A spatial light modulator structure is fabricated by forming moveable reflecting elements through plasma etching of silicon in a chlorine ambient. In accordance with one particular embodiment, a mirror comprising single crystal silicon is released from the surrounding material by plasma etching in an ambient including chlorine (Cl2), sulfur hexafluoride (SF6), and boron trichloride (BCl3). Cl2 serves as a source of reactive chlorine etching species for the plasma. SF6 provides a source of fluorine, a reactive species enhancing the rate of etching single crystal silicon. BCl3 provides boron, which becomes incorporated on the surface of the etched single crystal silicon as a passivation layer controlling etch profile. Plasma etching of the single crystal silicon to release the mirrors takes place in the absence of oxygen, in order to avoid unwanted formation of silicon oxide residue that can adversely affect mechanical and optical properties of the resulting device.