Evaluation of Si pre-amorphization for obtaining ultra-shallow junctions

Two pre-amorphization techniques, shallow and deep amorphization using Si implants have been evaluated for obtaining shallow p-type junctions using B or BF₂ implants followed by a Rapid Thermal Anneal (RTA) step. The effect on diffusion behavior and evolution of end-of-range dislocation loops has been studied experimentally using secondary ion mass spectrometry and planar and cross-sectional transmission electron microscopy. The shallow preamorphization followed by the dopant implant does not help in reduction of junction depth for either B or BF₂ implants. Deep amorphization does help reduce junction depth. The pMOSFET leakage for deep amorphization scheme under a drain bias of 2.5 V is low (~pA/μm). However, the reverse diode leakage for different diode structures for deep preamorphization is high (~nA) for a reverse bias of 3.6 V