JPH04365331A - Semiconductor device - Google Patents

Abstract

PURPOSE:To reduce the occurrence of short inferiority by forming a metallic part for earth so that the top may be in the position lower than the respective tops of a drain pad and a gate pad. CONSTITUTION:A drain pad 1 and a gate pad 2 are made on one main surface of a semiconductor substrate 6 such as GaAs, etc., and it has a metallic part 4 for earth which surrounds a drain pad 1 and a gate pad 2 around the substrate 6 being processed lower than that face. Accordingly, the metallic part 4 for earth is made in the position lower than the drain pad 1 and the gate pad 2. Hereby, when connecting the drain pad 1 and the gate pad 2 to the outside terminal such as the strip lies, etc., on a package by a bonding wire, the interval between the bonding wire and the metallic part 4 for earth can be secured enough, and the occurrence of the short inferiority by the contact with the metallic part for earth can be reduced.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor device, and more particularly to a semiconductor device having a semiconductor substrate in which a grounding metal portion is formed around a drain pad and a gate pad, such as a gallium arsenide FET for high frequency power amplification. .

0002

[Prior art] Gallium arsenide FET for high frequency power amplification
These semiconductor devices have a PHS structure in which a substrate of a semiconductor such as gallium arsenide is lined with a metal layer to serve as a heat sink.

As shown in FIG. 2, a conventional semiconductor device of this type has a drain pad 1 and a gate pad 2 formed on one main surface of a substrate 6 made of a semiconductor such as gallium arsenide.
It had a grounding metal part 4 surrounding the drain pad 1 and the gate pad 2. The height from the top surface of the substrate 6 to the top surface of the grounding metal part 4 was approximately the same as the height to the top surfaces of the drain pad 1 and gate pad 2, respectively. Further, since the source pad 3 is used with a grounded source, the source pad 3 is connected to a grounding metal part 4.

[0004] The drain pad 1 and the gate pad 2 are connected to external terminals such as strip lines on the package by bonding wires 7 across the upper surface of the grounding metal part 4. Generally, in order to improve the high frequency characteristics of this type of semiconductor device, it is required that the bonding wire 7, which serves as unnecessary impedance, be made as short as possible. In addition, in addition to prioritizing high-frequency characteristics for the package, the height of external terminals such as strip lines is set lower than drain pad 1 and gate pad 2, considering productivity and compatibility with the user's circuit. design was often adopted.

[0005]

[Problems to be Solved by the Invention] In the conventional semiconductor device described above, when connecting the drain pad and gate pad to external terminals such as strip lines on the package using bonding wires, it is necessary to make the bonding wires as short as possible. Furthermore, when the external terminal of a strip line or the like is located at a low position, it often comes into contact with an intermediate grounding metal part, resulting in a short circuit failure.

[0006]

[Means for Solving the Problems] A semiconductor device of the present invention includes:
In a semiconductor device having a semiconductor substrate in which a grounding metal portion is formed around a drain pad and a gate pad, the top surface of the grounding metal portion is located at a position lower than the respective top surfaces of the drain pad and the gate pad. It is to be formed.

[0007]

Embodiments Next, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 shows an embodiment of the semiconductor device of the present invention, in which (A) is a plan view and (B) is a schematic cross-sectional view taken along the line AB.

As shown in FIG. 1, the semiconductor device of this embodiment has a drain pad 1 and a gate pad 2 formed on one main surface of a semiconductor substrate 6 made of gallium arsenide or the like, and is processed to be lower than that surface. A grounding metal portion 4 surrounding the drain pad 1 and gate pad 2 is provided around the substrate 6 . Therefore, ground metal portion 4 is formed at a lower position than drain pad 1 and gate pad 2. Further, since the source pad 3 is used with a grounded source, the source pad 3 is connected to a grounding metal part 4.

Next, a method for forming the structure of the semiconductor device of this embodiment will be explained.

FIGS. 3A to 3D are schematic partial cross-sectional views of a part of a wafer showing an example of the manufacturing process of the semiconductor device of this embodiment. First, in (A), the chip boundary 6
The entire substrate 6, including the source pad 3, is masked with a photoresist 5, leaving about 50 μm around the periphery of the substrate 6, which will become the source pad 3. Next, as shown in (B), etching is performed to a depth of approximately 10 μm. Next, as shown in (C), the photoresist 5 is removed, and the entire substrate 6 other than the peripheral area where the grounding metal part 4 is formed and the boundary 61 are covered with a second photoresist 51. Mask with resist 5. At this time, a portion of about 5 μm at the tip of the source pad 3 is not masked because it is connected to the grounding metal portion 4. Next, as shown in (D), a metal layer such as gold is grown to a thickness of about 2 μm. After removing the photoresist 51, the wafer is attached to a quartz plate, the scribe portion is etched from the back surface, and a metal layer is grown on the back surface, thereby processing the back surface. After processing the back side, separate each chip.

As described above, the grounding metal portion 4 is formed at a position approximately 10 μm lower than the surface where the drain pad 1 and gate pad 2 are located.

[0013]

As explained above, in the semiconductor device of the present invention, the upper surface of the grounding metal part is formed at a lower position than the upper surfaces of the drain pad and the gate pad, so that the drain pad and the gate pad are lower than each other. When connecting the gate pad to an external terminal such as a strip line on the package using a bonding wire, a sufficient distance is secured between the bonding wire and the grounding metal part.
This has the effect of greatly reducing the risk of contact with a grounding metal part and causing a short circuit.

[Brief explanation of drawings]

FIG. 1 is a plan view and a schematic cross-sectional view showing an embodiment of a semiconductor device of the present invention.

FIG. 2 is a plan view and a schematic cross-sectional view showing an example of a conventional semiconductor device.

FIG. 3 is a schematic partial cross-sectional view of a part of a wafer showing an example of the manufacturing process of the semiconductor device of this example.

[Explanation of symbols]

1 Drain pad 2 Gate pad 3 Source pad 4 Metal part for grounding 5,51 Photoresist 6 Board 61 Boundary

Claims (1)

[Claims] 1. In a semiconductor device having a semiconductor substrate in which a grounding metal portion is formed around a drain pad and a gate pad, the upper surface of the grounding metal portion is higher than the respective upper surfaces of the drain pad and the gate pad. A semiconductor device characterized in that it is formed at a low position.