Diffraction grating microfabrication by ICP technique with two-layer lift-off processing in single crystal diamond

The rectangular diffraction grating on single crystal diamond was fabricated with the wavelength of 10.6 μm. A novel method called bi-layer lift-off technology was used to form the hard mask. This approach simplified the patterning process of the thick Al film and made the deep etching on single crystal diamond achievable according to our requirement. The fabrication steps and the bi-layer lift-off technology are demonstrated in detail. We characterized the diamond grating and found that the angles of its sidewalls were almost vertical (within 3°), with a mean roughness of Ra = 3.01 nm on the bottom and 12.4 nm on the top.