Arsenosilica film source for microwave transistor

Arsenosilica films have been used to investigate arsenic diffusions into silicon with the object of using the dopant for emitter of a microwave transistor. A detailed study of the effect of film spin speed and different drive-in ambient on the formation of surface defects was carried out. Cross-sections of arsenic (emitter) and boron (base)_diffused junctions with oxide as the mask showed that pull of the base under the emitter (retardation) was a function of total base doping Q. For Q > 10¹⁵ atoms/cm², some push (enhancement) of the base was observed. These results are contrary to those observed previously. Microwave power transistors fabricated with arsenic emitters showed superior performance over that of phosphorus emitter.