JPH0573262B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a semiconductor device, and particularly to a semiconductor device incorporating a microwave integrated circuit.

[Conventional technology]

Conventionally, thermal limitations have been a problem when attempting to obtain medium or high output characteristics in semiconductor devices incorporating microwave integrated circuits.

FIG. 2 is a cross-sectional view of an example of a conventional microwave integrated circuit.

An internal circuit 2 for microwaves is formed on a semiconductor substrate 1 such as GaAs, and is drawn out to a bonding pad 3. 200~250μ by polishing the semiconductor substrate, etc.
m to improve heat dissipation. Even with this method, only a small output could be obtained.

In order to increase the output, the semiconductor substrate 7 is
The thickness is approximately 100 μm, and PHS (Plated Heat
Attempts were made to improve the heat dissipation effect by forming a heat sink (called a sink) with a thickness of approximately 100 μm using gold plating, etc., but this required a large area for integrated circuits, making it impractical in terms of cost and reliability. .

[Problem that the invention seeks to solve]

In the conventional semiconductor device described above, when GaAs is used for the semiconductor substrate, GaAs has poor thermal conductivity compared to Si, and the dissipation of heat generated from transistors and the like forming the internal circuit becomes a problem. Therefore, with the structure shown in Figure 2, only a small-output microwave integrated circuit can be obtained, and the PHS structure has a large chip area of 2 mm□ to 4 mm□, resulting in high cost and poor reliability. I had a problem with it coming down.

[Means for solving problems]

The semiconductor device of the present invention includes a semiconductor substrate, a microwave internal circuit integrated and formed on the surface of the semiconductor substrate, and a region of the microwave internal circuit dug from the back surface of the semiconductor substrate toward the front surface. a recess for reducing the thickness; an air hole provided around the microwave internal circuit and reaching the surface of the recess;
and a metal layer provided on the surface of the recess.

〔Example〕

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

FIGS. 1a and 1b are a plan view and a sectional view taken along the line A-A' of an embodiment of the present invention.

This embodiment includes a semiconductor substrate 1, a microwave internal circuit 2 integrated and formed on the surface of the semiconductor substrate 1, and a region of the microwave internal circuit 2 dug from the back surface of the semiconductor substrate 1 toward the front surface. , an air hole 4 provided around the microwave internal circuit 2 and reaching the surface of the recess 5 , and a metal layer 6 provided on the surface of the recess 5 . . The substrate thickness in the area where the internal circuit 2 is formed is 50 to 80 μm. The shape of the air hole 4 may be either cylindrical or truncated conical.

In the present invention, the thickness of the semiconductor substrate 1 is maintained at the same thickness at the start of manufacturing, and is not made thinner as explained in FIG. 2. This is because the thicker the chip periphery, the higher the mechanical strength. The recesses may be formed by either wet etching (chemical etching) or dry etching (plasma etching, etc.). At least one air hole 4 shall be provided. In this embodiment, four are provided, but six or eight may be provided.

The semiconductor chip thus produced is mounted in a container using a brazing material.

With the above structure, the thickness of the substrate in the internal circuit part that generates heat is thin, so even if a substrate with poor thermal conductivity such as GaAs is used, the generated heat can be quickly transferred to the metal layer 6. and is dissipated through the metal layer 6 and the brazing material. Furthermore, air heated by heat radiation from the metal layer 6 escapes to the upper part through the air holes 4. Due to these factors, heat dissipation performance is significantly improved.

〔Effect of the invention〕

As explained above, the present invention has an inverted concave shape in which the substrate thickness of the heat generating part is thinner than other parts, the inner surface of the recess is coated with a metal having good heat conduction, and air holes are provided around the heat generating part. Since the heated air is allowed to escape, the heat dissipation performance is greatly improved, which has the effect of providing high-frequency semiconductor devices for medium and high power outputs.The improved heat dissipation performance also improves reliability. It has the effect of improving.

[Brief explanation of drawings]

1A and 1B are a plan view and a sectional view of an embodiment of the present invention, and FIG. 2 is a sectional view of an example of a conventional microwave integrated circuit. DESCRIPTION OF SYMBOLS 1... Semiconductor substrate, 2... Internal circuit, 3... Bonding pad, 4... Air hole, 5... Recessed part,
6...Metal layer.

Claims (1)

[Claims] 1. A semiconductor substrate, a microwave internal circuit integrated and formed on the surface of the semiconductor substrate, and a recess that is dug from the back surface of the semiconductor substrate toward the front surface to reduce the thickness of the region of the microwave internal circuit. A semiconductor device comprising: an air hole provided around the microwave internal circuit and reaching the surface of the recess; and a metal layer provided on the surface of the recess.