René Raaijmakers
1 May

Nearfield Instruments’ metrology equipment has penetrated high-volume memory chip fabrication at Samsung. This marks a breakthrough for atomic force microscopy in IC manufacturing environments.

After an intensive evaluation period, Quadra, Nearfield Instruments’ metrology system, has penetrated high-volume chip manufacturing at Samsung. This was confirmed by Young Hoon Sohn, vice president of Metrology and Inspection at Samsung’s memory division at the TNO Semicon Innovation Day, held 17 April at the High Tech Campus in Eindhoven.

Sohn presented via an online video link and responded to questions from Bits&Chips that Samsung uses Nearfield’s Quadra devices in addition to ASML’s Yieldstar for optical metrology. Quadra maps the surface of chips with atomic force measurements. By deploying many atomic force probes in parallel, the Rotterdam-based company achieves high throughput.

Samsung has so far kept quiet about its use of the Dutch scale-up’s technology, but Sohn said his team has now been working with Nearfield for five years. “They are doing great”, he said. In his presentation, Sohn outlined the increasing need for metrology as details on chips continue to shrink. The need to check everything increases as chips become more complex. Chip manufacturers are using a broad spectrum of techniques to analyze errors and verify that all features are in the correct place – all to to minimize defects.

Nearfield Instruments Quadra in serieproductie 1000026593
Assembly space at Nearfield Instruments in Rotterdam, with several Quadras under construction.

Echoes

Until recently, Samsung used AFM only in R&D, but not yet in IC mass production. At that stage, everything has to be working perfectly. Manufacturers detest any disruptions in their manufacturing operations. In high-volume manufacturing, metrology has so far been limited to optical inspection (high throughput, low resolution) or e-beam inspection (high resolution, but slow). Sohn demonstrated in his presentation that multi-atomic force inspection (multi-AFM) represents the middle ground. AFM has thus reached the mature stage. Moreover, from Sohn’s presentation and answers to questions from the audience, it was clear that Nearfield’s AFM solution has now advanced to Samsung’s high-volume production.

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Sohn explained that especially the measurement of photoresist structures in (high-NA) EUV lithography is currently a major challenge. The smallest features are around 10 nanometers wide and only a few tens of nanometers thick. Optical techniques accomplish little at this scale, and even electron beams do not provide sufficient contrast without damaging the material. This presents an opportunity for Nearfield’s nondestructive metrology technique.

As shrinkage in the horizontal plane stagnates, chip manufacturers are increasingly looking for the continuation of Moore’s law in the third dimension. Here, too, Nearfield’s instruments can make themselves useful. In addition, the Rotterdam-based company is developing an acoustic technique to use AFM probes to map 3D structures under the non-transparent chip surface, similar to echoes in the medical world, but at the nano level.

Samsung Venture Investment (the strategic investment arm of Samsung Electronics, of which Samsung Semicon is a subsidiary) is a relatively small investor in Nearfield. Other investors include Invest-NL, ING, Innovation Industries, Eugene Investment & Securities and TNO Tech Transfer.