High-resolution x-ray diffraction study of free-standing gallium arsenide coiled membrane force sensors produced by micrmachining

摘要

Abstract: High Resolution X-ray diffractometry and topography techniques have been employed successfully to evalute crystalline quality and long term stability of coiled membranes. The process of membrane fabrication involved photolithography, implantation by 4 MeV N$+$PLU$PLU$/ ions in n-type GaAs substrates followed by selective etching. A five crystal x-ray diffractometer was employed in setting with MoK$alpha$-1$/ exploring beam for x-ray diffraction experiments. Exploring beam width was reduced to approximately 10 $mu@m to selectively illuminate different segments of the membrane. Diffraction curves recorded from the bulk crystal surrounding the sensor were quite sharp with half widths in the range: approximately 15-26 arc sec, where as the diffraction curves from sensor segments were quite broad due to appreciable deformations. The sensor segments were tilted with respect to each other as well as with respect to the substrate. High resolution x-ray diffraction topographs directly revealed that the sides of the cavity were not vertical, but tapered, there is a thin freely hanging strip over the tapered regions due to under- etching and the bottom of the cavity is uneven with perturbations in the range: $POM 4 $mu@m. !8