JPH01165166A - Schottky barrier diode - Google Patents

Abstract

PURPOSE:To produce a thermal noise caused by a spreading resistance by a method wherein the rear of a certain region directly under a Schottky part is etched so as to leave a thin epitaxial layer called a buffer layer to form an etched surface and an ohmic contact part is formed on the etched surface instead of the side of the Schottky part. CONSTITUTION:A Schottky part 5 is provided between the surface of an active layer 1-3 and the beam lead 3 of a Schottky electrode. A beam lead 4 has a conventional structure and a part of it reaches the inside of a buffer layer 1-2. After the beam leads 3 and 4 are provided on a wafer, a resist layer 7 for a mask is formed on the rear of the wafer and the rear of the wafer is etched so as to expose a part of the beam lead 4 reaching the inside of the buffer layer 1-2 and to leave the thin buffer layer 1-2. Then metal for an ohmic contact is evaporated and the resist 7 and the unnecessary evaporated metal on the resist 7 are removed along its circumference by lifting-off. The remaining evaporated metal 8 is subjected to a thermal treatment to form an ohmic contact between the evaporated metal 8 and the buffer layer 1-2.

Description

Detailed Description of the Invention [Industrial Application Field] The present invention relates to a Schottky barrier diode (hereinafter referred to as SBD) in which a Schottky electrode and an ohmic electrode are disposed on the surface in a beam lead shape so that it can be directly assembled into a microwave strip line. ).

[Conventional technology]

SBDs for microwave detectors, etc., have Schottky electrodes and ohmic electrodes arranged in the form of beam leads on the surface so that they can be assembled directly into microwave strip lines without using a package in order to keep stray capacitance small. There is something I did.

3(a) and 3(b) are a plan view and a schematic sectional view showing the structure of an example of a conventional SBD of this type, and FIG. 3(b) is a diagram (
) is shown along the AA' plane.

In the figure, 1-1 is a substrate, 1-2 is a buffer layer, 1-3
is an active layer, 2 is an insulating film, 3 is a beam lead-shaped Schottky electrode arranged on the surface, 4 is a beam lead-shaped ohmic electrode arranged on the surface, 5 is a Schottky part,
6 is an ohmic part.

A conventional SBD has a structure in which a Schottky portion 5 and an ohmic portion 6 are formed in portions that are etched from the surface.

[Problem that the invention seeks to solve]

In conventional SBDs with the structure described above, in the microwave region, current flows horizontally through the semiconductor layer at a depth of several tens of micrometers due to the skin effect, and resistance components such as diffusion resistance become large. There was a problem.

It is an object of the present invention to solve the above-mentioned problems and provide a device in which resistance components such as spread resistance do not become large even in the microwave region.

[Means for solving problems]

In order to achieve the above object, the SBD of the present invention is made by etching the ohmic part not on the side of the Schottky part but on the back surface of a certain area directly under the Schottky part until a thin Epi layer called a buffer layer remains. It is formed on the etched surface.

[Embodiments of the invention]

FIG. 1 is a schematic sectional view showing the structure of an embodiment of the present invention;
FIG. 2 is a schematic cross-sectional view showing an example of the manufacturing method of the embodiment shown in FIG. 1, in which the same reference numerals as those in FIG. be.

A beam lead 3 of a Schottky electrode with a Schottky part 5 formed between the surface of the active layer 1-3 and a beam having a structure similar to the conventional one but with a part reaching into the buffer layer 1-2. A resist layer 7 mask as shown in the figure is formed on the back side of the wafer on which the leads 4 have been provided, and the buffer layer 1-2 of the beam lead 4 is placed at a depth from the back side of the wafer.
Etching is performed until a portion of the beam lead 4 that reaches inside is exposed and a thin buffer layer 1-2 remains (in this case, the etching stop depth can be checked at the portion of the beam lead 4 that reaches inside the buffer layer). Next, an ohmic metal (for example, AuGe/Ni/Au for GaAs) is deposited and lifted off at the peripheral edge of the resist layer 7, and the resist 7 and unnecessary deposited metal on the resist 7 are removed. The buffer layer 1 of the vapor-deposited metal 8 is heat-treated.
Make the connection with 2 ohmic. Since the vapor-deposited metal 8 is connected to the beam lead 4 at the exposed portion, the provided beam lead 4 becomes an ohmic electrode.

Thereafter, each chip is separated by etching to obtain a product having the structure shown in FIG.

In this case, the main part that causes spreading resistance in the microwave region is removed, so the spreading resistance can be kept low.

〔Effect of the invention〕

As explained above, according to the present invention, the beam lead W
In the SBD, the spreading resistance in the microwave region is small, and in the case of a detector, etc., there is an effect that thermal noise caused by the resistance is reduced.

[Brief explanation of the drawing]

FIG. 1 is a schematic sectional view showing the structure of an embodiment of the present invention;
FIG. 2 is a schematic cross-sectional view showing an example of the manufacturing method of the embodiment shown in FIG. 1, and FIGS. 3(a) and (b) are conventional SBDs of this type.
FIG. 2 is a plan view and a schematic sectional view showing the structure of an example. 1-1...Substrate, 1-2...Buffer layer, 1-3-
...Active layer, 2... Insulating film, 3.4... Beam lead, 5... Schottky part, 6... Ohmic part, 7... Resist, 8... Vapor deposited metal. Inside, the same reference numerals indicate the same or corresponding parts. Patent applicant New Japan Radio Co., Ltd. Figure 3

Claims (1)

[Claims] In a Schottky barrier diode that has Schottky electrodes and ohmic electrodes arranged in a beam lead shape on the surface so that it can be directly assembled into a microwave strip line, etching the back surface of a certain area directly under the Schottky part until a thin buffer layer remains. A Schottky barrier diode characterized in that an ohmic portion is formed by vapor-depositing a metal on the etched surface.