Structure and method for collar self-aligned to buried plate

Abstract

A structure and method are provided for forming a collar surrounding a portion of a trench in a semiconductor substrate, the collar having a lower edge self-aligned to a top edge of a buried plate disposed adjacent to a lower portion of the trench.

1 - 15 . (canceled)  
   
   
       16 . A structure including a capacitor formed along a sidewall of a trench in a semiconductor substrate, the structure including a collar surrounding a middle portion of the trench, the collar having a lower edge self-aligned to a top edge of a buried plate disposed adjacent to a lower portion of the trench.  
   
   
       17 . A structure as claimed in  claim 16 , wherein the collar consists essentially of an oxide.  
   
   
       18 . A structure as claimed in  claim 17 , wherein the structure further includes a transistor having a channel region formed in the semiconductor substrate, the transistor having a conductive connection to the capacitor.  
   
   
       19 . A structure as claimed in  claim 18 , wherein the channel region of the transistor extends vertically along a sidewall of the trench above the collar.  
   
   
       20 . A structure as claimed in  claim 17 , wherein the buried plate is doped with arsenic.  
   
   
       21 . A structure formed inside a semiconductor substrate, said structure comprising: 
 a trench;    a capacitor formed along a sidewall of said trench; and    a collar surrounding a middle portion of said trench, said collar having a lower edge, said lower edge being self-aligned to a top edge of a buried plate disposed adjacent to a lower portion of said trench.    
   
   
       22 . The structure according to  claim 21 , wherein said collar consists essentially of an oxide.  
   
   
       23 . The structure according to  claim 22 , further comprising a transistor having a channel region formed in the semiconductor substrate, the transistor having a conductive connection to the capacitor.  
   
   
       24 . The structure according to  claim 23 , wherein the channel region of the transistor extends vertically along a sidewall of the trench above the collar.  
   
   
       25 . The structure according to  claim 22 , wherein the buried plate is doped with arsenic.  
   
   
       26 . A semiconductor device formed in a substrate, said semiconductor device comprising: 
 a trench filled at least partially with a conductive material;    a capacitor formed around a lower portion of said trench; and    a collar formed above said lower portion of said trench, said collar having a lower edge, said lower edge being self-aligned to a top edge of a buried plate disposed adjacent to said lower portion of said trench.    
   
   
       27 . The semiconductor device according to  claim 26 , wherein said buried plate is doped with arsenic.  
   
   
       28 . The semiconductor device according to  claim 27 , wherein said capacitor comprises said buried plate, said conductive material filling said trench, and a layer of dielectric material being disposed between said buried plate and said conductive material.  
   
   
       29 . The semiconductor device according to  claim 26 , wherein said collar consists essentially of an oxide.  
   
   
       30 . The semiconductor device according to  claim 26 , further comprising a transistor having a channel region formed in the semiconductor substrate, said transistor having a conductive connection to the capacitor.  
   
   
       31 . The semiconductor device according to  claim 30 , wherein said channel region of said transistor extends along a sidewall of said trench above said collar.  
   
   
       32 . The semiconductor device according to  claim 31 , wherein said transistor has a gate conductor, said gate conductor being isolated from said capacitor by a trench top oxide.