Etching of infrared sensor membrane and infrared sensor

摘要

The invention relates to an infrared thermal sensor (1) comprising a substrate (2) having a cavity (3), a cavity bottom wall formed by a continuous substrate surface. The sensor comprises a membrane (4) adapted for receiving heat from incident infrared radiation, a beam (8) suspending the membrane (4), and a thermocouple (9). This membrane comprises openings (5,6) extending through the membrane (4) for facilitating the passage of an anisotropic etchant for etching the cavity (3) during manufacture. Each opening has a cross-section with a length to width ratio of at least 4. The width direction of respectively a first and a second set of openings is oriented according to respectively a first crystallographic orientation (Y) and a second crystallographic orientation (Z), these orientations (Y;Z) corresponding to different directions lying in loosely packed crystal lattice faces of the semiconductor substrate.