Pattern fabrication technique for Ta-Ge amorphous X-ray absorber on a SiC membrane by inductively coupled plasma

We developed a pattern etching method for Ta-Ge (Ta3Ge) amorphous X-ray abs orbers on a SiC membrane using a mixture of Cl-2 and BCl3 gases with a sing le-layer e-beam resist. For this work, an inductively coupled plasma (ICP) etcher with a helium back surface cooling system was used. High etching sel ectivity and anistropic etching were achieved by regulating electrode tempe rature and BCl3 concentration ratio. The etching selectivity of Ta3Ge to th e resist is 6.5. Ta3Ge patterns of 0.1 mu m dimensions with vertical sidewa lls were fabricated. Good etching rate uniformity was also obtained over a 61-mm-diameter membrane field. We found that Ru him was a suitable etching stopper material because it has high dry-etching durability and can be easi ly removed by oxygen plasma etching.