LOW-PRESSURE DEPOSITION OF DOPED SIO2 BY PYROLYSIS OF TETRAETHYLORTHOSILICATE (TEOS) .1. BORON AND PHOSPHORUS DOPED FILMS

Borophosphosilicate glass (BPSG) with high dopant levels has been obtained by combining the low pressure TEOS-borosilicate glass (BSG) and phosphosilicate glass (PSG) processes at an optimum deposition temperature of 620 degree C. The process has been improved with regard to uniformity and run-to-run stability by introducing the trimethylborate used for the boron doping from the front end, while the phosphine employed requires a quartz injector. Experiments with BPSG and BSG showed that a void free trench filliing is only feasible for trenches with tapered walls, but a heat-treatment at 900 degree C reduces the cavities to small bubbles in the trench center and planarizes the surface.