Single mask trench fred with enlarged Schottky area

Details Single mask trench fred with enlarged Schottky area Single mask trench fred with enlarged Schottky area

2002-04-25

2003-12-02

Utech, Benjamin L. (Department: 1765)

Semiconductor device manufacturing: process

Chemical etching

Combined with coating step

C438S700000, C438S723000, C438S724000, C438S743000, C438S744000

Reexamination Certificate

active

06656843

ABSTRACT:

FIELD OF THE INVENTION
This invention relates to fast recovery diodes and more specifically relates to a single mask process for the manufacture of a fast recovery diode with an increased Schottky diode area with a trench topology.
BACKGROUND OF THE INVENTION
The manufacture of fast recovery diodes with trench topology now requires the use of plural mask steps and have a relatively small Schottky diode area relative to the die or chip area.
It would be desirable to provide a fast recovery diode having an enlarged Schottky area for a lower forward voltage drop and to make the device with a reduced number of masks steps, preferably a single critical step.
BRIEF SUMMARY OF THE INVENTION
In accordance with the invention a novel fast recovery diode is made with a single critical mask step which defines a trench etch region. A locos-type process is also employed to enable the selective removal of nitride in the active area before metallization. In the resulting device, the bottoms of the trenches receive a local P type diffusion, producing small P-N junctions at each trench, while the full trench walls and the mesas between trenches receive a Schottky-forming metal.


REFERENCES:
patent: 5637898 (1997-06-01), Baliga
patent: 5726094 (1998-03-01), Schwalke et al.
patent: 6229181 (2001-05-01), Kravtchenko et al.
patent: 6235609 (2001-05-01), Sengupta et al.
patent: 6475875 (2002-11-01), Hau et al.
patent: 6566708 (2003-05-01), Grover et al.

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