High voltage semiconductor device
First Claim
1. A high voltage semiconductor device comprising a semiconductor body having a barrier-forming means for providing a barrier with a portion of said semiconductor body, and electrode connection means for applying a voltage in excess of 100 volts across said barrier to form a depletion layer extending throughout said portion in at least a high voltage mode of operation, said portion comprising a plurality of first regions of a first conductivity type interleaved with a plurality of second regions of a second conductivity type, said first and second regions extending longitudinally traverse to said barrier, at least said first regions providing electrically parallel current paths extending through said portion transverse to said barrier in at least one mode of operation, said first and second regions being depleted of free charge-carriers across their thickness in said high voltage mode of operation to form interleaved positive and negative space charge regions, said positive and negative space charge regions serving to carry high voltage in excess of 100 volts by said depletion layer spreading from said barrier across said portion when depleted of free charge-carriers, said first and second regions having a length perpendicular to their thickness for carrying a voltage in excess of 100 volts across said portion when depleted of free charge carriers, said first and second regions each having a thickness and doping concentration to balance said space charge per unit area formed in each of said first and second interleaved regions when depleted of free charge-carriers by said depletion layer and carrying said voltage in excess of 100 volts, said space charge per unit area being balanced at least to such an extent that an electric field resulting from said space charge is less than a critical field strength at which avalanche breakdown would occur in said portion.
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Abstract
A field effect transistor, a bipolar transistor, a PIN diode, a Schottky rectifier or other high voltage semiconductor device comprise a semiconductor body having a depletion layer formed throughout a portion in at least a high voltage mode of operation of the device, such as, by reverse biasing a rectifying junction. The known use of a single high-resistivity body portion of one conductivity type to carry both the high voltage and to conduct current results in a series resistivity increasing approximately in proportion with the square of the breakdown voltage. This square-law relationship is avoided by the present invention in which a depleted body portion comprising an interleaved structure of first and second regions of alternating conductivity types carries the high voltage which occurs across the depleted body portion. The thickness and doping concentration of each of these first and second regions are such that when depleted the space charge per unit area formed in each of these regions is balanced at least to the extent that an electric field resulting from any imbalance is less than the critical field strength at which avalanche breakdown would occur in the body portion. The first regions in at least one mode of operation of the device provide electrically parallel current paths extending through the body portion.
564 Citations
49 Claims
- 1. A high voltage semiconductor device comprising a semiconductor body having a barrier-forming means for providing a barrier with a portion of said semiconductor body, and electrode connection means for applying a voltage in excess of 100 volts across said barrier to form a depletion layer extending throughout said portion in at least a high voltage mode of operation, said portion comprising a plurality of first regions of a first conductivity type interleaved with a plurality of second regions of a second conductivity type, said first and second regions extending longitudinally traverse to said barrier, at least said first regions providing electrically parallel current paths extending through said portion transverse to said barrier in at least one mode of operation, said first and second regions being depleted of free charge-carriers across their thickness in said high voltage mode of operation to form interleaved positive and negative space charge regions, said positive and negative space charge regions serving to carry high voltage in excess of 100 volts by said depletion layer spreading from said barrier across said portion when depleted of free charge-carriers, said first and second regions having a length perpendicular to their thickness for carrying a voltage in excess of 100 volts across said portion when depleted of free charge carriers, said first and second regions each having a thickness and doping concentration to balance said space charge per unit area formed in each of said first and second interleaved regions when depleted of free charge-carriers by said depletion layer and carrying said voltage in excess of 100 volts, said space charge per unit area being balanced at least to such an extent that an electric field resulting from said space charge is less than a critical field strength at which avalanche breakdown would occur in said portion.
Specification