In the world of optical defect inspection, finding on defect on a 300mm wafer can be like trying to find a single coin on the island of Taiwan. Now imagine being able to find that coin in just an hour, along with any other coins that look exactly like it. That’s exactly what NanoPoint will allow manufacturers to do.
KLA-Tencor’s NanoPoint is a new family of patented technologies for its 2900 series defect inspection system.
“[NanoPoint is] a new algorithm,” said Satya Kurada, product marketing manager at KLA-Tencor. “We now have the ability to generate care areas significantly smaller to inspect smaller areas, and remove noise from the pattern of interest. This will focus inspection resources on critical patterns.”
KLA-Tencor believes that NanoPoint represents an entirely new way to discover and monitor defects, at optical speed and on existing optical defect inspection equipment. By automatically generating millions of very tiny care areas based on user-defined patterns of interest, NanoPoint focuses the resources of the optical inspection system on critical patterns, as identified either by circuit designers or by known defect sites. During chip development, NanoPoint can reveal the need for mask re-design within hours, potentially accelerating the identification and resolution of design issues from months to days. During volume production, NanoPoint can selectively track defectivity within critical patterns—allowing process monitoring with sensitivity and speed far beyond the industry’s experience to date.
“This is a huge shift in the strategy of what customers could potentially do,” said Kurada. “This technology basically has our customer off-loading the e-beam, because of the sensitivity of which they could with this.”
Traditional e-beam approaches have worked very well, said Kurada, but e-beam optical inspection runs into challenges with wafer processing.
“Because we’re packing so much more tightly, defects that used to be non-nuisance are becoming yield killers,” said Kurada. “Traditional methods are having trouble finding these now. NanoPoint’s evolution is based on canceling out the noise to find the defects. Now it is using pattern-based inspection.”
Pattern-based optical inspection can identify all the weak points, said Kurada, because it identifies patterned noise maps. This allows for not only a cleaner inspection of tinier areas, but a faster completion time as well. What used to seven days, Kurada says will now only take one hour.
“Our customers are highly motivated to continue to extend optical inline defect inspection beyond the 20nm node,” said Keith Wells, vice president and general manager of the Wafer Inspection (WIN) Division at KLA-Tencor. “They want the speed and baseline preservation that only optical inspection can provide—and our challenge is to design equipment that can discover defects whose size is further and further below the inspection wavelength. In the past, we have offered various improvements to the light source, optics and other subsystems, but NanoPoint addresses the issue from a new angle. Based on customer feedback, I believe that NanoPoint is a breakthrough technology with the potential for applicability across a broad range of layers and process modules.”