Method and apparatus for forming a dielectric film using helium as a carrier gas

Abstract

The present invention relates to the deposition of dielectric layers, and more specifically to a method and apparatus for forming dielectric layers such as borophosphosilicate glass (BPSG) having improved film uniformity, higher deposition rate, superior gap fill/reflow capability, and smoother surface morphology. The method forms a dielectric layer with a process using helium carrier gas that produces substantially less downstream residue than conventional methods and apparatus, thereby reducing the need for chamber cleaning and increasing throughput of processed wafers. The present invention utilizes helium instead of nitrogen as carrier gas in a process for forming a dielectric layer such as BPSG to provide various unexpected benefits. According to one aspect, the present invention forms a dielectric film on a substrate, and prolongs a period between chamber cleanings in a system by using helium which produces substantially less downstream and upstream residue than a process using nitrogen. The method includes introducing a process gas containing silicon, oxygen, and first dopant atoms into the chamber; using helium as the carrier gas in the system; and processing more substrates between cleanings than a process using nitrogen as carrier gas. A further aspect of the invention includes annealing the dielectric films formed on the substrates at a lower temperature than required by the process using nitrogen as carrier gas.