Improvement of 90nm technology VIA photo alignment through TiN hard mask removing above previous photo alignment mark area

Wen-Shiang Liao; Hsin-Hung Lin; Yu-Huan Liu; Mao-Chyuan Tang; Sheng-Yi Huang; Cheng-Han Wu; Yue-Gie Liaw; Tung-Hung Chen; Tommy Shih; Kun-Ming Chen

doi:10.1117/12.772286

26 March 2008 Improvement of 90nm technology VIA photo alignment through TiN hard mask removing above previous photo alignment mark area

Wen-Shiang Liao, Hsin-Hung Lin, Yu-Huan Liu, Mao-Chyuan Tang, Sheng-Yi Huang, Cheng-Han Wu, Yue-Gie Liaw, Tung-Hung Chen, Tommy Shih, Kun-Ming Chen

Author Affiliations +

Proceedings Volume 6923, Advances in Resist Materials and Processing Technology XXV; 69233Y (2008) https://doi.org/10.1117/12.772286
Event: SPIE Advanced Lithography, 2008, San Jose, California, United States

Abstract

As the IC product scribe line of logic 90nm (L90) technology shrinks from 80µm to 62μm, the wafer quality (W.Q.), will become weak and less distinguishable during the subsequent ASML scanner stepper's photo mask aligning. Many wafers having photo mask aligning errors will eventually lead to wafer scrapping. In order to improve the photo alignment signal (W.Q.) acquired from the relatively smaller 62μm scribe-line's alignment mark while proceeding with the VIA layer photo aligning directly to its previous metal layer, it is found that removing the TiN hard mask (H.M.) just above the previous inter-metal dielectric (IMD) and alignment mark area can help the deep ultra-violet (DUV) 193nm wavelength ASML scanner stepper successfully acquires a better alignment signal and alignment accuracy (A.A.). However, due to copper (Cu) residues and CMP dishing after metal copper CMP, it has been found that both large area "half size open" and "full size open" approaches for TiN removing in the scribe-line alignment area can not be used. Hence, for safer photolithography aligning margin the "sizing + 0.25μm" mark on the scribe line's photo alignment area is suggested for better signal acquiring, whose experimental results in UMC shows that around 90% of the alignment signal (W.Q.) can be verified. The alignment accuracy (A.A.) can also be improved through using this technique and is accurate enough as compared to the conventional scanner alignment method used for above 0.13μm generation technology.

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Wen-Shiang Liao, Hsin-Hung Lin, Yu-Huan Liu, Mao-Chyuan Tang, Sheng-Yi Huang, Cheng-Han Wu, Yue-Gie Liaw, Tung-Hung Chen, Tommy Shih, and Kun-Ming Chen "Improvement of 90nm technology VIA photo alignment through TiN hard mask removing above previous photo alignment mark area", Proc. SPIE 6923, Advances in Resist Materials and Processing Technology XXV, 69233Y (26 March 2008); https://doi.org/10.1117/12.772286

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KEYWORDS

Optical alignment

Tin

Photomasks

Copper

Semiconducting wafers

Signal detection

Scanners

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