Method and apparatus for a dual-inlaid damascene contact to sensor

摘要

A dual-inlaid damascene contact having a polished surface for directly communicating an electrically conductive layer to a semiconductor layer. A dielectric layer is formed on the electrically conductive layer. A dual-inlaid cavity is formed by etching a via cavity and a contact cavity into the dielectric layer. A damascene contact is formed by depositing tungsten into the dual-inlaid cavity. Chemical-mechanical polishing is used to planarize and smooth a surface of the damascene contact until the surface is coplanar with the dielectric layer. A semiconductor layer is then deposited on the damascene contact. The semiconductor layer can be the node of an amorphous silicon P-I-N photodiode. Electrical interconnection between the node of the photodiode and the electrically conductive layer is accomplished without using an intermediate electrode, and the smooth damascene contact improves surface adhesion, reduces contact resistance, and provides a discrete connection to the semiconductor layer. The damascene contact may be polished to provide a light reflective surface finish for reflecting light incident on the damascene contact back into the semiconductor layer to improve the quantum efficiency of the P-I-N photodiode.