Innovative low pressure borophosphosilicate glass processes for nano devices

Abstract

Doping of oxide with phosphorous can trap mobile ions and reduce the re-flow temperature. By adding boron the reflow temperature can be reduced further without excessive phosphorous, which may cause metal corrosion. Borophosphosilicate glass (BPSG) and phosphosilicate glass (PSG) processes are mainly used for premetal dielectric (PMD) applications. In the present study, a new low pressure BPSG process has been developed which can be used for Flash memory and Logic devices. It is shown that films with phosphorus and boron concentrations in the range of 1.85-9.15 elemental wt% are deposited with film thickness 6000 Å BPSG and 100 Torr process has been found to achieve more stable film thickness. Decreasing the deposition pressure from 200 to 100 Torr results in a 50% increase in the deposition rate of twin-wafer SACVD BPSG and has zero effect on film properties. Throughput has been improvement by 20% on SACVD PMD BPSG application.