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Defect Detection for the 21st Century by Laura Peters; Senior Editor, Semiconductor International
For defect reduction and yield improvement in the 21st century, engineers face challenges of process integration that will require a new understanding of defects. Defect complexity increases, so that no one type of inspection tool will be able to fill all the needs of defect inspection, classification and eradication. Areas of particular concern will include new failure modes for integrated low-k dielectric and copper interconnect systems, defect examination in contracts and vias and dopant distribution control. Stress measurements may be used as a systematic process control parameter in advanced devices. These are some of the conclusions of Rajendra Singh, director of the Center of
Silicon Nanoelectronics and of Materials Science and Engineering at Clemson University (Clemson, S.C.), who presented his findings at KLA-Tencor’s Yield Management Solutions Seminar in July. According to Singh, atomic roughness of interfaces will play a critical role in determining defect type and distribution. The ubiquitous optical microscope will be gradually replaced by optical review stations and scanning electron micro-
F i g u re 1: Trends relating pr ocess temperature and time in t e rms of stress, perf o rma nce, reliability a nd yield .
Table 1.
Potential technology solutions for patterned wafer inspection Technology node
Process R&D phase
Yield ramp phase
Volume production phase
250 nm
1994 (83 mm) Optical imaging
1996 (167 mm) Optical imaging Light scattering
1998 (250 mm) Optical imaging Light scattering
180 mm
1996 (60 mm) Optical imaging SEM-based
1998 (120 mm) Optical imaging Light scanning
2000 (180 mm) Optical imaging Light scattering Holography
150 mm
1998 (50 mm) SEM-based
2000 (100 mm) Optical imaging Light scattering Holography
2002 (150 mm) Optical imaging Light scattering Holography
130 mm
2000 (43 mm) SEM-based
2002 (86 mm) Optical imaging Light scattering Holography
2004 (130 mm) Optical imaging Light scattering Holography Novel
100 mm
2003 (33 mm) SEM-based EUV, X-ray Novel
2005 (47 mm) UV imaging UV scattering UV holography Novel
2007 (100 mm) UV imaging UV scattering UV holography Novel
Source: SEMATECH
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Yield Management Solutions
scopes, visible to ultraviolet inspection tools, and scanning probe micr oscopes. As the industry transitions from oxynitride capacitor dielectrics in DRAMs to high-k dielectrics such as Ta2O5 and BaSrTiO3, defect characterization for amorphous materials must adapt to characterize polycrystalline materials. The composition and roughness of the metal/dielectric interface in metal gates comprised of W or W xNy become critical. Threedimensional doping profile techniques will be needed to characterize shallow junctions created by solid phase epitaxy or other methods.
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Best of YMS
Yield Management Seminar Series A valuable venue for innovative ideas Decreasing silicon allowance for silicides places new requirements on the quality of the silicon/silicide interface for minimal roughness. Porous low-k materials are inherently non-homogeneous in structure, unlike SiO2. Singh explained that tantalumbased barrier materials for copper may introduce stress-related reliability concerns, and pinholes and non-uniformity-related defects in barrier layers become a greater issue below 40 nm in thickness. Table 1 illustrates the expected extension of current patterned wafer inspection methods and the timeline for bringing new technologies into R&D phases, yield ramp-up and volume production. In the interest of minimizing thermal budget, processes must be created to reduce the activation energy and use in-situ measurements to maximize performance, throughput and yield (figure 1), expecially for large diameter wafers. â?ˆ Reproduced with permission from SEMICONDUC TOR INTERNATIONAL, November 1998. Copyright 1998 Cahners Business Information. SEMICONDUCTOR INTERNATIONAL is a trademark of Cahners Business Information. All rights reserved.
KLA-Tencor’s Yield Management Solutions Seminars (YMS2) focus on value-added, integrated solutions for yield management and process control. Key topics include CMP, lithography, in-line monitoring and yield strategies, with an emphasis on copper. To reserve your space at the upcoming YMS2, contact Judy Dale by email at: judy.dale@kla-tencor.com. DATE: TIME: LOCATION:
Wednesday, October 20th 9:00 a.m. to 6:00 p.m. Hyatt Regency Austin on Town Lake
For future YMS 2, please complete and return the enclosed business reply card. Call for future papers
Papers should focus on using KLA-Tencor tools and solutions to enhance yield through increased productivity and performance. Topics of interest include defect inspection, lithography, CMP, film measurement and yield management strategies. If you are interested in presenting a paper at one of our upcoming yield management seminars, please submit a one page abstract to: Judy Dale by fax at (408) 875-4144 or email at: judy.dale@kla-tencor.com.
YMS2 at a Glance DATE December 2 February 16 April 5
LOCATION Makuhari, Japan Seoul, Korea Munich, Germany
Autumn 1999
ABSTRACT DEADLINE September 1, 1999 November 1, 1999 January 7, 2000
Yield Management Solutions
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