High power MOSFET with low on-resistance and high breakdown voltage

A high power metal oxide silicon field effect transistor device exhibiting relatively low on-resistance and relatively high breakdown voltage;

• said device comprising:
• a wafer of semiconductor material having first and second opposing semiconductor surfaces;
• said wafer of semiconductor material having a relatively lightly doped major body portion for receiving junctions and being doped with impurities of one conductivity type;
• at least first and second spaced base regions of the opposite conductivity type to said one conductivity type formed in said wafer and extending from said first semiconductor surface to a first depth beneath said first semiconductor surface;
• the space between said at least first and second base regions defining a common conduction region of one conductivity type at a given first semiconductor surface location;
• first and second source regions of said one conductivity type formed in each pair of said at least first and second base regions respectively at first and second first surface locations and extending from said first and second first surface locations to a depth less than said first depth;
• said first and second source regions being laterally spaced along said first semiconductor surface from the facing respective edges of said common conduction region thereby to define first and second channel regions along said first semiconductor surface between each pair of said first and second source regions, respectively and said common conduction region;
• source electrode means connected to said source regions;
• gate insulation layer means on said first surface, disposed at least on said first and second channel regions;
• gate electrode means on said gate insulation layer means and overlying said first and second channel regions;
• a drain conductive region remote from said common region and separated therefrom by said relatively lightly doped major body portion;
• a drain electrode coupled to said drain conductive region;
• said common region being relatively highly doped, compared to said relatively lightly doped major body portion and extending from said given first semiconductor surface location to a depth greater than the depth of said source region but less than said first depth of said first and second spaced base regions, whereby resistance to current flow at the junctures between said first and second surface channel regions and said common region and between said common region and said relatively lightly doped major body portion is reduced.