Implantation Defects Below Mask Edges in Silicon: Structure and Effect on Devices

Abstract

High‐dose As+ implantation and subsequent annealing produces defects just below the edge of oxide spacers or field oxide masks. They have been identified to be vacancy‐type half‐loop dislocations with Burgers vectors 1/3 ‘111’ by transmission electron microscopy (TEM). Optical emission microscopy was used to localize sites with increased leakage current in n+p‐diode structures. Precision plan view thinning for TEM investigation was employed to show that not the dislocation loops but nickel precipitates were responsible for the leakage. The nickel precipitated in the strain field of the mask edge and the defects. Moreover, it is evident that mask edge defects act as nucleation centers for glide dislocations which are generated by the high stress of film edges exerted on the substrate.