JPH06101436B2 - Semiconductor device manufacturing method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention relates to the manufacture of semiconductor devices such as light emitting elements, light receiving elements, and memory devices, which are used in extremely many fields such as optical communication systems and optical information processing systems. Concerning the law. More specifically, it relates to a method for manufacturing a semiconductor device using a III-V group compound semiconductor.

[Outline of Invention]

Formed by metalorganic vapor phase pyrolysis (MOCVD) III
In a method of manufacturing a semiconductor device including a group-V compound semiconductor thin film, a general formula RR'X (X is S, Se, Te is used as a donor raw material when forming an n-type group III-V compound semiconductor layer.
It is characterized by using an organic compound represented by a group VI element such as R, R'is an alkyl group), and improves the control of doughing during formation of an n-type thin film of a III-V compound semiconductor.

[Conventional technology]

Conventionally, n-type III-V compound semiconductor thin films such as gallium arsenide (GaAs) and aluminum
Gallium Arsenide (AlGaAs), Indium Phosphorus (In
p), gallium, indium, phosphorus, arsenic (GaInPAs),
Aluminum gallium indium phosphide (AlGaIN
As an n-type dopant for forming P), etc., VI
Hydrogen sulfide (H ₂ S) and hydrogen selenide (H ₂ Se), which are hydrides of group elements, are used. These hydrides are supplied from a cylinder as a dilute gas diluted with a carrier gas. Fig. 4 shows the conventional atmospheric pressure type MO
The schematic diagram of a CVD apparatus is shown.

Inside the reaction tube 22 made of transparent quartz, a graphite susceptor 23 coated with SiC is set and a substrate 24 for growth is placed thereon. A thermocouple 25 for temperature monitoring is inserted inside the susceptor 23. Substrate 24 is reaction tube 22
It is heated by a heating furnace 26 located around the object by resistance heating, infrared heating, high frequency induction heating, or the like. The reaction tube 22 is connected to an exhaust system 29 and a gas treatment device 30 via valves 27 and 28, respectively. An organometallic compound that serves as a source of a group III element, such as trimethylaluminum (TMA
l) and triethylgallium (TEGa) are enclosed in a bubbler 31 and kept at a predetermined temperature by a thermostat 32. Hydrogen, which is a carrier gas, is filled in a cylinder 33, is purified by a gas purifier 34, and is then flow controlled by a mass flow controller 35. The organometallic compound is vaporized by the bubbling of the carrier gas introduced into the bubbler and supplied as vapor. That is, the supply amount can be controlled by the set temperature of the bubbler and the flow rate of the bubbling gas. The cylinder 36 contains a gas serving as a source of the group V element, such as arsine (AsH ₃ ) and phosphine (PH ₃ ), and the supply amount is controlled by the mass flow controller 35. Becomes n-type dopant for cylinder 37
H ₂ Se is diluted with hydrogen to a concentration of about 10 to 100 ppm and filled, and the supply amount is controlled by the mass flow controller 35. The respective raw material gases are diluted with the carrier gas and then merged, and the reaction tube is passed through the three-way valve 38.
Guided to 22. The three-way valve 38 switches the introduction of the source gas into the reaction 22 and the disposal to the gas treatment device 30. The source gas reaching the heating region including the heated substrate undergoes thermal decomposition and reaction, and an epitaxial film corresponding to the source is formed on the substrate. At this time, the characteristics of the n-type III-V compound semiconductor thin film to be formed, that is, the carrier concentration, the specific resistance, the peak wavelength of the photoluminescence spectrum, and the half width of the peak are changed by changing the supply amount of H ₂ Se. Change. Needless to say, precise control of the characteristics of the thin film is extremely important when manufacturing a semiconductor device.

[Problems and Objectives to be Solved by the Invention]

FIG. 5 shows a correlation diagram of the dopant supply amount and the carrier concentration obtained by the conventional technique. As an example,
S- or Se-doped n- grown at a substrate concentration of 700 ° C
Type GaAs is shown. Hydrogen sulfide 40 and hydrogen selenide 41 were used as dopants.

The vertical bars in the figure show the degree of variation in carrier concentration obtained under the same doping conditions, and the ∘ mark shows their average value.

As is clear from the figure, even if the amount of the supplied dopant is the same, the carrier concentration of the obtained thin film has a variation of 100 to 300%.

FIG. 6 shows the case where n-type GaAs was grown under the same growth conditions using the dopant gas filled in the same cylinder.
The dependence of the carrier concentration on the growth frequency is shown. H ₂ Se was used as a dopant. The circles and triangles indicate the cases where cylinders of different lots with the same H ₂ Se filling concentration were used.
Even for n-type GaAs that should have been produced under the same growth conditions,
It can be seen that the carrier concentration varies depending on the number of times of growth and the cylinder used. The variations in the carrier concentration cause variations in the specific resistance of the thin film, and in the manufactured semiconductor device, variations in the current-voltage characteristics, and in particular, in the light emitting element, the heat generation characteristics. The heat generation characteristic is closely related to the deterioration of the semiconductor device and is an extremely important item from the viewpoint of reliability.

The reason for the poor reproducibility of the carrier concentration of the thin film formed when H ₂ S or H ₂ Se is used as the n-type dopant is as follows.

1 H ₂ S and H ₂ Se react with a Group III organometallic compound as follows to form a non-volatile substance.

For example, in the case of triethylaluminum, a reaction such as 2Et ₃ Al + H ₂ S → Et ₂ AlSAlEt ₂ + 2EtH 2Et ₃ Al + H ₂ Se → Et ₂ AlSeAlEt ₂ + 2EtH proceeds.

In the gas phase, trimethylaluminum is
Reacts with ₂ S and H ₂ Se to produce aluminum sulfide, aluminum selenide, or their methyl-induced properties.

The reaction as described above also proceeds with other Group III organometallic compounds.

(See, for example, T. Mole and EAJaffery “Organo aluminuim Compounds” Elsevier Publishing Company, (1972) p.252 Material of the Institute of Electrical Engineers, EFM-82-12.) 2 H ₂ S and H ₂ Se are extremely corrosive. , Since it reacts with the inner wall of the cylinder and the piping material to form sulfides and selenides, the gas concentration in the cylinder changes over time and the amount controlled by the mass flow controller cannot be accurately supplied to the reaction tube. Will end up.

3 H ₂ S and H ₂ Se are gaseous bodies at normal pressure and liquefy when pressurized. In any of these states, it is toxic and highly reactive, so purification as a gas is difficult and there are many residual impurities. Incorporation of residual impurities contained in the dopant gas into the thin film reduces the controllability of doping.

Therefore, the present invention solves such a problem, and an object thereof is to show a dopant and a doping method for improving the purification of n-type doping in a III-V compound semiconductor thin film, and to provide a semiconductor device. The purpose of the present invention is to provide a method for manufacturing with good reproducibility.

[Means for solving problems]

The manufacturing method of the semiconductor device of the present invention is performed by the general formula RR′X (wherein
(X represents a Group VI element, R and R'represent an alkyl group)
Is characterized by forming a III-V group compound semiconductor thin film by an organometallic vapor-phase thermal decomposition method using the organic compound of n-type donor raw material.

[Action]

The organic compound represented by the general formula RR'X (X is a group VI element such as S, Se, Te, etc., and RR 'is an alkyl group) has the following characteristics.

1 It is a stable liquid with low reactivity at room temperature and can be purified by distillation.

2 Like the organometallic compounds of Group III, the supply amount can be controlled by bubbling the carrier gas.

3. It easily decomposes at a general growth temperature of 500 to 800 ° C by MOCVD of III-V compound semiconductor thin film.

4 Due to its low reactivity, RR 'supplied by reaction with vessel or piping material or reaction with Group III organometallic compound
No part of X is lost.

Since the organic compound RR'X of the group VI element has the above characteristics, it can be used as a dopant having higher controllability than H ₂ S or H ₂ Se.

〔Example〕

FIG. 1 shows a schematic view of an atmospheric pressure MOCVD apparatus used in the present invention. The basic structure is the same as the conventional atmospheric pressure type MOCVD device shown in FIG. 4, but a bubbler bubbler 11 for a dopant and a thermostatic chamber 12 for controlling the temperature thereof are provided in place of the cylinder 37 for the dopant gas. There is.

Figure 2 shows S, Se, and T for GaAs at a growth temperature of 700 ℃.
The doping characteristics of e are shown. Trimethylgallium (TMGa), arsine (AsH ₃ ) are used as raw materials, and dopants are
Diethyl sulfur (DES), diethyl selenium (DESe) and diethyl tellurium (DETe) were used. When any of the dopants was used, the carrier concentration increased with the dopant concentration, showing good linearity. Doping efficiency differs depending on the dopant because pyrolysis is DES <DESe.
This is because it tends to occur in the order of <DETe. When the carrier concentration obtained at the same dopant concentration is compared between the prior art and the present invention, the result of the present invention is a film having a lower carrier concentration.

This is because Group VI organic compounds are less prone to thermal decomposition than Group VI hydrides.

As is apparent from FIG. 2, n formed according to the present invention.
The variation in carrier concentration of the −-type GaAs film is 10 to 30% under the same growth condition, which is the variation in the conventional technology.
It is reduced to about 1/10.

FIG. 3 shows the growth frequency dependence of the carrier concentration of n-type GaAs grown under the same conditions using the dopants filled in the same bubbler, for two lots indicated by ◯ and Δ. Diethyl selenium was used as a dopant. It can be seen that the variation in carrier concentration due to the number of times of growth and the variation between different lots are highly suppressed as compared with the conventional technique.

In addition to DES, DESe, and DETe, which are diethyl derivatives of Group VI elements, and when dimethyl sulfur, dimethylselenium, and dimethyl tellurium, which are dimethyl derivatives, are used, the plots of the dopant supply amount and carrier concentration show the decomposition characteristics of the dopant. However, the linearity was as good as that of the diethyl derivative. Similar doping characteristics were obtained when a dialkyl derivative other than the dimethyl derivative and the diethyl derivative was used. In addition, the general formula RR'X
(R and R'are alkyl groups, X is a group VI element)
Derivatives of Group VI elements, such as methyl ethyl sulfur, methyl ethylene selenium, and methyl ethyl tellurium, can also be used as n-type dopants and are included in the present invention.

In the examples, the doping characteristics of S, Se, and Te into GaAs were shown, but AlGaAs, InP, InAsP, GaInAs are exactly the same.
It is possible to dope S, Se and Te into all III-V group compound semiconductor thin films such as P and AlGaInP, and the same level of effect as doping into GaAs was obtained.

Since the specific resistance of the thin film is inversely proportional to the carrier concentration, the variation in the carrier concentration is reduced, so that the variation in the specific resistance can be reduced. Therefore, it is obvious that variations in element characteristics such as current-voltage characteristics and heat generation characteristics of a semiconductor device manufactured using the n-type III-V compound semiconductor thin film formed according to the present invention can be reduced.

〔The invention's effect〕

As described above, according to the present invention, in a method for manufacturing a semiconductor device including a III-V group compound semiconductor thin film formed by metalorganic vapor phase thermal decomposition method (MOCVD method), n-type is exhibited.
A general formula RR'X (X is a group VI element such as S, Se, or Te as a donor raw material when forming a III-V group compound semiconductor thin film,
By using an organic compound represented by R and R'which is an alkyl group), the doping controllability at the time of forming an n-type thin film of a VI-V compound semiconductor can be improved. The present invention provides III-V
We believe that the contribution to the manufacture of semiconductor devices using n-type thin films of group compound semiconductors is extremely large.

[Brief description of drawings]

FIG. 1 is a schematic diagram of the structure of an atmospheric pressure MOCVD apparatus used in the present invention. 1 reaction tube, 2 susceptor made of graphite coated with SiC, 3 substrates, 4 thermocouples, 5 resistance heating furnace, infrared heating, high-frequency heating, etc. 6, 7 valve, 8 exhaust system, 9 gas processing system, 10 bubbler containing organometallic compound, 11 bubbler containing n-type dopant, 12 constant temperature bath, 1
3 cylinders containing carrier gas, 14 gas purifier, 15
Mass flow controller, cylinder containing raw material of 16V group element, 17 valve, 18 three-way valve FIG. 2 is a correlation diagram of the dopant supply amount and the carrier concentration obtained in the present invention. 19 diethyl sulfur, 20 diethyl selenium, 21 diethyl tellurium FIG. 3 is a graph of the growth frequency dependence of the carrier concentration obtained in the present invention. FIG. 4 is a schematic diagram of a conventional atmospheric pressure type MOCVD apparatus. 22 reaction tube, 23 SiC coated graphite susceptor, 24 substrate, 25 thermocouple, 26 resistance heating, infrared heating, heating furnace by high frequency heating, 27, 28 valve, 29 exhaust system, 30 gas treatment system, 31 organic Bubbler containing metal compound, 32 thermostat, 33 cylinder containing carrier gas, 34 gas purifier, 35 mass flow controller, cylinder containing raw material of 36V group element, cylinder containing 37n-type dopant, 38 three-way valve , 39 valve FIG. 5 is a correlation diagram between the dopant supply and the carrier concentration in the prior art. 40 hydrogen sulfide, 41 hydrogen selenide FIG. 6 is a graph showing the dependence of carrier concentration on the number of times of growth, which was obtained in the prior art.

Claims (1)

[Claims] 1. An organic compound of the general formula RR'X, wherein X represents a Group VI element and R and R'represent an alkyl group,
By using the metal-organic vapor-phase thermal decomposition method as a −-type donor material III
A method for manufacturing a semiconductor device, which comprises forming a group V compound semiconductor thin film.