JPS6228787Y2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to improvements in junction field effect transistors.

As shown in FIG. 1, a conventional junction field effect transistor includes a drain region 1, a gate region 2 surrounding the drain region 1, and a source region 3 surrounding the gate region 2, in order to increase the channel width and obtain a high gm. The gate region 2 was bent into a comb-teeth shape.

In such a junction field effect transistor, source and drain contact regions 4 and 5 are provided on the surfaces of the source and drain regions 3 and 1, and gate regions 2 and 2 are formed from the source and drain contact regions 4 and 5.
The path lengths of the source and drain regions 3 and 1 were designed to be approximately equal. However, although such a pattern does not cause any problems when used at low voltage, it is not suitable at all for a high voltage structure. That is, since the region between the drain and gate is used with a reverse bias, the electric field is concentrated at the comb-like tip of the drain contact region 5 of the drain region 1, causing avalanche breakdown.

The present invention has been devised in view of this point, and one embodiment of the present invention will be described in detail with reference to FIG.

As shown in FIG. 2, the junction field effect transistor according to the present invention includes a drain region 11, a gate region 12 surrounding the drain region 11, and a source region 13 surrounding the gate region 12. In order to increase gm and obtain a high gm, the gate region 12 is bent into a comb-like shape. Source and drain contact regions 14 and 15 are provided on the surfaces of the source and drain regions 13 and 11 for contact extraction, and are intertwined with each other in a comb-like shape.

A feature of the present invention lies in the shape of the drain contact region 15. The comb-like protruding tip of the drain contact region 15 is formed short, and the path b in the comb-tooth direction from the tip to the gate region 12 is designed to be longer than the path a in other parts.

The present inventor conducted an experiment using a junction field effect transistor with a channel region resistivity of 8 Ωcm, a substrate resistivity of 30 Ωcm, and a gate region 12 length of 3 μm.
The conventional structure (a = 10μm) had a breakdown voltage of 170V, but the structure of the present invention (a = 10μm, b = 15μm)
m), the withstand voltage was improved to 240V.

As described in detail above, according to the present invention, the path in the comb-like direction from the comb-like tip of the drain contact region where electric fields tend to concentrate to the gate region is made longer than other parts. This is useful because it can improve pressure resistance.

[Brief explanation of the drawing]

FIG. 1 is a plan view for explaining a conventional example, and FIG. 2 is a plan view for explaining the present invention. In FIGS. 1 and 2, half of the figures are omitted because they are symmetrical with dashed lines. 11 is a drain region, 12 is a gate region, 13
is a source region, 14 is a source contact region, 1
5 is a drain contact region.

Claims (1)

[Scope of utility model registration request] In a junction field effect transistor comprising a drain region, a gate region surrounding the drain region, and a source region surrounding the gate region, the gate region is bent into a comb-teeth shape to increase the channel width. Source and drain contact regions are provided on the surface of the drain region, and the source and drain contact regions are intertwined with each other in a comb-like shape, and the path from the comb-like tip of the drain contact region to the gate region is A junction field effect transistor characterized by having a path in the comb tooth direction larger than other parts.