Patent ID: 6159781
Filing Date: 2000-12-12
Classification: H01L

Abstract:
A process for preparing a T-gate structure for use in a semiconductor device, the T gate having a foot in contact with a semiconductor substrate and an enlarged head upon the foot and integral therewith, comprising the steps of:providing a semiconductor substrate; forming surrounding trench insulation regions within said substrate;depositing a dielectric layer overlaying said semiconductor and said surrounding trench insulation regions;etching a first trench within said dielectric layer leaving a dielectric depth of deposition between the bottom of the trench and said substrate which equals the height of the foot of the T-gate;forming sidewall spacers against the walls of said first trench; etching a second trench through the bottom of said first trench to the level of said substrate and forming a second trench in this manner the width of which equals the width of the foot of the T-gate where the formed second trench is centered with respect to said first trench;removing said sidewall spacers;depositing a conductive layer over the structure formed by said dielectric layer, said first trench and said second trench;performing Chemical Mechanical Planarization (CMP) of said deposited conductive layer down to the level of the top of said dielectric layer;etching said dielectric layer to the level of the top of said surrounding trench insulation regions along the left hand side of the left wall of said first trench and the right hand side of the right wall of said first trench further using the downward extensions of said left and right wall of said first trench as the line along which the etching process is extended in a downward direction;forming source and drain within said substrates and on the immediate inside or T-gate side of said surrounding trench insulation regions;performing large angle lightly doped depositions on the T-gate side of said source and drain; andforming salicide across the top of the T-gate structure and the top of said source and said drain.