JPS58128725A - Method and apparatus for manufacturing vapor phase epitaxial crystal - Google Patents

Abstract

PURPOSE:To obtain a desired epitaxial film with an excellent controllability, by a method wherein in forming a III-V semiconductor vapor phase epitaxial film from such a raw material as chlorides or hydrides of III and V family elements, the flow of introduced gases is made turbulent or laminar by operating a jig disposed on the downstream side of the container for the III family element. CONSTITUTION:A quartz jig 10 is stood up by means of a quartz 11. When a reaction tube 1 reaches a stationary temperature, AsCl3 diluted by H2 is introduced to start the vapor phase growth. As a result, the gas flow collides against the jig 10 to become turbulent, so that the AsCl3 gas well reacts with Ga4 and flows to the downstream side through the gap between the tube 1 and the jig 10. After the growth, the power source is turned OFF and purging gases are introduced through pipes 2, 3, and moreover, the jig 10 is brought down by means of the rod 11. As the result, the gas flow is made laminar. Therefore, the residual growth gases are efficiently purged, so that the growth of an undesired crystal is suppressed to such an extent that it can be neglected. A similar advantageous effect can be obtained also by forcing a valve-type jig 20 into the quartz tube 1 along its inner wall and opening the same.

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field of the Invention The present invention relates to a method and apparatus for producing a vapor phase epitaxial crystal of an IV group compound semiconductor, and particularly to a method and apparatus for producing a vapor phase epitaxial crystal to be grown. The present invention relates to a method and apparatus for manufacturing a vapor phase epitaxial crystal that has been improved to enable precise control.

[Technical background of the invention and its problems]

Vapor phase epitaxial crystals, particularly group (1) to V compound semiconductors, have come to be widely used as substrate materials for optical devices and microwave devices. In particular, in recent years, as device processing technology has improved and device structures have been improved, device characteristics have improved significantly, and in response, more advanced manufacturing technology has been required for the vapor phase crystals used for element preformation. It is becoming. For example, in semiconductor lasers, field effect transistors, etc., highly precise controllability is required in the formation of the active layer that serves as the operating region, and a technology is required to form a crystal with a desired carrier concentration and desired thickness at a high N density. It becomes.

However, the current epitaxial crystal growth method does not satisfy the above requirements in that undesired deposition continues on the substrate due to the growth gas remaining in the reaction tube after the growth is completed. This situation will be described below with regard to the current example of the method for producing vapor phase epitaxial crystals.

FIG. 1 is a simplified diagram of the GaAs vapor phase crystal manufacturing apparatus used in this example. The quartz reaction tube (1), which forms the main body of this device, has one end surface with arsenic trichloride (A), which is the raw material.
A quartz tube (2) for supplying hydrogen or hydrogen is opened, and a quartz tube (3) for supplying hydrogen or a doping gas, such as hydrogen sulfide, is opened through this end face.
) reaches the back of the reaction tube and opens. Ga metal (4
) is housed in a quartz container (5) and placed near the opening of the quartz tube (2) on the downstream side of the reaction tube (1). The GaAa substrate (6) to be grown is placed on a quartz support (7) located downstream in the reaction tube. Also (8)
is called a baffle plate, and when introducing 5cjB into the reaction tube through the quartz tube (2), Ga 141 and k
It is installed upstream of the opening area of the quartz tube (3) for the purpose of increasing the reaction efficiency with mcIB. By installing the baffle plate (8) in this way, As introduced into the reaction tube can be
Cj and gas collide with the baffle plate and are prevented from being directly transported to the lower fill, allowing Ga and AsCjl to react efficiently. Furthermore, the baffle plate is an ASC that has been introduced.
In order to change the flow of J3 gas from laminar to turbulent, the gases such as GaCJ and As4 are smoothly mixed near the GaAs substrate, and as a result, the stoichiometry of the growing GaAs crystal is improved by installing the baffle plate. ) 11
is maintained and uniformity is improved. Although not shown in the drawings, this reaction tube can be detached and detached at will on the downstream side of the location where the quartz support (7) is disposed, allowing members to be loaded inside or removed.

The procedure for manufacturing a GaAs crystal using the apparatus shown in FIG. 1 is roughly as follows. First, the reaction tube (1) is heated to a preset temperature. When the temperature reaches a steady state, AsCjl gas diluted with hydrogen is introduced into the reaction tube through the quartz tube (2). The introduced As(436iGa
(4) and is carried to the vicinity of the substrate by hydrogen gas.
Deposit m. Note that hydrogen gas flows through the quartz tube (3), and if necessary, doping gas is flown to adjust the carrier concentration to a desired level. AsCjm is allowed to flow for a predetermined time to form an epitaxial crystal layer of a desired thickness and desired carrier tIkI&, and the growth is terminated by stopping the AmCjl gas. When growth is completed, the power to the furnace body is turned off, purge gas, usually hydrogen, is introduced into the reaction tube through quartz tubes +21 and +31, and the crystals are taken out when the furnace body has cooled down.

When a crystal is manufactured using such a manufacturing apparatus, the GaAs crystal is deposited due to the growth gas remaining in the reaction tube when the furnace body is cooled after the growth is completed.

The baffle plate (8) is necessary from the viewpoint of maintaining the uniformity and stability of the growth as described above, or by installing such a baffle plate, gas escape during purging is prevented and GaAs This results in excessive crystal deposition. As a result of this deposition, the thickness of the crystal layer is usually increased by about 0.1 .beta.m, and in extreme cases by 0.2 .mu.m. Furthermore, since this deposition phenomenon occurs in an unsteady state with respect to both the temperature and the amount of light of the growth gas, it makes the carrier concentration unstable. For example, if hydrogen sulfide is introduced during deposition, the carrier 1181 in this deposited layer will be 1 even if the flow rate is l
x 10"cs-" or more. It is difficult to accurately control both the carrier sit and the thickness of the deposition phenomenon that occurs after the growth is completed, and it cannot be ignored when producing crystals with desired thickness and carrier concentration with excellent controllability. Not a problem.

[Purpose of the invention]

The object of the present invention is to provide an improved method and apparatus for manufacturing a vapor phase epitaxial crystal, which eliminates the above-mentioned problems.

[Summary of the Invention] That is, the present invention provides a method for producing a vapor phase epitaxial crystal of a group IV compound semiconductor using a chloride or hydride of a metal element and a group V element as raw materials.
A quartz jig that can be operated outside the reaction tube is placed downstream of the quartz container containing the metal elements on both sides of the reaction tube, and this jig is placed in the first position prior to the start of crystal growth to remove disturbances from the jig periphery. The Rk growth gas flow is guided to the downstream side, and when the growth is stopped, a second position is taken, and the purge gas escapes out of the system. A method for producing a vapor phase epitaxial crystal in which a jig is operated from outside the reaction tube, or +2) an apparatus used in the process of producing a vapor phase epitaxial crystal of a group V compound semiconductor, which While a raw material gas, which is a compound or a hydride, is being introduced into a quartz reaction tube, it is arranged at a first position so as to obstruct the flow of the raw material gas, and prevents the raw material gas flow from being turbulent and prevents the introduction of the raw material gas. Vapor phase epitaxial crystal manufacturing in which a quartz jig is arranged so as to be operated from the outside of the expansion tube to take a second position while introducing purge gas after stopping, so as to smoothly make the purge gas flow into a laminar flow. It's in the device.

[Embodiments of the invention]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 2 is a diagram showing the vapor phase epitaxial crystal manufacturing apparatus used in this example. The difference from the device shown in Figure 1 is that there are four quartz jigs placed in place of the baffle plate.

This quartz jig is equipped with a quartz rod for operating it from outside the reaction tube. Therefore, the parts numbered (II to (7)) in the figures are similar to those in Fig. 1 and are used in correspondence with those in Fig. 1. Fig. 3 is a perspective view of this quartz jig OI. The external shape of the reaction tube is such that the space for placing the quartz container (5) is narrowed to make the presence of the quartz jig effective.
) into the reaction tube ill.

is deformed so that it is placed in the expanded area on the downstream side of this jig.

The growth is carried out using the apparatus shown in FIG. 2 according to the following steps. First, the quartz jig LIIJ is set up in the position shown by the solid circle in the figure, and the reaction tube is heated to a predetermined m1tt. A diluted with hydrogen once the temperature reaches steady state
s Cjl is introduced into the reaction tube and growth is started. At this time, the flow of AsCjl gas once collides with the quartz jig 4 as shown by the solid line arrow in the figure, and after sufficiently reacting with 01, it heads downstream of the reaction tube (2) through the gap around the jig. In this case, the quartz jig αQ exhibits exactly the same function and effect as the baffle plate of the $11 wA example. After the growth for a predetermined time is completed, turn off the power to the furnace body, introduce purge gas from the quartz tube (2) and (31), and lower the quartz jig Ql to the lower RII by operating the quartz rod αυ. In this case, the inflowing purge gas becomes a laminar flow as the resistance to flow is removed, and flows through the reaction tube as shown by the dotted arrow.This causes the growth remaining in the reaction tube to Purging of the gas is performed efficiently, and the phenomenon of unnecessary growth crystal deposition that occurs when using the apparatus shown in FIG. 1 is suppressed to almost negligible 4IrIIL.

Now, on the semi-insulating GaAs substrate, the carrier concentration l
FIG. 4 shows a carrier INK profile when a Q"OR-" crystal layer is grown to a thickness of 0.3 Jm.

However, in the figure, the solid line curve A shows the result when the method according to the present invention is used, and the dotted line curve A shows the result when the conventional method using the apparatus shown in FIG. 1 is used. As can be seen from the figure, hi,! by the conventional method! Then, the thickness is 0.1jI+n near the surface.
Although a relatively high carrier concentration layer was observed, it was not observed at all when using the method according to the present invention, indicating that highly accurate control of carrier S* and thickness was performed.
Ru.

FIG. 5 shows an apparatus for producing a vapor phase epitaxial crystal using another embodiment of the present invention. In the figure, (7) is a jig made of quartz and has a trapezoidal cross section. When this jig is fitted into the reaction tube, the large-diameter bottom surface acts as a blocking surface for the inside of the tube. The wall surface of till is narrowed by the glue of the upstream Ua storage container (5) corresponding to the w surface of this jig. A stone capsule tube (silk) that integrally penetrates the center of the bottom surface of this jig is extended and pulled out of the reaction tube on the lower #L side, and connected to an exhaust port with an on-off valve (2). This stone pipe pipe υ
On the upstream side, it penetrates the large-diameter bottom of the quartz jig (2) and opens into the area where the Ga cap (4J) is installed. It corresponds to and is used synonymously.

Growth using the apparatus shown in the ms diagram is performed as follows. First, AaCJg is introduced through the quartz tube (2),
In the state where growth is taking place, the 5-quartz Eiji A4 is installed (slightly downstream of the constricted part of the reaction tube) as shown by the solid line in the figure, and the gas flow is maintained as shown by the solid line arrow.
After allowing the quartz jig to flow, the periphery of the jig is pushed out to the downstream side.■
to give the effect of a baffle plate. At this time, keep the valve @ closed.

When the specified growth is completed and the purge gas is introduced from the quartz tube il+ (31), by operating the quartz tube ring, the quartz jig head is pushed into the upstream position indicated by the dotted line, and the side surface of the quartz jig and the reaction tube are Make sure that the walls of the constricted part are in close contact with each other, and open the valve.Thus, the remaining growth gas in the vicinity of the Ga container (5) will flow directly into the quartz tube D. Only the purge gas flowing from the quartz tube (3) flows into the vicinity of the GaAm substrate and is guided to the exhaust port, and the deposition phenomenon after the growth is completely suppressed.

In the above embodiments, the case where a GaAs crystal is grown is described as an example, but the present invention is not limited to the type of crystal to be grown, and is broadly applicable to the growth of vapor phase epitaxial crystals of ■-V group compound semiconductors. It may be applied in this case.

[Brief explanation of the drawing]

FIG. 1 is a simplified diagram showing a cross section of a device used in a conventional method for producing a vapor phase epitaxial crystal, and Figure 2 is a simplified diagram showing a cross section of a device for producing a vapor phase epitaxial crystal according to the present invention.
FIG. 3 is a perspective view of the quartz jig in FIG. 2, FIG. 4 is a line diagram showing the carrier concentration 1 profile of the vapor phase epitaxial crystal layer according to the example of the present invention and the comparative example, and FIG. FIG. 3 is a simplified diagram showing a cross section of a vapor phase epitaxial crystal manufacturing apparatus according to another embodiment of the invention. (1)...Quartz reaction tube (2)...Quartz tube (3
)...Quartz tube (4)...Gallium (5
)...Quartz container (6)...GaAs Motoki (sword...Quartz support (8)...Baffle plate O
I...Quartz jig aυ...Quartz rod■...
・Quartz jig υ・・Quartz tube■・・Opening/closing valve agent Patent attorney Inoue −Male

Claims (1)

[Claims] (1) When producing a vapor phase epitaxial crystal of a group I-V compound semiconductor using a chloride or hydride of a group I metal element and a group V element as raw materials, A quartz jig that can be operated outside the reaction tube is placed in the lower part of the reaction tube, and prior to the start of crystal growth, this jig is placed in the first position to direct the turbulent growth gas flow from the periphery of the jig to the downstream side. A method for manufacturing a vapor phase epitaxial crystal, characterized by operating a jig from outside the reaction tube so as to guide the gas, take a second position around the growth stopper, and allow the purge gas to escape from the system +211- This is an apparatus used in the production of vapor phase epitaxial crystals of group V compound semiconductors, in which the source gas is introduced into a quartz reaction tube while the source gas is a chloride or hydrogen compound of a group V element. It is operated from the outside of the reaction tube to take the first position so as to obstruct the flow and make the raw material gas flow turbulent, and to take the second position while introducing the purge gas after stopping the raw material gas introduction. A vapor phase epitaxial crystal production apparatus in which a quartz jig is arranged to smoothly make the purge gas flow into a laminar flow.