Dopant Penetration Behavior of B-Doped P[sup +] Polycrystalline-Si[sub 0.73]Ge[sub 0.27]∕Al[sub 2]O[sub 3] or AlN–Al[sub 2]O[sub 3]∕n-Si Metal Insulator Semiconductor Capacitors

Abstract

B-doped p + polycrystalline-silicon (poly-Si) or silicon germanium (poly-Si 0.73 Ge 0.27 ) gate/Al 2 O 3 or top nitrogen incorporated Al 2 O 3 (N-Al 2 O 3 )/n-type Si(100) metal insulator semiconductor capacitors were fabricated using atomic layer deposition for the Al 2 O 3 or AlN/Al 2 O 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 2 O 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 2 O 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 2 O 3 )/n-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 .