Cover for an infrared detector and a method of fabricating a cover for an infrared detector

Abstract

A cover for an infrared detector and a method of fabricating the cover are disclosed. The cover comprises a wafer comprising a material such as silicon that transmits infrared radiation. The wafer has a first surface and a second surface opposite the first surface. An antireflective region is formed in the wafer to enhance transmission of infrared radiation through the cover. The antireflective region comprises a first plurality of antireflective elements such as moth-eyes formed in the first surface. The first plurality of antireflective elements are sized and shaped and arranged relative to one another to form a region of graded refractive index at the first surface so as to reduce the amount of infrared radiation reflected by the cover at the antireflective region. The cover comprises a wall extending from the first surface and surrounding the antireflective region. The wall comprises a plurality of layers of material deposited on the wafer so that, when the cover is bonded to a sensor substrate via the wall, a cavity is formed that encapsulates a sensor region of the sensor substrate. The depth of the cavity may be adjusted by depositing the plurality of layers of material with a combined thickness equivalent to the desired depth of the cavity. A second plurality of antireflective elements may be formed in the second surface to enhance the antireflective properties of the antireflective region.

Dependencies are inferred from the claim text.