Rad hard MOSFET with graded body diode junction and reduced on resistance

A radiation-hardened MOSFET comprising:

• a silicon wafer having a flat junction receiving region of a first conductivity type;
• a plurality of channel diffusions having an opposite conductivity type opposite of said first conductivity type and having a given concentration and a given depth positioned such that a space is defined between adjacent channel diffusions;
• a plurality of source diffusion regions of said first conductivity type in each of said channel diffusions, each of the source diffusion regions having boundary regions defining a plurality of respective invertible channel regions between boundary regions of said channel diffusions and said boundary regions of said source diffusions;
• a conductive gate polysilicon segment overlying at least a portion of a non-self-aligned gate oxide overlying each of said respective invertible channel regions and a portion of said source diffusions;
• and
• a plurality of second diffusions of said opposite conductivity type having a depth greater than said given depth and each of the plurality of second diffusions being disposed beneath respective ones of said channel diffusions and having a concentration less than said given concentration such that graded body diode regions are defined.

A vertical conduction MOSFET comprising a silicon wafer having a flat junction receiving region of a first conductivity type;

• a plurality of channel diffusions of an opposite conductivity type and having a boundary region, a given concentration and a given depth;
• a plurality of source diffusion regions of said first conductivity type in each of said channel diffusions and having another boundary region, the region between the boundary region of the channel diffusions and the source diffusions defining a plurality of invertible channel regions a conductive gate polysilicon segment overlying at least a portion of a non-self-aligned gate oxide overlying each of said invertible channel regions a plurality second diffusions of said opposite conductivity type having a depth greater than said given depth and disposed beneath each of said channel diffusions and having a lower concentration than said given concentration of said channel diffusions such that graded body diode regions are defined;
• a plurality of source electrodes in contact with a portion of respective source diffusions and respective ones of said channel diffusions;
• and a drain electrode in contact with a bottom surface of said silicon wafer, opposite of said plurality of source electrodes.