FIB repair of opaque defects for 64-Mb-DRAM-level binary masks

Kyung Hee Lee; Hanku Cho; Jin-Hong Park; Yonghoon Kim; Hee-Sun Yoon; Jung-Min Sohn

doi:10.1117/12.262830

27 December 1996 FIB repair of opaque defects for 64-Mb-DRAM-level binary masks

Kyung Hee Lee, Hanku Cho, Jin-Hong Park, Yonghoon Kim, Hee-Sun Yoon, Jung-Min Sohn

Proceedings Volume 2884, 16th Annual BACUS Symposium on Photomask Technology and Management; (1996) https://doi.org/10.1117/12.262830
Event: 16th Annual BACUS Symposium on Photomask Technology and Management, 1996, Redwood City, CA, United States

Abstract

For binary masks, focused ion beam (FIB) repair of opaque defects is of importance to improve mask yield and turn- around-time with the increasing packing density and continuing shrinkage of feature sizes. The effectiveness of the FIB mask repair is mainly limited by riverbedding, glass overetching, gallium staining, knock-on chrome, and image shift due to charging effect. These effects exert more influence on contact patterns than line and space patterns in the case of the same size of opaque defects under given design rule. In this paper, we investigate FIB repair of test masks which have background contact patterns with a variety of programmed opaque defects including unopened contact for feasible application of 64 M DRAM level. The geometry of the background contact pattern is designed for an approximate target critical dimension (CD), 0.41 micrometers whose feature size is a rough limit of the contact CD with reasonable depth-of-focus (DOF) and exposure time (ET) margin for binary masks when printed on a wafer with a 5X reduction i-line (365 nm) stepper. After repair with an optimum dose, a series of procedures for confirming its success is presented, that is, detectability, aerial image measurement software results, and wafer printability results. In addition, atomic force microscope results and 3D optical lithography simulation are presented for comparison. In our experiment and simulation results, (Delta) ET equals 100 msec and DOF equals 0.6 micrometers are obtained for the repaired contact.

Citation Download Citation

Kyung Hee Lee, Hanku Cho, Jin-Hong Park, Yonghoon Kim, Hee-Sun Yoon, and Jung-Min Sohn "FIB repair of opaque defects for 64-Mb-DRAM-level binary masks", Proc. SPIE 2884, 16th Annual BACUS Symposium on Photomask Technology and Management, (27 December 1996); https://doi.org/10.1117/12.262830

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KEYWORDS

Photomasks

Opacity

Semiconducting wafers

Glasses

Binary data

Gallium

Defect detection

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