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US 10,593,795 B2Granted
Scheme to align LDMOS drain extension to moat
AssigneeTexas Instruments Incorporated
InventorSeetharaman Sridhar
Life of this patent
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Abstract
An integrated circuit and method having an extended drain MOS transistor, wherein a diffused drain is deeper under a field oxide element in the drain than in a drift region under the gate. A field oxide hard mask layer is etched to define a drain field oxide trench area. Drain dopants are implanted through the drain field oxide trench area and a thermal drain drive is performed. Subsequently, the drain field oxide element is formed.
Claims16
An extended drain metal oxide semiconductor (EDMOS) transistor, comprising:
- a substrate having a surface;
- a drain field oxide element and an adjacent field oxide element extending into the substrate from the surface;
- a gate above the surface and extending partially over the drain field oxide element;
- a drain contact region located between the drain field oxide element and the adjacent field oxide element, the adjacent field oxide element having a bottom surface and a sidewall surface abutting the drain contact region, and the drain contact region abutting the drain field oxide element on a side opposite from the gate;
- a drain region including a drain p-n junction between the drain region and the substrate, wherein under the drain field oxide element the drain p-n junction has a first junction depth below the substrate surface and under the drain contact region the drain p-n junction has a second junction depth below the substrate surface, the first junction depth being greater than the second junction depth, and the p-n junction extending laterally no further than a corner formed by the bottom surface and the sidewall surface of the adjacent field oxide element.
2 more elements
Dependencies are inferred from the claim text.