JPH0414814A - Organometallic vapor growth apparatus - Google Patents

Abstract

PURPOSE:To directly evaporate a group V metal and to grow a group III-V compound thin film in a vapor phase by a method wherein an introduction path of a carrier gas used to transfer a group V metal vapor evaporated in a heating space is formed and a mixed gas of the group V metal vapor with the carrier gas is introduced into a reactor from the upper-stream part of a susceptor. CONSTITUTION:Particles 8 of metal arsenic are put in a heating chamber 5; a susceptor 4 and the heating chamber 5 are heated to a prescribed temperature by using a thermocouple 9 and a coil 10. After that, a mixed vapor of an alkyl compound of gallium with a carrier gas is sent into a reaction furnace 1 from an introduction port 2; a carrier gas is sent from an introduction path 6. An arsenic vapor evaporated in the heating chamber 5 is spouted, via a hole 7, to the reaction furnace 1 from a hole 11 made near a substrate 3; it is reacted with the alkyl compound of gallium. Thereby, a thin film of gallium arsenide can be grown on the substrate 3. The gas which has been passed on the substrate and the susceptor and which has been used for a reaction is discharged from the reaction furnace 1 via a gas discharge port 12.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an organometallic vapor phase growth apparatus used for growing thin films of m-v group compound semiconductors.

(Prior art) Conventionally, a method has been known for growing thin films of semiconductors made of Group II and Group V elements of the periodic table, such as gallium arsenide, indium phosphide, and aluminum gallium arsenide, by metal organic vapor phase epitaxy. . For example, ganium arsenide can be obtained by a thermal decomposition reaction of trimethylgallium and arsine as shown in the following formula.

Ga(CHs)s+AsHi=GaAs+3CH4
Further, when growing InP, trimethylindium (I n (CHx) -, hereinafter abbreviated as TMIn) and phosphine (PH) are used as In sources, and InP can be obtained by the following thermal decomposition reaction.

In(CHs)s+PH5=InP+3CH4 Various reactors such as horizontal furnaces and barrel furnaces have been proposed as devices for producing such m-v group compounds.
For example, in a barrel-type furnace, a semiconductor substrate is placed on a carbon susceptor and maintained at a predetermined temperature by high-frequency induction heating. Raw material gas and carrier gas, which are to be used to grow a thin film on a substrate, are fed into the furnace through a gas supply port, undergo thermal decomposition and react in the vicinity of the substrate, and a thin film is grown on the substrate. After the reaction is completed, the gas is discharged to the outside from the discharge port together with the carrier gas. Note that in order to suppress thermal decomposition of the gas supplied as a raw material outside the vicinity of the substrate, the reactor is designed to be cooled with cooling water.

However, as mentioned above, the method of growing the target thin film of gallium arsenide or the like by thermal decomposition in the gas phase using organometallic gases uses highly toxic materials such as arsine and phosphine as the group III source gas. Because of the use of semiconductor devices, there are significant restrictions in terms of equipment design, semiconductor manufacturing processes, and safety management. For this reason, a method has been proposed in recent years that uses metallic arsenic and red phosphorus directly without using gases such as arsine and phosphine, which have become problematic (R, B
hat (J, Electron Matter, vol.
14 (1985) 433, M. Naltoh et.
aL(J, Crystal Growth, vol.
93 In this method, for example, metal arsenic is heated at around 450° C. in a heating furnace provided separately from the reactor to evaporate the arsenic, and arsenic vapor is supplied into the reactor using hydrogen as a carrier gas. In this case, the arsenic vapor transport path between the heating furnace and the reaction furnace is generally heated by means such as a tape heater in order to prevent the arsenic vapor from solidifying.

Although the above method solves the safety problem of using highly poisonous gas, it not only complicates the equipment because it requires the special installation of a heating furnace for vaporizing arsenic. may adhere to the earthen walls of the reactor, causing so-called particles, making it impossible to obtain the vapor pressure of arsenic necessary for the gallium arsenide formation reaction, or even causing heated arsenic vapor to be introduced into the reactor. Therefore, there is a drawback that the crystal properties of the thin film cannot be improved because the raw material gas causes a reaction outside the vicinity of the susceptor.

Furthermore, gallium arsenide grown using this method is p-type and has a carrier concentration of 10'8 to IO"c in a horizontal device.
It is also known that "m-" is not good.

(Means for Solving the Problems) The present invention has been made in view of the above circumstances, and provides an improved device for growing a thin film of a group V compound in the vapor phase by directly evaporating a group V metal. ! It provides:

That is, the present invention provides an organometallic vapor phase growth apparatus for growing a thin film of a group V compound semiconductor by reacting a group B metal alkyl compound with a group III element. The susceptor is installed in the vicinity of the susceptor, and includes a heating space for heating and vaporizing the group III metal, and a carrier gas for transporting the group III metal vapor evaporated in this heating space to the vicinity of the substrate. The present invention provides a metal-organic vapor phase growth apparatus characterized in that an introduction path is provided so that a mixed gas of a Group 1 metal vapor and a carrier gas is introduced into a reactor from an upstream portion of a susceptor.

(Example) The present invention will be described in detail below based on one example shown in the drawing.

In FIG. 1, a horizontal reactor 1 has an inlet 2 for vapor and carrier gas of a group II metal alkyl compound on its left side, and a susceptor 3 is placed in the center of the reactor 1 so that a substrate 3 can be placed thereon. 4 is installed. The substrate 3 is installed with a gentle inclination so as to be substantially parallel to the above-mentioned gas flow direction, and a heating chamber 5 is provided immediately below the susceptor 4 for heating and evaporating group V elements by preheating the susceptor. Heating chamber 5
is charged with group III metal, and the V evaporated in the heating chamber 5
As group metals are transferred onto the substrate.

A carrier gas introduction path 6 and its discharge hole 7 are provided.

A method of growing a thin film of a group Ⅰ-group Ⅰ compound on the substrate 3 using this apparatus will be described below. First, metal arsenic particles 8 are placed in the heating chamber 5, and the susceptor 4 and the heating chamber 5 are heated to a predetermined temperature using the thermocouple 9 and the coil 10. After that, a mixed vapor of a gallium alkyl compound and a carrier gas is fed into the reactor 1 from the inlet 2, and a recarrier gas is fed from the inlet 6, and the arsenic vapor evaporated in the heating chamber 5 passes through the holes 7 to the substrate. Hole 11 provided near 3
A thin film of gallium arsenide is grown on the substrate 3 by discharging the gallium into the reactor 1 and reacting with an alkyl compound of gallium. The gas used in the reaction after passing over the substrate and susceptor is discharged from the reactor 1 through the gas discharge port 12.

In order to prevent areas other than the vicinity of the substrate from becoming high temperature, the reactor 1 is provided with a jacket 13 to allow cooling water to pass therethrough.

In the present invention, as long as the heating chamber 5 provided for evaporating the V group element is installed in the reaction furnace 1 and has a structure in which the evaporated group V element and its carrier gas are discharged near the substrate, There are no particular limitations on the installation method or structure of the heating chamber. The one in Figure 1 has a structure in which the susceptor holder is divided into two parts, 14 and 15, and a heating chamber is formed between the holders, which is easy to design and manufacture. Furthermore, since the susceptor is located directly above the heating chamber, the preheating can be used to evaporate metal arsenic, making it extremely effective for equipment operation and supply of Group V elements. .

In the reactor shown in Fig. 1, the heating chamber has a diameter of 5 to 10 mm.
It is preferable to install metallic arsenic of the order of fflII+ and evaporate the arsenic. Hydrogen as a carrier gas is introduced from a pipe provided at the rear of the susceptor holder while controlling the flow rate with a flow meter. The hole 7.11 has a horizontally elongated shape with a width approximately equal to or greater than the width of the board to be installed. Since the susceptor holder is heated, it must be made of a material that can withstand high temperatures; for example, in the case of quartz glass, a boron nitride dish that fits into the heating chamber 5 may be made and metal arsenic placed thereon.

The amount of arsenic evaporated is approximately determined by the temperature of the space and the flow rate of the carrier gas. In order to adjust the temperature of this heating chamber, ■ changing the material of the susceptor holder 15, ■ setting the bottom plate thickness (adjusting the amount of heat escaping to the bottom), ■ putting SiC coated carbon into the space and heating it, etc. It can be carried out.

Next, an application example of this device will be described.

GaAS was grown using the apparatus shown in FIG. 1 under the following conditions.

(i) TMGa () Limethylgallium) Flow rate 1 cc/min Arsenic transport gas
3j2/min total flow rate 10j
2/l1lin susceptor temperature 650°C (ii) TEGa D-type gas) Flow rate 1 cc/min Arsenic transport gas
3j2/win total flow rate 10j
lVmin Susceptor temperature 650°C Hall measurements of the GaAs obtained in (i) and (ii) revealed that (i) was p-type with a carrier concentration of 5.2×1 ()
It was GaAs with a high purity of +40In-1. (ii
) had a high resistance and could not be measured. This is considered to be because the carrier concentration has decreased sufficiently.

In addition, the arsenic paste adhered to the acta from the tip of the susceptor to the downstream side, and no adhesion was observed upstream from the susceptor.

Furthermore, since the susceptor holder forming the heating chamber is heated to a high temperature, it is preferable to use a heat-resistant, high-purity material, and quartz glass is recommended, but BN% SiC coated carbon may also be used. However, the present invention is not necessarily limited to such materials.

FIG. 2 is a cross-sectional view of another embodiment of the present invention.
is a barrel type furnace, 22 is a susceptor, 23 is a substrate attached thereon, 24 is a susceptor holder, 25 is a rotating shaft of the susceptor, 26 is an RF coil, 27 is a cooling jacket of the reactor, 28 is a bottom plate of the reactor, 29 is an exhaust port.

30 is a heating chamber provided inside the susceptor holder 24, and a carrier gas is fed into the heating chamber into which metal arsenic 31 is charged through a carrier gas introduction pipe. The heating chamber 30 has a double wall structure consisting of an inner wall 33 and an outer wall 34.
A hole 34a is provided at the bottom of 4. A gap 36 is provided between the outer wall 34 of the heating chamber 30 and a carbon ring 35 attached to the inside of the susceptor holder 24 and above the susceptor.

Further, a reaction gas introduction pipe 37 is formed concentrically with respect to the carrier gas introduction pipe 32, and a reaction gas introduction path 40 shown by an arrow is formed by a partition 38 and a tube wall 39 having holes 39a. Reference numeral 41 indicates a flow path for the reaction gas, and the gas is discharged from the discharge port 29 after the reaction is completed.

The device shown in this figure can rotate the susceptor, so
It is possible to make the semiconductor film formed on the substrate uniform.

The alkyl compound of the group (1) element and the carrier gas are discharged downward through the hole 39a according to the introduction path 40 supplied to the gas introduction pipe 37, and become a gas flow 41a. On the other hand, the group V element to be reacted with the above-mentioned gas is charged into the heating chamber 30, and is heated and evaporated by the preheating of the susceptor 24.
Entrained by the gas supplied from the carrier gas introduction pipe 32 from above, it passes through the gap of the double wall structure, is discharged from the gap 36, and merges with the reaction gas flow 41a from above. When the reaction gas flow 41a thus formed flows downwardly over the substrate 23, crystals of the group Ⅰ-group V compound grow on the substrate.

(Function) A space is provided near the susceptor to heat and evaporate group V metal,
Since the group V metal is evaporated by preheating the susceptor, a heating furnace is not required and the apparatus becomes simple.

Since the gas temperature is rising in the upper part of the susceptor, and the mixed gas of group V metal vapor and transport gas is introduced into the reactor from the upstream part of the susceptor, the group V metal in the upstream part of the reactor does not solidify (and the reactor Reactions in the upstream region can be avoided.

(Effects of the Invention) The apparatus of the present invention is capable of forming a semiconductor film on a substrate using vapors of group V metals and old group alkyl compounds without using toxic gases such as arsine and phosphine. Therefore, it is only necessary to limit the location to be heated to a high temperature to one location in the reactor.

Furthermore, it is possible to prevent the disadvantage of gas reactions occurring outside the vicinity of the substrate as in conventional devices, and also to eliminate the problem of Group V metals adhering to the reactor wall.
A high quality semiconductor thin film can be grown on a substrate.

[Brief explanation of drawings]

FIGS. 1 and 2 are cross-sectional views of an embodiment of the metal organic vapor phase epitaxy apparatus of the present invention. ■...Horizontal reactor 2...Carrier gas inlet 3...Substrate 4...Susceptor 5...Heating chamber 6...Carrier gas introduction path 7...Carrier gas discharge hole 8...・Metallic arsenic particles 9...Thermocouple 10...
RF coil 11...hole 12...exhaust port
13...Jacket 14.15...Susceptor holder 2...Barrel type furnace 22...Susceptor 23.
・Substrate 24 ・Susceptor holder 25 ・
...Rotating shaft 26...RF coil 27...
Cooling jacket 28...Bottom plate 29...Exhaust port
30...Heating chamber 31...Metal arsenic 32...Carrier gas introduction pipe 33...Inner wall 34...Outer wall 35...
Carbon ring 37... Reactive gas introduction pipe 39... Tube wall 41... Reactive gas flow path 36... Gap 38... Partition 40... Reactive gas introduction path Fig. 2

Claims (1)

[Claims] By reacting a group III metal alkyl compound and a group V element,
A metal organic vapor phase growth apparatus for growing a thin film of a group III-V compound semiconductor has a susceptor in which a substrate is installed approximately parallel to the main stream of gas in the reactor, and a group V metal is placed near the susceptor. In addition to a heating space for heating and evaporating the metal, a carrier gas introduction path is provided to transport the group V metal vapor evaporated in this heating space to the vicinity of the substrate, and a mixed gas of the group V metal vapor and carrier gas is transferred to the upstream part of the susceptor. An organometallic vapor phase growth apparatus characterized by being introduced into a reactor.