Reactive Ion Etching of Silicon Dioxide

The problem is explored of selectively etching SiO/sub 2/ over a silicon substrate by using a planar, dual plasma/reactive ion etching system with a 3000 W, 13.56 MHz rf power supply. Selective etching is achieved with CHF/sub 3/ at applied powers between 2500 and 3000 W by adjusting the chemistry of the plasma with the P/F ratio toward the onset of polymerization and then optimized by the pressure within the limits of the pumping speed of the system. 3 refs.