High-resolution depth profiling of ultrathin silicon oxide/nitride/oxide layers
ArticleZhang, Y., Oehrlein, G.S., Kroesen, G.M.W., Wittmer, M. & Stein, K. (1993). High-resolution depth profiling of ultrathin silicon oxide/nitride/oxide layers. Journal of the Electrochemical Society, 140(5), 1439-1441. In Scopus Cited 7 times.
We demonstrate that in situ ellipsometry in conjunction with reactive ion etching is capable of providing high-resolution (=0.3 nm) compositional depth profiles of thin (˜5 nm) silicon oxide/nitride/oxide (ONO) structures, which are superior to those which can be obtained by other methods. A low pressure (75 mTorr), low power (50 W) CF4 plasma was employed to etch slowly the ONO multilayer structure with Si3N4/SiO2 etch rate ratio of approximately 4. The instantaneous etch rate as a function of depth was measured by automated ellipsometry, providing a measure of the composition.