Photonics has attracted a great deal of interest due to the rapid growth of the telecommunications industry. As silicon has been studied for decades in the semiconductor and microelectronics industry, the experience and infrastructure developed can be implemented in the fabrication of photonic devices. Therefore, the development of new materials and processes for this application is crucial. In this thesis, the materials and techniques used in the fabrication of suspended structures and photonic devices are studied.

Anisotropic etching is an essential technique necessary for the fabrication of photonic devices such as waveguides. The need for a reliable and repeatable etching process is discussed, along with the development of anisotropic etching recipes for silicon, silicon nitride and nano-crystalline diamond (NCD). The effect of etch roughness, along with the methods to reduce the roughness is also discussed, as well as the effect of various etch parameters on the etch rate and selectivity.

Waveguides fabricated in nano-crystalline diamond (NCD) on a silicon substrate with a propagation loss of 4.6 dB/mm has been demonstrated. The silicon substrate has to be undercut in order to isolate the mode in the NCD core, as the guiding layer (NCD) has a lower refractive index than silicon. In order to achieve this, the silicon was isotropically etched through an ICP-RIE process using SF6.

SF6 has been studied as an isotropic silicon etchant as a replacement for vapour phase etchants such as XeF2. The etch rate is strongly dependent on the feature size, density and shape. This dependency is theoretically analysed, and supported experimentally. Also, the effect of this chemistry on photonic materials such as NCD, silicon nitride and silica, as well as on commonly used masking materials such as photoresists has been investigated.

Finally, a novel bonding process, which avoids the use of top down isotropic etching is presented. This can be beneficial as it enables the integration of various materials with silicon.