Semiconductor device

Abstract

A semiconductor device in which a main current flows in a direction of thickness of a semiconductor substrate and which offers satisfactory performance and breakdown voltage and also satisfactory mechanical strength of the semiconductor substrate, and which needs no inconvenient control of the exposure system etc. during a photolithography process. The semiconductor device has a semiconductor substrate having a first main surface, a second main surface opposite to the first main surface, and a recess defined in the second main surface by side surfaces and a bottom surface. A semiconductor region is provided in the bottom surface of the recess of the semiconductor substrate, semiconductor regions are provided in the surface of a peripheral region on the second main surface side, and insulating films are provided on the side surfaces of the recess to electrically insulate the semiconductor regions.

Description

TECHNICAL FIELD [0001] The present invention relates to a semiconductor device, and particularly to a semiconductor device in which the main current flows in the thickness direction of the semiconductor substrate. BACKGROUND ART [0002] In general, in a semiconductor device in which the main current flows in the direction of the thickness of the semiconductor substrate, the breakdown voltage increases as the semiconductor substrate thickness increases to a certain thickness determined by the resistivity of the substrate; the breakdown voltage becomes substantially fixed at the certain thickness or more. On the other hand, increasing the semiconductor substrate thickness increases the on-state resistance, which increases power dissipation and deteriorates performance. [0003] Thus, with a semiconductor device in which the main current flows in the thickness direction of the semiconductor substrate, the optimum substrate thickness is determined in consideration of the balance between pe...

AI Technical Summary

Benefits of technology

[0009] An object of the invention is to provide a semiconductor device in which a main current flows in the thickness direction of the semiconductor substrate and which offers satisfactory performance and breakdown voltage and also satisfactory mechanical strength of the semiconductor substrate, and which needs no inconvenient control of the exposure system etc. during photolithography process.

[0011] According to the first aspect of the semiconductor device of the invention, the first thickness, for example, can be set so that the semiconductor wafer is less likely to crack or break during manufacturing and so that no special focal depth control is needed for the exposure system etc.; this reduces occurrence of defects during manufacturing and reduces the manufacturing cost, and offers a semiconductor device achieving a balance between the reduction of on-state resistance and the sustainment of breakdown voltage.

[0013] According to the second aspect of the semiconductor device of the invention, the first thickness, for example, can be set so that the semiconductor wafer is less likely to crack or break during manufacturing and so that no special focal depth control is needed for the exposure system etc.; this reduces occurrence of defects during manufacturing and reduces the manufacturing cost, and offers a semiconductor device achieving a balance between reducing the on-state resistance and keeping the breakdown voltage. Furthermore, filling the at least one recess with a conductor layer enhances the mechanical strength of the semiconductor substrate and facilitates handling of the semiconductor substrate during semiconductor device manufacturing process.

Problems solved by technology

On the other hand, increasing the semiconductor substrate thickness increases the on-state resistance, which increases power dissipation and deteriorates performance.

There is an optimum substrate thickness also from the viewpoint of photolithography process, since, if the semiconductor substrate is extremely thin, then existing exposure systems etc. need focal depth control during formation of a given pattern by photolithography on the semiconductor substrate, causing great inconvenience.

Use of epitaxial-growth substrates is proposed in order to satisfy these conditions, but thickening epitaxial-growth layers takes time and increases cost.

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