Etch alignment of CCD mosaic hybrid

By relying on semiconductor lithography and processing techniques, we have fabricated a flat, precision aligned charge-coupled device (CCD) mosaic for astronomy. Modifications to the lithographic techniques used in micromachining lead to a significant reduction in various residue deposits, allowing a smooth surface suitable for CCD alignment. Details of the technique and the fabrication of a prototype mosaic are described. The composite device is flat to within /spl plusmn/5 /spl mu/m, with rows/columns oriented to within 20 ppm. The use of an existing technology with built in precision reduces many of the difficulties and expenses typically encountered with mosaic detector construction.