High power MOSFET with low on-resistance and high breakdown voltage
First Claim
1. 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 surface, disposed at least on said first and second channel regions;
gate electrode means on said gate insulation layer means;
said gate electrode means 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, 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;
said first and second source regions being formed by a process step in which the impurities for defining said first and second source regions are applied to said first and second first surface locations in a single step.
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Abstract
A high power MOSFET is disclosed in which two laterally spaced sources each supply current through respective channels in one surface of a semiconductor chip which are controlled by the same gate. The channels lead from the source electrodes to a relatively low resistivity region and from there to a relatively high resistivity epitaxially formed region which is deposited on a high conductivity substrate. The drain electrode may be either on the opposite surface of the chip or laterally displaced from and on the same side as the source regions. The epitaxially deposited semiconductor material immediately adjacent and beneath the gate and in the path from the sources to the drain has a relatively high conductivity, thereby to substantially reduce the on-resistance of the device without effecting the breakdown voltage of the device. The breakdown voltage of the device is substantially increased by forming a relatively deep p-type diffusion with a large radius in the n-type epitaxial layer beneath each of the sources.
103 Citations
50 Claims
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1. 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 surface, disposed at least on said first and second channel regions; gate electrode means on said gate insulation layer means;
said gate electrode means 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, 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; said first and second source regions being formed by a process step in which the impurities for defining said first and second source regions are applied to said first and second first surface locations in a single step. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25)
- said device comprising;
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26. 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;
said gate electrode means 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; said first and second source regions being formed by a process step in which the impurities for defining said first and second source regions are applied to said first and second first surface locations in a single step. - View Dependent Claims (27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50)
- said device comprising;
Specification