JPS6161547B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improvement in the manufacturing method of an MIS type semiconductor device using a compound semiconductor substrate.

Recently, MIS type semiconductor devices using compound semiconductor substrates made of InP, GaAs, GaInAsP, etc. have been attracting attention. MIS using such a compound semiconductor substrate
The manufacturing method for type semiconductor devices includes the step of forming an insulating film on the surface of a compound semiconductor substrate, but in general, the surface of compound semiconductor substrates is very easily oxidized by oxygen in the air. It is.

For this reason, conventional MIS using compound semiconductor substrates
As a step of forming an insulating film on the surface of a compound semiconductor substrate, which is included in the manufacturing method of a type semiconductor device, a new surface of the material is obtained on the compound semiconductor substrate by chemical etching using an etchant such as a hydrochloric acid solution, and then The compound semiconductor substrate with the new surface is placed in a reactor, and then an insulating film forming gas is supplied into the reactor and the compound semiconductor substrate is processed by CVD using the insulating film forming gas. A manufacturing method for MIS type semiconductor devices has been proposed that involves forming an insulating film on a new surface of the semiconductor device.

However, in the case of the conventional manufacturing method of MIS type semiconductor devices, in the process of forming an insulating film on the surface of the compound semiconductor substrate, chemical etching is used to create a new surface on the compound semiconductor substrate using the material. After that, before placing the compound semiconductor substrate with the new surface in the reactor, and after placing the compound semiconductor substrate with the new surface in the reactor, the compound semiconductor substrate with the new surface is placed in the reactor. Until the insulating film is formed on the new surface of the semiconductor substrate by the CVD method, the new surface of the compound semiconductor substrate is exposed to air. When the new surface is exposed to air, an insulating film on the surface of the compound semiconductor substrate is formed through a surface layer consisting of a composite of oxides of various forms of the material of the compound semiconductor substrate. That is, if we assume that the compound semiconductor substrate is made of InP and an insulating film of Al ₂ O ₃ is to be formed on a new surface of the compound semiconductor substrate of InP, as shown in FIG.
On the surface of compound semiconductor substrate 1 made of InP substrate
An insulating film 2 made of Al ₂ O ₃ is formed with a surface layer 3 made of a composite of oxides of various types of In, oxides of various types of P, and the like.

Therefore, the above-mentioned conventional method for manufacturing an MIS type semiconductor device has the disadvantage that it is not possible to obtain the desired MIS type semiconductor device with desired good characteristics. In other words, the conventional MIS type semiconductor device manufacturing method described above
A MIS type semiconductor device is constructed by forming a source region and a drain region made of an N-type semiconductor region from the front surface (principal surface) side in a compound semiconductor substrate made of P-type InP so as to form a channel region between them. A MIS type field effect transistor is obtained in which a gate electrode is arranged on the surface of the channel region via a gate insulating film made of Al ₂ O ₃ , and the gate insulating film in this case is the conventional MIS type semiconductor described above. For example, in the case where an insulating film is formed by a step of forming an insulating film on the surface of a compound semiconductor substrate included in the manufacturing method of a device, the above-mentioned film obtained by the conventional manufacturing method is
A MIS type field effect transistor has a drain current flowing through the source region and the drain region by applying a necessary bias voltage between the source region and the gate electrode with a necessary power supply connected between the source region and the drain region. Looking at the value of the drain current over time, as shown by curve A in Figure 2, electrons are initially captured at the capture center in the gate insulating film made of Al ₂ O ₃ . For this reason, it decreases slightly over time, but after a certain point, the gate insulating film made of Al ₂ O ₃ on the surface of the compound semiconductor substrate made of InP becomes In as described above in FIG. It is formed through a surface layer consisting of a composite of various forms of oxide of It has the disadvantage that it has the tendency to exhibit undesirable drain current characteristics in which the drain current characteristic suddenly decreases.

Therefore, the present invention proposes a method for manufacturing an MIS type semiconductor device using a novel compound semiconductor substrate free from the above-mentioned drawbacks, which will become clear from the detailed description below.

The present invention provides an MIS type semiconductor device using a compound semiconductor substrate including a step of forming an insulating film on the surface of the compound semiconductor substrate, as in the case of the conventional MIS type semiconductor device manufacturing method mentioned at the beginning. get
The manufacturing method for MIS type semiconductor devices is
The process of forming an insulating film on the surface of a compound semiconductor substrate, which is involved in the manufacturing method of MIS semiconductor devices, is different from the process of the conventional MIS semiconductor device manufacturing method mentioned at the beginning, as described below. Other than this, this method is the same as the conventional MIS type semiconductor device manufacturing method described at the beginning.

Therefore, the process of forming an insulating film on the surface of a compound semiconductor substrate according to the present invention will be mainly described below. an inert gas source 31 from which an inert gas is obtained;
Insulating film forming gas source 3 from which insulating film forming gas such as aluminum triisopropoxide gas can be obtained
2, a gas supply pipe 37 connected to a hydrogen chloride gas source 33 from which hydrogen chloride gas is obtained via on-off valves 34, 35, and 36, and a gas exhaust pipe 38 connected to an exhaust means (not shown). Externally,
In addition, the heater 4 is connected from the outside via the terminal pieces 39 and 40.
Reaction furnace 43 in which a substrate support stand 42 having 1 is housed
is prepared, and the substrate support stand 42 in the reactor 43 is prepared.
A compound semiconductor substrate 44 made of InP, GaAs, GaInAsP, etc. obtained in advance is supported thereon.

First, the exhaust means is activated to remove the reactor 43.
While releasing the gas inside the reactor 43 to the outside through the gas exhaust pipe 38, an inert gas is supplied into the reactor 43 from the inert gas source 31 through the on-off valve 34, so that the gas inside the reactor 43 becomes acidic. At the point where the gas is replaced with an inert gas that does not contain turbidity, a hydrogen chloride gas source 3 is introduced into the reaction tube 43.
5, hydrogen chloride gas is supplied via the on-off valve 36, while the heater 41 is energized and the compound semiconductor substrate 44 is heated via the substrate support 42 to the required temperature (when the compound semiconductor substrate 44 is made of InP).
The compound semiconductor substrate 44 is heated to a temperature of 200 to 300° C.) and then vapor phase etched using hydrogen chloride gas to remove the compound semiconductor substrate 44 from its surface to a required thickness of, for example, 500° C.
A new surface of the compound semiconductor substrate 44 made of the material is obtained by removing the material to a thickness of .ANG. or more.

Next, the supply of hydrogen chloride gas from the hydrogen chloride gas source 33 into the reactor 43 is stopped by the on-off valve 36, and the hydrogen chloride gas in the reactor 43 is replaced with the inert gas supplied from the inert gas source 31. The active gas is discharged to the outside through the gas exhaust pipe 38 and the reactor 4
3 becomes an inert gas atmosphere that does not contain hydrogen chloride gas, the insulating film forming gas from the insulating film forming gas source 32 is supplied into the reactor 43 via the on-off valve 35, while By energizing the heater 41, the compound semiconductor substrate 44 is heated to a required temperature (300 to 400° C. when the compound semiconductor substrate 44 is made of InP and the insulating film forming gas is aluminum triisopropoxide gas). Then, an insulating film is formed on the new surface of the compound semiconductor substrate 44 made of that material by CVD using an insulating film forming gas.

As described above, an embodiment of the method for manufacturing an MIS type semiconductor device according to the present invention has been clarified. 44 is placed in the reactor 43, hydrogen chloride gas is supplied into the reactor 43, and gas phase etching is performed using the hydrogen chloride gas to obtain a new surface of the material on the compound semiconductor substrate 44. In this process, an insulating film gas is supplied into the reactor 43 and an insulating film is formed on the new surface of the compound semiconductor substrate 44 using the same material by CVD using the insulating film forming gas. In this process, there is no possibility that the new surface of the material obtained on the compound semiconductor substrate comes into contact with air, and therefore, the insulating film on the surface of the compound semiconductor substrate 44 is different from that of the conventional material mentioned at the beginning. Unlike the manufacturing method, there is no layer formed through a surface layer made of a composite of various forms of oxides of the material of the compound semiconductor substrate, and it is formed directly on the surface of the material of the compound semiconductor substrate 44. It is something that will be done. That is, the compound semiconductor substrate 44 is now made of InP as in the conventional case described at the beginning, and an insulating film made of Al ₂ O ₃ is formed on the new surface of the compound semiconductor substrate made of InP. For example, as shown in FIG. 4, an insulating film 45 made of Al ₂ O ₃ on the surface of a compound semiconductor substrate 44 made of InP.
is formed directly on the surface of the nP material of the compound semiconductor substrate 44.

Therefore, according to the method for manufacturing an MIS type semiconductor device according to the present invention, it is possible to obtain a target MIS type semiconductor device having desired good characteristics, as in the case of the conventional manufacturing method mentioned at the beginning. It has the great feature that it does not have an undesirable appearance, and that it is possible to obtain the desired MIS type semiconductor device with the desired good characteristics. Incidentally, by the above-mentioned method for manufacturing an MIS-type semiconductor device of the present invention, the surface of the MIS-type semiconductor device can be fabricated within a compound semiconductor substrate made of P-type InP, in the same manner as described above for the conventional method for manufacturing an MIS-type semiconductor device. A source region and a drain region made of N-type semiconductor regions are formed from the (principal surface) side to form a channel region between them, and a gate insulating film made of Al ₂ O ₃ is formed on the surface of the channel region. A step of forming an insulating film on the surface of a compound semiconductor substrate included in the above-mentioned method for manufacturing a MIS-type semiconductor device of the present invention is obtained as an MIS-type field effect transistor having a gate electrode arranged therein. For example, in the case where the MIS type field effect transistor described above obtained by the manufacturing method of the present invention is formed by the source region and the gate with the required power supply connected between the source region and the drain region, When a required bias voltage is applied between the electrodes and a drain current is caused to flow through the source region and drain region, the value of the drain current with respect to time shows that even though a long time has elapsed, the value is As shown by line B in Figure 1, the length decreases slightly over time due to the fact that electrons are captured at the capture center in the gate insulating film made of Al ₂ O ₃ . The drain current characteristics of the MIS field effect transistor thus obtained can be significantly improved over the drain current characteristics shown by curve A in FIG. 5 (same as curve A in FIG. 2). .

In the above, the method for manufacturing an MIS type semiconductor device according to the present invention has been explained with reference to an embodiment in which the MIS type semiconductor device is obtained as a MIS type field effect transistor. It can be applied to various types of MIS type semiconductor devices that utilize the interfacial characteristics between films, and is not limited to cases where the compound semiconductor substrate is InP.
Even if GaAs, GaInAsP, etc. are used, the insulating film on the surface of the compound semiconductor substrate is not only formed of Al ₂ O ₃ but also SiO _{2 ,} GaInAsP, etc.
It will be obvious that the present invention can also be applied to the case where it is formed of Si ₃ N ₄ or the like.

[Brief explanation of the drawing]

Figure 1 shows MIS using a conventional compound semiconductor substrate.
Figure 2 is a schematic cross-sectional view showing an insulating film on the surface of a compound semiconductor substrate obtained by the process included in the manufacturing method of a MIS type semiconductor device using a conventional compound semiconductor substrate. obtained by twisting
A diagram showing the drain current characteristics of an MIS type field effect transistor, FIG. 3 is a schematic diagram showing a reaction furnace used in the method for manufacturing an MIS type semiconductor device using a compound semiconductor substrate according to the present invention, and FIG. 4 is a diagram according to the present invention. FIG. 5 is a schematic cross-sectional view showing an insulating film on the surface of a compound semiconductor substrate obtained by the process included in the manufacturing method of an MIS type semiconductor device using a compound semiconductor substrate, and FIG. FIG. 3 is a diagram showing drain current characteristics of an MIS field effect transistor obtained by a method for manufacturing an MIS semiconductor device. In the figure, 1 is a compound semiconductor substrate, 2 is an insulating film, and 3 is a compound semiconductor substrate.
31 is a surface layer, 31 is an inert gas source, 32 is an insulating film forming gas source, 33 is a hydrogen chloride gas source, 34 to 36
37 is a gas supply pipe, 38 is a gas discharge pipe, 41 is a heater, 42 is a substrate support stand, 43 is a reactor, 44 is a compound semiconductor substrate, and 45 is an insulating film.

Claims (1)

[Claims] 1. With the compound semiconductor substrate placed in a reactor, hydrogen chloride gas is supplied into the reactor, and gas phase etching is performed using the hydrogen chloride gas to obtain a new surface of the material on the compound semiconductor substrate. , and then supplying an insulating film forming gas into the reactor and forming an insulating film on a new surface of the compound semiconductor substrate made of the material by a CVD method using the insulating film forming gas. A method for manufacturing an MIS type semiconductor device using a compound semiconductor substrate, which is characterized by: