Characterization of atom diffusion in polycrystalline Si/SiGe/Si stacked gate : Fundamental and application of advanced semiconductor devices

We have fabricated poly-Si/Si 0.7 Ge 0.3 /Si stacked gate on 4 nm-thick SiO 2 /Si(100), and examined the diffusion of Ge and impurities as a function of annealing temperature in the range of 800-1000°C by energy dispersive X-ray spectroscopy (EDX) and secondary ion mass spectrometry (SIMS). It is reviealed that germanium atoms diffuse into 100 nm-thick silicon cap layer uniformly after 1000°C annealing for 30 min and the crystallinity of As + doped poly-SiGe is better than that of BF + 2 doped poly-SiGe. Also, in comparison with poly-Si gate MOS capacitors, we have confirmed that MOS capcitors with p + and n + SiGe gates show a 0.2 V reduction in the flat-band voltage for p + gate and no change for n + gate, with no increase in gate leakage current with respect to the oxide voltage. This result is attributable to the difference in the energy band structure between Si and Si 0.7 Ge 0.3 .