Patent ID: 6559502
Filing Date: 2003-05-06
Classification: H01L

Abstract:
A trench-gate field-effect semiconductor device having a semiconductor body, comprising:source and drain regions of one conductivity type in contact with a surface of the semiconductor body and spaced apart in a first direction by a body region of an opposite conductivity type and a voltage sustaining zone; a plurality of gate structures in respective trenches extending parallel to one another in a second direction perpendicular to said first direction for controlling a conduction channel in channel-accommodation portions of the body region extending along at least parallel side walls of each trench; each gate structure substantially filling its respective trench and being elongate in said first direction between first and second ends of its respective trench, the trench extending through the body region from the source region at a first end to terminate in the voltage sustaining zone at its second end; wherein the voltage sustaining zone comprises a side-by-side arrangement of first regions of the one conductivity type interposed with second regions of the opposite conductivity type in the second direction, both the first and second regions meeting the surface of the semiconductor body and being elongate in said first direction between the body region and the drain region; the respective trenches of the gate structures terminating with their second ends in first regions of the voltage sustaining zone that provide a path for majority charge carriers of the one conductivity type from the channel-accommodation portions of the body region to the drain region when the field-effect device is conducting, the second regions extending from portions of the body region beside the channel-accommodation portions to the drain region; and the dopant concentrations and dimensions of the first and second regions are such that when the zone is depleted of free charge carriers in a non-conducting mode of operation the space charge per unit area in the first and second regions balances at least to the extent that the electric field resulting from the space charge is less than the critical field strength at which avalanche breakdown would occur.