Insuperjunction with surrounding lightly doped drain region

Abstract

A semiconductor device has a substrate and a lightly doped drain (LDD) region formed in the substrate. A superjunction is formed in the LDD region.

1 . A semiconductor device, comprising:
 a substrate;   a lightly doped drain (LDD) region formed in the substrate; and   a superjunction formed in the LDD region, wherein a portion of the superjunction extends through the LDD region.   
     
     
         2 . The semiconductor device of  claim 1 , further including a MOSFET formed in the substrate to include the LDD region and super junction. 
     
     
         3 . The semiconductor device of  claim 1 , wherein the superjunction includes:
 a first stripe doped with a first type of dopant and extending through the LDD region; and   a second stripe doped with a second type of dopant.   
     
     
         4 . The semiconductor device of  claim 3 , wherein the first stripe includes a width less than a width of the second stripe while the superjunction remains charge balanced. 
     
     
         5 . The semiconductor device of  claim 3 , wherein the first stripe includes a dopant concentration less than a dopant concentration of the second stripe while the superjunction remains charge balanced. 
     
     
         6 . The semiconductor device of  claim 3 , wherein the first stripe includes a first dopant concentration at a first depth in the substrate and a second dopant concentration at a second depth in the substrate. 
     
     
         7 . The semiconductor device of  claim 1 , wherein the superjunction has a length with respect to a surface of the substrate, the superjunction having first and second stripes having opposite dopant types and first and second respective adjacent widths perpendicular to the length with respect to the surface of the substrate. 
     
     
         8 . The semiconductor device of  claim 3 , wherein the first stripe extends farther into the substrate than the LDD region. 
     
     
         9 . The semiconductor device of  claim 3 , further comprising:
 a gate over the substrate, wherein the first stripe is tapered toward the gate.   
     
     
         10 . A semiconductor device, comprising:
 a substrate;   a lightly doped drain (LDD) region formed in the substrate; and   a superjunction formed in the LDD region, wherein the superjunction includes a first stripe extending from a first depth in the substrate to a second depth in the substrate and a second stripe extending from the first depth in the substrate to a third depth in the substrate.   
     
     
         11 . The semiconductor device of  claim 10 , wherein the second depth in the substrate is different from the third depth in the substrate. 
     
     
         12 . The semiconductor device of  claim 10 , further including a gate formed over the substrate with a portion of the LDD region between the superjunction and gate. 
     
     
         13 . The semiconductor device of  claim 10 , wherein the first stripe extends through the LDD and the second stripe is surrounded by the LDD. 
     
     
         14 . The semiconductor device of  claim 13 , wherein the first stripe includes a width less than a width of the second stripe. 
     
     
         15 . The semiconductor device of  claim 13 , wherein the first stripe includes a dopant concentration less than a dopant concentration of the second stripe. 
     
     
         16 . The semiconductor device of  claim 10 , wherein the first stripe includes a dopant concentration gradient. 
     
     
         17 . The semiconductor device of  claim 10 , wherein the first stripe includes a width gradient.