Inductively coupled plasma of fluorocarbon plasma glass etching process on planar lightwave circuit device fabrication

The profile and etch depth of silica waveguide channel are inspected and measured with microscope and surface profiler respectively. Hexafluoroethane (C₂F₆) and tetrafluoromethane (CF₄) plasma etching conditions were investigated for planar lightwave circuit (PLC) requirement. From the microscope images, suspected insufficient height of waveguide channel and chromium mask etch-off problem occurred after ICP etching by using CF₄etch gas. By changing the fluorocarbon etch gas from CF₄ to C₂F₆, chromium mask remained after etching process and found that there are some improvement of waveguide channel profile and selective etch for the etch results. The aim of 8 micron waveguide channel height is achieved by using C₂F₆ gas in ICP etching. This is agreed with process knowledge that fluorocarbon etch gas C₂F₆ is better than CF₄ and suit the need for planar lightwave circuit silica etching process.