JPH033230A - Semiconductor vapor growth method - Google Patents

Abstract

PURPOSE:To shorten the time of rise and fall of growth pressure by letting carrier gas flow so as to do decompressed vapor growth after once breaking the supply of material gas and exhausting air from the inside of a reaction chamber, in laminating semiconductor crystalline layers different in properties by decompressed vapor growth. CONSTITUTION:Period T1 is high pressure growth, period T2 is low pressure growth, and period T3 is vacuum exhaust, and period T4 is high pressure growth. To shift from the high pressure growth of period T1 to the low pressure growth of period T2, it shall be decompressed immediately as it is. To return to the high pressure growth from the low pressure growth, two sequences of periods T3 and T4 are required. Accordingly, when the low pressure growth of period T2 has finished, the material gas is stopped immediately so as to do vacuum exhaust, and then carrier gas is introduced and when it becomes stationary pressure, the material gas is introduced. This way, the time of rise and fall of the growth pressure can be shortened, and further the material gas never stays inside the reaction chamber 16.

Description

[Detailed Description of the Invention] [Summary] This method relates to a semiconductor vapor phase growth method suitable for growing semiconductor crystal layers having different properties even though they have the same composition. The purpose of this process is to arbitrarily change the semiconductor crystal layer to efficiently stack multiple layers of semiconductor crystal layers having different characteristics and good quality. When a second semiconductor crystal layer having different properties from the first semiconductor crystal layer is deposited by vacuum vapor growth at a pressure higher than the vacuum vapor growth pressure, the supply of material gas is cut off and The structure includes the steps of once evacuation of the reaction chamber, and then a step of flowing a carrier gas to bring the reaction chamber to the high pressure state, and then flowing a material gas to grow a second semiconductor crystal layer in a reduced pressure vapor phase. do.

[Industrial application field]

The present invention relates to a semiconductor vapor phase growth method suitable for growing semiconductor crystal layers having the same composition but different characteristics.

Currently, semiconductor devices having various functions are manufactured by laminating multiple layers of semiconductor crystal thin films on a substrate.

Therefore, there is a need for a technique that can efficiently grow semiconductor crystal thin films of good quality and various characteristics.

[Conventional technology]

In general, when manufacturing a semiconductor device, regardless of whether it is silicon-based or compound semiconductor-based, it is essential to grow a semiconductor crystal layer on a substrate and build elements therein.

BACKGROUND ART Conventionally, a low pressure vapor phase growth method has been frequently used to form an epitaxially grown semiconductor crystal layer, and when this method is carried out, the pressure inside a reaction chamber is kept constant.

[Problem to be solved by the invention]

Usually, the properties of a semiconductor crystal layer, such as electrical properties, optical properties, and plane orientation, greatly depend on the growth pressure. Therefore, with conventional techniques, only semiconductor crystal layers with limited characteristics can be obtained.

Therefore, by changing the pressure during growth, it is possible to stack multiple semiconductor crystal layers with various characteristics.

However, changing the pressure during the growth of a semiconductor crystal layer is not currently practiced. The reasons for this are: (1) There is not much of a problem when the pressure is lowered, but when it is raised rapidly, the growth gas stagnates and an unfavorable transition layer is formed at the interface, which impedes growth. This has an adverse effect and makes it impossible to grow a high-quality semiconductor crystal layer.

(2) Due to the reason stated in (1) above, it is necessary to take time to increase and decrease the pressure, and the growth time becomes very long.

The present invention makes it possible to arbitrarily change the pressure during the low-pressure vapor phase growth of a semiconductor crystal layer, thereby efficiently stacking multiple semiconductor crystal layers having different characteristics and high quality.

[Means to solve the problem]

In the semiconductor vapor phase growth method according to the present invention, there is a step of growing a first semiconductor crystal layer (for example, p-type GaAs thin film 21B) in a reduced pressure vapor phase, and then a step of growing a first semiconductor crystal layer (for example, a p-type GaAs thin film 21B) in a vacuum phase, and then having different characteristics from the first semiconductor crystal layer. a second semiconductor crystal layer (e.g. n-type caA
s thin film 21A) under the reduced pressure vapor phase growth pressure (for example, 10"
' (To r r) ) higher pressure (e.g. 10
(Torr)) When stacking layers by vapor phase growth under reduced pressure, the supply of material gases (for example, TMG and ASH3) is cut off and the inside of the reaction chamber (for example, reaction chamber 10) is once evacuated, and then the carrier gas is (for example, H) to bring the reaction chamber into the high pressure state, and then flowing a material gas to grow a second semiconductor crystal layer in a reduced pressure vapor phase.

[Effect]

By adopting the above-mentioned means, it is possible to shorten the time for raising and lowering the growth pressure, and there is no stagnation of material gas in the reaction chamber. The pressure can be changed arbitrarily, the characteristics are different,
Moreover, it is possible to efficiently stack multiple high-quality semiconductor crystal layers, and an intermediate-pressure-grown semiconductor crystal layer is generated between the low-pressure-grown semiconductor crystal layer and the high-pressure-grown semiconductor crystal layer. There is no fear that it will happen.

〔Example〕

FIG. 1 shows an explanatory view of essential parts for explaining an example of a semiconductor vapor phase growth apparatus used to carry out the present invention.

In the figure, 1 and 2 are mass flow controllers, 3 and 4 are gas switching valves, 5 and 6 are exhaust pipes, 7 and 8 are gas supply pipes, 9 is a valve, 10 is a reaction chamber, and 11 is a susceptor. , 12 is a heater, 13 is a wafer, 1
4 is a reaction chamber manifold, 15 is a needle valve, 16
17 is a vacuum pump, 17 is an exhaust pipe, and 18 and 19 are material gases, respectively.

FIG. 2 is a diagram for explaining the growth sequence of one embodiment of the present invention.

In the figure, T1. T2. T3. T4 indicates the period of the sequence. Note that TI to T4 constitute one cycle.

In FIG. 1, the reaction chamber 10 is evacuated by closing the valve 9 and operating the vacuum pump 16.

Now, a case will be described in which growth is repeated while changing the pressure in the reaction chamber 16 in two stages, high and low.

As can be seen from FIG. 2, there are four different growth pressure sequences in -cycles.

That is, period T1 is high pressure growth, period T2 is low pressure growth, period T3 is vacuum evacuation, and period T4 is high pressure growth.

Since there is no separate problem in transitioning from high-pressure growth in period T1 to low-pressure growth in period T2, the pressure is immediately reduced.

In order to return from low-pressure growth to high-pressure growth, two sequences of periods T3 and T4 are required, since the above-mentioned problems will occur if the growth is left as is. Therefore, once the low-pressure growth in period T2 is finished, the supply of material gas is immediately stopped and vacuum evacuation is performed, and then the carrier gas is introduced, and when the pressure reaches a steady state, the material gas is introduced. Yes, then the cycle repeats.

In this way, the time for increasing and decreasing the growth pressure can be shortened, and the material gas does not remain in the reaction chamber 16.

FIG. 3 is a cross-sectional side view of a main part of a semiconductor wafer in which GaAs thin films are laminated in multiple layers according to the present invention.

In the figure, 20 is a GaAs substrate, 21A is an n-type GaA
s thin film and 21B indicate a p-type QaAs thin film, respectively.

Here, the n-type caAsfjl film 21A and the p-type GaAs
Each film 21B has a thickness of 100 [people].

In order to obtain this wafer, it is preferable to conduct the process in exactly the same manner as in the embodiment described with reference to FIGS. 1 and 2 under the following conditions.

(11 Material Gas Trimethyl Gallium (TMG: (CH3) 3G
a) Arsine (AsH3) (2) Ratio of group ■ and group ■ (A s Hs / TMG) V
/II[: 75 (3) Carrier gas hydrogen (H2) (4) Growth temperature T, :s5o ('C) (5) Growth pressure p-type (carrier concentration is 4 X 10" (C11 bow)
): 10-' (To r r) In the case of n-type (carrier concentration is 8X10" (low 3)):
LO (Torr) (6) Sequence period Tl: 2 [seconds] T2: 2C seconds] T3: 1 (seconds) T4: 2C seconds] In this case, vacuum is about 10-' (Torr). shall point.

In the wafer obtained in this way and shown in FIG.
It was confirmed that the pn interface is clearly separated, and therefore it seems suitable for forming a doped superlattice.

〔Effect of the invention〕

In the semiconductor vapor phase growth method according to the present invention, a semiconductor crystal layer having the characteristics of When stacking layers by vacuum vapor phase growth at high pressure, the supply of material gas is cut off, the reaction chamber is once evacuated, carrier gas is flowed to bring the reaction chamber to the high pressure state, and material gas is then flowed to the same high pressure. Semiconductor crystal layers having different characteristics as described above are grown in a reduced pressure vapor phase.

By employing the above configuration, the time for increasing and decreasing the growth pressure can be shortened, and there is no stagnation of material gas in the reaction chamber. The pressure can be changed arbitrarily, the characteristics are different,
Moreover, it is possible to efficiently stack multiple high-quality semiconductor crystal layers, and an intermediate-pressure-grown semiconductor crystal layer is generated between the low-pressure-grown semiconductor crystal layer and the high-pressure-grown semiconductor crystal layer. There is no fear that it will happen.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram of essential parts for explaining an example of a semiconductor vapor phase growth apparatus used to carry out the present invention, and FIG. 2 is a diagram for explaining the growth sequence of an embodiment of the present invention. 3 each shows a cutaway side view of a main part of a semiconductor wafer in which GaAs thin films are laminated in multiple layers according to the present invention. In the figure, l and 2 are mass flow controllers,
3 and 4 are gas switching valves, 5 and 6 are exhaust pipes, 7
and 8 is a gas supply pipe, 9 is a valve, 10 is a reaction chamber, 11
12 is a heater, 13 is a wafer, 14 is a reaction chamber manifold, 15 is a needle valve, 16 is a vacuum pump, 17 is an exhaust pipe, and 18 and 19 are material gases, respectively.

Claims (1)

[Claims] A step of growing a first semiconductor crystal layer in a reduced pressure vapor phase, and then growing a second semiconductor crystal layer having different characteristics from the first semiconductor crystal layer under the reduced pressure vapor growth pressure. When layering is performed by vacuum vapor phase growth at high pressure, the supply of material gas is cut off and the inside of the reaction chamber is once evacuated. Next, the reaction chamber is brought into the high pressure state by flowing carrier gas, and then the material gas is 1. A method for vapor phase growth of a semiconductor, comprising the step of growing a second semiconductor crystal layer in a low pressure vapor phase by depositing a second semiconductor crystal layer.