Method and structure to improve body effect and junction capacitance

Abstract

A method and structure implant a first-type impurity within a substrate to form a channel region within the substrate adjacent a top surface of the substrate; form a gate stack on the top surface of the substrate above the channel region; and implant a second-type impurity within the substrate to form source and drain regions within the substrate adjacent the top surface. The channel region is positioned between the source and drain regions. The second-type impurity has an opposite polarity with respect to the first-type impurity. The method and structure implant a greater concentration of the first-type impurity, relative to a concentration of the first-type impurity within the channel region, to form a primary body doping region within the substrate below (relative to the top surface) the channel region; and to form secondary body doping regions within the substrate below (relative to the top surface) the source and drain regions.

1 . A method of forming a transistor structure comprising:
 implanting a first-type impurity within a substrate to form a channel region within said substrate adjacent a top surface of said substrate;   forming a gate stack on said top surface of said substrate above said channel region;   implanting a second-type impurity within said substrate to form source and drain regions within said substrate adjacent said top surface, said channel region being positioned between said source and drain regions, said second-type impurity having an opposite polarity with respect to said first-type impurity; and   implanting a greater concentration of said first-type impurity, relative to a concentration of said first-type impurity within said channel region, to form a primary body doping region within said substrate below, relative to said top surface, said channel region; and to form secondary body doping regions within said substrate below, relative to said top surface, said source and drain regions.   
     
     
         2 . The method according to  claim 1 , said implanting of said greater concentration of said first-type impurity causing said secondary body doping regions to be positioned at a greater depth below said top surface of said substrate than said primary body doping region. 
     
     
         3 . The method according to  claim 2 , said greater depth corresponding to an amount said gate stack extends above said top surface of said substrate. 
     
     
         4 . The method according to  claim 1 , said implanting of said greater concentration of said first-type impurity causing said secondary body doping regions to be separated from said source and drain regions by an area of said substrate. 
     
     
         5 . The method according to  claim 1 , said implanting of said greater concentration of said first-type impurity causing said primary body doping region to be positioned between said secondary body doping regions. 
     
     
         6 . A method of forming a transistor structure comprising:
 implanting a first-type impurity within a substrate to form a channel region within said substrate adjacent a top surface of said substrate;   forming a gate stack on said top surface of said substrate above said channel region;   implanting a second-type impurity within said substrate to form source and drain regions within said substrate adjacent said top surface, said channel region being positioned between said source and drain regions, said second-type impurity having an opposite polarity with respect to said first-type impurity;   implanting a greater concentration of said first-type impurity, relative to a concentration of said first-type impurity within said channel region, to form a primary body doping region within said substrate below, relative to said top surface, said channel region; and to form secondary body doping regions within said substrate below, relative to said top surface, said source and drain regions,   said implanting of said greater concentration of said first-type impurity causing said secondary body doping regions to be separated from said primary body doping region by a portion of said substrate, and   said implanting of said greater concentration of said first-type impurity causing said secondary body doping regions to be positioned at a different depth below said top surface of said substrate than said primary body doping region.   
     
     
         7 . The method according to  claim 6 , said implanting of said greater concentration of said first-type impurity causing said secondary body doping regions to be positioned at a greater depth below said top surface of said substrate than said primary body doping region. 
     
     
         8 . The method according to  claim 7 , said greater depth corresponding to an amount said gate stack extends above said top surface of said substrate. 
     
     
         9 . The method according to  claim 6 , said implanting of said greater concentration of said first-type impurity causing said secondary body doping regions to be separated from said source and drain regions by an area of said substrate. 
     
     
         10 . The method according to  claim 6 , said implanting of said greater concentration of said first-type impurity causing said primary body doping region to be positioned between said secondary body doping regions. 
     
     
         11 . A method of forming a transistor structure comprising:
 implanting a first-type impurity within a substrate to form a channel region within said substrate adjacent a top surface of said substrate;   forming a gate stack on said top surface of said substrate above said channel region;   implanting a second-type impurity within said substrate to form source and drain regions within said substrate adjacent said top surface, said channel region being positioned between said source and drain regions, said second-type impurity having an opposite polarity with respect to said first-type impurity; and   implanting a greater concentration of said first-type impurity, relative to a concentration of said first-type impurity within said channel region, to form a primary body doping region within said substrate below, relative to said top surface, said channel region, said primary body doping region being formed to be positioned between said source and drain regions within each said transistor structure; and to form secondary body doping regions within said substrate below, relative to said top surface, said source and drain regions.   
     
     
         12 . The method according to  claim 11 , said implanting of said greater concentration of said first-type impurity causing said secondary body doping regions to be positioned at a greater depth below said top surface of said substrate than said primary body doping region. 
     
     
         13 . The method according to  claim 12 , said greater depth corresponding to an amount said gate stack extends above said top surface of said substrate. 
     
     
         14 . The method according to  claim 11 , said implanting of said greater concentration of said first-type impurity causing said secondary body doping regions to be separated from said source and drain regions by an area of said substrate. 
     
     
         15 . The method according to  claim 11 , said implanting of said greater concentration of said first-type impurity causing said primary body doping region to be positioned between said secondary body doping regions.