New Surfscan SP2XP summons ghosts from the haze

by Ed Korczynski, Senior Technical Editor

Building on its venerable Surfscan unpatterned-wafer inspection legacy, the new SP2XP system from KLA-Tencor Corp. is designed for the 45nm IC manufacturing requirements for all types of bare wafers. The company claims the system can detect all major types of defects of interest, and quickly group wafers into defect-free, reworkable, and scrap categories.

Sumitomo, SEH, and Soitec have already beta-tested the new system with 45nm-generation wafers. “The new Surfscan SP2XP system is the only system that provides the SOI sensitivity, independent of film thickness, that we require to address 45nm chipmaking, while at the same time providing a major leap forward in productivity,” noted Christophe Maleville, VP of process engineering at Soitec.

KLA-Tencor claims that >98% of all 300mm product wafers in the industry are touched by an SP1 or an SP2 at least once. IC makers all do some manner of incoming quality inspection (IQC) on bare silicon wafers¿typically 20%-100%, depending upon many factors¿and the system’s output data files are in standard KLARF.

The technology will be extended beyond bare-substrate inspection to the large number of blanket film tool-monitoring applications required in semiconductor manufacturing, such as qualification and monitor wafers, and backside inspections. “We will follow up with a release for the IC market sometime in the calendar year,” promised Rahul Bammi, KLA-Tencor’s director of marketing.

The addition of a new brightfield channel to dual-incidence darkfield channels provides five input signals, with a sixth signal provided by the noise-like intrinsic micro-roughness of the wafer surface (the SURFimage). Multichannel comparison algorithms then separate unacceptable “intrinsic” defects from re-workable ones, in a single rules-based binning (RBB) step.

The system’s UV wavelength confines the laser beam to the wafer surface, minimizing false counts from buried defects and providing 30nm sensitivity. With one order of magnitude greater SURFimage resolution, the new system can capture previously unnoticed defect types. Shallow CMP scratches, orange peel, watermarks, slurry residue, and surface roughness changes can emerge from the intrinsic background haze like ghosts from a fog.

The company says the new system delivers 20%-50% higher throughput (depending on the operating mode) compared with the SP2, even with the added detection capabilities, which translates into a lower cost-of-ownership. “We expect rapid adoption,” Bammi stated. ¿ E.K.


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