Lateral double-diffused MOS transistor devices suitable for source-follower applications

A lateral double-diffused MOS transistor, which comprises:

• a semiconductor substrate of a first conductivity type;
• a first semiconductor layer of a second conductivity type opposite to that of the first on a first major surface of said substrate;
• a second semiconductor layer of said first conductvity type on said first layer;
• a third semiconductor surface layer of said second conductivity type on said second layer, the product of the net doping concentration and the thickness of said first, second and third semiconductor layers each being selected to accordance with the RESURF principle such that the product of doping concentration and layer thickness is typically approximately 10.sup.12 atoms/cm.sup.2 ;
• a first surface-adjoining channel region of said first conductivity type in said third layer and connected to said second semiconductor layer;
• a surface-adjoining source region of said second conductivity type in said channel region;
• a first surface-adjoining drain contact region of said second conductivity type in said third layer and spaced apart from said first channel region;
• an extended drain region formed from a portion of said third layer between said first drain contact region and said first channel region;
• an insulating layer on the surface of said transistor and covering at least that portion of the first surface-adjoining channel region located between said source and said extended drain regions;
• a first gate electrode on said insulating layer, over said portion of the first channel region and electrically isolated from said third layer;
• and
• source and first drain electrodes connected respectively to the source and first drain contact regions of the transistor.