Cmos process active waveguides on five layer substrates

Abstract

A standard CMOS process is used to fabricate optical, optoelectronic and electronic devices at the same time on a monolithic integrated circuit. FIG.shows an active waveguide formed by a standard CMOS process on a five layer substrate. The waveguide is a silicon strip loaded waveguide with a three layer core made of a silicon strip on a silicon slab with a silicon dioxide layer between the strip and slab. The active waveguide has two doped regions in the silicon slab adjacent to and on either side of the waveguide. FIG.A is a table summarizing the elements of the waveguide of FIG.and the CMOS transistors of FIGS.and, which are formed from the same materials at the same time on the same silicon substrate. In a standard CMOS process, a layer of metallic salicide can be deposited on those selected portions of an integrated circuit, where it is desired to have metallic contacts for electronic components, such as transistors. The deposition of a salicide into optical elements such as the core of an optical waveguide or a light scatterer will damage the elements and prevent the passage of light through those sections of the elements. Prior to the deposition of the salicide, a salicide blocking layer is deposited on those parts of an integrated circuit, such as on an optical waveguide or a light scatterer, which are to be protected from damage by the deposition of salicide. The salicide blocking layer is used as one layer of the cladding of a silicon waveguide and a light scatterer.