JPS6134982A - Manufacture of semiconductor diode - Google Patents

Abstract

PURPOSE:To obtain a high-quality semiconductor diode, by heating a substrate within a growth chamber evacuated to an ultra-high vacuum, and introducing from the outside a gas containing component elements to be grown on the substrate so that monomolecular layers of these elements are epitaxially grown one by one. CONSTITUTION:A gate valve 2 is opened so that a growth chamber is evacuated to about 10<-7>-10<-8>Pa by means of an ultra-high vacuum evacuating unit 3. A GaAs substrate 18 is then heated by a heater 16 to about 300-800 deg.C and a valve 8 is opened for 0.5-10sec to introduce TMG12 into the chamber until the pressure therein becomes about 10<-1>-10<-7>Pa. That TMG is then discharged from the growth chamber 1, and a valve 5 is opened for 2-200sec to introduce AsH3 13 into the chamber 1 until the pressure therein becomes 10<-1>-10<-7>Pa. According to this method, a crystalline monomolecular layer of GaAs can be grown. An impurity can be added in a similar manner as the growth of GaAs: in case of P type impurity, a gas containing Ga of Family III and Zn of Family II, and in case of N type impurity, a gas containing As of Family V and S of Family VIis introduced. Thus, a monomolecular layer added with P or N type impurity can be grown.

Description

[Detailed description of the invention] [:g! Technical field of Ming Dynasty] The present invention relates to a method of manufacturing a semiconductor diode.

[Prior art and its problems] Conventionally, metal organic chemical vapor deposition (hereinafter referred to as MO-CV) has been used as a vapor phase epitaxy technique for obtaining thin film crystals of semiconductors.
D method), molecular beam epitaxy method (hereinafter referred to as MFIE)
(hereinafter referred to as ALE method), atomic layer epitaxy (hereinafter referred to as ALE method), and the like are known. However, in the MO-CVD method, group (I) and V-group elements are introduced as a source and hydrogen gas or the like is used as a carrier at the same time into a reaction chamber and grown by thermal decomposition, resulting in poor quality of the grown layer. Further, there are drawbacks such as difficulty in controlling the monolayer order.

On the other hand, the 1E method, which is well known as a crystal growth method using an ultra-high vacuum, uses physical adsorption as the first step, so the quality of the crystal is inferior to the vapor phase growth method using a chemical reaction. GaAs
When growing a compound semiconductor with an m-v radiation period such as
Group ① and Group V elements are used as sources, and the sources themselves are installed in the growth chamber. For this reason, it is difficult to control the amount of released gas and evaporation obtained by heating the source, and to replenish the source, making it difficult to keep the growth rate constant for a long time. In addition, the vacuum equipment becomes complicated due to evacuation of evaporates, etc. 6 Furthermore, it is difficult to precisely control the stoichiometric composition (stoichiometry) of compound semiconductors, and as a result,
There is a drawback that high quality crystals cannot be obtained.

Furthermore, the ALE method has been proposed by T,5untola et al. for υ,S,P,
As explained in NQ4058430 (1977), a semiconductor element is supplied in a pulsed manner and attached to a substrate, thereby growing a crystal one atomic layer at a time.
It is not possible to grow single crystals of semiconductors. That is, in order to form a single crystal thin film, M, P of the same group
The method used by e5sa et al. is not the ALE method, but the 1984
Proceedings of the Vacuum Society of America (J, Vac, Sci, Tec
The method is based on the above-mentioned MBE method, as disclosed in J. H. H. H. H. H. H. H. H. H. H. H. H. H. H. H. H. H. H. H. H. H. H. H. H. H. H. H. H. H. H. H. H. H. H. H. H. H. H. H. H. H. H. H. H. Hnol, A2 (1984) 418).

As described above, while it is difficult to form high-quality crystals that satisfy the stoichiometric composition on the order of a monomolecular layer using the MO-CVD method and the MBIE method, the ALE method has the disadvantage that a single crystal cannot be obtained. Ta.

[Objective of the Invention] The present invention eliminates the drawbacks of the prior art described above, improves the quality of the crystal growth layer by controlling the stoichiometric composition, and forms the growth film with the precision of a monomolecular layer. It is an object of the present invention to provide a method for manufacturing quality semiconductor diodes.

[Summary of the Invention] Therefore, the present invention involves heating a substrate in a growth tank evacuated to an ultra-high vacuum, irradiating it with light, and introducing a gas containing a component element to be grown onto the substrate from the outside. This method is characterized by controlling the growth film thickness with precision in molecular layer units, growing a single crystal that satisfies the stoichiometric composition, and making it possible to obtain high-quality semiconductor diodes.

[Embodiments of the Invention] Hereinafter, embodiments of the present invention will be described by taking as an example a case where GaAs is used as a semiconductor.

FIG. 1 shows a configuration diagram of a semiconductor diode manufacturing apparatus according to an embodiment of the present invention, where ■ is a growth tank made of metal such as stainless steel, 2 is a goo 1-valve, and 3 is a growth tank 1. An exhaust device for evacuation to ultra-high vacuum, 4 a nozzle for introducing a gas containing Ga such as GaCQ3 or TMG (trimethyl gallium), 5 a nozzle for introducing ASHs, 6
1 is a nozzle for introducing a gas containing Zn such as TMZ (1-limethylzinc), 7 is a nozzle for introducing a gas containing S such as H2S, and 8, 9, and 10.11 are valves that open and close the nozzles, and are gas sources. 12 (TMG, GaC113, etc.), 13
(AsH3), Ill (DMZ), 15 (H2S, etc.), and 16 is a heater for heating the substrate, and is a W (tungsten) wire sealed in quartz glass, and the wiring is omitted in the illustration. 17 is a thermocouple for temperature measurement, ]8
is a GaAs substrate, 19 is a pressure gauge for measuring the pressure inside the growth tank, 20 is a light source for irradiating the substrate, and 2j is a window for the light source 20. Here, as the light source 20, a mercury lamp, a laser, etc. can be used.

With the above configuration, in order to grow a GaAs crystal on the substrate 18, first the gate valve 2 is opened and the ultra-high vacuum pump 3 is opened.
The growth tank was adjusted to 10-7 to 10” pascal (
Hereinafter, it is abbreviated as Pa). Next, after heating the GaAs substrate 18 to, for example, about 300 to 800° C. with the heater 1G, the TNG] 2 is heated to about 300° C. to 800° C.
-1 to 1O-7Pa by opening the valve 8 for 0.5 to 10 seconds. Next, after the TMG is evacuated from the growth tank, Asll 313 is introduced by opening the valve 5 for 2 to 200 seconds so that the pressure within the growth tank 491 is 10-'' to 10-'' Pa. As a result, GaAs
A single molecular layer of crystals can be grown.

On the other hand, impurity addition is done in the same way as for the growth of GaAs; in the case of n-type, a gas containing Ga of group II and Zn of group II is introduced, and in the case of n-type, a gas containing As of group II and As of group II is introduced. 6 can be achieved by introducing a gas containing S, and one molecular layer doped with p- and n-type impurities can be grown.

At this time, by irradiating ultraviolet rays from the light source 20 at the same time as heating the substrate 18, the growth temperature can be lowered to 400°C or less, and autodoping or interdiffusion of impurities can be suppressed. Become.

In this molecular layer epitaxial growth or photomolecular layer epitaxial growth, gases containing group ■-V component elements are introduced alternately, and growth proceeds through chemical reactions, making it possible to perfect the stoichiometric composition. High-quality crystals can be grown one molecular layer at a time.

FIG. 2 shows the manufacturing process when manufacturing a diode by the epitaxial growth method described above using the apparatus shown in FIG. 1, and 31 shown in FIG.
-3Ω·[) GaAs substrate. On this substrate 31, as shown in FIG.
Grow a μm n-layer. Furthermore, as shown in the figure (c), an electrode 33 of Au7Ge or Au-Ge-Ni layer which becomes an ohmic contact with the n0 substrate 31 and an electrode 33 of the Au7Ge or Au-Ge-Ni layer as shown in the figure (d), are connected to the zero layer 32. An electrode 34 is provided to form a diode.

In this case, a Gunn diode can be formed if an alloy such as Au- or Ge is used as the electrode w134 to form an ohmic contact with the 0 layer 32. On the other hand, Au, P
t.

When a well-known Schottky barrier forming metal such as W, Cr, Tj, N], Hf, 11 is used, a good Schottky barrier diode can be formed.

FIG. 3 shows the manufacturing process of another diode. As in the case of FIG. 2, an O layer 35 is epitaxially grown on a GaAs substrate 31 using the apparatus shown in FIG. 1, and electrodes 33 are formed on the upper and lower surfaces. 34 to manufacture the diode. At this time, by epitaxially growing the 0 layer 35 so that the impurity density distribution increases from the substrate 31 side to the surface, a variable capacitance diode, so-called varactor diode, can be manufactured. In this case, by appropriately adjusting the impurity density distribution, structures such as stepped junctions, inclined junctions, and super-stepped junctions can be easily realized. Further, since the growth temperature can be set to 350° C. by irradiating the substrate with light, an ideal impurity density distribution can be obtained without interdiffusion of impurities, autodoping, etc.

It goes without saying that in one or more embodiments, the epitaxial layer grown on the substrate may be p-type.

FIG. 4 is another embodiment of the present invention, showing the manufacturing process of a pn junction diode. As in the case of FIG. 2, the 0 layer 3 is formed on the GaAs substrate 31 using the apparatus of FIG.
After forming 2 (FIGS. 4(a) and 4(b)), a P'' (p=3 to 6×10 −3 Ω·cm) GaAs layer 36 is formed thereon (FIG. 4(C)). After that, the n+ layer 31
Make ohmic contact with Au-Ge or Au-Ge-Ni.

An electrode 33 is formed (FIG. 4(d)). On the other hand, p middle layer 3
6, an electrode 36 is formed by making ohmic contact with Au--Zn, Ag--Zn, In--Zn, etc. (FIG. 4(e)). Thereby, a pn junction diode can be manufactured.

FIG. 5 shows yet another embodiment of the present invention, in which p + n +
-n--The manufacturing process of a tunnel injection type transit time negative resistance diode (tannet diode) having a -n+ groove structure is shown. As in the case of FIG. 2, using the apparatus of FIG. 1, an n-layer Cp=1-2 is formed on the GaAs substrate 31.
xlO-3Ω-cm) GaAs layer 40 is 0.1-0.
After forming a layer of 2 μm (FIGS. 5(a) and (b)), a layer of n (impurity density 1014-5×
A GaAs layer 42 (about 1.0"cm"-') is formed (FIG. 5(C)). The thickness Wd of the traveling region is given by Wd = □, where f is the oscillation frequency and Vs is the carrier saturation speed.

When f Vs = ], It becomes 750A.

Next is tunnel injection n” (5X), 017 to 102
'rB-'') GaAs layer 42) p''(5x101''-
102'cm') GaAs layers 43 are sequentially formed (FIGS. 5(d) and 5(e)).

Here, the thickness and impurity density of the n-middle layer 42 are, for example, 5 cm, 300 to 500 λ, or 1. X10"cm', 100 to 300 people is sufficient. The impurity density of the p+ layer is], X], 019cm-
Second, it is desirable for the thickness to be 0.5 μn1 or less for heat dissipation. After that, AH-Z to P"WI43
n, Au-Zn, 'In-Zn, etc. are made into ohmic contact, and an Au plating layer is formed thereon to form an electrical receiver 44 (Fig. 5(f)). The substrate is made thin so that the total thickness is about 10 μm or less (Fig. 5 (g). Next, Au-G is applied to the 04' layer 31.
e or Au-Ge-Ni with ohmic contact 1~
Then, an Au plating layer is formed thereon to form an electrode 45 (FIG. 5(h)).

This allows a tannet diode to be formed. In addition, in-vat diodes using avalanche injection can also be manufactured in a similar manner.

As described above, a good epitaxial layer can be formed at approximately 400° C. or lower by the molecular layer or photomolecular layer epitaxial growth method, so that a tannet diode with a very sharp impurity density distribution can be formed.

In one or more embodiments, GaA is used as the semiconductor material.
Although an example using s has been described, the present invention is not limited to this, and elemental semiconductors such as Sl and Ge, and InP.

It goes without saying that a compound semiconductor such as GaP, a III-V compound semiconductor, or even a II-Vl compound semiconductor can be used. In addition, the board is not limited to n-child board,
P-thousand conductors, semi-insulating ones, or.

Needless to say, it may be an intrinsic semiconductor.

[Effects of the Invention] As described below, according to the present invention, a crystalline film of a semiconductor can be separated.
It is possible to grow crystallinity with high accuracy on a layer-by-layer basis, and it is also possible to control the addition of impurities and substances on a layer-by-layer basis.
Since it is possible to obtain an impurity density distribution as steep as 71, high quality semiconductor diodes can be manufactured.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram of a semiconductor diode manufacturing apparatus according to an embodiment of the present invention, FIGS. 2 to 5 are explanatory diagrams of the manufacturing process of a diode manufactured by the apparatus of FIG. 1, and FIG. (a
) to (d) are explanatory diagrams of the manufacturing process of Gunn diodes or Schottky barrier diodes, and Fig. 3 (a) to (d)
Figure 4 (a) is an explanatory diagram of the manufacturing process of a varactor diode.
- (e) are explanatory diagrams of the manufacturing process of a pn junction diode, and Figs. 5 (a) to (11) are explanatory diagrams of the manufacturing process of a tannet diode having a p + n + -n-100 structure. 1... Metal, 2... Goo 1-valve, 3... Exhaust capacity, 4, 5, 6.7... Nozzle, 8, 9, 10.1
1...Valve. 1.2, 13, 14.15... gas source, 16...
Heater, 17...Thermocouple, 18...GaAs
Board, 19...pressure gauge. 20...Light source, 21...Window. Agent Patent Attorney Crest 1) Makoto, Figure 7 Figure 2 Figure 3 (a)
(a)(b)
(b) (C)
(C) (d)
(d) Figure 4 (a) (b) (c) (d) 3) in Figure 5
(f)lni

Claims (8)

[Claims] (1) In a method of growing a semiconductor crystal on a substrate by introducing a gas containing a crystal component element from the outside into a growth tank that is evacuated to a vacuum, the growth tank is evacuated to an ultra-high vacuum, and the A semiconductor diode characterized in that a semiconductor diode is manufactured by heating a semiconductor diode, introducing a predetermined amount of gas containing a component element desired for crystal growth, and epitaxially growing one molecular layer at a time to form a crystal layer with a predetermined thickness. manufacturing method. (2) In claim 1, the inside of the growth tank is evacuated to a pressure of 10^-^7 Pascal or less, and the substrate is heated to 300 to 800°C, and the components of the semiconductor whose crystals are to be grown are heated. The gas containing the element is heated to 0 within the pressure range of 10^-^1 to 10^-^7 Pascals in the growth tank.
．． A method for manufacturing a semiconductor diode, comprising growing a molecular layer using a method of introducing the substrate onto the substrate for 5 to 200 seconds. (3) A method for manufacturing a semiconductor diode according to claim 1, in which the substrate is epitaxially grown while being irradiated with light. (4) A method for manufacturing a semiconductor diode according to claim 1, wherein a part of the epitaxial growth layer has the same conductivity type as the substrate. (5) A method for manufacturing a semiconductor diode according to claim 1, wherein a part of the epitaxial growth layer has a conductivity type opposite to that of the substrate. (6) A method for manufacturing a semiconductor diode according to claim 1, wherein the substrate is a semi-insulating or intrinsic semiconductor. (7) A method for manufacturing a semiconductor diode according to claim 1, wherein at least a portion of the epitaxial growth layer has a uniform impurity density distribution. (8) A method for manufacturing a semiconductor diode according to claim 1, wherein at least a portion of the epitaxially grown layer has an uneven impurity density distribution.