Gf. Mclane et al., REACTIVE ION ETCHING OF TA-SI-N DIFFUSION-BARRIERS IN CF4+O2, Journal of vacuum science & technology. B, Microelectronics and nanometer structures processing, measurement and phenomena, 12(4), 1994, pp. 2352-2355
Ta36Si14N50 amorphous layers were reactive ion etched in CF4+O2 plasma
s, The etch depth was determined as a function of gas composition, pre
ssure, and cathode power. Adding small amounts of O2 to CF4 increased
the etch rates up to approximately 15% O2 concentration, with etch rat
es then decreasing with further addition of O2. Etch rates increased w
ith both pressure and power. Etching proceeded only after an initial d
elay time which depended upon gas composition and power. The delay is
probably caused by a surface native oxide which must be removed before
etching can commence. The presence of a surface oxide was observed fr
om Auger electron spectroscopy intensity depth profile measurements an
d is estimated to be 2 nm thick. Under optimal conditions, the etch ra
te of Ta36Si14N50 is about seven times higher than for SiO2, thus prov
iding a high degree of selectivity for integrated circuit processing.