New Technology Captures Defects of Interest at 45nm
Posted date : May 11, 2007

New in-line inspection equipment from KT reaches new heights in accuracy for sorting out cleanable particles from killer defects.

At the 45nm node, the very nature of the defects and the particularities of the substrate impact light scattering detection methodologies.

KLA-Tencor’s new Surfscan SP2XP system not only captures more shallow defects like stains or residues, it significantly improves the ability to distinguish cleanable particles from killer defects.

This system offers the ability to scan each wafer using both oblique- and normal-incidence scans without reloading the wafer (Figure 1). It also incorporates a brightfield channel that operates simultaneously with both oblique and normal incidence modes without removing the wafer from the system, to detect additional challenging defect types.

Enhanced accuracy increases yield

New algorithms compare scattering intensities from five different channels to bin (categorize) defects with substantially higher accuracy and purity. Because the shape, size and material of the defect and of the wafer substrate affect the manner in which the defect scatters light, normal and oblique incidence angles, narrow and wide collection channels, and selectable polarizations provide flexibility to capture all defect types.
Soitec was a key beta partner with KLA-Tencor in development of the Surfscan SP2XP technology, and is one of the first substrate manufacturers in the world to put the system into production. This new level of defect binning enables Soitec to offer an additional degree of incoming quality control for its customers.

Figure 1. The optical design of KT’s new Surfscan SP2 XP™. While the wafer spins below, the darkfield subsystem illuminates a spot on the wafer from a normal or oblique angle of incidence. Darkfield collectors span either narrow or wide solid angles. A separate, normal-incidence brightfield DIC channel operates simultaneously with either of the darkfield channels

For IC manufacturers, the new defect classification technology in the Surfscan SP2XP can separate killer defects like voids from the relatively innocuous particles and other fall-on defects, which may be cleanable or otherwise re-workable.

The SP2XP system also increases the dynamic range of the darkfield channels by 16x, enabling more defects to be sized beyond the previous saturation limit and providing classification of more defect types. By comparing sizing from the oblique and normal darkfield scans, wafers having only large particles would not be scrapped.

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