JPH01110720A - Vapor growth method of iii-v compound semiconductor - Google Patents

Abstract

PURPOSE:To make it possible to form the hetero junction having a sharp compositional change by a method wherein the pressure of the main piping is brought lower than that of the sub-piping when the flow passage of raw gas is switched from the sub- piping to the main piping, and when the raw gas flow passage is switched from the main piping to the sub-piping, the pressure of the main piping is made higher than that of the sub-piping in advance. CONSTITUTION:Two or more layers of different kinds of vapor growth layers can be formed continuously by the III-V compound semiconductor vapor growth device equipped with the main piping 107, in which the carrier gas of hydrogen or mainly composed of hydrogen and raw gas is mixed and introduced to a reaction chamber 106, and a sub-piping 110 with which the raw gas is introduced to an exhaust hole 109, not to the reaction chamber 106. In order to switch the raw gas flow passage from the sub-piping 110 to the main piping 107 in the abovementioned case, the pressure of the main piping 107 is brought lower than that of the sub-piping 110 in advance, and also in order to switch the raw gas flow passage from the main piping 107 to the sub-piping 110, the pressure of the main piping 107 is brought higher than that of the sub-piping 110 in advance. The above-mentioned raw gas is composed of organic compound consisting of a plurality of group III an elements and the hydrogen compound or organic compound consisting of one or more kinds of group V elements.

Description

Detailed Description of the Invention [Object of the Invention] (Industrial Field of Application) The present invention is directed to the production of organic compounds of the ■-■ group by thermal decomposition of an organometallic compound consisting of a group ■ element and a hydrogen compound or an organic compound consisting of a group ■ element. Vapor phase growth method for compound semiconductors (Metal Or
Ganic Chemical Vapor Dep
The present invention relates to the NO-CVD method (hereinafter abbreviated as NO-CVD method), and particularly to a vapor phase growth method for increasing the compositional steepness at the interface of different types of semiconductor junctions (Peter junctions).

(Prior Art) The MO-CVD method is attracting attention as an epitaxial crystal growth method that is more easily mass-produced than the molecular beam crystal growth method (MBE method). Especially recently, gallium arsenide (GaAs)
/ Aluminum, gallium, arsenic (AjlGaAs
), multi-quantum well (MQIj) lasers, which grow heterojunctions such as indium phosphide (InP)/indulum gallium arsenic (InGaAs) and have functions greater than those using conventional single-layer films. .

The growth of crystals for devices such as high electron mobility transistors (OEMTs) is active, and in crystals using the above-mentioned heterojunction, it is usually important to form a heterojunction interface with a steep compositional change.

In this MO-CVD method, the flow rate of the growth gas can be increased, so it is relatively easier to form a steep interface than other vapor phase growth methods such as the chloride VPE method.
The reality is that the steepness of the interface is still inferior to that formed by the E method, and in principle the only way to improve the steepness of the interface is to quickly switch the gas.

For this purpose, (i) an on-off valve to switch the raw material gas;
Place the mouth as close to the reaction vessel as possible.

Improvements related to the equipment, such as devising the shape of the reaction vessel to shorten the residence time of the gas as much as possible.C. Regarding growth conditions, such as reducing the growth rate by minimizing the flow rate of the raw material gas of group ■, which is proportional to the growth rate. Improvements are being made.

Furthermore, in recent years, a method that is becoming more and more membrane-based is to install two pipes: a main pipe that directly introduces the raw material gas into the reaction vessel, and a sub-piping that directly introduces the raw material gas into the exhaust port without introducing it into the reaction vessel. There is a method of switching the flow path between the main and sub-pipes. With this method, there is almost no pressure fluctuation in the reaction vessel due to gas switching, so there is no gas turbulence and rapid gas replacement occurs, resulting in a steep interface. is planned.

The conventional device will be described below with reference to FIG. 1, which is applied to the present invention. An undoped GaAs layer is formed on a GaAs substrate.

An example will be described in which an n-type AQGaAs layer and an n-type GaAs layer are grown in this order.
゜103, 104.105 contains, in this order, trimethylgallium (TMG), which is a type of organic compound of Ga,
Trimethylaluminum (TMA), which is a type of organic compound of aluminum, hydrogen arsenide (AsH3), and monosilane (SiH4), which is a hydride of silicon (SL), which is an n-type impurity, are respectively stored, and 101 reacts this raw material gas. This is a storage container for hydrogen used as a carrier gas for transportation to a container.

In the apparatus shown in FIG. 1, a main pipe 107 serves to transport the raw material gas and carrier gas to the reaction vessel 10.
A sub-piping 110 is installed to guide the raw material gas and carrier gas to the exhaust port 109 instead of to the reaction vessel 106.
A substrate 112 is placed.

In this way, the feature of this device is that the main pipe 10 is used as a gas pipe.
7 and a sub-piping 110 are installed, and the flow path of the source gas can be freely selected by opening and closing the valves 113 to 120. Furthermore, the flow rate of hydrogen flowing into the sub pipe 110 branched from the main pipe 107, and the sub pipe 11
By appropriately selecting the opening/closing degree of the pressure regulating valve 121 provided near the zero outlet, the pressures in the main pipe 107 and the sub pipe 110 can be maintained as equal and constant as possible.

By devising such piping arrangement, for example, TM
A flow path is connected to main pipe 1 by opening and closing valves 115 and 116.
When changing from 07 to sub piping 110, the reaction vessel 106
This reduces the phenomenon in which the flow of both pipes is disturbed. Furthermore, using this device, the above-mentioned undoped GaAs/n-type A
The growth procedure for forming a three-layer heterojunction made of 12GaAs/n-type GaAs is as follows.

First, open valves 113 and 117, TMG, AsH3
is sent to the reaction vessel 106 to grow the GaAs layer.
At this time, TMA = SxH, opens the valves 116 and 120 to flow a constant amount of TMA to the sub pipe 110 side until it reaches the vicinity of the main pipe 107.

Fill with SiH4. Then, when growing the n-type Al2GaAs layer, valves 116 and 120 are closed, and valve 1
15. Open 119 and connect to main pipe 107 (TMA,
An n-type A12GaAs layer is grown by introducing SiH.

To stack an n-type GaAs layer on this n-type AQGaAsJa, contrary to the method described above, the TMA valve 115 is closed.
16 and allow TMA to flow into the sub-piping 110 to produce n-type GaA.
The s-layer is deposited and grown.

(Problem to be Solved by the Invention) The compositional steepness of the GaAs/n-type 1GaAs/n-type GaAs interface deposited on the semiconductor substrate formed by the above-described growth procedure was measured using Auger electron spectroscopy (AES). When investigated by measuring the depth distribution of
As is clear from the figure, the GaAs layer is n-type Al2GaAs
About 105 people at the interface, about 100 people at the n-type AQGaAs/undoped n-type Ga-As interface, and the sag at the interface is 2.
It was found that this amount extends to as much as 5 atomic layers. After various studies on the causes of this sag, we found that in equipment with the above-mentioned piping structure, pressure fluctuations in the reaction vessel can be prevented by equalizing the pressure in the main piping and sub-piping and switching the valves, but the valve in the TMA piping The result was that the raw material gas entering the gap between the outlet of No. 115 and the connection part of the main pipe could not be replaced quickly enough.

It is an object of the present invention to provide a novel method for vapor phase growth of a ■-■ group compound semiconductor that eliminates the above-mentioned drawbacks.

[Structure of the invention]

(Means for solving the problem) In order to achieve this object, the present invention includes a main pipe that mixes the carrier gas and raw material gas and leads them into the reaction vessel, and a sub pipe that leads not into the reaction vessel but to the exhaust port. When continuously forming two or more vapor-phase growth layers of different types using a vapor-phase growth apparatus for m-v group compound semiconductors equipped with In order to switch the source gas flow path from the main pipe to the sub pipe, a method is adopted in which the pressure inside the main pipe is made higher than that of the sub pipe in advance.

(Function) In this way, in the present invention, when forming a plurality of heterojunctions on a semiconductor substrate, a vapor phase growth apparatus is used to obtain compositional steepness at the interface of composite element layers of different compositions made of m-v group compounds. Rather, a pressure difference is created between the main piping and the auxiliary rudder pipe installed in the main piping, and the slight disturbance in the gas flow that occurs when the valves attached to these pipes are switched is due to raw material gas entering the gap between the main piping and the auxiliary rudder pipe. The present invention was completed on the basis of the knowledge that it is more effective to quickly carry out the substitution of the above for obtaining the compositional steepness of the interface.

That is, in the vapor phase growth method of the ■-v group compound semiconductor according to the present invention, TMG and AsH are first flowed through the main pipe to deposit a GaAs layer on the m-■ group compound semiconductor substrate by the vapor phase growth method, and then the TMA flow path is Switch from the sub piping side to the main piping and
Before forming the As layer, the pressure in the main pipe is adjusted to be lower than that in the sub pipe. Through this process, T
When switching the flow path of the MA from the sub-piping side to the main piping side, a pressure difference is created between the surface rudder pipes, and as a result, the TMA piping between the valve outlet on the main piping side and the connection with the main piping is
The time required for MA replacement is shortened. Further, in order to deposit a GaAs layer subsequent to the AQGaAs layer, contrary to the above, the pressure in the main pipe is adjusted in advance to be higher than that in the sub pipe.

Through these operations, when the valve on the sub-piping side of the TMA piping continues to be opened and the valve on the main piping is closed, the raw material gas is drawn in due to the pressure difference generated between the main and sub-pipes in a very short period of time, and the valve The replacement of TMA between the outlet and the connection part was accelerated, and the sagging of AQ atoms at the interface between the AaGaAs layer and the GaAs layer became extremely small.

(Example) The present invention will be explained in detail with reference to FIGS. 1 and 2.

Although some descriptions overlap with those of the prior art due to convenience, they will be explained again.

As an example, undoped GaAs/n-type AQGaAs
An example of vapor phase growth of a three-layer structure of n-type GaAs will be explained using the vapor phase growth apparatus shown in FIG. 7MG102 and AsH3
A predetermined amount of each of 103 is poured into the main pipe 107, guided into the reaction vessel 106, and placed on the support stand 111.
A GaAs layer to which no impurities are added is deposited and grown on an As substrate 112. In this GaAs layer growth process, TM
A103°5iH4105 opens valves 116 and 120, closes valves 115 and 119, and allows a predetermined amount to flow into sub-piping 110.

By the way, this vapor phase growth apparatus includes a reaction vessel 106 and a TMG.

Container 1 filled with TMA, AsH3, and SiH, respectively
02.103゜10/I, 105 are connected by main pipe 107 and sub pipe 110, and valve 1 is installed between these surface rudder pipes.
13.114.115.116゜117, 118.11
9.120 will be installed, and two of these valves will be formed for each container for opening and closing.

(The younger valve numbers correspond to the younger reaction vessels in order.) Although the wording is different, the reaction vessel 106 is made of semi-insulating GaAs.
The support table 111 on which the substrate 112 is placed is further mounted on the reaction vessel 1.
An exhaust port 109 and a pressure regulating valve 121 are installed at the end of 06, and 101 is a carrier gas container for transporting the raw material gas to the reaction container 106.

The auxiliary rudder pipe 110 has a 7MA103. SiH, 105
As mentioned above, a predetermined amount of hydrogen is flowing into the auxiliary rudder pipe 110, and in this case, the flow rate of hydrogen flowing into the auxiliary rudder pipe 110 and the opening/closing degree of the pressure regulating valve 121 installed near the exhaust port connection are adjusted. A feature of the present invention is that the pressure in the pipe 107 is kept lower than that in the auxiliary rudder pipe 110 by, for example, 0.05 kg/cd.

Following the formation of the GaAs layer, valves 116 and 120 are closed and at the same time valves 115 and 119 are opened.
．． 5iH4105 is poured into the main pipe 107 to form an n-type AQG.
Form an aAs layer. This 7MA103.5iH410
5 into the main pipe 107, by creating a pressure difference between the main and sub pipes in advance and opening the valves 115 and 119, TMA and SiH4 flow quickly, so the gas switching time is shortened compared to the conventional method. .

Next, when forming the n-type Aj2GaAslj, the pressure in the main pipe 107 is lowered, for example, by 0.05 k than that in the auxiliary rudder pipe 110.
The g/a# is adjusted by adjusting the flow rate of hydrogen flowing in the auxiliary rudder pipe 110 and the degree of opening/closing of the pressure regulating valve 121. Following the formation of this n-type 1GaAsi, the valve 116 of the TMA piping is opened, the valve 115 is closed, and the n-type AQGaA
Grow the s-layer.

In this step, contrary to the above, the supply to the TMA container 103 is immediately stopped due to the pressure difference established in advance between the main and sub-pipes. Figure 2 shows the results of AES measurement of the steepness of the composition of A2 atoms at the interface of the AQGaAslQaAs layer, which is placed on a semi-insulating semiconductor substrate made of a ■-■ group compound by such a process. Thus, the sag width of AQ atoms at the junction interface of the AQGaAs/GaAs layer was 40 and 37, respectively, close to the measurement limit of AES.

As described above, it has been found that by applying the 1-V group compound semiconductor vapor phase growth method according to the present invention, it is possible to form a heterojunction with excellent interface steepness.

In the above embodiments, the formation of a heterojunction using 1GaAs/GaAs has been described, but the growth material is not limited to this, and may be formed using other ■-■ group compound semiconductors, such as InP.
Of course, this method can be applied to the growth of InGaAs, etc., and is not limited to making the heterojunction interface steeper, but also enables steep addition when adding impurities.

Furthermore, in the above embodiment, the pressure difference between the main and auxiliary rudder pipes was set to 0.05k.
Although g/(d is used, the present invention is not limited to this value, and the expected effect can be obtained by setting a substantial pressure difference between each growth step.

〔Effect of the invention〕

As described above, the special vapor phase growth apparatus applied in the present invention is equipped with a main pipe that guides the raw material gas into the reaction vessel and an auxiliary rudder pipe that guides the raw material gas not into the reaction vessel but into the exhaust port. When carrying out vapor phase growth of multiple layers consisting of ■-■ group compounds, the raw material gas flow path.

It is necessary to switch the main piping to the auxiliary rudder pipe, and as described above, the method of the present invention adopts a method of creating a height difference in the pressure of the main and auxiliary piping depending on the switching direction.

However, this flow path switching method makes it possible to form a heterojunction with a steep compositional change, which has the great advantage of improving the characteristics and reliability of a semiconductor device that uses this heterojunction.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing an outline of the vapor phase growth apparatus necessary for the present invention;
FIG. 2 is a diagram showing its characteristics, and FIG. 3 is a diagram showing the characteristics of a conventional vapor phase growth layer. 101~105: Container 107: Main piping 113~
120: Valve 111: Support stand 106 two reaction vessels 109: Exhaust port 110: Sub-rudder pipe 11
2: Semiconductor substrate agent Patent attorney Inoue - Dansenbo J@et al. -

Claims (3)

[Claims] (1) A main pipe that mixes hydrogen or a carrier gas containing hydrogen as a main component and a raw material gas and leads it into the reaction vessel, and a sub-piping that leads the raw material gas not into the reaction vessel but to the exhaust port III
- When continuously forming two or more different types of vapor-phase growth layers using a V-group compound semiconductor vapor-phase growth apparatus, before switching the source gas flow path from the sub-piping to the main piping, A method for manufacturing a semiconductor gas of a III-V compound semiconductor characterized in that the pressure in the main piping is lower than that in the sub-piping, and the pressure in the main piping is made higher than that in the sub-piping before switching the source gas flow path from the main piping to the sub-piping. Phase growth method. (2) The source gas is composed of an organic compound consisting of a plurality of Group III elements and a hydrogen compound or organic compound consisting of one or more Group V elements. Vapor phase growth method for group V compound semiconductors. (3) The raw material described in claim 2 is III-V.
A method for vapor phase growth of a III-V compound semiconductor, characterized in that the compound semiconductor is composed of an additive that forms an n-type or p-type region.