Characterization of Electrically Active Defects in Si Using CCD Image Sensors.

摘要

The purpose of the work has been to characterize electrically active defects in silicon using a CCD area imager as a test structure. CCD imagers have been fabricated on a variety of substrate materials and operated to determine the location and density of dark current producing defects; the defects have been characterized by x-ray topography and by conventional and scanning transmission electron microscopy. Four classes of defects with five specific origins have been found to be dark current sources: (1) Dislocations from device stresses, from process stresses, and from the unfaulting of stacking faults. (2) Stacking faults nucleated from frontside damage. (3) A defect located at the Si/Si02 interface. (4) A defect of atomic dimensions that causes banding in the dark current pattern. No evidence of precipitation was found on any dark current producing defect. The electrical activity of dislocations is consistent with a model in which undissociated perfect dislocations in the depletion region are dark current sources, while dissociated dislocations (split into two Shockley partial dislocations) are not electrically active.