Semiconductor device with field threshold MOSFET for high voltage termination
AssigneeAlpha and Omega Semiconductor Incorporated
InventorsHamza Yilmaz, Madhur Bobde
Life of this patent
Estimating the term…
Abstract
This invention discloses a semiconductor power device disposed in a semiconductor substrate comprising a lightly doped layer formed on a heavily doped layer and having an active cell area and an edge termination area. The edge termination area comprises a plurality P-channel MOSFETs. By connecting the gate to the drain electrode, the P-channel MOSFET transistors formed on the edge termination are sequentially turned on when the applied voltage is equal to or greater than the threshold voltage Vt of the P-channel MOSFET transistors, thereby optimizing the voltage blocked by each region.
Claims8
A method for manufacturing a Semiconductor Power device disposed on a semiconductor layer of a first conductivity type comprising an active area and a termination area, the method further comprising:
- forming a power device in the active area and forming a plurality of laterally cascaded MOSFETs in the termination area by forming a plurality of dopant floating guard rings (FGRs) of a second conductivity type each encompassing a heavy dopant region of the second conductivity type to function as drain regions and source regions of the laterally cascaded MOSFETs wherein the drain and source regions disposed in two adjacent FGRs on opposite sides of a gate disposed on a top surface of the semiconductor layer extending over the two adjacent FGRs above a dopant region of the first conductivity type disposed between the two adjacent FGRs and forming the dopant region of the first conductivity type between the two adjacent FGRs to adjust a threshold of turning on the MOSFET for applying a voltage between the source region and the drain region disposed laterally on two opposite sides of the dopant region of the first conductivity type;
- and
- connecting each of the gates of the laterally cascaded MOSFETs to the drain region of the second conductivity type of each of the cascaded lateral MOSFETs functioning as a chain of field threshold MOSFETs in the termination area.
Dependencies are inferred from the claim text.