Silicon nitride deposited by electron cyclotron resonance plasma enhanced chemical vapor deposition for micromachining applications

An investigation of the influence of the process parameters pressure and now on the room-temperature deposition of electron cyclotron resonance plasma enhanced chemical vapor deposition (ECR-PECVD) of silicon nitride has been performed. The suitability of these films for micromachining applications has been studied, in particular for the use with KOH:isopropyl:H2O etching solutions. The deposition rate and the effect of process parameters on the physical properties of the films, as-deposited and after KOH etching, were investigated. Buffered HF etch rate, refractive index, and the infrared absorption spectra, especially the Si-N peak absorption wavenumber, were studied. We have found that films that withstand KOH etching with little modification of their physical properties can be obtained at room-temperature for depositions with low flows and low process pressures.