JPS6380555A - Semiconductor device - Google Patents

Abstract

PURPOSE:To improve the mechanical strength of a semiconductor substrate by partly selectively reducing the thickness of a semiconductor substrate directly under a heat generating element, such as a transistor, and forming a structure having a metal layer having good thermal conductivity at a part in which the substrate is thinly removed. CONSTITUTION:A semiconductor substrate 1 directly under a heat generating element 4, such as a transistor is partly selectively thinly removed, and a metal layer 3 formed by plating with good thermal conductivity is formed at the removed part. The layer 3 is electrically or thermally connected by a metal layer 6 for plating conduction pass. The substrate 1 and the layer 3 are further electrically and thermally secured to an element vessel 5 by a bonding metal layer 2. The heat generated from the element 4 is partly dissipated through air, but mostly transmitted through a semiconductor substrate and the metal layer having good thermal conductivity to the vessel. Thus, the mechanical and thermal strength of the whole substrate are improved to reduce a thermal resistance.

Description

Detailed Description of the Invention [Industrial Application Field] The present invention relates to a heat dissipation structure for a semiconductor device, and in particular, the present invention relates to a heat dissipation structure for a semiconductor device, and in particular to a method for dissipating heat generated from a heat generating element such as a high output transistor on the upper surface of a semiconductor substrate to the lower surface of the semiconductor substrate. The present invention relates to a structure that improves the electrical characteristics and reliability of a semiconductor device by lowering the thermal resistance from the heating element to the element container when dissipating heat to the element container in which the semiconductor device is individually attached.

[Conventional technology]

Conventionally, in this type of semiconductor device, as shown in FIG. 2, heat generated by a heat generating element 4 such as a transistor on the upper surface of a semiconductor substrate 1 is efficiently radiated to an element container 5 through the lower surface of the semiconductor substrate 1. The entire lower surface of the semiconductor substrate 1 is shaved thinly, and a metal layer with good thermal conductivity is formed on the entire lower surface of the thinned semiconductor substrate 1 to lower the thermal resistance from the heating element to the element container.

[Problem that the invention seeks to solve]

In the conventional semiconductor device described above, the entire bottom surface of the semiconductor substrate is shaved to a thickness of 20 to 40 μm, which significantly deteriorates the mechanical and thermal expansion strength of the semiconductor substrate, resulting in poor reliability and handling properties of the semiconductor device. There are drawbacks to doing so.

Furthermore, from the same point of view, it has been considered difficult to reduce the thickness of a semiconductor substrate to 20 μm or less.

In addition, it has the disadvantage that it cannot be used in semiconductor devices constituting integrated circuits or the like that require a large area semiconductor substrate due to mechanical and thermal reliability.

[Means for solving problems]

In the semiconductor device of the present invention, the heat generated from the heat generating element on the upper surface of the semiconductor substrate is removed by selectively removing a thin layer of the semiconductor substrate immediately below the heat generating element, and forming a metal layer with good thermal conductivity in the area where the semiconductor substrate is removed. The heat dissipation structure improves the thermal resistance up to the element container, and the semiconductor substrate is partially thinly removed, improving the mechanical and thermal strength and reliability of the entire semiconductor substrate. The thickness of the semiconductor substrate can be reduced to several micrometers, the thermal resistance can be reduced compared to conventional semiconductor devices, and the structure can be applied to large-area semiconductor substrates.

[Embodiment] Next, the present invention will be explained with reference to the drawings. Fig. 1 is a sectional view of an embodiment of the present invention.

The heat generating element 4 such as a transistor is located on the upper surface of the semiconductor substrate 1. The semiconductor substrate 1 immediately below the heat generating element 4 is partially selectively removed thinly, and the removed portion is plated with good heat conductivity, etc. There is a metal layer 3 according to Further, the metal layer 3 is electrically or thermally connected by a plating conductive bus metal layer 6. Furthermore, the semiconductor substrate 1 and the metal layer 3 are
It is electrically and thermally fixed to the element container 5 by the adhesive metal B2.

A portion of the heat generated by the heating element 4 is radiated through the air, but most of the heat is transmitted to the element container through the thinned semiconductor substrate and through the gold layer with good thermal conductivity. At that time, due to the thickness of the semiconductor substrate, which has relatively poor thermal conductivity,
A thermal resistance characteristic of the semiconductor device is determined. Furthermore, since the semiconductor substrate has the weakest mechanical and thermal strength in a semiconductor device, the reliability becomes worse as the area of the thinner portion of the semiconductor substrate increases. In the semiconductor device of the present invention, the thickness of the semiconductor substrate directly under the heating element is thin, and the area of the thin portion of the semiconductor substrate is reduced.

〔Effect of the invention〕

As described above, the present invention provides a structure in which a semiconductor substrate directly under a heat generating element such as a transistor is partially thinned, and a metal layer with good thermal conductivity is provided in the thinly removed portion of the semiconductor substrate. This has the effect of improving the mechanical strength of the semiconductor substrate and improving the reliability and handling of the semiconductor device. It also has the advantage that it can be applied to semiconductor devices such as integrated circuits and monolithic circuits that require large area semiconductor substrates.

Furthermore, the thickness of the semiconductor substrate directly under the heating element can be reduced from 20 μm, which was the limit of conventional semiconductor devices, to several μm, which has the effect of improving the thermal resistance characteristics of the semiconductor device.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of an element of a semiconductor device according to the present invention. FIG. 2 is a sectional view of a conventional example. 1... Semiconductor substrate, 2... Metal layer for adhesion. 3...Metal layer with good thermal conductivity such as plating. 4... Heat generating element such as a transistor. 5... Element container, 6... Metal layer for plating conduction path. Agent: Patent Attorney Susumu Uchihara, 't゛゛a,

Claims (1)

[Claims] It has a heat generating element such as a transistor on the top surface of the semiconductor substrate,
A semiconductor device in which the semiconductor substrate directly under the heating element has a thin region by selectively removing it from the lower surface side, and a metal layer having good thermal conductivity is provided in the portion where the semiconductor substrate is removed.