JPS62291020A - Vapor growth device - Google Patents

Abstract

PURPOSE:To enable a growth layer to be formed particularly having steep and excellent layer impurity concentration in thin film lamination growth of a compound semiconductor, by making a reactant gas introduction tube branch via a branching valve and then introducing reactant gases to a chamber from the first branched introduction tube having impurities and from the second branched introduction tube having no impurity. CONSTITUTION:When lamination growth of a thin film is performed on a substrate 3 by introducing reactant gases into a reactor chamber 1, an introduction tube for reactant gases containing constituents for thin film semiconductor formation is made to branch via a branching valve 19. The reactant gases are introduced there from respective introduction tubes 21 and 22, with impurities added to the first branched tube 21 and with no impurity added to the second branched tube. When undoped GaAs is made to grow on the substrate 3, for example, the branching valve 19 is controlled to introduce TMG 17, AsH3 18, and H2 13 in the direction of the tube 20. When n<+>AlGaAs is then made to grow, TMG 17, TMA 16, AsH3 18, and H2 13 are introduced via the branching valve 19 to the tube 21 and to be supplied to the substrate 3 with H2Se 14 added via a valve 8.

Description

Detailed Description of the Invention 3. Detailed Description of the Invention Industrial Field of Application The present invention is directed to vapor phase growth, which can provide a good growth layer with a steep impurity concentration between layers, especially in the layered growth of thin films of compound semiconductors. It is related to the device.

Conventional technologyRecently, research and development of Hedeco-junction devices using compound semiconductors has been actively conducted3.As a thin film epitaxial growth method, instead of the conventional liquid phase epitaxy (LPE) method, ultra-thin film multilayer Molecular beam shrimp taxo (MBE) method and vapor phase formation (halide VPE, M○VP) method that facilitates structure formation
E) Law dominates. Among these, the MOVPE method is an organic metal vapor phase epitaxy method using an organic metal, and is attracting attention as a method with particularly high mass productivity. Figure 2 shows a schematic diagram of the reactor chain (-) of a conventional general MOVPE device. The substrate temperature is monitored and controlled by a thermocouple 5. 6 is an introduction pipe for introducing the reaction gas into the reactor chamber 1, and 7 is an exhaust pipe for exhausting the gas after the reaction in the reactor chamber 1 to the outside. Yes.On the gas introduction side, 8
,9,10°11.12. There are three boat valves, and in response to the introduction of H213, which is the main carrier gas, each of the three boat valves is turned on.

AsH318 is added to gear rear gas H213.

For example, when fabricating Alo, 3Gao, 7AS/GaAS double heterojunction lasers, n” G a A
271m n GaAs(n) 1 x 10 on s substrate
cm) +21trrr n-1Aio, 3G
ao, -rAs (n, -i 1n1o18cm-3
) ro, 1μm undoped GaAs (n<1016
cm”).

2 pm p' Ae, 3Gao, 了As (p)1
x 1018cm-5)+171m p-”GaAs
(1) > I x 1018 cm-6) are grown sequentially. n-'-GaAs (n)
1018 cm-3), TMGl7 is added to 1
0cc/min (0°C).

AsHa 18 at 15 cc, //min, H2S
Turn on valves 11, 12, 8, and 2
1/min of H213 and introduced into the reactor chamber 1 via the introduction pipe 6, and the substrate 3 (substrate temperature 780°C) heated by induction with the RF coil 4''-n''-
G a A s is epitaxial growth.

p + A lo , 3 G a o , 7 A 8 (
In the case of epitaxial growth of P > I
℃), TMGl7 is 10 cc/min (0℃)
, AsH318 is 15 cc/min, D E
Z 15 is 5 cc/min (0°C) of each reaction gas of H213 2 /I! Connect valves 10, 11, 12, and 9 to each line of 7 min.
7. Supply the mixed reaction gas to the substrate 3- by causing it to flow.

Other layers can be manufactured in the same manner.

However, in the case of the above-mentioned semiconductor laser, this conventional method requires laminated growth with an impurity concentration structure such as n''-undope-p''-. Therefore, the steepness of the impurity concentration between these layers becomes extremely poor. For example, an undoped layer (G of a semiconductor laser)
a As active layer) is n GaAs (~1017
cm-3) and p″A 7 o , 3G a o ,
7 A The 8th layer is a p layer with poor crystallinity compensated by n-type impurities.
At! (, 3G'o, r' layer, which causes problems such as an increase in threshold current and a decrease in quantum efficiency. This is because the introduction tube 6 that supplies the reactive gas onto the substrate 3 is n This is due to the fact that it is used for epitaxial growth of type semiconductors, p-type semiconductors, and undoped semiconductors.

A portion of the introduction pipe 6 is made 8 inches in diameter per layer to increase the flow rate to suppress the residual gas of impurities, or a sheathed heater is wrapped between the valve 8 and the tip of the introduction pipe 6 to suppress the residue of impurities. Even if you do, it will not be completely removed.

I can't do it. It is said that the memory effect of H2S e is particularly large, but even if the impurity is replaced with SIH4 or 512H6, no essential solution will be reached. This problem is not limited to semiconductor lasers, but also becomes a serious problem when manufacturing electrical devices such as HEMTs due to the decrease in the mobility of the two-dimensional electron gas layer.

Means for Solving the Problems The technical means of the present invention for solving the above-mentioned problem of the steep drop in interlayer impurities that causes performance deterioration of semiconductor devices is n-type.

If three types of dopant types, p-type and undoped type, are required, the introduction pipes introduced into the reactor chamber should be made independent, and the main gear gas and constituent element gases can be connected to the n-type introduction pipe and p-type respectively through branch valves. Introductory pipe for
The main purpose is to branch into an undope type introduction pipe. Impurities for n-type and p-type dopants are added to the reaction gas introduction pipe after the branch valve.

Function The function of the present invention can be explained as follows. Introduction using H2Se as an n-type dopant Since the tube is used only for forming an n-type semiconductor thin film (reactant gas flows), there is a p-type dopant in the n-type semiconductor. All Zn (formed from DEZ) cannot be mixed. This is because, at this time, no reaction gas or carrier gas is supplied from the p-type semiconductor formation introduction tube (5 huts are applied).

When forming an undoped type semiconductor thin film, undope
Since the gear gas and constituent element gas flow only through the mold introduction pipe, high purity without contamination with p-type and n-type dopants is achieved.
An ndope type semiconductor thin film can be easily obtained.

By using the present invention, not only can time-consuming processes such as periodic purging of the inlet tube and dry baking be eliminated, but also a good thin film multilayer laminated film with a steep impurity concentration can be produced with good reproducibility by simply switching the branch valve. is obtained.

Embodiment An embodiment of the present invention will be described with reference to FIG. The same numbers as in the conventional example refer to the same members. For example, T MA 16, which is a constituent element of a compound semiconductor, is added to the carrier gas H213.
, TMG 17*A 5H318, constituent element gas and carrier gas are introduced by branch valve 19 through valves 10, 11, and 12, respectively.

When undoped GaAs is epitaxially grown on the substrate 3, the constituent element gas (T
The branch valve 19 is controlled so that the carrier gas is introduced. Next n'A
TMGl 7 when epitaxially growing eo, 3Gao, and 7AS.

TMA 16, A s H318 branch valve 19
H2 is introduced into the inlet pipe 21 side through the valve 8.
Se14 is TMG 17, TMA 16
, A sH18, H213, various reaction gases are mixed, and supplied to the substrate 3-f: n''' Al
o, 3Gao, 7A8 are epitaxially grown. Also, when growing p'-G a A s, 7MG
17, A8H318, H213 are guided to the introduction pipe 22 side via the branch valve 19, and DEZ15 is introduced via the valve 9.
is 7MG17. Various reaction gases are added to AsH18 and H213, mixed, and supplied onto the substrate to form p+GaAs.
is epitaxially grown.

In addition, the supply amounts of the various gases mentioned above are TMA
=3 cc/min (20℃), TMG =10
cc/m1n (0°C).

9 be.

AsH3=15 cc/min, H2Se=5cc
(H2 dilution 2ooppm# degrees), D E Z = 6
cc/min (0°C).

H2-213/m1n, and the substrate temperature is 780
"The C2 growth rate is 1 μm/br for each layer. Depending on the combination, GaAs, AlGaAs, n-type, p-type.

Growth is possible in both undoped types. Note that it is effective to provide branch valves 23, 24, and 25 for purging each inlet pipe 20, 21, and 22 after branch valve 19 for more accurate control of impurity concentration and cleaning. . It is also effective to use a diameter of 1A inch for each of the inlet tubes 20, 21, and 22 in order to improve gas mixing, increase the flow rate of the mixed gas, and suppress gas components remaining on the inner wall of the inlet tube.

In this embodiment, an epitaxial vapor phase growth apparatus at normal pressure has been described, but pressure regulating valves are installed in each of the inlet pipes 20, 21, and 2.
2, it can also be used as a reduced pressure vapor phase growth apparatus. Furthermore, even when only a single layer is grown, it is sufficient to use only one introduction tube, and it is clear that this method can be sufficiently applied in this case as well.

10B-1 Effects of the invention Using the present invention, n I-Alo, 3Gao, 7A
8 (ni> 1 x 10'8cm')/un
dope GaAs(n(1x10 cm)/p
” Alo, s Gao, 7A s (p 2
When a double Peter junction structure of 1 x 10" 8crn, 3) was formed and the steepness of the impurities was evaluated using SIMS analysis, it was found that the impurities of Zn as a p-type dopant and Se as an n-type dopant were heterogeneous. The steepness at the interface is less than 20 Å and extremely low J: results are obtained.As a matter of course, Ss impurities are mixed into the undoped GaAs and the subsequent p'A10.3Gao and 7As layers. All of them disappeared.

The present invention is not limited to impurities such as D E Z and H2S e in the A73 Ga As / Ga As system, but also other impurities such as DMZ.

It can of course be applied to any material such as SiH4, Cp2Mq, etc., but it can also be applied to any constituent element system such as InGaAsP/InP, and it can also be applied to the n1pi structure where a quantum well structure can be formed by impurity doping, making it an essential component for compound semiconductor devices. It is extremely effective for forming a good thin film multilayer heterostructure.

11・＼−

[Brief explanation of the drawing]

It is a diagram. 1...Rear rear connector (, 2...Susceptor, 3...Substrate, 6...Introduction pipe,
19...branch)(ru)゛、20.21.22・
...Introduction pipe.

Claims (5)

[Claims] (1) When a reactive gas is introduced into a reactor chamber in which a substrate is placed and a thin film is layered and grown on the substrate,
A gas introduction pipe for a reaction gas containing constituent elements for forming a thin film semiconductor is branched into at least two directions via a branch valve, a first impurity is added to the branched first introduction pipe, and a second impurity is added to the branched first introduction pipe. No impurities were added to the inlet tube of each of the above first tubes.
. A vapor phase growth apparatus, characterized in that the reaction gas is introduced into the reactor chamber via a second introduction pipe to form a thin film on the substrate. (2) The vapor phase growth apparatus according to claim 1, wherein the branch valve is a three-way branch valve, and a second impurity is added to the third introduction pipe. (3) When laminating thin films on a substrate, the first thin film is formed using a first introduction tube, and the second thin film is formed using a second introduction tube. The vapor phase growth apparatus according to item 1. (4) The vapor phase growth apparatus according to claim 1, wherein the tip portions of each gas introduction tube introduced into the reactor chamber are provided adjacent to each other. (5) The vapor phase growth apparatus according to claim 1, wherein the reaction gas contains an organometallic gas.