Design and fabrication of rugged FRED, power MOSFET or IGBT
AssigneeMicrosemi Corporation
InventorsShanqi Zhao, Dumitru Sdrulla
Life of this patent
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Abstract
An improved Fast Recovery Diode comprises a main PN junction defining a central conduction region for conducting high current in a forward direction and a peripheral field spreading region surrounding the central conduction region for blocking high voltage in the reverse direction. The main PN junction has an avalanche voltage equal to or lower than an avalanche voltage of the peripheral field spreading region so substantially the entire said main PN junction participates in avalanche conduction. This rugged FRED structure can also be formed in MOSFETS, IGBTS and the like.
Claims8
A MOS gate-controlled power device having enhanced avalanche ruggedness, the device comprising:
- a semiconductive substrate including a first layer (112, 213) having a doping type of a first polarity in a first concentration (N+);
- a second layer (114, 214) having a doping type of the first polarity in a second concentration (N) less than the first concentration;
- a body region (122, 322) formed in the second layer having a doping type of a second polarity opposite the first polarity in a third concentration (P);
- a first enhanced region (222, 422) formed in the body region having a doping type of the second polarity in a fourth concentration (P+) greater than the third concentration;
- a source region formed in a portion of the body region adjoining the enhanced region (222, 422) and body region (122, 322) having a doping type of the first polarity in a fifth concentration (N+) greater than the second concentration;
- an insulated gate structure formed on a surface of the second layer in position to overlie a channel portion of the body region extending along the surface between the source region and a drift region of the second layer;
- and
- a second enhanced region (120, 220) of the doping type of the first polarity in a sixth concentration (N+) greater than the second concentration (N);
- the body region extending to a first depth and the first enhanced region extending to a second depth within the second layer to form a PN junction therewith;
- and
- the second enhanced region extending to a third depth within the second layer, the third depth exceeding both the first depth and the second depth so that avalanche breakdown occurs in the first enhanced region.
Dependencies are inferred from the claim text.