Magazine autumn99 defectdetection

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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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Autumn 1999

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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