Dopant Penetration Behavior of B-Doped P_+ Polycrystalline-Si_(0.73)Ge_(0.27)/Al_2O_3 or AlN-Al_2O_3-Si Metal Insulator Semiconductor Capacitors

摘要

B-doped p~+ polycrystalline-silicon (poly-Si) or silicon germanium (poly-Si_(0.73)Ge_(0.27)) gate/Al_2O_3 or top nitrogen incorporated Al_2O_3 (N-Al_2O_3)-type Si(100) metal insulator semiconductor capacitors were fabricated using atomic layer deposition for the Al_2O_3 or AlN/Al_2O_3 layer to investigate B penetration and device reliability. The adoption of a poly-Si_(0.73)Ge_(0.27) electrode greatly reduced the B penetration into the substrate through the Al_2O_3 layer and enhanced the activation of the implanted dopant compared to the poly-Si electrode under a given activation annealing condition. The acquired work function engineering by the poly-Si_(0.73)Ge_(0.27) electrode also reduced the threshold voltage of the device. Deposition of a thin AlN layer on top of the Al_2O_3 layer further reduced the B diffusion into the dielectric which greatly enhanced the dielectric reliability.The poly-Si_(0.73)Ge_(0.27)/(N-Al_2O_3)-type Si capacitors showed the smallest leakage current density of 3.0 X 10~(-7) A/cm~2 at 1 V and a large charge-to-breakdown value of 8.5 C/cm~(-2).