Active solid-state devices (e.g. – transistors – solid-state diode – Field effect device – Having insulated electrode
Reexamination Certificate
2006-01-31
2006-01-31
Pham, Long (Department: 2814)
Active solid-state devices (e.g., transistors, solid-state diode
Field effect device
Having insulated electrode
C257S329000, C257S331000, C257S341000
Reexamination Certificate
active
06992352
ABSTRACT:
This invention describes a process for making a high density trench DMOS (Double-diffused Metal Oxide Semiconductor) transistor with improved gate oxide breakdown at the three-dimensional trench corners and better body contact which can improve the latch-up immunity and increase the drive current. A guard-ring mask is used to define a deep body to cover the three-dimensional trench corners, which can prevent early gate-oxide breakdown during the off-state operation. Another function of the guard-ring mask is to define self-aligned deeper trenches at the terminations of the trenches. The deeper trenches at the terminations of the trenches will result in thicker gate oxide grown at the terminations. This layer of thicker oxide is used to prevent the pre-mature gate oxide breakdown at the three-dimensional trench corners. A trench spacer is formed after the N-body drive-in step by depositing a layer of oxide and then followed by an oxide etch-back step. This spacer is used to prevent any unwanted impurities to penetrate through the trench sidewall and get into the device channel during the high dosage source implantation step.
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Lai Tommy Mau Lam
Sin Johnny Kin On
Analog Power Limited
Buchanan & Ingersoll PC
Louie Wai-Sing
Pham Long
LandOfFree
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