Mechanism Behind the Stress‐induced Change in Boron and Arsenic Diffusion in Silicon Devices and Its Experimental Verification

There are contradictory reports regarding the effects of uniaxial compressive stress on boron diffusion in silicon. Some reported on the stress‐induced retardation of boron diffusion, whereas some reported on the stress‐induced enhancement of boron diffusion. This work serves to reconcile the conflicting reports on the effects of shallow trench isolation‐induced compressive stress on boron diffusion in silicon. We propose that there are two opposing mechanisms that affect the strain‐induced change in boron diffusion. Mechanism 1, which is related to the strain‐induced reduction in the silicon lattice constant, will lead to a retardation of the boron diffusion of the S/D extension implants. Mechanism 2, which is related to the formation of transient dislocations in silicon during the ramping up period of the S/D annealing, will lead to an enhancement of boron diffusion of the S/D extension implants. The interactions between the two opposing mechanisms would affect the on current versus S/D overhang characteristics as well as the off current versus S/D overhang characteristics. Similar theory can be extended to arsenic diffusion.