Patent ID: 9478640
Filing Date: 2016-10-25
CPC Classification: H01L

Claim Text:
1. A laterally diffused metal oxide semiconductor (LDMOS) device comprising: a substrate having a first type of conductivity; a drift region having a second type of conductivity and being formed in the substrate; a doped region having the first type of conductivity and being formed in the substrate, the doped region being laterally adjacent to the drift region; a drain region having the second type of conductivity and being formed in the drift region, the drain region being located at an end of the drift region farthest from the doped region; and a buried layer having the first type of conductivity and being formed in the drift region, the buried layer continuously extending along a straight line in a direction from the drain region to the doped region and having an end in close proximity to the drain region, the buried layer having a continuous and substantially flat upper surface along the straight line and a step-like bottom surface, and wherein a maximum depth of the buried layer decreases progressively along the straight line in the direction from the drain region to the doped region.