JPS59132171A - Manufacture of semiconductor element - Google Patents

Abstract

PURPOSE:To improve an ideal coefficient of a diode, by performing beam etching by the mixed gas ions of argon ions and oxygen ions. CONSTITUTION:A diode having a Schottky junction comprises an N<+> GaAs substrate 1, an N-GaAs layer 2, a Ti electrode 3 forming a Schottky junction, and an AuGe/Ni/Au electrode 4 forming ohmic contact with the substrate 1. In manufacturing the Schottky diode, the layer 2 is made clean by etching immediately before the electrode 3 is evaporated. When ion beam etching is used by the mixed gas ions of argon ions and oxygen ions, an ideal coefficient is improved.

Description

DETAILED DESCRIPTION OF THE INVENTION (Technical Field) The present invention relates to a method for manufacturing a Schottky junction semiconductor device with good electrical characteristics.

(Background Art) Figure 1 is a cross-sectional view of a diode forming a Schottky junction, where 1 has a carrier density of about 1×lOcnn.
-GaAs substrate, 2 is an n-GaAs layer with a thickness of about 2000X with a carrier density of about lXl0 cm, 3 is a Ti electrode forming a Schottky junction, and 4 is an Au-Ge layer forming an ohmic contact with the n''-GaAs substrate 1'. /Ni/Au
It is an electrode. In the fabrication of such a Schottky diode, just before depositing the 30Ti electrode, 2 n-GaAs
The surface must be cleaned by etching. When using chemical etching, foreign matter on the surface is removed using a chemical reaction, so it is impossible to remove chemically inert foreign matter, and generally these foreign matter are removed from the surface of the GaAS substrate. Since the above distribution is non-uniform, the Schottky diode manufactured in this way has a poor distribution of variations in electrical properties.

(Object of the Invention) The object of the present invention is to perform cleaning by physical etching, in which argon ions (Ar) and oxygen ions (0
The ideal coefficient n of the diode is improved by employing ion beam etching using mixed gas ions with □)'.

(Structure of the Invention) FIG. 2 is a characteristic diagram for explaining the present invention, in which the horizontal axis represents ion energy and the vertical axis represents the ideal coefficient n in the rectification characteristics of the diode 9.

FIG. 2 shows Ar102 (1:
1) In addition to ion etching characteristics, Ar ion etching characteristics and chemical etching characteristics are shown.

Ar102 (=1:1) ion etching characteristics are as follows: After ion beam etching the n-GaAs2 surface with mixed gas ions with a flow rate ratio of Ar and O2 of 1:1, a T1 electrode is deposited on the etched surface, and then, A Schottky semiconductor device was produced by annealing at 300° C. for 20 minutes in a N2 gas atmosphere at atmospheric pressure, and then a Schottky semiconductor device was fabricated with a Schottky T1 electrode 3 and an ohmitter Au-Ge/Ni/Au electrode 4.
The n value was measured by applying a bias voltage between the two. The n-GaAs surface ion-beam etched with Ar102 (1:1.) gas is Ar,l!
It is very clean because it is physically snoked and tarred by ZQ2 ions, and there is little variation between elements. Furthermore, ion beam etching damages the surface layer of GaAs to a depth of several hundred times, but Ar
2 is mixed at a flow rate ratio of 1:1, 100
When etching with ion energies of 300 eV and 300 eV, the n values are 118 and 123, which are quite good, and the effect on leakage current is as good as chemical etching. As a result, in ion beam etching using a mixed gas of Ar and '02, the degree of damage to the surface layer is slight even if the surface is cleaned by ions with an energy of less than about 30'OeV, and the degree of damage to the surface layer is slight at 300°C in N2 at atmospheric pressure. It can be seen that it is easily recovered by heat treatment for 20 minutes. As an example of heat treatment at a temperature of 300° C. or higher, the n value hardly changes even if the Schottky diode shown in FIG. 1 is heat-treated at 350° C. for 20 minutes in an N2 atmosphere at atmospheric pressure. On the other hand, as is clear from FIG. 2, when Ar ion beam etching was used, the n value was poor at 13 G at 100 eV, and was not recovered by heat treatment at 300° C. for about 20 minutes. Note that when the energy of Ar ions was reduced to 50 eV, the n value recovered to 114 by heat treatment at 300°C for 20 minutes in a N2j atmosphere at -atmospheric pressure, but the n value recovered to 114;
If the ion energy is lowered to about 0ev, the etching speed will be uneven depending on the location, and it will actually become difficult to etch the upper surface.

Also, the example on the left of etching with 02 ions is 300
Schottky diode etched with eV at 300℃
When heat treated at 350C, the n value becomes 13] and 111, indicating that the heat treatment at 350C is more effective. L Kashio
The etching rate of 2 ions is about 1/1o, which is about 2 times smaller than that of Ar ions, and OK Ar
Ion beam etching using a mixed gas of Ar and 02 is suitable for cleaning the GaAs surface because the etching rate increases considerably by mixing the two gases.

(Effects of the Invention) In the present invention, the mixture of Ar and O2, which has a physical sputtering effect, cleans the semiconductor surface using sions, so oxides, organic substances, etc. attached to the surface can be easily removed. Since it is possible to form a Schottky junction with excellent reproducibility and in-plane distribution of electrical characteristics, it can be used for -) etching of dirt recesses in MESFETs. Therefore, inorganic semiconductors other than GaAs can also be applied.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing an example of a Schottky semiconductor device, and FIG. 2 is a characteristic diagram used to explain the present invention, which is an explanatory diagram of the dependence of the n value of the Schottky semiconductor device on ion energy. 1.-n-GaAs substrate, 2- n-GaAs layer,
3-n. 4. Ohmic electrode. Patent Applicant: Oki Electric Industry Co., Ltd. Figure 1 Figure 2 To IsunoEne V - (eVl Procedural Amendment (Salmon) 1 Indication of Case 1982 Patent Application No. 005847 2 Name of Invention Method for Manufacturing Semiconductor Elements 3 Relationship with the case of the person making the amendment Patent application Personnel office (
105) 1-7-12-4 Toranomon, Minato-ku, Tokyo.
Agent address (105) 1-7-1 Toranomon, Minato-ku, Tokyo
No. 2 No. 5, Subject of amendment 1. Detailed explanation of the invention in the specification” column and “Brief explanation of the drawings j” column - 6. Contents of amendment Attachment 2, Contents of amendment I1, page 2, line 13 After ``by etching'' in the eyes, ``
Insert "Semiconductor surface" r+/su (2) In the 20th line of the second chapter of the same book, "Ion energy" is corrected to "Ion energy". (3) In the 10th line of No. 3 of the same book, the phrase "Schottky semiconductor device" is corrected to "Schottky junction semiconductor device." (4) On page 3, line 20 of the same book, ``Ion Energy is corrected to ``Ion Energy''. (5) In the 6th line of No. 5 of the same book, the phrase "of 02 ions" is corrected to "of GaAs by 02 ions." 1, page 6, lines 3 and 5, the words "Shosso semiconductor device" are corrected to read "Schottky junction semiconductor device." (7) In the same book, page 6, line 5, "ion energy" is corrected to "ion energy."

Claims (1)

[Claims] A process of etching the semiconductor surface by irradiating the semiconductor surface with an ion beam using mixed gas ions of argon ions and oxygen ions, a process of forming a metal forming a Schottky junction on the etched surface, and then a heat treatment to recover from the ion beam damage. A method for manufacturing a semiconductor device, comprising the steps of: