Contact metallization on strained-Si

摘要

Metal-semiconductor interfaces play a crucial role in electronic and optoelectronic devices. Strained-Si hetero-structure devices are expected to play an important role due to its compatibility with Si processing technology. The interfacial reactions and chemical phase formation between nickel and ultrahigh vacuum chemical vapor deposited (UHVCVD) strained-Si layers on relaxed Si_(0.75)Ge_(0.25) layers have been studied in the temperature range of 300-900℃ for forming low resistive and uniform silicide films for future generation strained-Si metal oxide semiconductor field-effect transistors (MOSFETs). The silicide films were characterized by scanning electron microscopy (SEM) and cross sectional transmission electron microscopy (XTEM). Smooth and uniform nickel monogermanosilicide films have been obtained for samples annealed around 450℃. Ni/strained-Si Schottky barrier diodes (SBDs) have been fabricated and characterized in the temperature range of 150-300 K for the determination of barrier height (φ_b) and ideality factor (n). SBDs having epitaxial strained-Si layer thickness of 200 and 520 A have been modeled by incorporating an interfacial layer and associated series resistance to achieve a better agreement with the experimental data. Schottky barrier height (SBH) was found to decrease with a decrease in the measurement temperature while the ideality factor was found to increase. The interface states have been characterized using the capacitance-voltage (C―V) characteristics of the diodes.