New preamorphization technique for very shallow p⁺-n junctions

A novel method for the fabrication of shallow p+-n junctions, using preamorphization by heavy ion of opposite conductivity type (antimony) is presented. The antimony preamorphization conditions are optimized to yield low leakage for shallow junctions. Excellent junction characteristics are demonstrated for sub-0.1-μm junction depths. The high antimony ion mass produces a sharp crystalline/amorphous interface and the defects can be controlled with minimal thermal budget. The n-type conductivity of antimony compensates the boron, resulting in shallower and sharper p+-n junctions. The combination of low leakage, shallow junction, and high boron activation at reduced thermal cycles demonstrates the feasibility of a truly low-temperature process, for applications extending to the 0.1-μm CMOS regime.