Characteristics of surface mount low barrier silicon Schottky diodes with boron contamination in the substrate?epitaxial layer interface
Unusual negative resistance characteristics were observed in low barrier HMIC (Heterolithic Microwave Integrated Circuit) silicon Schottky diodes with HF (hydrofluoric acid)/IPA (isopropyl alcohol) vapor clean prior to epitaxial growth of silicon. SIMS (secondary ion mass spectroscopy) analysis and the results of the buried layer structure confirmed boron contamination in the substrate/epitaxial layer interface. Consequently the structure turned into a thyristor like p-n-p-n device. A dramatic reduction of boron contamination was found in the wafers with H20/HCl/HF dry only clean prior to growth, which provided positive resistance characteristics. Consequently the mean differential resistance at 10 mA was reduced to about 8.1 ?. The lower series resistance (5.6?5.9 ?) and near 1 ideality factor (1.03?1.06) of the Schottky devices indicated the good quality of the epitaxial layer.