High-speed NMOS circuits made with X-ray lithography and reactive sputter etching

The performance of fine line NMOS circuits fabricated with X-ray lithography and reactive sputter etching shows that NMOS can be competitive with other high-speed technologies. Enhancement and depletion mode silicon gate devices with 0.25 µm junction depth, 200 Å gate oxide and 0.7 µm channel length have been used in a 175 ps delay per stage ring oscillator with a 5V power-delay product of .24 pJ and a 600 MHz, 4 stage counter. Slight technology changes also produced a 92 ps delay ring oscillator with a 5V power delay product of 0.53 pJ.