Our research in diamond-based devices has been enabled by a number of tools developed specifically for its nanofabrication. Material constraints inherent in this platform preclude more traditional fabrication methods - in particular, there is no current technology for growing high-quality, single-crystal diamond on top of a dissimilar substrate. For research in optics and mechanics, such a platform is often needed to provide the necessary mode confinement. In our group, we have developed a number of techniques which go beyond these traditional schemes.
Thin Film Fabrication
Our thin film fabrication approach relies on the reactive ion etching of thin, polished (~20 um) diamond substrates to the thickness required for the device. First demonstrated for applications in quantum optics [Nano. Lett. 12, 3, (2012)], the process has been improved considerably to provide a repeatable means to fabricate high Q (~1 million) optical resonators for nonlinear optics [Nat. Photon. 8, (2014)]. After a thin diamond substrate has been sourced, the sample is bonded onto a sapphire carrier wafer and thinned with alternating plasma chemistries (Ar/Cl2 and O2) until it reaches the requisite thickness. Afterwards, the sample is transferred from the sapphire carrier wafer to the final substrate (typically SiO2), where it is then bonded. With the diamond film now firmly on the substrate, the sample processing continues as for normal devices.