Post metal etch clean process using soft mask

Abstract

A method of patterning a metal layer that cleans the residue from a metal etch process without removing a photoresist etch mask. The method is particularly useful for the fabrication of micromirror devices, or other MEMS devices that use photoresist spacer layers. A photoresist layer is spun on to the mirror metal layer in step 906. The photoresist is patterned and developed in step 908 to form openings to the metal layer. The openings define areas where the mirror metal layer will be removed. The patterned photoresist is inspected in step 910. The mirror metal layer is etched in step 912 using the patterned photoresist layer as an etch mask. After the mirror metal has been etched, the webbing and other residues are removed in a clean up process 914 that uses photoresist developer as a solvent to remove the webbing. After the developer clean up process, the mirrors are inspected in step 916 to verify the proper gaps have been etched between the mirrors and the removal of the mirror etch residue. A photoresist saw prep coating is then spun onto the wafer in step 918, the wafers are sawn in step 920 and scrubbed in step 922 before the mirrors are undercut in step 924. The undercut process removes the photoresist spacer layers on which the hinge yoke and mirror have been fabricated, allowing mirrors to rotate about the torsion hinges.

Dependencies are inferred from the claim text.