Active solid-state devices (e.g. – transistors – solid-state diode – Field effect device – Having insulated electrode
Reexamination Certificate
2005-05-03
2005-05-03
Nelms, David (Department: 2818)
Active solid-state devices (e.g., transistors, solid-state diode
Field effect device
Having insulated electrode
C257S328000, C257S329000, C257S331000, C438S259000, C438S270000, C438S271000, C438S589000
Reexamination Certificate
active
06888196
ABSTRACT:
In a vertical MOSFET comprises: a semiconductor layer (1, 2, 9, 10) having first and second surfaces opposite to each other and trenches (6) formed on the first surface; trench gates (8) formed in the trenches; a unit cell formed in a region of the semiconductor layer surrounded by the trench gates, the unit cell comprising a base layer (9) and a source layer (10) formed on the base layer and having the first surface as a principal semiconductor surface, the unit cell having a contact hole (12) formed on a center of the principal semiconductor surface and extending from the principal semiconductor surface through the source layer to an inside of the base layer; a contact (17) formed in the contact hole; a source electrode (18) formed on the contact; and a drain electrode (19) formed on the second surface, the contact is formed to a depth different to a peak depth which is a position having a maximum impurity-concentration in a depth direction of the base layer. The unit call further comprises a base contact layer (14) formed within the base layer so as to enclose a bottom of the contact and to bring the base contact layer into contact with the bottom of the contact.
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B. Jayant Baliga, “Power Semiconductor Devices,” Chapter 7, PWS Publishing Company, 1996, pp. 367-373.
Satoshi Matsumoto et al., “A High-Performance Self-Aligned UMOSFET with a Vertical Trench Contact Structure,” IEEE Transactions on Electron Devices , V. 41, 1994, pp. 814-818.
Akihiko Osawa et al., “2.5V-Driven Nch 3rd Generation Trench Gate MOSFET,” Proceedings of International Symposium on Power Semiconductor Devices and ICs, IEEE, 1999, pp. 209-212.
Sang-Gi Kim et al., “Trench Corner Rounding Technology Using Hydrogen Annealing for Highly Reliable Trench DMOSFETs,” Proceedings of International Symposium on Power Semiconductor Device and ICs, IEEE, 2000, Catalog No.: 00CH37094C, pp. 87-90.
Huynh Andy
NEC Electronics Corporation
Nelms David
Young & Thompson
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