(168c) Defect Engineering for Ultra-Shallow Junctions Using Solid-Solid Interfaces

The behavior of defects within silicon can be changed significantly by controlling the chemical state at nearby surfaces or solid interfaces. Experiments have shown that certain chemical treatments change the ability of a free surface to act as a ?sink? for point defects such as interstitials. When the surface is made chemically active, this ability rises. The surface can then remove Si interstitials selectively over impurity interstitials, leading to less transient enhanced diffusion and better dopant activation during annealing after implantation. End-of-range damage can be removed more efficiently as well. Such behavior is kinetically quantified through an annihilation probability. Although annihilation probabilities for interstitials have been measured under various conditions for free surfaces, very little understanding exists for the corresponding quantity at solid-solid interfaces.

The present work seeks to fill that gap through measurements of annihilation probabilities at interfaces between silicon and several kinds of oxides and nitrides. The method employs implantation of isotopically labeled Si (mass 30) in Si host lattice, annealing, and simulation of the subsequently measured SIMS profiles. Marked differences are observed among the various interfaces.