JP3038463B2 - Vapor growth method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for growing a crystal in a vapor phase, and more particularly to a metal organic chemical vapor deposition (MOCVD) method. Note that the substrate mounting member includes a so-called susceptor, tray, or the like, which is used for mounting the substrate with the back surface of the substrate in direct contact with the surface thereof.

[0002]

2. Description of the Related Art Generally, when an epitaxial film is grown on a substrate by a vapor phase growth method such as MOCVD,
It is as follows. That is, a substrate is placed on a substrate placing member such as a susceptor or a tray, placed in a crystal growth chamber, and the raw material is placed in the crystal growth chamber while maintaining the substrate mounting member at a temperature at which the source gas can be decomposed. Introduce gas. At this time, there is a method of cleaning the substrate mounting member for each growth from the viewpoint of keeping the conditions for each growth constant. However, since the reproducibility is not always obtained and the productivity is reduced, the mounting member is not cleaned. Has been proposed by the present applicant in advance (Japanese Patent Application No. 05-310545). The desired coating amount is a minimum coating thickness that does not change the characteristics of a thin film grown on a substrate during vapor phase growth even when coating is performed further. In addition,
The surface of the substrate mounting member other than the region on which the substrate is placed continues to be covered during the vapor phase growth.

[0003]

However, there has been a problem that the desired coating amount must be determined in advance by experiments.

[0004]

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems, and an object of the present invention is to make it possible to judge that a desired coating amount has been reached (end point) during coating.

That is, according to the present invention, when a source gas is introduced into a crystal growth chamber and a thin film is vapor-phase-grown on the surface of a substrate placed on a substrate mounting member, the substrate mounting member must be cleaned beforehand. The surface of the substrate mounting member, excluding the region where the substrate is mounted, is to be grown on the surface of the substrate.
Using source gas under the same conditions as the source gas for thin film growth
In the method of coating with the grown film, it is preferable that the surface temperature of the substrate mounting member is stabilized during the coating step.
Then, the end point of the coating step is determined.

Another object of the present invention is to provide a vapor phase growth method wherein the surface temperature of the substrate mounting member is measured by a radiation thermometer.

First, the present inventors focused on the surface temperature of the substrate mounting member (+ coating film) during the coating process.

A radiation thermometer is generally used as a means for measuring the surface temperature. When measuring with a radiation thermometer, it is necessary to clarify the emissivity of the substance to be measured. However, since the coating film as a target in the present invention is a compound composed of three or more elements, and is polycrystalline, the emissivity differs depending on the composition, the surface smoothness, and the like.
Measuring temperature with a radiation thermometer has been difficult.

[0009] However, the present inventors have considered that the absolute value of the temperature is not always necessary. Therefore, the emissivity was fixed to an arbitrary value, and the progress of coating, the display temperature (not the absolute temperature) of the radiation thermometer at that time, and the change in the characteristics of the obtained epitaxial film were examined. As a result, it was found that there was a strong correlation between the change in the display temperature of the radiation thermometer and the change in the characteristics of the epitaxial film, and that the temperature stabilization and the characteristics stabilization time were the same.

[0010] Specifically, under general growth conditions by MOCVD, In ₀ .
_{73 Ga 0. 27 AS 0.} 61 P 0. 39 film (PL (photoluminescence)
A wavelength of 1.3 μm) was epitaxially grown. In addition, II
Trimethylindium (
TMI) and triethylgallium (TEG) were used, and arsine (AsH ₃ ) and phosphine (PH ₃ ) were used as source gases for group V elements.

First, an InP substrate was placed on a cleaned and baked substrate placing member and placed in a crystal growth chamber. Originally, a so-called dummy substrate was placed at the time of coating,
The original substrate was used to confirm the relationship between the characteristics of the epitaxial film, the coating amount, and the temperature. While passing PH ₃ into the net 100 cc growth chamber, the substrate mounting member is grown at the growth temperature (650 ° C,
Measure the backside of the substrate mounting material with a thermocouple. ), Raise the temperature, hold
After the temperature of the substrate mounting member has stabilized, the above InGaASP
Flow rates of AsH ₃ , TMI and TEG corresponding to the composition of the membrane were introduced for a time period of about 1 μm growth of the membrane.

Thereafter, the introduction of TMI and TEG is stopped,
The introduction of AsH ₃ and PH ₃ was stopped while cooling the substrate mounting member, and after reaching room temperature, the InP substrate after epitaxial film growth was removed from the growth chamber, and its PL wavelength and film thickness were measured. For the surface temperature, use the emissivity of the radiation thermometer.
It was fixed at 0.4 and measured.

The result of repeating the above steps 10 times is shown in FIG.
Shown in From the third time, the PL wavelength of the epitaxial film is 1.3
μm stable, and the display temperature of the radiation thermometer is 610 ℃
And stabilized. Therefore, it can be understood that the present invention can be applied to actual growth from the third time when the display temperature of the radiation thermometer is stabilized.

[0014]

Embodiments of the present invention will be described below. First, a dummy substrate was placed on a cleaned and baked substrate placing member and placed in a crystal growth chamber. While passing PH ₃ to the net 100 cc growth chamber substrate placement member the growth temperature (650
Measure the backside of the substrate mounting material with a thermocouple at ℃. ) The heated, held, the temperature of the substrate mounting member is stably, In _{0. 73} Ga _{0.
27 AS 0. 61 P 0.} 39 film flow AsH ₃ that corresponds to the composition of the (PL wavelength 1.3 .mu.m), introducing TMI and TEG continued to grow. For the surface temperature, use the emissivity of the radiation thermometer.
It was fixed at 0.4 and measured.

FIG. 2 shows the relationship between the coating time and the temperature indicated by the radiation thermometer at this time. From this figure, it is understood that the display temperature of the radiation thermometer is stable after the coating time of 120 minutes.
In the above experiment, the coating time was up to 200 minutes in order to confirm the stability of the display temperature of the radiation thermometer. However, the coating was grown again under the same conditions, and the display temperature of the radiation thermometer was measured. At a coating time of 140 minutes when the temperature became 3 ° C. or less, and as a result of growing an InGaAsP film having the above composition using an InP substrate instead of the dummy substrate,
From the first time, a film having a desired composition could be grown.

[0016]

According to the present invention, it is possible to determine that the desired coating amount has been reached (end point) regardless of the coating composition during coating of the coating. Waste can be eliminated, which is effective in cost reduction.

[Brief description of the drawings]

FIG. 1 is a diagram showing the relationship between the number of times of film growth and its PL wavelength.

FIG. 2 is a diagram showing a relationship between a coating time and a temperature indicated by a radiation thermometer.

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Claims (4)

(57) [Claims] When a source gas is introduced into a crystal growth chamber and a thin film is vapor-phase-grown on a surface of a substrate placed on a substrate mounting member, the substrate mounting member is washed beforehand. The surface of the mounting member, excluding the region where the substrate is mounted, is used for growing a thin film to be grown on the surface of the substrate.
In a method of coating with a film grown using a source gas under the same conditions as a source gas, an end point of the coating step is determined based on a stable surface temperature of the substrate mounting member during the coating step. A vapor phase growth method characterized by the above-mentioned. 2. The coating according to claim 1, wherein the coating comprises at least three elements.
The method of claim 1, wherein: 3. The method according to claim 1, wherein the coating is In, Ga, As or P.
Characterized by being composed of three or more elements selected from
The vapor phase growth method according to claim 1. 4. A claim from claim 1 to the surface temperature of the substrate mounting member is characterized in that it is measured by a radiation thermometer
3. The vapor phase growth method according to any one of 3 .