ACLV degradation: root cause analysis and effective monitoring strategy

Anna Tchikoulaeva; Andre Holfeld; Markus Arend; Eugen Foca

doi:10.1117/12.793047

19 May 2008 ACLV degradation: root cause analysis and effective monitoring strategy

Anna Tchikoulaeva, Andre Holfeld, Markus Arend, Eugen Foca

Proceedings Volume 7028, Photomask and Next-Generation Lithography Mask Technology XV; 702816 (2008) https://doi.org/10.1117/12.793047
Event: Photomask and NGL Mask Technology XV, 2008, Yokohama, Japan

Abstract

Stability of across field line variation (ACLV) is crucial in advanced semiconductor manufacturing. Degraded signatures cause deterioration of transistor parameters and yield loss. After having contained haze issues, the IC industry is now confronting a new reticle degradation mechanism. It has been reported, that targeting energy is changing with the number of exposures and later on a rapid increase of ACLV is observed. Although effective monitoring and correction methods have been introduced, the root cause of this type of reticle degradation has not been fully elucidated. Our AIMS^TM, SEM and optical CD measurements on reticle demonstrated consistency with wafer CD measurements and clearly show that pattern distortions on wafers originate from the front side of the reticle. The results indicate the transmission loss to be gradually distributed over the reticle surface causing CD variations. In the most acute case, changes in the center area could be detected by the reticle inspection tool. Dependency of degradation rate on percentage of the clear field on the reticle and reticle type was observed. Finally, using a variety of analytical techniques including AFM, ion and gas chromatography, TOF-SIMS, Auger and TEM we have been able to identify the root cause of this problem. Our experimental results do show that the structural degradation of the absorber film is the primary cause for CD change. Possible mechanisms behind this effect are discussed.

Citation Download Citation

Anna Tchikoulaeva, Andre Holfeld, Markus Arend, and Eugen Foca "ACLV degradation: root cause analysis and effective monitoring strategy", Proc. SPIE 7028, Photomask and Next-Generation Lithography Mask Technology XV, 702816 (19 May 2008); https://doi.org/10.1117/12.793047

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