Process method and structure for high voltage mosfets

Abstract

This invention discloses a semiconductor power device disposed in a semiconductor substrate. The semiconductor power device comprises a plurality of trenches formed at a top portion of the semiconductor substrate extending laterally across the semiconductor substrate along a longitudinal direction each having a nonlinear portion comprising a sidewall perpendicular to a longitudinal direction of the trench and extends vertically downward from a top surface to a trench bottom surface. The semiconductor power device further includes a trench bottom dopant region disposed below the trench bottom surface and a sidewall dopant region disposed along the perpendicular sidewall wherein the sidewall dopant region extends vertically downward along the perpendicular sidewall of the trench to reach the trench bottom dopant region and pick-up the trench bottom dopant region to the top surface of the semiconductor substrate.

I claim: 
     
         1 . A semiconductor power device disposed in a semiconductor substrate comprising:
 a trench formed at a top portion of the semiconductor substrate extending laterally across the semiconductor substrate along a longitudinal direction wherein the trench further comprises a laterally notch having a laterally notch trench sidewall oriented along a nonlinear direction relative to the longitudinal direction to expose an entire vertical length of the trench sidewall facing the longitudinal direction to receive directly dopant ions projected by a tilted implant along the longitudinal direction to form a full-length sidewall dopant region along the entire vertical length of the notch trench sidewall; and   a trench bottom dopant region disposed below the trench bottom surface and an upper partial sidewall dopant region disposed on an upper portion of the trench sidewalls along the longitudinal direction wherein the full-length sidewall dopant region disposed along the notch trench sidewall extends vertically downward along the intersecting sidewall in the nonlinear portion of the trench to reach the trench bottom dopant region to pick-up the trench bottom dopant region to the top surface of the semiconductor substrate.   
     
     
         2 . The semiconductor power device of  claim 1  wherein:
 the laterally notch trench sidewall extends along a perpendicular direction relative to the longitudinal direction. 
 
     
     
         3 . The semiconductor power device of  claim 1  wherein:
 the trench is padded with an insulation layer covering sidewalls and the trench bottom surface. 
 
     
     
         4 . The semiconductor power device of  claim 1  wherein:
 the trench is padded with an insulation layer covering sidewalls and the trench bottom surface wherein the insulation layer covers the sidewalls and the trench bottom surface having approximately a same thickness. 
 
     
     
         5 . The semiconductor power device of  claim 1  wherein:
 the trench is padded with an insulation layer covering sidewalls and the trench bottom surface wherein the insulation layer covering the sidewalls having a smaller layer thickness than the insulation layer covering the trench bottom surface. 
 
     
     
         6 . The semiconductor power device of  claim 1  wherein:
 the trench is configured to have the laterally notch trench sidewall distributed at designated locations on the entire area of the semiconductor substrate. 
 
     
     
         7 . The semiconductor power device of  claim 1  further comprising:
 a high voltage (HV) MOSFET device. 
 
     
     
         8 . The semiconductor power device of  claim 1  further comprising:
 a high voltage (HV) IGBT device. 
 
     
     
         9 . The semiconductor power device of  claim 1  wherein:
 at least one of the trenches having at least two laterally notch trench sidewalls.