JPH02240918A - Purification of raw gas for thin film formation - Google Patents

Abstract

PURPOSE:To prevent the deterioration of the characteristics of a semiconductor crystal by a method wherein a raw gas containing a material to be introduced into a reaction furnace is brought into contact with a catalyst facilitating chemical combination of hydrogen with oxygen before the introduction into the reaction furnace. CONSTITUTION:The inside of the main body 2 of a vessel is heated by a heater wire 4 and a raw gas containing a material in a gaseous state passes therethrough while coming into contact with a platinum wire 3. Inside the main body 2 of the vessel, on the occasion, the platinum wire 3 and the passing raw gas are kept at a prescribed temperature by a temperature controller 7 so that the platinum wire 3 may act effectively as a catalyst. As a result, the raw gas passing through a gas purifier 1 is refined by the platinum wire 3 and chemical combination of hydrogen with oxygen contained in this gas is thereby facilitated. By facilitating the chemical combination of the oxygen with the hydrogen in the raw gas in this way, an aluminum oxide is prevented from mixing in a single-crystal thin film of a compound semiconductor containing aluminum and thus the characteristics of the single-crystal thin film are improved.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention mainly relates to metal organic vapor phase synthesis (MOVPE).
The present invention relates to a method for purifying a raw material gas containing raw materials introduced into a reactor when forming a single crystal thin film of a compound semiconductor containing aluminum.

[Conventional technology]

Metal-organic vapor phase synthesis (MOVPE) converts a liquid organic metal into a gaseous state using high-purity hydrogen as a carrier gas and transports it to a reactor. A gaseous hydrogen compound is introduced into the reactor,
A mixture of these raw material gases is reacted in a reactor to deposit a compound semiconductor thin film on a substrate in the reactor.

Since organometallic vapor phase synthesis uses organic metals, it is possible to grow semiconductor crystals containing aluminum, which cannot be grown using chloride vapor phase synthesis. However, since aluminum oxides are mixed into the crystal, There has been a problem in that this crystal has an adverse effect on the characteristics of devices manufactured. Conventionally, therefore, a method has been used in which the raw material gas is supplied after passing through a molecular sieve or after being brought into contact with a ternary alloy of gallium-aluminum-indium.

[Problem to be solved by the invention]

However, in such conventional methods, unless the purity of the molecular sieve or ternary alloy is extremely high, the raw material gas may be contaminated, and depending on the type of raw material gas, the raw material gas itself may be contaminated with molecular sieves. There was a problem that the materials could be collected.

The present invention discloses that the deterioration of the characteristics of a compound semiconductor crystal containing aluminum is due to the combination of aluminum and oxygen (02), and that oxygen (0) as an element is converted into water vapor (H2O).
does not deteriorate the properties of the crystal even if it exists in the form of
Focusing on the Effect of Oxygen and Water Baber by Sunakawa (Journal of Crystal Growth Vol. 68, 1984, 157 pages), we focused on the effects of oxygen (02) in the raw material gas. The object is to provide a method for purifying a raw material gas for forming a thin film, which actively combines oxygen (0□) with hydrogen (H2) and converts oxygen (0□) into water vapor (H2O).

[Means to solve the problem]

In order to achieve the above object, in the present invention, when forming a single crystal thin film of a compound semiconductor containing aluminum in a reactor,
In a method for purifying a raw material gas containing a raw material introduced into a reactor, the raw material gas is brought into contact with a catalyst that promotes the combination of hydrogen and oxygen before the reactor.

In this case, it is preferable that the catalyst is made of platinum.

[Effect]

If the raw material gas is brought into contact with a catalyst that promotes the combination of hydrogen and oxygen before the reactor, the combination of oxygen and hydrogen in the raw material gas will be promoted and water vapor will be produced.

Furthermore, by using platinum as a catalyst, the combination of oxygen and hydrogen can be promoted simply and effectively.

〔Example〕

First, a gas purifier embodying the present invention will be described with reference to FIG.

This gas purifier 1 includes a container body 2 using a stainless steel tube, a mall-shaped platinum wire 3 housed as a catalyst inside the container body 2, and a heater wire 4 wound around the outer circumference of the container body 2. It is composed of a heater power source 5 that supplies electricity to the heater wire 4. The heater power source 5 is controlled by a temperature controller 7 via a temperature sensor 6 attached to the container body 2.

However, the inside of the container body 2 is heated by the heater wire 4, and the raw material gas containing the gaseous raw material passes therethrough while contacting the platinum wire 3. At this time, inside the container body 2, the platinum wire 3 and the raw material gas passing therethrough are maintained at a predetermined high temperature by the temperature controller 7 so that the platinum wire 3 effectively acts as a catalyst. As a result, the raw material gas that has passed through the gas purifier 1 is purified by the platinum wire 3, and the combination of hydrogen and oxygen contained in this gas is promoted.

In addition, by using platinum wire 3, which is made by processing platinum into a linear shape, as a catalyst, the specific area can be increased and the contact area with the raw material gas can be increased. Forgiving body 2 required when using a processed one
The inner partition wall etc. can be omitted and the handling becomes easier.

In this embodiment, the container body 2 is made of a stainless steel tube with a diameter of 178 inches, and the inside has a diameter of 0.05 mm and a total length of 31 mm.
A platinum wire 3 with a length of 0 m is molded and housed in a molded shape with a length of 51, and the heater wire 4 is used to heat the inside of the Qiki zero body 2 from 250 degrees to 3 degrees.
00 degrees (higher than room temperature <30.0 degrees or less). Further, in this case, in order to reduce impurities, the platinum wire 3 was subjected to ultrasonic cleaning and drying in acetone or methanol, cleaning with hydrochloric acid, and further cleaning and drying with pure water before use.

In this embodiment, the container body 2 is heated by the heater wire 4, but it may be housed in an electric heating furnace.

Next, with reference to FIG. 2, a case where the gas purifier 1 is attached to a semiconductor growth apparatus 8 using so-called metal organic vapor phase synthesis (MOVPE) will be described.

This semiconductor growth apparatus 8 is for growing crystals of aluminum gallium indium phosphide, and includes a reactor 9 for growing the crystals, and a sulfosphine cylinder 10 for supplying phosphine (PH3), a hydrogen compound, to the reactor 9. ,
Trimethylaluminum (TMA), an organometallic
) Bubblers 11 and 11.1 storing trimethyl gallium (TMG) and trimethyl indium (TMI), respectively
1, and a hydrogen cylinder 12 that supplies high-purity hydrogen, which is a carrier gas for these organometallics.

The phosphine cylinder 10 and the reactor 9 are connected through a hydrogen compound pipe 13, and a flow rate regulating valve 14 and a gas purifier 1 are interposed in the hydrogen compound pipe 13. Then, phosphine (PH3) whose flow rate is adjusted to a predetermined level by the flow rate regulating valve 14 is supplied to the reactor 9 through the gas purifier 1.

Further, the hydrogen cylinder 12 and the reactor 9 are connected to the carrier pipe 15 via bubblers 11, 11.11 provided in parallel in the middle.
Trimethyl aluminum (TMA), J trimethyl gallium (TMG) and trimethyl indium (T
M I ) is adjusted to a predetermined flow rate by each flow rate adjustment valve 16 provided upstream of each bubbler 11, and the hydrogen cylinder 12
The reactor 9 is supplied with high-purity hydrogen from the reactor 9.

The hydrogen compound pipe 13 and the carrier pipe 15 are connected to the reactor 9
The hydrogen compound and the organic metal are simultaneously introduced into the reactor 9 via the on-off valve 17.

On the other hand, the reactor 9 is composed of a quartz container 18, and a substrate 2 supported by a susceptor 19 is placed in the center of the interior of the container 18.
0 is accommodated, and a high moon wave coil 21 for heating the substrate 20 is provided on the outer periphery. Then, in this container 18, as mentioned above, phosphine (PH3
) and the organometallic trimethylaluminum (TMA
), a mixed gas of trimethyl gallium (TMG), trimethyl indium (TMI), and high purity hydrogen is introduced, and the substrate 20 is heated by the high frequency coil 21.
A thin film of a semiconductor qt crystal containing aluminum is deposited on the substrate 20. The gas after precipitation is led to an exhaust gas treatment device (not shown) via an exhaust pipe 22.

In the present invention, phosphine (PH3) is converted to 20
%, and the flow rate is 50 cubic centimeters per minute. Additionally, trimethylaluminum (TMA), trimethylgallium (TMG) and trimethylindium (TMI
) are set at 20 degrees and 20 degrees by each bubbler 11, respectively.
The flow rates of high purity hydrogen are 1.0, 32.0 and 7 cubic (2) per minute, respectively.

As a result, a thin film of aluminum gallium indium phosphide with good optical properties can be formed.

In this example, a case has been described in which a thin film of aluminum gallium indium phosphide is formed, but a thin film of other compound semiconductors containing aluminum such as aluminum indium phosphide, aluminum gallium arsenate, or aluminum indium phosphide may also be formed. Of course, it is also useful in other cases.

Further, although the gas purifier 1 is provided in the middle of the hydrogen compound pipe 13, it may be provided downstream of the connection between the hydrogen compound pipe 13 and the carrier pipe 15.

〔Effect of the invention〕

As described above, according to the present invention, by promoting the combination of oxygen and hydrogen in the raw material gas, it is possible to prevent aluminum oxide from being mixed into a single crystal thin film of a compound semiconductor containing aluminum, and to manufacture the product. It has the effect of improving the properties of single crystal thin films of compound semiconductors.

[Brief explanation of drawings]

FIG. 1 is a partial sectional view of a gas purifier implementing the method of the present invention, and FIG. 2 is a schematic diagram of a semiconductor growth apparatus. DESCRIPTION OF SYMBOLS 1... Gas purifier, 2... Container main body, 3... Platinum wire, 8... Semiconductor growth apparatus, 9... Reactor.

Claims (1)

[Claims] 1. In a method for purifying a raw material gas containing a raw material introduced into a reactor when forming a single crystal thin film of a compound semiconductor containing aluminum in a reactor, the raw material gas is subjected to a reaction. A method for purifying a raw material gas for thin film formation, characterized by bringing it into contact with a catalyst that promotes the combination of hydrogen and oxygen before a furnace. 2. The method for purifying a raw material gas for forming a thin film according to claim 1, wherein the catalyst is made of platinum.