A method or process is disclosed for etching deep, high-aspect ratio features into silicon dioxide material layers and substrates, including glass, fused silica, quartz, or similar materials, using a plasma etch technology. The method has application in the fabrication and manufacturing of MEMS, microelectronic, micro-mechanical, photonic and nanotechnology devices in which silicon dioxide material layers or substrates are used and must be patterned and etched. Devices that benefit from the method described in this invention include the fabrication of MEMS gyroscopes, resonators, oscillators, microbalances, accelerometers, for example. The etch method or process allows etch depths ranging from below 10 microns to over 1 millimeter and aspect ratios from less than 1 to 1 to over 10 to 1 with etched feature sidewalls having vertical or near vertical angles. Additionally, the disclosed method provides requirements of the etched substrates to reduce or eliminate undesired effects of an etch.