JPS5882570A - Semiconductor device - Google Patents

Abstract

PURPOSE:To obtain the device provided with an interface having scanty density of the surface state and is stable thermally by a method wherein a second III-V group compound semiconductor layer to act as the insulating layer at a low temperature is accumulated on a first III-V group compound semiconductor layer. CONSTITUTION:A gate electrode 8 is provided on a substrate 3 consisting of the N type InP or GaAs layer 2 accumulated on a semiinsulating InP layer 1 interposing the III-V group compound semiconductor layer 7 added with Fe, Cr, O, etc., to form a deep level, and ohmic source and drain electrodes 5, 6 are adhered on the main surface 4 of the substrate 3. A crystal of the same component element or a GaAlAsP crystal having the lattice constant nearly the same with the layer 2 is used for the layer 7. Although the layer 7 is semiinsulating at the normal temperature, but indicates the high insulating property at the liquid nitrogen temperature, and is able to be used as the gate insulating film. The layer 7 is formed by epitaxial growth enabling to obtain easily the necessary film thickness, and when it is used in a low temperature range to act as the insulating film, it is extremely stable thermally, and moreover the interface having scanty density of the surface state can be obtained between the substrate 3 and the layer 7, and acts entirely in the same manner with the usual MISFET.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a semiconductor device that functions at low temperatures and has a structure in which an insulating layer is formed on the main surface of a semiconductor substrate at low temperatures.

There is a MISIJ field effect transistor using an m-■ group compound semiconductor substrate as an M type semiconductor device;
An 8-type field effect transistor comprising an insulating layer formed by a chemical conversion method, a thermal fermentation method, or a thermal nitridation method has been proposed. However, in the case of an insulating film formed by such a method, although it is well formed to form an interface with few surface states with the ■-■ group compound semiconductor substrate, it has poor thermal stability. However, it has the disadvantage that it cannot be formed with a relatively large thickness.

Conventionally, it has been proposed that the insulating layer serving as the gate insulating film of the MlS type field effect transistor is formed by vacuum evaporation or sputtering. However, in the case of an insulating film formed by such a method, although it is thermally stable, it is made of a material different from that of the m-v group compound IY4 semiconductor substrate. It has the disadvantage that it is formed to form an interface with a low surface state density between the substrate and the substrate, and is separated from the substrate.

Therefore, the present invention aims to propose a new type of semiconductor device free from the above-mentioned drawbacks, which will become clear from the detailed description below.

Figure wJ1 shows a first embodiment of a semiconductor device according to the present invention, which has a semiconductor substrate 6 made of a ■-■ group compound semiconductor having a structure in which an N-type semiconductor 712 is formed on a semi-insulating semiconductor substrate body 1. A source electrode 5 and a drain electrode 6 are ohmically attached to the main i14 of the semiconductor substrate 3, and between the source electrode 5 and the drain electrode 6 on the soil surface 4,
F. forms a deep unit that exhibits insulating properties at low temperatures.
A gate electrode 8 is arranged through a layer 7 made of an m-■ group compound semiconductor doped with impurities such as Cr10,
It has an MIa type field effect transistor configuration. In this case, the semiconductor layer 2 is made of single-crystal InP or single-crystal GaAg, and when the semiconductor layer 2 is made of InP, the layer 7 is made of single-crystal InP or a material having a substantially stronger lattice constant, such as InA.
gAs P-based 1ll-v group compound semiconductor, and when the semiconductor layer 2 is made of GaAs, single crystal GaAs
Or the lattice constant is approximately equal to that, for example, G1A/AsP
It is made of an m-■ group compound semiconductor.

The above is the first embodiment of the semiconductor device according to the present invention. According to such a structure, the layer 7 is kept at a low temperature (liquid nitrogen temperature).
It works at low temperatures by exhibiting high insulating properties, but in this case the layer 7 is a Kawa-II group compound semiconductor made of impurities that form a deep level, so as mentioned at the beginning It has no drawbacks.

Next, embodiment #I2 of the semiconductor device according to the present invention will be described with reference to FIG. 2 and FIG. It has an MI8 diode structure in which electrodes 25 and 24 are ohmically attached on the semiconductor layer 22 and on the side of the substrate 21 opposite to the semiconductor layer 22@, and FIG. 5 shows a semi-insulating semiconductor substrate 31 made of InAs. Source regions 52 and 33 of N+ type are formed within the substrate 31, and electrodes 38 and S9 doped with impurities forming a deep level are attached on the substrate 31.

In the case of a semiconductor substrate, the substrate 21 in FIG. 2 is made of IoAa, and the layer 22 is made of Ajab or a lattice constant of Ajab or a compound semiconductor having a lattice constant substantially equal to that of Ajab.

[Brief explanation of the drawing]

FIGS. 1, 2, and 3 are diagrams showing embodiments of a semiconductor device according to the present invention. Figure 1 Figure 2 Figure 3 Riichi! --131 Procedural Amendment Written Patent dated November 24, 1986, Showa Year Application No. Saimei Name Semiconductor Device 3, Relationship with the case of the person making the amendment Patent Applicant Attorney 5, Supplement 1 6, Supplement 1 7, Supplementary Description (corrected full text) 1. Title of the invention: Semiconductor device 2. Claim 1: Insulating property is provided at low temperature on the main surface of the semiconductor substrate made of the first ■-■ group compound conductor. 1. A semiconductor device characterized in that a layer made of a second ■-■ group compound semiconductor doped with an impurity forming a deep level is formed as an insulating layer at a low temperature. 2. In the semiconductor device according to claim 1, the first ■-■ group compound semiconductor is InP, and the second Nagi-V group compound semiconductor is InP or has a lattice constant similar to that of InP. A semiconductor device characterized by being made of a substantially high-density V group compound semiconductor. (5) In the semiconductor device as set forth in claim 1, the first group 11-2 compound semiconductor is made of GaAs,
The above-mentioned second arashi-1 semiconductor device is characterized in that the group compound semiconductor is made of GaAs or a group compound conductor having a lattice constant substantially equal to GaAs. 4.4 In the semiconductor device described in Section 1 of Claims,
The first I-I group compound semiconductor is Iaim, and the second I-I group compound semiconductor is A/8b or an I-V group compound semiconductor having a lattice constant substantially equal to A/8b. semiconductor devices. 5.41 In the semiconductor device described in claim 1,
The first group-III compound semiconductor is lm8b,
A semiconductor device characterized in that the second group compound semiconductor is made of AJPsb or a group compound semiconductor having a lattice constant substantially equal to that of AJPsb. 3. Detailed Description of the Invention The present invention relates to a semiconductor device that functions at low temperatures and has a structure in which an insulating layer is formed on the main surface of a semiconductor substrate at low temperatures. As such a semiconductor device, there is an MI8Il field effect transistor using an I-II group compound semiconductor substrate;
Conventionally, in a field effect transistor, the insulating layer acting as the gate insulating layer is an insulating layer formed by anodizing, thermal oxidizing, or thermal nitriding on an m-v group compound semiconductor substrate. something is proposed. However, in the case of an insulating layer formed by such a method,
Since the insulating layer is made of the oxide or nitride of the material constituting the Oboro-V group compound semiconductor substrate, it can be formed well to form an interface with few surface states with the NL-V group compound semiconductor substrate. However, it had the disadvantage of questionable thermal stability. Another drawback is that the insulating layer cannot be formed to have a relatively large thickness compared to Ffr. Furthermore, conventionally, in the M18 type field effect transistor, the insulating layer acting as the gate insulating layer is formed by a vacuum evaporation method or a sputtering method using a chemical compound other than the material constituting the 1tv group compound semiconductor substrate. , for example 8i0
．． , U, O, etc., have also been proposed. However, in the case of an insulating layer formed by such a method,
Although it is formed to have good thermal stability, its insulating layer is made of an oxide of a material different from the material constituting the m-■ group compound semiconductor substrate, so it is not compatible with the 1-■ group compound semiconductor substrate. It has the disadvantage that it is not formed to form an interface with a low surface state density between the two. Therefore, the present invention has been described above. This will become clear from the detailed description below. FIG. 1 shows a first embodiment of a semiconductor device according to the present invention, in which a semiconductor substrate 3 made of a ■-■ group compound semiconductor has a structure in which an N-type semiconductor layer 2 is formed on a semi-insulating semiconductor substrate body 1. A source electrode 5 and a drain electrode 6 are attached to the main surface 4 of the semiconductor substrate 3, and the main surface 4
A deep unit that exhibits insulating properties at low temperatures is formed between the source electrode 5 and the drain electrode 6 above. F., Or
A gate electrode 8 is disposed through a layer 7 made of an m-■ group compound semiconductor doped with impurities such as , 0, etc.
81 has a field effect transistor configuration. In this case, the semi-insulating semiconductor substrate body 1 has a resistance of 107 to 10Ω.
- The semiconductor layer 2 is made of single crystal InP or single crystal GaAs having a carrier concentration of 10 to 101 m2. Further, the layer 7 made of a Group 11 compound semiconductor to which impurities are added to form deep units is a semiconductor. When the body layer 2 is made of single-crystal InP, the single-crystal 1nP doped with impurities forming a deep unit or the single-crystal 1nP having substantially the same lattice constant as that, for example, In)hlAsP-based single-crystal -■
The semiconductor layer 2 is made of a group compound semiconductor, and the semiconductor layer 2 is made of a single crystal ()&A
In the case of 1, it is made of impurity-doped single crystal GaAs forming a deep unit, or a GaMhP-based single crystal 1-V group compound semiconductor having approximately the same lattice constant as that of single crystal GaAs. The above is the first embodiment of the semiconductor device according to the present invention. According to such a structure, even if the layer 7 is made of a ■-■ group compound semiconductor, the layer 7 is made of a ■-■ group compound semiconductor. Because they are doped with impurities that form deep levels, they exhibit high resistivity and semi-insulating properties at room temperature, but at low temperatures (liquid nitrogen temperature) By reducing the concentration of active electrons in the semiconductor, it exhibits a much higher resistivity than at room temperature, and therefore exhibits high insulation properties. Therefore, according to the structure of the first embodiment of the semiconductor device according to the present invention described above in FIG. It is something to do. (The first part of the semiconductor device according to the present invention shown in FIG. 1)
According to the embodiment, the layer 7 acts as an insulating layer at low temperatures, but the layer 7 is exposed to the same winter temperature as the semiconductor layer 2 of the semiconductor substrate 3 doped with impurities forming deep units. is a group V compound semiconductor with approximately equal lattice constants (if the semiconductor layer 2 is made of single crystal InP, the semiconductor layer 2 is made of single crystal 1nP or a single crystal compound semiconductor with a lattice constant equal to that of single crystal 1nP, and the semiconductor layer 2 is made of single crystal GμS). In some cases, the layer 7 is made of single-crystal GaAs or a single-crystal group-III compound semiconductor with the same lattice constant as that of single-crystal GaAs, so the layer 7 forms an interface with few surface states with the semiconductor layer 2 of the semiconductor substrate 3. It is well formed. Layer 7 is also thermally stable in the low temperature range where it acts as an insulating layer. Furthermore, the layer 7 can be easily formed to a desired thickness by, for example, epitaxial growth. Therefore, the first embodiment of the semiconductor device according to the present invention, which is described above with reference to FIG. It is something. Next, a second embodiment of the semiconductor device according to the present invention will be described with reference to FIG. An electrode is formed on the main surface of the conductive substrate 21 via a layer 22 made of a 4-V compound semiconductor doped with impurities such as Fe and 0R10 that exhibit insulating properties at low temperatures and form deep levels. 2s
MI8! is arranged, and an electrode 24 is attached on the main surface of the semi-insulating semiconductor substrate 21 on the opposite side to the layer 22 side. !
! It has a diode configuration. In this case, the insulating semiconductor substrate 21 is made of single crystal In
A layer 22 made of a group compound semiconductor made of A1 and doped with impurities forming deep units is a single crystal A/8.
b or InP with a lattice constant approximately equal to it, In8
It is made of a 1sP-based, InabAs-based, or GaSbAs-based single-crystal type -■ group compound semiconductor. The above is the second embodiment of the semiconductor device according to the present invention. According to this configuration, the layer 22 is a l-V group compound 1 semiconductor doped with impurities forming deep units. Therefore, in the same way as the layer 7 in the embodiment 1 of the semiconductor device according to the present invention described above in FIG. When single crystal MSb added as an impurity becomes -1 o 1
It has a high specific resistance of 2Ω1 or more) and operates as a normal MIa type diode. Thus, in FIG.
According to the embodiment, the layer 22 acts as an insulating layer at low temperatures, but the layer 22 is connected to the semiconductor substrate 21 as in the first embodiment of the present invention described above. Since it is made of a ■-■ group compound semiconductor with the same or sometimes the same lattice constant, the lm122 forms an interface with few surface states with the semiconductor substrate 21, as in the case of the first embodiment of the present invention described above. It is well formed and thermally stable in the low temperature range where it acts as an insulating layer, and it can be easily formed to the required thickness. It has certain great characteristics. Next, a third embodiment of the semiconductor device according to the present invention will be described with reference to FIG. An N+ type semiconductor region 62 as a drain region and an N+ type semiconductor region 33 as a drain region are formed in the region between the semiconductor regions 32 and 65 on the main surface of the semi-insulating semiconductor substrate 31. A gate electrode 35 is disposed through a layer 64 made of a V-group compound doped with impurities such as F, Cr, and O, which forms a deep level exhibiting .
Further, it has an N-channel MIa type field effect transistor configuration in which source electrodes 5B and 39 are attached to semiconductor regions 32 and 53. In this case, the semi-insulating semiconductor substrate 31 is made of single crystal In8b
The layer 34 made of a group I-V compound semiconductor doped with impurities to form a deep level is single crystal uSb.
Alternatively, it is made of a single-crystal group-V compound semiconductor having substantially the same lattice constant as this. The above is an embodiment of the semiconductor device tjpJ6 according to the present invention. According to such a structure, the layer 64 is made of an oboro-■ group compound semiconductor doped with impurities that form a deep level. Therefore, like the pigeon 22 in the embodiment wJ2 of the semiconductor device according to the present invention described above in FIG.
It operates as a la-type field effect transistor. Thus, the third embodiment of the semiconductor device according to the present invention described above in FIG.
According to the embodiment, the layer 34 acts as an insulating layer at low temperatures, but the layer 34 is the same as the semiconductor substrate 31, as in the second embodiment of the invention described above. Alternatively, since the layer 54 is made of a half-solid compound of the ■-v group having approximately the same lattice constants, the layer 54 has a surface level difference between it and the semiconductor substrate 31, as in the case of the embodiment @2 of the present invention described above. It is well formed as it allows for the formation of few interfaces, it is thermally stable in the low temperature range where it acts as an insulating layer, and it can be easily formed to the required thickness. It has the following great characteristics. In the above, embodiments have been described in which the present invention is applied to an MIa type field effect transistor configuration and an MIa type diode configuration. It will be obvious that the present invention can be applied to various semiconductor devices having a structure in which a layer is formed. 4. Brief explanation of the drawings Figures 1, 2 and IIg! FIG. 1 is a cross-sectional view showing a first embodiment, a second embodiment, and a fifth embodiment of a semiconductor device according to the present invention. In 1, 1 is a semi-insulating semiconductor substrate body, 2 & a semiconductor layer,
5.21 and Sl are semiconductor substrates, 44 years old main surface, 5 and 5
8 is a source electrode, 6 and 39G are a drain electrode, 7.2
2 and 34 are layers made of a 1i-v* compound semiconductor from which impurities forming deep units have been removed, exhibiting insulating properties at low temperatures, 8 and 35 are gate electrodes, and 23 and 24 are electrodes, respectively. . Applicant: Nippon Denki II Telephone Corporation

Claims (1)

[Claims] A ts2 i formed by doping an impurity forming a deep level exhibiting insulating properties at low temperatures on the main surface of a semiconductor substrate made of a 1.4i1 IV group compound semiconductor. - A semiconductor device characterized in that it has a structure in which a layer made of a V group compound semiconductor is formed as an insulating layer at low temperatures. 2. In the semiconductor device according to claim 1, the first IV group compound semiconductor is made of InP, and the second I-Y group compound semiconductor is InP or has a lattice constant similar to that of InP. A semiconductor device characterized in that it is made of approximately the same ■-V group compound semiconductor. (5) In the semiconductor device set forth in claim 1, the I-V group compound semiconductor j11 is made of GaAs, and the second A-V group compound semiconductor is GaAt or has a lattice constant approximately equal to that of GaAs. 1. A semiconductor device characterized by being made of an identical P-V group compound semiconductor. 4.4I In the semiconductor device described in claim 1,
The first IV group compound semiconductor is InA@,
A semiconductor device characterized in that the second IV group compound semiconductor is made of IJ8b or an IV group compound semiconductor having a lattice constant substantially equal to IJ8b. 5. In the semiconductor device set forth in claim 1, the first ■-Ma group compound semiconductor is Iaab,
A semiconductor device characterized in that the second l-V group compound semiconductor is made of muj8b or an I-V group compound semiconductor having a lattice constant substantially equal to that of muj8b.