Borophosphosilicate glass (BPSG) is an essential insulating material used to modify thecomplex topography of highly dense, next generation dynamic random access memory (DRAM)devices. The shallow junctions in 16 and 64 Meg DRAMs can only be maintained by severely restricting the time, temperature, and atmosphere of all thermal process steps following the junction implant.
In this paper we present the results of rapid thermal process (RTP) assisted reflow of BPSG over complex topographies and compare the results of RTP to furnace reflow in both dry and wet ambients. We also compare the out-diffusion of boron and phosphorous from BPSG films during the RTP and furnace reflow. We found an optimum RTP cycle that completely removes voids in the vicinity of overhang geometries and provides sufficient activation of the underlying dopants (as compared to a furnace reflow and activation cycle). In this study we used the results of boron and phosphorous profile redistribution, underlying dopant activation, and the amount of reflow to compare RTP and furnace processing techniques.