STRUCTURE FOR IMPROVING THE ELECTRICAL CHARACTERISTICS OF POLYSILICON CONTACTED n-p JUNCTION
Original Publication Date: 1989-Feb-01
Included in the Prior Art Database: 2005-Jan-27
This article describes the use in a shallow n-p junction of a bipolar transistor of a conducting oxide layer, such as RuO2, IrO2, etc., sandwiched between the polysilicon layer and a metal layer such as Pt or W. In emitter-based junctions used in current bipolar technology, the emitter is contacted by an n+-polysilicon layer. A platinum silicide layer is then formed on top of the polysilicon layer, as shown in Fig. 1, to provide external ohmic contact to the emitter. Current-voltage characteristics have shown that a large number of these junctions formed in the same wafer exhibit high leakage (generation-recombination) current under reverse bias condition. In other words, the reverse current is found to be much higher than 1 pA at a reverse voltage of 1 V at room temperature.