Dry etching techniques for nanostructures

Dry etching techniques are needed for the fabrication of nanostructures used in high performance devices. Multiple requirements must be satisfied for dry etching since different factors influence etch characteristics. For nanostructures, especially when the aspect ratio is high, etch rate and profile could vary with the device dimensions and etch depth. However, this feature size dependent etch characteristics can be minimized with appropriate etch conditions. Monitoring during dry etching can be made using optical emission spectroscopy and mass spectrometry. By monitoring high signal-to-noise ratio, etching can be stopped within a few nm of the desired layer. Endpoint accuracy is dependent on surface smoothness and response time of the system.