Evolution of sidewall roughness during reactive-ion etching of polymer waveguides

Abstract

Articles you may be interested inPotassium hydroxide polishing of nanoscale deep reactive-ion etched ultrahigh aspect ratio gratings J. Vac. Sci. Technol. B 31, 06FF02 (2013); 10.1116/1.4820901Effect of mask thickness on the nanoscale sidewall roughness and optical scattering losses of deep-etched In P ∕ In Ga As P high mesa waveguides Sidewall roughening of fluorinated polyether waveguides fabricated by reactive-ion etching in pure oxygen plasma was investigated. Variation of sidewall roughness ͑SWR͒ was observed by scanning electron microscopy, and was measured and confirmed by atomic force microscopy. Lower-pressure SWR variation along the vertical depth is due to the combination of both the shadowing and the first-order reemission effect, and higher-pressure SWR variation is postulated to be due to a continuous shadowing effect. It was discovered that the autocorrelation length ͑ACL͒ calculated from the experiment varies in a similar manner as the SWR does along the depth of the waveguides. This variation of ACL suggests that the surface-roughness evolution at the sidewalls during plasma etching possesses the same etch dynamics as that of planar thin-film etching. With the increase of pressure, the average value of roughness exponent increases.

Study of roughness evolution during reactive ion etching

“…As mentioned in previous chapters that the SWR is neither constant along the depth of the waveguides nor can it be equated to the LER of the sidewall. Variation of SWR was measured by AFM at different pressures for the samples treated with O2/N2 plasma and details of the RIE parameters are provided in Table 9 treated sample was that the variation of SWR was the largest in case of pure O2 and hence, the effect on SWR and its variation can easily be realized at such a high pressure [83][84]. It was found that with O2/N2 plasma, the nitrogen containing bonds such as N", CN" and CNO" were furthermore observed in the planar films as shown in…”