Back-End Processing Using Low-Moisture Content Oxide Cap Layer

摘要

A method for fabricating image sensors and other semiconductor ICs that controls the amount of hydrogen generated during back-end processing. The back-end processing includes forming multiple metallization layers after front-end processing is completed (i.e., after forming the pre-metal dielectric), where each metallization layer includes a patterned aluminum structure, an interlevel dielectric (ILD) layer including TEOS-based oxide formed over the patterned aluminum structure. A cap layer including a low-moisture content oxide such as silane oxide (i.e., SiO2 generated by way of a silane CVD process) is formed over at least one ILD layer. The cap layer serves as an etch-stop for the subsequently-formed metal layer of a next metallization layer by isolating the underlying ILD material from the plasma environment during aluminum over-etch, which significantly reduces the production and migration of hydrogen into front-end structures.

主权项

1. A method for fabricating a semiconductor integrated circuit, the method comprising:
generating front-end structures including one or more doped diffusion regions disposed in a semiconductor substrate, one or more polycrystalline silicon structures disposed over a surface of the substrate, and a pre-metal dielectric layer over the one or more polycrystalline silicon structures; forming a plurality of metallization layers over the pre-metal dielectric layer, wherein forming at least one of said metallization layers includes:
forming a patterned metal structure;forming an interlevel dielectric (ILD) layer comprising a TEOS-based oxide over the patterned aluminum structure; andforming a cap layer over the ILD layer, wherein forming the cap layer comprises forming a high-density, low-moisture content oxide material having a minimum thickness of 100 A.