Surface Morphology Change of Titanium Nitride Film after Metal Layer Photolithography Rework Causing Oxide Film De-lamination

Abstract

Typical photolithography rework process involves a resist wet strip following by a dry descum process. It is found that the de-lamination phenomena correlate to longer descum timing in the rework route. Hypothesis of the de-lamination suggests a change in the surface roughness of TiN after being subjected to descum process. This hypothesis is supported by various experiments conducted. Surface morphology of TiN changes from columnar structure to thorn shape protuberance. The sheet resistivity of TiN is also increased with increase of descum time. Optimization of the descum time during metal layer photolithography rework makes the surface of TiN smoother and it eliminates the de-lamination issue. The mechanism of this effect is also discussed in this paper