Hyung-Seung Song

Inductively coupled plasma etching of SiO2 layers for planar lightwave circuits

We have systematically studied the etching characteristics of SiO 2 layers using an inductively coupled plasma (ICP) etching system. The surface morphology, etch rate, selectivity, and sidewall angle have been studied as a function of varying pressure, gas flow rate, capacitive r.f. power, and inductive r.f. power. Chrome was used as an etch mask, and CF 4 or SF 6 was used as a reactive gas. Using either one of the gases, excellent results were obtained. Depths exceeding 6 μm were etched with few observable defects and near vertical sidewalls. This process was applied to make SiO 2 waveguides for planar lightwave circuits.

Inductively coupled plasma etching of Ge-doped boron-phosphosilicate glass for planar lightwave circuit devices

Abstract Boron-phosphosilicate glass films were deposited on silicon wafers using H 2 /O 2 flame hydrolysis deposition. GeO 2 was doped up to 12 wt% for core layer. Boron and phosphorus contents were varied up to 24 and 2.4 wt%, respectively. Doping level was controlled by changing the flow rate of gaseous chemicals. The layers were patterned and then etched using inductively coupled plasma to form optical waveguides. Cr and CF 4 were used as the etch mask and the reactive gas, respectively. The effect of germanium on the etch rate is small. The etch rate of the 24 wt% boron-doped layer was larger by about 10%, compared to the 12 wt% boron-doped layer. The etch rate, selectivity and plasma-induced surface damage were affected by chamber pressure, gas flow rate, capacitively coupled power and inductively coupled power. DC bias voltage between electrode and plasma in the process chamber was the parameter which has the largest effect in controlling the etch results. DC bias voltage could be effectively controlled by capacitively coupled power and inductively coupled power.