Deep Structures Wet Etched Into Lithium Niobate Using a Physical Mask

The present work is an investigation and characterization of a new technique for etching and masking Lithium niobate (LiNb03) to realize high aspect ratio trenches. LiNb03 is a single crystal optically clear (from 350 nm to 5 micometer wavelength), piezoelectric material. It is also inert to most reactants and has a high curie temperature (the temperature that a material loses its piezoelectric effect). These properties allow LiNb03 to be used as a sensor or actuator in harsh environments. To realize this actuator/sensor a multilevel lithium niobate deep etching technique is currently unavailable. The present work uses a chrome gold mask and a solution of hydrofluoric acid and nitric acid at 90 C to etch the LiNb03. The new wet etch method developed yields a an etch rate of 50 /micrometer per hour on the -z face and a 250 nm per hour on the +z face.