JPH0615436B2 - Liquid phase epitaxial growth system - Google Patents

Description

TECHNICAL FIELD The present invention relates to a liquid phase epitaxial growth apparatus, and more particularly to a liquid phase epitaxial growth apparatus suitable for realizing good quality crystals with good reproducibility.

[Conventional technology]

Conventionally, a well-known liquid phase epitaxial growth apparatus has been used for crystal growth of an emitting diode and a semiconductor laser used as a light source of a compact disk, a video disk, or the like.

The conventional liquid phase epitaxial growth apparatus described above is disclosed, for example, in "Compound Semiconductor Handbook," published by Sanence Forum Co., Ltd., 1982, "Section 2, Epitaxial Growth Method, 2-1 Liquid Phase Epitaxial Growth Method," on pages 96 to 101, and Japanese Patent Publication. As described in No. 60-19137, a growth chamber formed of a quartz tube and having a predetermined gas atmosphere, a second temperature detector for monitoring the temperature inside the growth chamber, and a surrounding of the growth chamber A temperature control unit formed of a heater formed by a kathal wire so as to surround it, a first temperature detector installed between the growth chamber and the heater for operating the temperature control unit, and the growth unit. A sliding part for sliding a crystal growth boat for charging a raw material for crystal growth is provided in the chamber, and the sliding chamber is provided until the temperature in the growth chamber reaches a preset temperature. The temperature control unit operates the heater based on the output signal from the temperature detector 2 and after the temperature inside the growth chamber reaches the set temperature, the temperature inside the growth chamber is decreased to a predetermined value from the start of the temperature decrease. When the time has elapsed, the growth boat is slid by the drive of the sliding portion to grow the raw material for crystal growth.

In the crystal growth, the important temperature to be controlled is the temperature in the growth chamber monitored by the second temperature detector. This is the temperature in the growth chamber (detected by the second temperature detector in advance). Temperature) and the temperature detected by the first temperature detector for control are prepared to detect the temperature in the growth chamber.

[Problems to be solved by the invention]

In the above-mentioned conventional technique, in order to set the temperature inside the growth chamber to a predetermined temperature, the temperature is set outside the growth chamber that is associated in advance with the temperature detected by the second temperature detector provided inside the growth chamber. Since the temperature controller is controlled by using the first temperature detector, it is possible to bring the growth chamber to a predetermined temperature in a relatively short time.

However, on the other hand, even if the temperature in the growth chamber changes for each growth due to fluctuations in the flow rate of gas (usually H ₂ ) flowing in the growth chamber, deterioration of the heater, etc., the temperature cannot be corrected. There was a field where fluctuations of up to 3-4 ° C occurred.

Further, in order to always maintain the temperature inside the growth chamber at the same temperature, it is necessary to operate the temperature control unit using the output signal of the second temperature detector provided inside the growth chamber.

However, when the temperature inside the growth chamber is raised to a set temperature by using the second temperature detector, the second temperature detector,
The growth chamber, a soaking tube made of quartz or S: C, and asbestos or a gap exist between the heater (heating element) attached to the temperature control unit, and a large amount of heat generated by the growth chamber. Since the heat of the heater is radiated and propagated through the time constant to raise the temperature in the growth chamber, the temperature control unit controls the temperature in the temperature rising process until the temperature in the growth chamber reaches the set temperature from the actual temperature. There is a large time difference from the start of operation until the temperature in the growth chamber reaches the set temperature, and it takes a long time (5 to 6 hours) if it is impossible to achieve the same stable temperature.

An object of the present invention is to provide a liquid phase epitaxial growth apparatus which solves the above-mentioned problems of the prior art and enables high quality crystals with small fluctuations in the thickness of the growth phase to be grown with good reproducibility.

[Means for solving problems]

The above-mentioned purpose is a growth chamber capable of adjusting to a predetermined atmosphere, a heating means provided outside the growth chamber, and a first temperature detecting means in the growth chamber provided between the outer wall of the growth chamber and the heating means. A second temperature detecting means inside the growth chamber provided in the growth chamber, a crystal growth boat capable of carrying in and out between the inside and outside of the growth chamber, and a predetermined set temperature according to a signal from the first temperature detecting means. And a temperature switching means for switching the detection means from the first temperature detection means to the second detection means when the temperature in the growth chamber reaches a desired set temperature.

[Action]

The present invention relates to a first temperature detector that correlates temperature control in a relatively wide temperature range until the temperature in the growth chamber reaches a set temperature with a temperature detected by a second temperature detector installed in the growth chamber in advance. Since the temperature controller controls the heating element based on the output signal of, the temperature inside the growth chamber can reach the set temperature in a short time.

Then, after the temperature inside the growth chamber that has reached the set temperature is maintained for a predetermined time, detection of a relatively narrow temperature range in which the temperature falls to the temperature required for crystal growth is detected by the second temperature detector inside the growth chamber. At the same time, the temperature controller controls the heating element based on the output signal from the second temperature detector, and the sliding portion drives the crystal growth boat, so that the crystal can be always grown under the same temperature condition.

〔Example〕

Hereinafter, a liquid phase epitaxial growth apparatus which is an embodiment of the present invention will be described with reference to the drawings.

In FIG. 1, reference numeral 1 designates a growth chamber, which is made of quartz and has an inside filled with water or an inert atmosphere. Two
Is a temperature control unit, and a heating resistor such as a Kanthal wire that surrounds the periphery of the growth chamber 1 and controls heating of the growth chamber 1 is operated by output signals of a first temperature detector 3 and a second temperature detector 4 described later. I'm trying to do it. A temperature switching unit 7 of FIG. 2 is provided between the temperature control unit 2 and the first temperature detector 3 and the second temperature detector 4. The first temperature detector 3 is installed outside the growth chamber 1 and detects a temperature until the inside of the growth chamber 1 reaches a set temperature,
The detected temperature is converted in accordance with a conversion table of the temperature detected by the second temperature detector 4 created in advance. The second temperature detector 4 is adapted to directly detect the temperature in the growth chamber 1 installed in the growth chamber 1. Reference numeral 5 is a sliding portion so that the crystal growth port 6 can be carried in and out of the growth chamber 1 in response to an output signal from the second temperature detector 4. The crystal growth boat 6 carries a growth raw material (not shown) made of a compound semiconductor such as aluminum, gallium, and arsenic.

Since the liquid phase epitaxial growth apparatus according to the present invention is configured as described above, its operation will be described below.

The temperature inside the growth chamber 1 is detected by the first temperature detector 3 and the temperature inside the growth chamber 1 is detected by the first temperature detector 3 until the temperature inside the growth chamber 1 reaches a set temperature sufficient to uniformly melt the raw material for growth. The temperature control unit 2 controls the temperature based on the output signal of 1 to raise the temperature in the growth chamber 1.

In this case, the temperature rising characteristic of the temperature in the growth chamber 1 is more than the temperature rising characteristic of the output signal from the first temperature detector 3, and the thermal time constant interposed between the growth chamber 1 and the temperature control 2 is higher. It occurs after a minute, but it reaches the specified temperature in a short time (about 30 minutes) by setting the relationship between the temperature in the growth chamber 1 and the first temperature detector 3 in advance in a comparison table. Can be made.

Then, when the temperature in the growth chamber 1 rises to a set temperature, the first temperature detector 3 is switched to the second temperature detector 4 to control the temperature based on the output signal from the second temperature detector 4. The section 2 controls the temperature to keep the inside of the growth chamber 1 at the set temperature for a predetermined time.

Then, when the temperature in the growth chamber 1 reaches the temperature required for crystal growth of the raw material for growth, the second temperature detector 4
Detects this and outputs a signal to the sliding portion 5, so that the sliding portion 5 drives the crystal growth boat 6 to grow the raw material 1 for growth of crystals.

Therefore, it is possible to maintain a stable temperature with high accuracy without impairing the temperature controllability in the growth chamber 1.
Moreover, since the drive control of the sliding portion 5 for crystal growth of the raw material for growth is performed by the second temperature detector 4 provided in the growth chamber 1 via the temperature control portion 2,
The growth raw material can always be crystal-grown under the same temperature condition, and when applied to the crystal growth of a semiconductor laser, for example, it is possible to grow a good-quality crystal with little fluctuation in the growth layer thickness with good reproducibility. Therefore, the productivity and yield of the semiconductor laser can be significantly improved.

〔The invention's effect〕

According to the present invention, it is possible to maintain a highly accurate and stable temperature without impairing the temperature controllability in the growth chamber, and it is possible to always grow crystals of the raw material for growth under the same temperature condition. When applied to laser crystal growth, it is possible to grow a good quality crystal with little fluctuation in the growth layer film thickness with good reproducibility, and to greatly improve the productivity and yield of semiconductor lasers.

[Brief description of drawings]

FIG. 1 is an explanatory view of essential parts of a liquid phase epitaxial growth apparatus which is an embodiment of the present invention, and FIG. 2 is a block diagram showing respective essential parts of a liquid phase epitaxial growth apparatus which is an embodiment of the present invention. 1 ... Growth chamber, 2 ... Temperature control part, 3 ... First temperature detector, 4 ... Second temperature detector, 5 ... Sliding part, 6 ... Crystal growth boat, 7 ... Temperature Switching unit.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Akihiko Sato 111 No. Nishiyokote-cho, Takasaki-shi Gunma Hitachi Takasaki factory (72) Inventor Seiichi Yamada 111 No. Nishiyoko-te, Takasaki-shi Gunma Hitachi, Ltd. Factory Takasaki Factory

Claims (1)

[Claims] 1. A growth chamber capable of adjusting to a predetermined atmosphere, a heating means provided outside the growth chamber, and a first temperature detecting means in the growth chamber provided between the outer wall of the growth chamber and the heating means. A second temperature detecting means inside the growth chamber provided inside the growth chamber, a crystal growth boat that can carry in and out between the inside and outside of the growth chamber, and a predetermined setting based on a signal from the first temperature detecting means. Liquid phase epitaxial growth apparatus comprising temperature control means for controlling the temperature and temperature switching means for switching the detection means from the first temperature detection means to the second detection means when the temperature in the growth chamber reaches a desired set temperature. .