Drain extended MOS transistor with improved breakdown robustness
AssigneeTexas Instruments Incorporated
InventorSameer Pendharkar
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Abstract
A drain-extended metal-oxide-semiconductor transistor (40) with improved robustness in breakdown characteristics is disclosed. Field oxide isolation structures (29c) are disposed between the source region (30) and drain contact regions (32a, 32b, 32c) to break the channel region of the transistor into parallel sections. The gate electrode (35) extends over the multiple channel regions, and the underlying well (26) and thus the drift region (DFT) of the transistor extends along the full channel width. Channel stop doped regions (33) underlie the field oxide isolation structures (29c), and provide conductive paths for carriers during breakdown. Parasitic bipolar conduction, and damage due to that conduction, is therefore avoided.
Claims9
1-17. (canceled)
A method of fabricating a drain-extended transistor, comprising:
- forming a first lightly-doped region of a first conductivity type at a selected location of a semiconductor surface of a body;
- forming a second lightly-doped region of a second conductivity type at a selected location of the semiconductor surface;
- implanting dopant of the first conductivity type into selected locations of the first lightly-doped region;
- forming isolation structures at the selected locations of the first lightly-doped region at which dopant of the first conductivity type is implanted in the implanting step, and an isolation structure at a selected location of the second lightly-doped region;
- forming a gate electrode over the surface, the gate electrode overlapping portions of the isolation structures at selected locations of the first lightly-doped region, and overlapping a plurality of channel regions of the first lightly-doped region disposed between the isolation structures;
- forming a source region at a selected location of the first lightly-doped region;
- and
- forming at least one drain region at a selected location of the second lightly-doped region, the at least one drain region spaced apart from the plurality of channel regions by the isolation structure at the selected location of the second lightly-doped region.
Dependencies are inferred from the claim text.