NMOS Epitaxy - Defect Free and Low Resistivity Films

The nMOS epitaxy process has several challenging process requirements, especially related to resistivity, film selectivity, and defect control. Lower film deposition temperatures can help reduce film resistivity, however, selectivity, defectivity, and growth rates are compromised. Cyclic deposition and etch processes are typically required to recover film selectivity and growth rates. Cyclic process contains a non-selective deposition step to optimize the film resistivity/carbon concentration and an etch step to optimize morphology and selectivity. Various process parameters are explored in this paper to achieve in-situ phosphorus doped selective Epi with low resistivity and defect free microstructure.