ELECTRICAL AND PHYSICAL CHARACTERIZATION OF TETRAETHYLORTHOSILICATE-O-3 BOROPHOSPHOSILICATE GLASS

The reflow properties of tetraethylorthosilicate-O-3 (TEOS-O-3) boroph osphosilicate glass (BPSG) under furnace and rapid thermal processing conditions that we have studied show good void-free, subquarter micron gapfill, and planarization. Thick BPSG films on reflow exhibit positi ve charge buildup at the oxide/Si interface that cause a shift in the flatband voltage. The amount of phosphorous in the BPSG film, the BPSG Nm thickness, and the BPSG deposition temperature determine the exten t of this flatband shift. We observed a linear correlation of the flat band shift and the amount of carbon migration and pileup at the oxide/ Si interface during reflow. Using current-voltage, triangular voltage sweep, and secondary ion mass spectroscopy and field threshold voltage measurements, we demonstrate that under appropriate deposition condit ions the flatband shift can be brought to negligible levels.