BE apparatus at the same time as the growth. Especially DFB
, the height of the grating, which is essential for DBR lasers, can be grown with high precision.

Therefore, it is useful not only for InP-based and GaAs-based homoepitaxial systems, but also for heteroepitaxial growth of compound semiconductors on silicon.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram of an embodiment of the semiconductor thin film forming apparatus of the present invention, FIG. 2 is the relationship between the height of the diffraction grating and the intensity of diffracted light, and FIG.
The figure is a schematic diagram of another embodiment of the present invention, Figure 4 is a relationship between the height of the diffraction grating and the intensity of diffracted light, Figure 5 is a schematic diagram of another embodiment of the invention, and Figure 6 is a diagram of the diffraction grating. FIG. 7 is a schematic view of another embodiment of the present invention, and FIG. 8 shows the relationship between the thickness of a spot-shaped thin film and the intensity of scattered light. 1...Substrate 2...Window 3...Diffracted light 4...Growth chamber, first laser beam optical power meter, second laser beam, 0th order and diffracted light, half mirror・Diffraction light・Laser light source・Chipper・Lock-in amplifier No.] Figure No. rs-Mitsuko nml No. 4 No. 1 Height + nml Figure 8 Figure 8 also bot l2 (,μ1.PL)

Claims (4)

[Claims] (1) A semiconductor thin film forming apparatus comprising an organometallic molecular beam epitaxy apparatus and a first laser optical system for irradiating a substrate in the organometallic molecular beam epitaxy apparatus. a window at a position where the first laser beam of the device is diffracted;
and a semiconductor thin film forming apparatus, characterized in that a means for measuring light intensity is installed outside the apparatus. (2) In a semiconductor thin film forming apparatus comprising an organometallic molecular beam epitaxy apparatus and a first laser optical system for irradiating a substrate in the organometallic molecular beam epitaxy apparatus, a first laser beam is applied to the substrate in the apparatus. a window installed in the device, and a window installed outside the device, in order to irradiate the first laser beam irradiation portion, and a means for measuring the reflected light; a second laser light source, a window installed at a position where the second laser light is reflected, and a means for measuring the light intensity of the second laser light outside the device. Semiconductor thin film forming equipment. (3) A semiconductor thin film forming apparatus comprising an organometallic molecular beam epitaxy apparatus and a first laser optical system for irradiating a substrate in the organometallic molecular beam epitaxy apparatus; a second laser light source installed inside the apparatus to irradiate the first laser beam irradiation area; 1. A semiconductor thin film forming apparatus comprising means for measuring the light intensity of a second light source installed at a position where the second laser beam is diffracted. (4) In a semiconductor thin film forming apparatus comprising an organometallic molecular beam epitaxy apparatus and a first laser optical system for irradiating a substrate in the organometallic molecular beam epitaxy apparatus, a first a window at a position where the first laser beam of the device is scattered; and a means for measuring the reflected light;
and a semiconductor thin film forming apparatus, comprising means for measuring light intensity outside the apparatus.