RESIDUES, POLYCRYSTALLINE SILICON VOIDS, AND ACTIVE AREA DAMAGE WITH THE POLYCRYSTALLINE SILICON BUFFERED LOCAL OXIDATION OF SILICON ISOLATION PROCESS

The effectiveness of various post-field oxidation mask deprocessing se quences has been investigated for the polycrystalline silicon (polysil icon) buffered local oxidation of silicon isolation process. The gener ation of residues is a minor issue when the gate oxide formation is pr eceded by the growth and removal of a sacrificial oxide. For sub-0.5 m um ultralarge scale integration technologies, the development of stres s induced voids in the buffer polysilicon film is a more severe proble m. Stress concentrations that damage both the polysilicon and pad oxid e films at the same location result in pitting of the active areas.