Singapore tips sub-surface wafer metrology

Researchers from Nanyang Technological University in Singapore are developing a metrology system that claims to detect sub-surface defects in raw or reclaimed silicon wafers.

The machine, dubbed the PCT/2004/SC000039, is said to detect sub-surface defects in silicon wafers down to 28-nm, said Bryan Ngoi, director of the NanoFrontier program at Nanyang.

There is no equipment in the market today that can detect sub-surface defects, he said. We are able to measure sub-surface defects.

ADE Corp. and KLA-Tencor Corp. are the leading suppliers of commercial metrology tools for silicon wafer defect applications in the market.

Nanyang's tool is a non-destructive, in-line metrology system, based on digital speckle shearography, Ngoi said. In some cases, digital speckle shearing interferometry uses a CCD camera and computer processing to produce data images.

Developed in the past decade, shearography is a coherent-optical measuring and testing method, similar to holographic interferometry. It is effective in non-destructive testing, strain measurement, and vibration analysis.

Nanyangs tool is still in the R&D stage and the university is developing the machine with an undisclosed partner. The university has built one pilot system. It hopes to commercialize the product in two or so years.

- Mark LaPedus

EE Times