Field controlled thyristor with buried grid
AssigneeGeneral Electric Company
InventorsDouglas E. Houston, Surinder Krishna
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Abstract
A novel grid structure for a field controlled thyristor includes a current controlling grid structure interdigitated with a cathode structure in which the surface area of the cathode structure is substantially greater than that of the grid structure. High forward blocking voltage gain (anode voltage/grid voltage) and low on-state losses in a turn-off type field controlled thyristor are accomplished by providing a surface grid portion and a buried portion which are connected to the surface grid structure and substantially underlies the cathode structure. The buried grid structure is constructed in a manner to provide a high aspect ratio for the channel region.
Claims5
A field controlled thyristor comprising:
- a semiconductor substrate of one type conductivity and having opposed major surfaces;
- a uniform anode injecting region of opposite type conductivity in one of said major surfaces;
- a current controlling grid structure comprising a plurality of surface-adjacent grid regions of opposite type conductivity in the other major surface and a like plurality of buried grid regions contacting said surface-adjacent grid regions, said surface-adjacent regions being of higher conductivity than said buried grid regions;
- a plurality of surface-adjacent cathode regions of one type conductivity in said other major surface and within the interstices of said surface-adjacent grid regions, said surface-adjacent cathode regions having a larger surface area than said surface-adjacent grid regions and a higher conductivity than said substrate;
- and
- wherein each of said buried grid regions are further characterized by having portions extending laterally under adjacent cathode regions and are spaced from the next adjacent buried grid region by a width, b, with each buried grid having a depth, c, the ratio of the depth to the width being in a range of 0.5 to 5.0 and substantially determining the magnitude of the grid-to-cathode voltage required to block substantial current flow from anode to cathode with a given anode-to-cathode voltage for a given substrate resistivity.
Dependencies are inferred from the claim text.