Semiconductor device and method for manufacturing the semiconductor device

Abstract

A semiconductor device which can make the generation of gate parasitic oscillations more difficult than a semiconductor device of the related art is provided. The semiconductor device 10 includes: a drift layer 15 which is constituted of a reference concentration layer 4 and a low concentration layer 3; a gate electrode structure 20; a pair of source regions 8a 8b, a pair of base regions 7a 7b, and depletion-layer extension regions 6a 6b which are formed in the reference concentration layer below the base regions 7a 7b, wherein the depletion-layer extension regions 6a 6b are formed such that a lower surface of the depletion-layer extension region is deeper than a boundary between the low concentration layer 3 and the reference concentration layer 4 and projects into the low concentration layers 3, and a dVDS / dt-decreasing diffusion layer 30 which contains an n-type impurity at a concentration higher than the concentration of the impurity which the reference concentration layer 4 contains and decreases dVDS / dt when the semiconductor device is turned off is formed on a surface of the reference concentration layer 4.

Description

technical field [0001] The present invention relates to a semiconductor device and a manufacturing method thereof. Background technique [0002] Conventionally, there is a semiconductor device that can be miniaturized without increasing the ON resistance of the semiconductor device and has good withstand voltage characteristics (for example, refer to Patent Document 1). Figure 8 It is a sectional view of such a conventional semiconductor device 90 . [0003] The conventional semiconductor device 90 is a power MOSFET such as Figure 8 As shown, it has: a reference concentration layer 4 containing an n-type impurity (first conductivity type impurity) of the first reference concentration and an n-type impurity lower than the first reference concentration provided on the lower surface of the reference concentration layer 4 Drift layer 5 made of low concentration layer 3, the gate electrode (polysilicon layer 11 of gate electrode structure 20) formed by gate insulating film 9 on...

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Problems solved by technology

[0011] However, in the conventional semiconductor device 90, although it is possible to miniaturize the semiconductor device without increasing the ON resistance of the semiconductor device, the switching speed (Switching Speed) becomes fast, so that the circuit is cut off under certain usage conditions. When the parasitic oscillation of the gate is easy to occur, in order to suppress this parasitic oscillation, it may be necessary to change the circuit constant

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