Electron-beam-induced current and TEM studies of stacking faults formed by the oxidation of boron-implanted silicon

The electron-beam-induced conductivity (EBIC) of emitter-base junctions was studied in a scanning electron microscope, and the image contrast of process-induced stacking faults was investigated by transmission electron microscopy (TEM). Emitter-base (e-b) junctions were formed by phosphorus diffusion into boron-implanted bases on 〈100〉 silicon. The implanted bases were preannealed in an oxidizing atmosphere, which generates stacking faults. The e-b junctions were designed with metal contacts removed such that the active e-b region was ’’open’’ to EBIC analysis. Leaky junctions (i.e., 104 nA/cm2) were found when relatively high concentrations of oxygen were used in the annealing atmosphere (e.g., 10% O2). These junctions exhibited a mottled contrast in the EBIC mode, indicative of a high density of recombination centers. Relatively low-leakage junctions (i.e., 10 nA/cm2) were found when a 1%-O2 atmosphere was used and the junctions contained an occasional stacking fault. These stacking faults exhibited an EBIC contrast characteristic of recombination at partial dislocations bounding the faults. Diffraction-contrast experiments using TEM showed that isolated stacking faults in the base region were extrinsic in nature and were not decorated by heavy metal microprecipitates. The generation currents for ’’clean’’ extrinsic stacking faults were estimated to be in the range 10−2–10−4 nA per stacking fault for these junctions.