JPH04221815A - Method for growing semiconductor thin film - Google Patents

Abstract

PURPOSE:To accurately recognize the part of a crystal partially grown on a semiconductor substrate or controlled in composition when a semiconductor thin film is selectively grown or the composition of the thin film is controlled by irradiating the semiconductor substrate with light. CONSTITUTION:Fig. 2 shows the difference in growing speed of an InGaAs film between the part irradiated with laser light and another part not irradiated with the laser light. It can be understood from the figure that a semiconductor thin film of a different composition and different thickness can be formed at a desired location on a substrate by making the scanning speed at both ends of a line to be scanned slower than that at the other area when the scanning is made with the laser light.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention is a method of growing a semiconductor thin film by irradiating the substrate with laser light to promote or suppress the thin film growth reaction, thereby forming a different thickness at any location on the substrate. Or it relates to a method of forming semiconductor thin films having different compositions.

0002

2. Description of the Related 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
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 (MOMBE) device, Techniques have been developed for selectively forming a semiconductor thin film on a portion of a semiconductor substrate or controlling the composition thereof. When thin films with selectively different thicknesses or compositions are formed using this thin film growth method, if the differences are made smaller, the differences in step, reflectance, and refractive index between the selectively grown region and the surrounding area will be reduced. It was small, and it was difficult to identify the selectively grown region after thin film growth.

0003

SUMMARY OF THE INVENTION The present invention has been proposed to improve the above-mentioned drawbacks, and its purpose is to selectively grow or control the composition of a semiconductor thin film while irradiating a semiconductor substrate with light. The purpose of this method is to accurately grasp the parts of crystals that have been partially grown or whose composition has been controlled on a substrate.

0004

[Means for Solving the Problems] In order to achieve the above object, the present invention uses an organometallic epitaxy method to irradiate and scan a part of the substrate with a laser beam, thereby forming a III-III film on a single crystal substrate. - A semiconductor thin film growing method characterized in that when growing a V group semiconductor thin film, the scanning speed at both ends of the scanning line is made slower than the scanning area excluding both ends in scanning the laser beam. It is something to do.

[0005]

[Operation] The present invention uses organometallic molecular beam epitaxy to grow a semiconductor thin film on a single crystal substrate while irradiating light. Since a semiconductor thin film having a composition and thickness different from other locations can be formed in one location, and the location can be specified, alignment with a mask can be easily performed.

[0006] The present invention aims at partially increasing the growth rate of an InP film or a GaAs film by irradiating the film with light under a constant growth temperature condition.
In the growth of S films and InGaAsP films, under growth conditions in which the growth rate of the film remains constant or decreases as the substrate temperature rises, a portion of the substrate surface is irradiated with light to partially increase the substrate temperature. This is because it has been found that both the growth rate and Ga composition in the light irradiated area and the P composition in the case of a quaternary system decrease compared to the non-irradiated area.

The growth conditions under which the film growth rate remains constant or decreases as the substrate temperature increases means the following. FIGS. 3 and 4 show the growth rate and substrate temperature dependence of the Ga composition in InGaAs when an InGaAs thin film is grown on, for example, an InP substrate using an organometallic molecular beam epitaxial apparatus.

In FIG. 3, the horizontal axis represents the substrate temperature, and the vertical axis represents InGaA.
In FIG. 4, the horizontal axis shows the substrate temperature, and the vertical axis shows the Ga composition x in In1-x GaX As. Trimethylindium, triethylgallium and arsine were used as raw materials. Growth conditions other than substrate temperature were kept constant. From Figures 3 and 4, the substrate temperature ranges from 500°C to 550°C.
The growth rate and Ga composition are almost constant at ℃. Both the growth rate and Ga composition begin to decrease above 550°C, and at 600°C
In this manner, both the growth rate and the Ga composition become constant. This result shows that the growth rate and composition can be controlled by keeping other growth conditions constant and changing only the substrate temperature to an appropriate value. Therefore, when the substrate temperature is 500℃ or higher, 6
In the range below 00°C, if a part of the substrate surface is irradiated with light and the substrate temperature is partially increased to 600°C or higher, both the growth rate and Ga composition of the light-irradiated area will decrease compared to the non-irradiated area. , pattern formation and change of Ga composition become possible.

FIG. 1 shows the dependence of the difference in growth rate between a portion irradiated with laser light and a portion not irradiated with laser light during growth of a GaAs film on the laser scanning speed. It can be seen that the difference decreases as the laser scanning speed increases. For example, when growing a multiple quantum well (MQW) or a single quantum well (hereinafter referred to as SQW), the difference between the irradiated area and the non-irradiated area is small. For example, if a laser is scanned at a constant speed and a SQW is grown with a thickness of 100 angstroms in the laser irradiated area, the difference in thickness between the laser irradiated area and the non-laser irradiated area is less than 100 angstroms, and that area can be identified. It is difficult to do so. Therefore, by stopping scanning for a short time at the start and end points of laser scanning, the thickness of those parts can be increased, and this can be used to specify the position. The same is true in the case of InP.

FIG. 2
shows the dependence of the growth rate difference between a portion irradiated with laser light and a portion not irradiated with laser light during growth of the InGaAs film on the laser scanning speed. It can be seen that the difference decreases as the laser scanning speed increases. For example, when a SQW is grown with a thickness of 100 angstroms in the laser irradiated area by scanning the laser at a constant speed, the difference in thickness between the laser irradiated area and the non-laser irradiated area is less than 100 angstroms, and it is difficult to identify that area. It is difficult. Therefore, in laser scanning, by stopping scanning for a short time at the start and end points of the scan, the thickness of those parts can be made thinner, and this can be used to specify the position. The same applies to InGaAsP. Next, a specific example will be explained.

[0011]

[Example] Next, an example of the present invention will be described. It should be noted that the embodiments are merely illustrative, and it goes without saying that various changes and improvements can be made without departing from the spirit of the present invention.

(Example 1) Using an organometallic molecular beam epitaxial device, a 1W argon laser beam (514.
GaAs was grown at a substrate temperature of 400° C. while scanning a 1 cm section with a period of 10 Hz and stopping for 10 msec at both ends. At both ends, the difference between the laser irradiated part and the non-irradiated part was about 1000 angstroms, and the position could be identified without using a microscope. However, parts other than both ends could not be seen using an optical microscope. Therefore, when the film thickness distribution was measured on a line connecting both ends, the laser scanning part could be identified, and it was found that the difference from the surrounding area was about 150 angstroms.

(Example 2) Using an organometallic molecular beam epitaxial device, a 0.5 W argon laser beam (51
InP was grown at a substrate temperature of 400°C while irradiating a 0.5 cm section with a 10 Hz cycle and scanning at 1/10 of the central part between 0.05 cm at both ends. did. At both ends, the difference between the laser irradiated part and the non-irradiated part was about 1300 angstroms, and the position could be identified without using a microscope. However, parts other than both ends could not be seen using an optical microscope. Therefore, when the film thickness distribution was measured on a line connecting both ends, the laser scanning part could be identified, and it was found that the difference from the surrounding area was about 110 angstroms.

(Example 3) Using an organometallic molecular beam epitaxial apparatus, a 2W argon laser beam (514.
5 nm) was scanned at a period of 10 Hz over a 0.8 cm section, gradually slowing down at both ends of the 0.05 cm section, and stopping at both ends.
GaAs was grown. At both ends, the laser irradiated area was approximately 800 angstroms thinner than the non-irradiated area, and the position could be identified without using a microscope. However, parts other than both ends could not be seen using an optical microscope. Therefore, when we measured the film thickness distribution on the line connecting both ends, we were able to identify the laser scanning part and found that it was approximately 100 angstroms thinner than the surrounding area.

(Example 4) A 2.2 W argon laser beam (51
4.5nm) in a 1.5cm section at a cycle of 10Hz and stopping for 15msec at both ends,
InGaAsP was grown at a substrate temperature of 560°C. At both ends, the laser irradiated area was approximately 1200 angstroms thinner than the non-irradiated area, and the position could be identified without using a microscope. However, parts other than both ends could not be seen using an optical microscope. Therefore, when we measured the film thickness distribution on the line connecting both ends, we were able to identify the laser scanning part and found that it was approximately 150 angstroms thinner than the surrounding area.

[0016]

Effects of the Invention As described above, if the growth method of the present invention is used, a desired location on the substrate can have a different composition than other locations.
A thick semiconductor thin film can be formed and its position can be specified. Therefore, when patterning this thin film using photolithography after growth, it is easy to align it with a mask, making it suitable for optical devices such as multi-wavelength lasers and optical/electronic integrated devices, which are expected to be key devices in the future. Useful for forming circuits (OEICs).

[Brief explanation of the drawing]

FIG. 1 shows the relationship between the laser scanning speed and the growth rate of the irradiated area relative to the non-irradiated area in GaAs and InP.

FIG. 2 shows the relationship between the laser scanning speed and the growth rate of the irradiated area relative to the non-irradiated area in InGaAs and InGaAsP.

FIG. 3 shows the relationship between the growth rate of an InGaAs film and the substrate temperature.

FIG. 4 shows the Ga composition in the InGaAs film shown in FIG. 3.

Claims (1)

[Claims] 1. When growing a III-V semiconductor thin film on a single-crystal substrate by scanning a part of the substrate while irradiating a laser beam using an organometallic epitaxy method, the laser beam is A method for growing a semiconductor thin film, characterized in that, in scanning, the scanning speed at both ends of a scanning line is slower than in the scanning area excluding both ends.