Bidirectional power FET with substrate-referenced shield

[54] BIDIRECTIONAL POWER FET WITH SUBSTRATE-REFERENCED SHIELD

[75] Inventors: Herman P. Schutten, Milwaukee;

James A. Benjamin, Waukesha, both of Wis.; Robert W. Lade, Fort Myers, Fla.

[73] Assignee: Eaton Corporation, Cleveland, Ohio [21] Appl. No.: 421,933 [22] Filed: Sep. 23, 1982

[51] Int. C1.3 H01L 29/78; H01L 29/06;

H01L 29/40

[52] U.S. CI 357/23.4; 357/55;

357/53; 357/23.14; 357/41

[58] Field of Search 357/23 HV, 23 VD, 23 MG,

357/39, 41, 47, 53, 55

[56] References Cited

U.S. PATENT DOCUMENTS

2,994,811 8/1961 Senitzky 357/55

3,629,667 12/1971 Lubart et al 357/39

4,163,988 8/1979 Yeh et al 357/23 VD

4,199,774 4/1980 Plummer 357/41

4,219,835 8/1980 Van Loon 357/53

4,243,997 1/1981 Natori et al 357/22

4,300,150 11/1981 Colak 357/52

4.364.073 12/1982 Becke et al 357/23 VD

4.364.074 12/1982 Garnache et al 357/41

4,414,560 11/1983 Lidow 357/39

4,455,740 6/1984 Iwai 29/571

4,470,062 9/1984 Muramatsu 357/55

FOREIGN PATENT DOCUMENTS

0073585 6/1979 Japan 357/39

2089118 6/1982 United Kingdom 357/23 MG

OTHER PUBLICATIONS

P. Ou-Yang, "Double Ion-Implantation V-MOS Tech.," J. of S-S Ckts., vol. SC-12 #1, Feb. 1977, pp. 3-10.

H. Lee et al., "Short-Channel Field-Effect Transistors

Bidirectional power FET structure is disclosed with high OFF state voltage blocking capability. A shielding electrode is insulated between first and second gate electrodes in a notch between laterally spaced source regions and channel regions joined by a common drift region around the bottom of the notch. The shielding electrode is ohmically connected to the substrate containing the common drift region to be at the same potential level thereof and within a single junction drop of a respective main electrode across the junction between the respective channel containing region and drift region. The steering diode function for referencing the shielding electrode is performed by junctions already present in the integrated structure, eliminating the need for discrete dedicated steering diodes. The shielding electrode prevents the electric field gradient toward the gate electrode on one side of the notch from inducing depletion in the drift region along the opposite side of the notch. This prevents unwanted inducement of conduction channels in the drift region during the OFF state of the FET.

19 Claims, 8 Drawing Figures