Low-k SiBN (Silicon Boron Nitride) Film Synthesized by a Plasma-Assisted Atomic Layer Deposition

In this study, SiBN films were prepared by plasma assisted atomic layer deposition (PAALD) using dichlorosilane, boron trichloride and ammonia as source gases. In this material system, the reaction control of boron, silicon and nitrogen is a key issue because nitrogen reacts more readily with boron than with silicon. On the other hand, ammonia radicals created by remote plasma during PAALD enhance the reaction between silicon and nitrogen. Therefore, PAALD enables an enhanced controllability of silicon and boron contents. SiBN films with dielectric constant of 4.45 to 5.47 were applied to buried- contact (BC) spacer instead of SiN films in 70 nm DRAM device, and 12 - 24% reduction of bit-line loading capacitance (CBL) was obtained. Low-k SiBN films using PAALD are promising materials for insulating interlayer such as Si3N4 spacer for future sub-70 nm DRAM devices.