A Tantalum Thin-Film Resistor Process Compatible with Silicon Integrated Circuits

摘要

A major problem in the production of silicon integrated circuits has been to reduce the size of the individual circuit and to provide high valued resistors. Tantalum thin-film resistors of 500 ohms per square sheet resistivity require less than 40 percent of the area that 200 ohms per square diffused resistors require. The tantalum is sputtered onto and through an aluminum rejection mask and is delineated by etching away the aluminum. The resistors are contacted using evaporated aluminum and are oxidized up to value. Resistors of 1/2-mil line widths have been made with mean values to within about 5 percent and with spreads of 15 percent of the mean. Ratios of resistance have been made with mean values approaching 2 percent of theoretical and with spreads of 10 percent of the mean. These resistors are compatible with the silicon monolithic process. (Author)