JPS5483779A - Junction type field effect semiconductor device - Google Patents

Abstract

PURPOSE: To reduce a noise voltage low by making mutual conductance (gmo) large and gate diffusion resistance RG small without deteriorating a threshold level and reverse dielectric strength.

CONSTITUTION: In N-type epitaxial layer 12 on P-type substrate 11, P⁺-type substrate extraction layer 13, P⁺-type gate layer 14, N⁺-type drain 15, and N⁺- type source 16 are formed. The places, where a source and drain ar expected to be formed, surrounded with gate layer 14 are shorted to substrate 11 at the same time as the formation of substrate extraction layer 13, so that the gate width for a noise- source resistance will be from substrate extraction layer 13 at the external circumference separating epitaxial layer 12 to the region where a drain or source layer is shorted to the substrate. When this distance is denoted by Z' and the sheet resistance of the gate is by Ps, RG is nearly equal to Ps×Z'/nl, so that RG can be reduced with no special process. In this way, the noise voltage can be reduced without deteriorating Vth and reverse dielectric strength, while gate width z is being made smaller.

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