JPH043922A - Manufacture of semiconductor device - Google Patents

Abstract

PURPOSE:To obtain a semiconductor device, in which the resistance of an ohmic junction is lowered, by ohmic-joining a source electrode and a drain electrode on a Ge implantion layer formed in an active layer in an ohmic-joined position. CONSTITUTION:In a MES FET, Ge implantion layers 9 are formed on an active layer 2 in positions, where a source electrode 3 and a drain electrode 4 are ohmic-joined, and the source electrode 3 and the drain electrode 4 composed of the two layers of an AuGe layer 6 and an Ni layer 7 are formed on the Ge implanted layers 9, but trivalent Ga and pentavalent As bond in a latticed manner in the active layer 2. Since crystallizability is damaged when Ge ions are implanted but recrystallization can be accomplished by executing heat treatment and the positions of Ga are replaced with partial Ge ions and N-type impurities are formed, AuGe and Ni constituting the source electrode 3 and the drain electrode 4 are evaporated onto the Ge implanting layers 9, to which N-type impurities are formed. Ge in AuGe is diffused easily into the Ge implanted layer 9 and alloyed through heat treatment, and an ohmic junction having low resistance is shaped. Accordingly, a semiconductor device in which the resistance value of a junction section is lowered is acquired.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to semiconductor devices, particularly MES (■etalse
The present invention relates to a method for manufacturing a MES FET with improved ohmic characteristics of a source electrode and a drain electrode.

[Conventional technology]

For example, MES F-ET, which has excellent high frequency characteristics, is used in satellite communications that require high frequency and high power. MES FET is an F-ET formed by a Schottky junction between a metal and a semiconductor, and its structure is
In the MES F-ET shown in the figure, n-type impurity ions are introduced into a semi-insulating GaAs substrate (1) to form an active layer (2) through which current flows. , the source electrode (3) and the drain electrode (4) are ohmically connected, and the source electrode (3) and the drain electrode (4)
A gate electrode (5) is connected by a Shore key. The source electrode (3) and the drain electrode (4) have an AuGe layer (6) in ohmic contact with the active layer (2),
It is composed of two layers: Ni layer (7). In the ohmink junction, AuGe-Ni and the active layer (2) are alloyed by heat treatment after depositing AuGe-Ni on the active layer (2). On the other hand, the gate electrode (5) to be Schottky bonded is simply a metal bonded to the active layer (2), and the active layer (2) directly below the gate electrode (5)
A depletion layer (8) is formed therein. The depletion layer (8) is a region where carriers do not exist, and the region of the depletion layer (8) is expanded by applying a reverse bias voltage between the gate and the source.

Now, when a drain-source voltage is applied, the active layer (2
) causes a drain-source current to flow. This drain-source current can be increased or decreased by changing the thickness of the depletion layer (8). The thickness of the depletion layer (8) is varied by increasing or decreasing the reverse bias voltage between the gate and source. Therefore, the drain-source current can be controlled by changing the reverse bias voltage.

[Problem to be solved by the invention]

The source electrode (3) and the drain electrode (4) are ohmically connected to the active layer (2) into which n-type impurities are introduced, so that a drain-source current flows.

Therefore, the smaller the resistance value in the ohmic junction, the more efficiently the drain-saw input current can flow. In particular, MES for satellite communication, which requires high frequency and high power.
In the F-ET, a large drain-source current flows, so if the resistance value in the ohmic junction is large, losses such as heat generation will occur.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a method of manufacturing a semiconductor device in which the resistance of the ohmic junction between a source electrode and a drain electrode is reduced.

[Means to solve the problem]

In order to achieve the above object, the present invention has a semi-insulating substrate (1
) with n-type impurities introduced into the active layer (2), AuGe
-Ni source electrode (3) and drain electrode (4) are ohmically bonded, and a gate electrode (5) is seat-key bonded between the picture electrodes (3) and (4). ) and the drain electrode (4), a Ge injection layer (9) is formed in the active layer (2) at a position where ohmic contact is made between the source electrode (3) and the drain electrode (4). ) is characterized by ohmic connection.

[Effect]

When AuGe constituting the source and drain electrodes is deposited on the Ge injection layer, the Ge in the AuGe easily becomes Ge.
It is diffused into the injection layer and alloyed. Therefore, the resistance value of the ohmic contact between the source electrode and the drain electrode and the Ge injection layer becomes small.

〔Example〕

One embodiment of the present invention will be described with reference to FIGS. 1 to 3. However, the same parts as the conventional ones are given the same reference numerals, and the explanation is omitted.

The MES FET according to the present invention is characterized in that a Ge injection layer (9) is formed on the active layer (2) at a position where the source electrode (3) and the drain electrode (4) are connected to each other through ohmink contact. That is, on this Ge injection layer (9), an AuGe layer (
A source electrode (3) and a drain electrode (4) consisting of two layers, 6) and a Ni layer (7), are laminated.

By the way, the active layer (2), when expressed in plan, is a combination of trivalent Ga and pentavalent A3 in a lattice shape, as shown in FIG. When Ge ions are implanted into such an active layer (2), the crystallinity is impaired, but they are recrystallized by heat treatment, and as shown in Figure 3, some Ge ions become Ga ions. replaced in position. Since Ge is a tetravalent atom and Ga is a trivalent atom, when a Ge ion is substituted at the position of Ga, electrons are left over and an n-type impurity is generated. In this way, the AuGe that forms the source electrode (3) and the drain electrode (4) is placed on the Ge implanted layer (9) in which n-type impurities are generated in the AuG of the active layer (2) by implantation of Ge ions. and evaporate Ni. By heat treatment, the Ge of AuGe becomes a Ge injection layer (9)
Due to the Ge contained therein, it is easily diffused into the Ge injection layer (9) and alloyed to form a low resistance ohmic junction, thereby completing the source electrode (3) and drain electrode (4).

〔Effect of the invention〕

According to the present invention, since the source electrode and the drain electrode are ohmically bonded on the Ge injection layer, the resistance value of the junction is reduced, no loss such as heat generation occurs, and a large drain-source current can be efficiently handled. (It can flow.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view of the MES FET according to the present invention, and FIG.
The figure shows the molecular structure of the active layer, and FIG. 3 shows the molecular structure of the Ge injection layer. FIG. 4 is a cross-sectional view of a conventional MES FET. (1) one substrate, (2) -active layer, (3
)・-source electrode, (4) -drain electrode, (
5) -Gate electrode, (9) -Ge injection layer. a As AS Substrate 1 2:f)-+Fang

Claims (1)

[Claims] (1) Manufacturing a semiconductor device in which a source electrode and a drain electrode of AuGe/Ni are ohmically bonded to an active layer doped with n-type impurities on a semi-insulating substrate, and a gate electrode is Schottky bonded between the two electrodes. In the method, a Ge injection layer is formed in the active layer at a position where the source electrode and the drain electrode are ohmically connected, and the source electrode and the drain electrode are ohmically connected on the Ge injection layer. Method.