1.5nm metrology tool targets advanced node

The need for more advanced metrology instruments is increasing as Moore's Law approaches the next two semiconductor technology nodes, 11nm and 7nm. These fine-scaled rulers need to be as much as 10 times finer than the semiconductors they are measuring to accommodate the sustained progress of Moore's Law.

The previous finest scale rulers today were spaced at 4nm, invented by aBeam Technologies Inc. (Hayward, Calif.) in cooperation with the Lawrence Berkeley National Lab (LBNL, Calif.) using e-beam lithography, atomic layer deposition and nano-imprint. For the latest standard, extending Moore's Law to 7nm, Argonne National Laboratory pitched in with aBeam and LBNL to create what they claim as the finest metrology tool in the world, at 1.5nm.

Designed pseudo-random 1.5nm test patterns (left) and a scanning electron microscope (SEM) image of it (right) (Source: aBeam Technologies)

"The techniques used in this work came from the semiconductor industry; we are not in a position to talk about the details at the moment. This is, however, not a typical CMOS process flow. We used silicon and tungsten silicide since we needed good contrast in the materials to characterise and tune nanometrology equipment. The technology itself, however, is not limited to these selected materials, a wide variety of materials can be used," said Sergey Babin, president of aBeam.

Transmission electron microscope (TEM) image of 1.5nm random test pattern (left) and a double close-up (right). (Source: aBeam)

The novel materials are used as test patterns for which to calibrate and test the metrology instruments to be used on fabricated advanced node semiconductors. The patterns involve thousands of lines with precise line widths that nevertheless appear to be random, but which can be combined to measure any relevant line width.

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