JPS63204717A - Vapor growth device - Google Patents

Abstract

PURPOSE:To obtain a steep junction by a method wherein raw gas is jetted out and reflected in reverse direction from the gas introducing tube provided on the substrate to be grown, a gas stream is converted to forward direction, it is abutted on the substrate to be grown, and the planar distribution of a grown layer is made uniform. CONSTITUTION:Raw gas is introduced from a gas introducing tube, the raw gas is contacted to the reverse current head 11 of a tip part, the gas is jetted out in reverse direction (in the upward direction at an angle of 20 deg. against gas lead-in direction axis). Then, the raw gas jetted out in reverse direction is contacted to an umbrella type gas reflecting plate 12, it is converted into forward direction, abutted on a wafer 3, thermally decomposed, and the prescribed crystal layer is grown. Then, when the growth of crystal is stopped, a gas reflecting plate 12 is moved upward by a magnet 13. When the raw gas jetted out in the reverse direction by striking a counterflow head 11 strikes the reflection plate 12 and the shoulder part of the reaction tube 1, it in reflected toward outside, it comes in between the liner tube 2 and the reaction tube 1 and discharged from the air exhausting hole between the reaction tube 2 and the liner tube 2. Accordingly, the opening and the closing of a vale 10 and the switching of a magnet 13 are combined, and the switching can be conducted instantaneously by operating the magnet.

Description

[Detailed Description of the Invention] [Summary] This is a vertical vapor phase growth apparatus in which raw material gas is ejected in the opposite direction from a gas introduction pipe provided on a growth target substrate. Furthermore,
The raw material gas ejected in the opposite direction is reflected, converting the gas flow in the forward direction and bringing it into contact with the growth substrate. In addition, the angle of the reflection direction is changed by a desired means to prevent the raw material gas from coming into contact with the growth substrate too quickly. In the vapor phase growth apparatus configured in this manner, the in-plane distribution of the grown layer becomes uniform, and a steep junction can be obtained.

[Industrial Application Field] The present invention relates to structural improvement of a vapor phase growth apparatus (CVD apparatus).

When manufacturing semiconductor devices, a vapor phase growth method is used to grow another semiconductor layer or a layer of a different material on a semiconductor substrate, and this is the most basic and important technology in manufacturing semiconductor devices.

Among such vapor phase growth methods, for example, metal organic pyrolysis vapor phase growth (MOCVD) has recently been developed.
Ganic Chemical Vapor Dep
A method has been developed in which crystal growth is performed by thermally decomposing organic metal gas as a raw material gas, and is a method capable of low-temperature growth. In addition, various vapor phase growth methods are known, such as a conventional method of thermally decomposing an inorganic reaction gas to grow crystals.

However, when manufacturing a compound semiconductor device by such a vapor phase growth method, it is desired that a junction be as steep as possible and that the in-plane distribution of the grown layer be uniform.

[Prior Art] Recently, for example, RHT (Resonance Het)
ero bipolar transistor) has been developed, and it is important to form the RHT so that the base width is only about 100 cm, and the junction transition region is about 10 to 20 people. However, although the formation of such a steep junction transition region is currently being investigated using molecular beam epitaxial growth (MBE), the MBE method
There is a drawback that fect) is likely to occur, and a satisfactory result has not always been obtained. Therefore, the possibility of using the MOCVD method is being considered.

Now, FIG. 2 shows a schematic cross-sectional view of an MOCVD apparatus for growing crystals using the conventional MOCVD method.

In the figure, 1 is a vertical reaction tube, and 2 is a liner tube.

3 is a wafer (substrate to be grown), 4 is a susceptor that rotates while heating the wafer, 5 is a heater, 6 is an exhaust port, 7 is a source gas supply port, and 8 is a gas introduction pipe.

9 is a gas injection head, 10 is a valve, and the reaction tube, liner tube, introduction tube, etc. are all made of transparent quartz material.

Note that the liner tube 2 is a shielding tube installed to prevent the reaction tube 1 from becoming contaminated, and since raw material gas decomposition products adhere to the inside of the liner tube 2 during each growth process, it must be replaced after each growth process. It is something that will be done.

For example, when continuously growing an InP crystal layer and an InGaAs crystal layer on an InP substrate using such a MOCVD apparatus, the temperature of the substrate is 700°C and the degree of vacuum is 76T.
orr (1/10 atmosphere), and remove I from the InP layer.
When converting into an nGaAs layer, the source gas is changed and the growth is performed. As the raw material gas, for example, trimethylindium (TMI; In(CB,
).

), the Ga source is trimethyl gallium (TMG; Ga
(CHI), ), P source contains phosphine (PH3
), arsine (AsH3) is used as the As source,
Purified hydrogen (H2) is used as the carrier gas.

Such organometallic gases can be decomposed at low temperatures and are suitable for steep bonding.

[Problems to be Solved by the Invention] By the way, when growth is performed under reduced pressure using a vertical MOCVD apparatus, the exchange of source gases becomes faster due to exhaust gas, which is convenient for steep bonding. There is a tendency for non-uniform film thickness distribution to occur, with less collisions and more growth at the center of the substrate (wafer) and less growth at the periphery. This tendency becomes more severe as the degree of pressure reduction increases.

Therefore, for example, an MOCVD apparatus as shown in FIG. 2 is used, and a gas injection head 9 is provided so that the raw material gas uniformly contacts the wafer surface. In this way, non-uniformity in film thickness distribution can be considerably eliminated.

However, since the gas injection head 9 was provided, the raw material gas could not be switched quickly and the cutting would be poor, making it unsuitable for steep joining.
The advantages of the OCVD method will be diminished.

The present invention proposes a vapor phase growth apparatus that reduces these problems.

[Means for solving the problem] The purpose is to eject source gas in the opposite direction to the growth substrate (wafer), and then reflect the ejected source gas in the opposite direction to create a gas flow in the forward direction. The source gas is brought into contact with the growth substrate by converting it, and the reflection direction of the source gas is changed by changing the angle of reflection by a desired means so that the source gas does not instantly contact the growth substrate. This is achieved by the constructed vapor phase growth apparatus.

[Function] That is, the MOCVD device according to the present invention jets the raw material gas in the opposite direction from the gas introduction pipe, and further reflects the raw material gas jetted in the opposite direction to convert the gas flow in the forward direction. and bring it into contact with the wafer.

Moreover, when switching gases, the reflection angle is changed depending on the other means so that the raw material gas does not come into contact with the wafer instantly. In this way, the raw material gas will come into contact with the entire surface of the wafer in a shower-like manner, similar to a gas injection head, and the distribution of the growth layer will be uniform, and the raw material gas can be switched quickly, resulting in steep bonding. .

[Example] Hereinafter, embodiments will be described in detail with reference to the drawings.

Figures 1 (al) and (bl) show a schematic cross-sectional view of the MOCVD apparatus according to the present invention; Figure (b) shows the state in which the source gas is removed from the wafer. In these figures, 11 is an inverted conical backflow head (first member), and 12 is an umbrella placed around the gas introduction pipe. A vertically movable gas reflecting plate (second member) 13 is a magnet, and other members that are the same as those in FIG. 2 are given the same symbols.

The MOCVD apparatus according to the present invention is constructed as shown in Fig. 1, and when growing, firstly, in the state shown in Fig. The raw material gas is applied to the backflow head 11 and ejected in the opposite direction (upward at an angle of 20° with respect to the gas introduction tube axis). Next, the raw material gas ejected in the opposite direction is transferred to an umbrella-shaped gas reflecting plate 12.
When it hits the wafer 3, it changes direction in the forward direction and hits the wafer 3,
A predetermined crystal layer is grown by thermal decomposition. Next, when stopping the growth, the gas reflection plate 12 (having a ferromagnetic material inside the quartz material) is moved upward by the magnet 13, and the first
Make the state as shown in figure (bl). Then, the raw material gas that hits the backflow head 11 and blows out in the opposite direction will flow through the gas reflection plate 1.
When it hits the upper shoulders of the reaction tubes 2 and 1, it is reflected outward and enters between the liner tube 2 and the reaction tube 1, and is discharged from between the reaction tube 2 and the liner tube 2 to the exhaust port. . Therefore, the opening and closing of the valve 10 and the switching of the magnet 13 can be combined, and the switching can be performed instantaneously by operating the magnet. Therefore, since the transition region is formed into a steep junction and the raw material gas is brought into contact with the wafer in a shower during growth, a uniform film thickness distribution can be obtained.

A specific example of growing a crystal layer using this MOCVD apparatus will be described. In order to continuously grow undoped rnPii and InGaAs layers on an n''-InP substrate in the (100) plane direction, the following source gases were used at a substrate temperature of 700°C and a reduced pressure of 76 Torr.The In source was TMI;
The Ga source is TMG, the P source is PH3, the S source is ASH3, and the carrier gas is H2, and the molar ratio of the group II raw material gas to the group II raw material gas is set to 70. First, M
Set the OCVD equipment to the state shown in Figure 2 (al) and set H2 and PH.
3 and then TMI. Next, TM
At the same time as stopping I, the device is placed in the state shown in Figure 2 (bl). In that state, PH is stopped and switched to flow AsH3, then the device is returned to the state shown in Figure 2 (a), and TMI and T
MG flows in. As a result of growing in this way, the variation in the film thickness distribution in the diametrical direction of a wafer with a diameter of 21 mm was ±5.
%, and an extremely steep junction surface with a transition region width of about 10 layers between the InP layer and the InGaAs layer could be obtained.

As described above, the MOCVD apparatus according to the present invention is a high-performance apparatus that can grow a crystal layer of very high quality.

[Effects of the Invention] As is clear from the above description, according to the vapor phase growth apparatus of the present invention, a crystal layer with uniform in-plane distribution and extremely steep junctions can be grown, and a semiconductor This greatly contributes to improving the performance of the device.

[Brief explanation of the drawing]

FIG. 1 (al) and (b) show MOC and VD according to the present invention.
Cross-sectional view of apparatus FIG. 2 is a cross-sectional view of a conventional MOCVD apparatus. In the figure, 1 is a reaction tube, 2 is a liner tube, 3 is a wafer, 4 is a susceptor, 5 is a heater,
6 is an exhaust port, 7 is a raw material gas supply port, 8 is a gas introduction pipe,
9 is a gas injection head, 10 is a valve, 11 is a backflow head, 12 is a gas reflection plate, and 13 is a magnet. Conventional d1 bolt Q (VD fold work diagram 2 "D house 1

Claims (2)

[Claims] (1) In the reaction tube of a vertical vapor phase growth apparatus, raw material gas is ejected from the gas introduction tube placed above the growth substrate in the opposite direction to the growth substrate, and the raw material is further ejected in the opposite direction. changing the direction of reflection of the raw material gas by reflecting the gas and converting the gas flow in a forward direction so as to contact the growth substrate, and changing the angle of the reflection by a desired means;
A vapor phase growth apparatus characterized in that the source gas is configured so that it does not instantly contact a substrate to be grown. (2) disposing a first member in the shape of an inverted cone at the tip of the gas introduction pipe into which the raw material gas flows, and making the raw material gas injected from the tip hit the first member and eject in the opposite direction; The raw material gas ejected in the opposite direction is applied to a second umbrella-shaped member disposed around the gas introduction pipe and reflected in the forward direction to convert the gas flow of the raw material gas and brought into contact with the growth substrate, and further , the second
The method is characterized in that by moving the member away from the growth substrate, the angle of the reflection direction is changed so that the reflection instantly flows out of the liner tube provided around the growth substrate. A vapor phase growth apparatus according to claim 1.