Investigation of Phosphorus Spin on Dopant on SOI Wafer

Abstract

Silicon on insulator (SOI) wafer has allowed the integrated circuit (IC) industry to create superior, high-performance solutions. In addition, doping techniques are vital in the silicon sector due to the need to regulate the material electrical properties. The spin on dopant (SOD) approach is an alternative method that involves spinning a solution containing dopant onto SOI wafers. This research aims to determine the impact of thermal diffusion temperature and soaking time on sheet resistance of doped SOI wafer using SOD approach. Additionally, the homogeneity of doping was studied by utilizing mapping techniques. Three inches boron-doped SOI wafers were cut and cleaned according to Radio Corporation of America (RCA) standards. N-type dopants of Filmtronics SOD P509 were deposited on SOI wafer by using a spin coater, for 40 seconds at 4,000 revolutions per minute (rpm). The thermal diffusion temperature and soaking time were set between 700°C to 1000°C for 30 to 120 minutes. After thermal diffusion, hydrofluoric acids (HF) were diluted and used to etch samples. All materials were evaluated using a four-point probe, Hall Effect and Atomic Force Microscope (AFM). The results show that when the thermal diffusion soaking time increases, sheet resistance decreases until activated dopants are saturated. When sheet resistance decreases, dopant concentration rises. Temperature and soaking time increase carrier density and surface roughness, while decreasing Hall mobility. From mapping techniques, it shows low non-uniformity value which less than 10% suggests good thermal diffusion control.