Fabrication de capteurs pyroelectriques comprenant une couche pyroelectrique mince necessitant une polarisation electrique
The method for group manufacturing of pyroelectric sensors by forming a thin pyroelectric layer on the upper side of a silicon wafer, where each sensor comprises several pixels (4) and each pixel is defined by an upper electrode (6) situated on the face side and a lower electrode on the rear side of the layer, includes the following steps: (a) The formation of electrical connections in the form of strip conductors (28,30) between the upper electrodes and a contact pad (32), and the formation of resistances (36) connected in series with the upper electrodes, as a protection against a short-circuit. (b) The electric polarization of the pyroelectric layer by applying a voltage between the contact pad (32) of upper electrodes and the lower electrodes. (c) The electrical insulation of upper and/or lower electrodes of one or more sensors by cutting the strip conductors (28) along dotted lines (44) and separating sensors, so that each pixel can deliver an elementary electrical signal. The lower electrodes are also in the form of proper electrodes that are mutually connected by strip conductors (24) and to a contact pad (26). The upper and lower electrical connections present intersections (40) when projected onto the plane of wafer, and the lower connections are laid out so that the intersections are between the electrodes and the resistances. The resistances and electrical connections are laid out on the thin layer substantially horizontal on the upper side of wafer. In the second embodiment, the first electrical connections are formed in part by strip conductors on the lower side of wafer and feedthroughs, and the resistances are associated at least in part at the level of feedthroughs. The sensors are formed each by a two-dimensional array of pixels. The contact pads (38) connect the electrodes to the resistances, and the pads are the contacts of pixels in functioning when the resistances are inactive. The values of resistances are substantially equal and define an impedance of pixels allowing a uniform deposition of an absorption layer of e.g. platinum black on the pixels by electrochemical method.