Process optimization for optical CD correlation improvement of ADI and AEI 3D structure by using iODP

Anice Lee; Chung-Yi Lin; F. Y. Chen; Wen-Hao Chang; Sean Hsu; Allen Li; Ying Luo; Youxian Wen

doi:10.1117/12.814023

23 March 2009 Process optimization for optical CD correlation improvement of ADI and AEI 3D structure by using iODP

Anice Lee, Chung-Yi Lin, F. Y. Chen, Wen-Hao Chang, Sean Hsu, Allen Li, Ying Luo, Youxian Wen

Proceedings Volume 7272, Metrology, Inspection, and Process Control for Microlithography XXIII; 727244 (2009) https://doi.org/10.1117/12.814023
Event: SPIE Advanced Lithography, 2009, San Jose, California, United States

Abstract

To fully characterize the lithography process, it is critical to have accurate CD and profile of photo resist structure at ADI stage. Traditionally, CDSEM can only provide limited profile information, and is extremely challenged to be integrated for real-time in line wafer level process control because of throughput issue. Over the past few years, optical digital profilometry (ODP(R)) developed by Timbre Technologies, Inc., has been adopted for real-time process control in Litho for optical CD and shape monitoring. In this paper, the integrated ODP(R) reflectometer is applied to study process signatures of 3D complicated ADI and AEI structures of a 70nm DRAM process. The DT structures from the 70nm node process studied in this paper, are elliptical photo resist via developed over a thin film stack at ADI, and via etched deeply through the thick (over 5um) dielectric film at AEI. At ADI, the ODP(R) library is qualified by careful cross check with CDSEM data. CD results from iODP(R) show very good correlation to that from CDSEM. The iODP® measurement for a FEM wafer shows smoother and cleaner Bossung curves than the CDSEM does. At AEI, the library is then qualified for top CD measurement in comparison to CDSEM, and also to results at ADI. With implementing iODP(R) measurements into both ADI and AEI structures, their signature patterns from ADI to AEI for 70nm DT process can be matched successfully. Such a signature pattern match indicates the strong correlation between ADI and AEI processes and can be fully made use of for APC. It is a significant step toward IM APC control considering ADI and AEI process steps together.

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Anice Lee, Chung-Yi Lin, F. Y. Chen, Wen-Hao Chang, Sean Hsu, Allen Li, Ying Luo, and Youxian Wen "Process optimization for optical CD correlation improvement of ADI and AEI 3D structure by using iODP", Proc. SPIE 7272, Metrology, Inspection, and Process Control for Microlithography XXIII, 727244 (23 March 2009); https://doi.org/10.1117/12.814023

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KEYWORDS

Critical dimension metrology

Semiconducting wafers

Photoresist processing

Process control

Finite element methods

Etching

Metrology

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