JPS5994866A - Semiconductor device having schottky junction - Google Patents

Abstract

PURPOSE:To restrain aluminum migration and thus obtain a Schottky junction which makes low-resistant the connection among a gate electrode, memory, and a wiring by a method wherein a device is composed by successively laminating an aluminum layer, layer of a metal except aluminum, and an aluminum layer on a compound semiconductor layer. CONSTITUTION:The gate electrode is formed by successively laminating the Al layer 21, the hetero metal 22 such as Ti or Ni, and the Al layer 23 on a GaAs substrate 1. The Al layer 21 forms a Schottky junction between the GaAs substrate 1. Next, a Ti layer 24, a Pt layer 25, and an Au layer 26 are successively laminated as the wiring to connect the gate electrode to a bonding pad. Since the surface of the hetero metallic layer 22 is thus covered with the Al layer 23, an insulator layer is not formed, and the Al layer 23 is joined to the Ti layer in low resistance. The migration of the Al layers 21 and 23 is restrained because of providing the hetero metallic layer 22 and the Ti layer 24, resulting in no generation of problems such as disconnection.

Description

[Detailed description of the invention] The present invention relates to a semiconductor device having a Schottky junction.

With the recent development of communication systems, semiconductor devices used therein are required to operate at higher frequencies and at higher speeds. Compound semiconductor devices have been developed based on these requirements.

A typical example is a field effect transistor (hereinafter referred to as QaA8・FE) using gallium arsenide (hereinafter referred to as QaAs).
(denoted as T). Semiconductor devices using compound semiconductors,
Particularly in semiconductor devices using QaAs, Schottky junctions are mainly used, and in these devices, it is most important to obtain a high quality Schottky junction.

Conventionally, At has been widely used as a metal for forming Schottky junctions in compound semiconductors because of its excellent Schottky properties, heat resistance, workability, and the like.

FIG. 1 is a cross-sectional view of an example of a conventional GaA 3'' FET.

A gate electrode 2 and source and drain electrodes 3 and 4 are formed on a GaAS substrate 1. source and drain electrodes 3,
In No. 4, an Au-Ge alloy and Ni are used as metals to form an ohmic contact. For example, 1 Au-Ge alloy
Form Ni to a thickness of 50OA,
Alloyed by heat treatment.

For the gate electrode 2, At is used as a metal forming a Schottky junction.

However, At tends to cause a phenomenon called migration, in which At crystal grains move during energization, resulting in wire breakage and other problems in terms of long life. As a means to solve this migration problem, Ti is added on top of At.
It was devised to place different metals such as , Ni, etc.

FIG. 2 is a cross-sectional view of an example of a gate electrode portion of a conventional GaAs-FET.

An At layer 11 and a dissimilar metal layer 12 of Ti or Ni are formed on the GaAs substrate 1, and Ti/Pt/Au is formed as a wiring for leading out the gate electrode to the bonding butt.
Layer 13 is provided and connected.

In this way, by providing the dissimilar metal layer 12 of Ti or Ni, the problem of pht migration is solved, but during the device manufacturing process, T1 or Ni, which is more reactive than At, is oxidized and the insulating layer 14, layer 12 and layer 1
3 is connected through a high resistance layer.

The present invention eliminates the above drawbacks, suppresses migration of aluminum, and provides a semiconductor device having a Schottky junction that can realize a connection between a gate electrode and a wiring with low resistance.

A semiconductor device having a Schottky junction of the present invention includes an aluminum layer that contacts a compound semiconductor layer to form a Schottky junction, and at least one layer of a metal other than aluminum provided on the aluminum layer. and an aluminum layer provided on the metal layer.

Next, embodiments of the present invention will be described using the drawings.

FIG. 3 is a sectional view of one embodiment of the present invention.

Upper rAt layer 21 of GaAs substrate 1. Dissimilar metal layer 22 of Ti or Ni. A gate electrode is formed by sequentially stacking At layers 23. It goes without saying that the At layer 21 forms a Schottky junction with the GaAs substrate 1.

Next, as wiring for connecting the gate electrode to the bonding pad, a Ti layer 24, a Pt layer 25, and an Au layer 2 are formed.
6 are stacked one after another. In this invention, since the surface of the dissimilar metal layer 220 is covered with the At layer 23, an insulator layer as shown in FIG. 2 is not formed, and the HT layer 23 and the Ti layer 24 are bonded with low resistance. On the other hand, migration of the At layers 21 and 23 is suppressed by providing the dissimilar metal layer 22 and the Ti layer 24, and problems such as disconnection do not occur.

Although QaAs was used for the substrate 1 in the above embodiment, the present invention can be similarly applied to other compound semiconductors.

As described in detail above, according to the present invention, it is possible to obtain a semiconductor device having a Schottky junction type gate electrode that suppresses aluminum migration and can connect the gate electrode and the bonding butt with low resistance. The effect is great.

[Brief explanation of drawings]

Figure 1 is a sectional view of an example of a conventional GaAs*FET, Figure 2 is a cross-sectional view of an example of a conventional GaAs*FET.
The figure shows a conventional GaAs*FET game)! FIG. 3 is a cross-sectional view of an example of the pole portion, and FIG. 3 is a cross-sectional view of an embodiment of the present invention. 1...QaAs substrate, 2...gate electrode, 3, 4...source and drain electrode, 11
...At layer, 12...Different metal layer, 1
3...Ti/Pt/Au layer, 14...
Insulator layer, 21... At layer, 22...
Different metal layer, 23... At layer, 24...
・Ti layer, 25...PT layer, 26...
Au layer.

Claims (1)

[Claims] an aluminum layer that contacts a compound semiconductor layer to form a Schottky junction; at least one layer of a metal other than aluminum provided on the aluminum layer; and an aluminum layer provided on the metal layer other than aluminum. What is claimed is: 1. A semiconductor device having a 7-metal junction, comprising: