[19p-E305-1~15] 13.3 Insulator technology

▼ [19p-E305-13] Improvement of Si_0.78Ge_0.22 MOS interface properties by using TiN/Y₂O₃ gate stacks with TMA passivation

〇TsungEn Lee¹, Kasidit Toprasertpong¹, Mitsuru Takenaka¹, Shinichi Takagi¹ (1.The Univ. of Tokyo)

Keywords:SiGe, interface trap density, high-k dielectric

SiGe MOSFETs have stirred much attention as p- channel devices, because of the high hole mobility and the appropriate bandgap. However, the undesired formation of GeO_x in the interfacial layers (IL) can be regarded as an origin of the MOS interface degradation [1]. We have recently reported reduction in D_it by TiN/ALD Y₂O₃ gate stacks with PMA at 450^oC [2, 3]. However, the further improvement of interface properties in the SiGe MOS gate stacks has not been fully obtained yet. In this study, we present a new passivation process by Trimethylaluminum (TMA) treatment prior to Y₂O₃ ALD in TiN/Y₂O₃/ SiGe gate stack formation to achieve the SiGe MOS interfaces with lower D_it. The MOS interface properties and the physical origins of the interface improvements with optimized cycle number of TMA passivation are systematically examined.