Semiconductor device manufacturing: process – Forming bipolar transistor by formation or alteration of...
Reexamination Certificate
1999-10-29
2001-08-14
Smith, Matthew (Department: 2825)
Semiconductor device manufacturing: process
Forming bipolar transistor by formation or alteration of...
C438S268000, C438S273000, C438S305000, C438S586000
Reexamination Certificate
active
06274451
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a method of fabricating a gate-control electrode for an insulated-gate bipolar transistor (IGBT).
This type of transistor is generally mounted on an integrated-circuit wafer provided with emitter, collector and gate-control electrodes which are soldered to corresponding connection locations of the wafer.
During operation, the gate-control electrode selectively controls the transition of the IGBTs to the closed or open state. It must necessarily be insulated from the emitter and collector electrodes.
BRIEF SUMMARY OF THE INVENTION
The object of the invention is to provide a method of fabricating a gate-control electrode for an IGBT, making it possible, from a plate of electrically conducting material which is covered with an electrically insulating layer and, on one of its large faces, delimits a connection pad intended to be soldered to the gate, to produce a gate-control electrode insulated from the rest of the plate.
It therefore relates to a method of fabricating a gate-control electrode for an insulated-gate bipolar transistor, characterized in that it includes the steps consisting in:
on the connection pad, forming an electrically conductive layer covering the electrically insulating layer;
on the plate, forming an electrically conductive track for supplying the connection pad; and
burying the supply track.
The fabricating method according to the invention may furthermore have one or more of the following characteristics, taken individually or in any technically feasible combination.
the plate is made of an anodized metallic material, in particular aluminium, the electrically conductive layer and the supply track being formed by local metallization of the anodized layer,
the local metallization of the anodized layer is carried out by laser processing,
subsequent to the laser processing of the anodized layer, a layer of metal is deposited on the track which is formed,
it furthermore includes a step consisting in burying the supply track under a second electrically insulating layer,
the step consisting in burying the supply track consists in anodizing the latter,
furthermore, a layer of antioxidant material is deposited on the pad,
the antioxidant material is selected from nickel, chromium, gold, or an alloy of these materials.
REFERENCES:
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patent: 5319237 (1994-06-01), Legros
patent: 5391908 (1995-02-01), Walker et al.
patent: 5404040 (1995-04-01), Hshieh et al.
patent: 5451798 (1995-09-01), Tsuda et al.
patent: 5521406 (1996-05-01), Tserng et al.
patent: 2335953 (1977-07-01), None
patent: 98 02 925 (1998-01-01), None
Patent Abstracts of Japan, vol. 098, No. 006, Apr. 30, 1998; & JP 10 056131 A (Denso corp), Feb. 24, 1998.
Changey Nicolas
Crouzy Sophie
Petitbon Alain
Ranchy Eric
Alstom Holdings
Anya Igwe U.
Smith Matthew
Sughrue Mion Zinn Macpeak & Seas, PLLC
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