Method of Forming Shallow Trench Isolation With Selectively Doped Sidewalls
Original Publication Date: 1988-Jul-01
Included in the Prior Art Database: 2005-Feb-15
A process is disclosed for selectively doping the sidewalls of shallow trenched silicon semiconductors by implanting a dopant into the trench fill material and subsequently outdiffusing the dopant from the trench fill material into the adjacent silicon. This technique provides for a selective and self-aligned doping method. One of the potential device problems encountered in the development of shallow trench isolation (STI) for advanced CMOS process technologies is a high leakage current at the upper corners of the device region bounded by the STI. One technique for reducing this leakage is to form a trench with a relatively shallow slope and/or to form a slight bird's beak at the upper trench corner. Because these techniques result in a relaxation of the isolation groundrules, a reduction in device density results.