JPH05211176A - Field-effect transistor and manufacture thereof - Google Patents

Abstract

PURPOSE:To prevent a solder from adhering on the surface of an element by a method wherein a scribing region on the surface of an element formation finished semiconductor substrate is etched to form a first metal film to cover the scribing region and its vicinity and the periphery of a second metal film to cover the rear of the substrate is junctioned with the first metal film. CONSTITUTION:A scribing region on the surface of an element formation finished gallium-arsenic substrate 1 is etched and a scribe metal film 2 consisting of a gold plating is formed on this region. Then, the rear of the substrate 1 is etched or ground, is made thin until a flat part of the metal film 2 is exposed and a gold plating is selectively applied to this rear to form a rear metal film 3. Then, the metal film 2 on the scribing region is etched using this metal film 3 as a mask to complete a gallium-arsenic element. The film 2 and 3, to which tweezers come into contact at the time of adhesion of the element to a package, exist on the sides, which are positioned on the rear, of the side surfaces of the gallium-arsenic element, the adhesion area of the element is large, the element hardly exfolitates and a possibility of adhesion of a solder to the element surface is eliminated.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a field effect transistor and a manufacturing method thereof, and more particularly to a high power GaAs field effect transistor for a microwave band and a manufacturing method thereof.

[0002]

2. Description of the Related Art A conventional GaAs field effect transistor will be described with reference to FIG.

A gallium arsenide substrate 1 is covered with a scribe metal 2 formed horizontally from the periphery of the front surface and a back surface metal 3 formed on the back surface.

When a chip (die) is bonded to a package (container) using tweezers, it has a structure for protecting the gallium arsenide substrate 1 which is very brittle and easily broken.

Since both ends of the tweezers are sandwiched, they come into contact with the scribe metal 2 and the back surface metal 3 protruding from the gallium arsenide substrate 1.

[0006]

In FIG. 3, since the scribe metal 2 has a small adhesion area with the gallium arsenide substrate 1, the adhesion is weak. When a force for gripping the chip is applied from both ends, the scribe metal 2 and the back surface metal 3 protruding from the gallium arsenide substrate 1 bend in the back surface direction, and the scribe metal 2 peels off.

Further, when the chip is mounted on the package, the tweezers holding the chip are finely moved to conform the solder and adhere. If the tweezers come into contact with the solder at that time, the place where the tweezers come into contact with the chip is at the same height as the surface of the element, so that there is a problem that the solder comes up through the tweezers and the solder adheres to the surface of the element.

[0008]

In the field effect transistor of the present invention, a scribe region on the surface of a semiconductor substrate on which element formation has been completed is etched, and a first metal film covering the scribe region and its vicinity is formed. The periphery of the second metal film that covers the back surface of the semiconductor substrate is joined to the first metal film.

According to the method of manufacturing a semiconductor device of the present invention, a step of etching a scribe region on the surface of a semiconductor substrate on which elements have been formed and then depositing a first metal film on the scribe region, and a back surface of the semiconductor substrate. Etching to expose the first metal film in the scribe region, selectively depositing a second metal film on the back surface of the semiconductor substrate, and using the second metal film as a mask. And a step of etching the first metal film in the scribe region.

[0010]

EXAMPLE FIG. 1D shows a first example of the present invention.
Will be described.

A scribe metal 2 and a backside metal 3 are horizontally projected on the backside of the gallium arsenide substrate 1.

Next, a manufacturing method of the first embodiment of the present invention will be described with reference to FIGS. 1 (a) to 1 (d).

First, as shown in FIG. 1A, the scribe region of the gallium arsenide substrate 1 on which elements have been formed has a depth of 3 mm.
Etching 0-60 μm. Next, a scribe metal 2 made of gold plating having a thickness of about 1 μm is formed.

Next, as shown in FIG. 1B, the back surface of the gallium arsenide substrate 1 is etched or ground to be thinned until the flat portion of the scribe metal 2 is exposed.

Next, as shown in FIG. 1C, the back surface of the gallium arsenide substrate 1 is selectively plated with gold to a thickness of 10 to 3
A backside metal 3 of 0 μm is formed.

Then, as shown in FIG. 1D, the scribe metal 2 in the scribe region is etched by using the back surface metal 3 as a mask to complete a GaAs field effect transistor.

Next, a second embodiment of the present invention will be described with reference to FIG.

In this embodiment, when the gallium arsenide substrate 1 is thinned, the gallium arsenide 1 in the scribe region has a thickness of 10
Leave ~ 20 μm. Next, the gallium arsenide 1 in the scribe region is selectively etched.

By leaving the gallium arsenide 1 under the scribe region, variations in the etching depth of the scribe region from the surface of the gallium arsenide 1 can be absorbed, so that the condition of the etching precision of the first scribe region is relaxed. It

[0020]

EFFECTS OF THE INVENTION The scribe metal and the back surface metal, which the tweezers contact when the gallium arsenide element is bonded to the package, are on the back surface side of the gallium arsenide element side surface. In addition, the scribe metal has a large adhesion area and the force in the peeling direction is dispersed in terms of shape, so that the scribe metal is difficult to peel off. Further, since the position of contact with the tweezers is lower than the surface of the element and the solder does not easily rise to the surface of the element, there is no risk of the solder sticking to the surface.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a first embodiment of the present invention in process order.

FIG. 2 is a sectional view showing a second embodiment of the present invention.

FIG. 3 is a cross-sectional view showing a conventional field effect transistor.

[Explanation of symbols]

 1 gallium arsenide substrate 2 scribe metal 3 backside metal

Claims (2)

[Claims] 1. A scribe region on the surface of a semiconductor substrate after element formation is etched to form a first metal film covering the scribe region and its vicinity, and a periphery of a second metal film covering the back surface of the semiconductor substrate. A field effect transistor in which is bonded to the first metal film. 2. A step of etching a scribe region on the surface of a semiconductor substrate on which element formation has been completed, and then depositing a first metal film on the scribe region, and etching the back surface of the semiconductor substrate to etch the scribe region of the scribe region. First metal film is exposed, a second metal film is selectively deposited on the back surface of the semiconductor substrate, and the first metal film in the scribe region is masked with the second metal film. And a method of manufacturing a field effect transistor including the step of etching.