Formation of deep amorphous region to separate junction from end-of-range defects

摘要

A method of manufacturing a MOSFET semiconductor device includes forming a gate electrode over a substrate and a gate oxide between the gate electrode and the substrate. Inert dopants are then implanted within the substrate to form amorphized source/drain regions in the substrate extending to a first depth significantly greater than the intended junction depth. The amorphized source/drain regions are implanted with source/drain dopants such that the dopants extend into the substrate to a second depth less than the first depth, above and spaced apart from the end-of-range defect region created at the first depth by the amorphization process. Laser thermal annealing recrystallizes the amorphous regions, activates the source/drain regions and forms source/drain junctions. Because the recrystallization front velocity towards the substrate main surface is greater than the dopant atom velocity in the liquid substrate during laser thermal annealing, the junctions are not pushed down to the amorphous/crystalline silicon interface. Thus, end-of-range defects are located in a region below and spaced apart from the junctions, and the defects are not located in the activated source/drain regions. Junction leakage as a result of the end-of-range defects is thereby reduced.