Micro- and nanoscale dimensional metrology at PTB

Quantitative dimensional measurements of nano- and microstructures are increasingly in demand following rapid developments in, for instance, the semiconductor industry, precision engineering industry, microsystem techniques and materials science. The sizes of the nano- and microstructures range from nanometres to hundreds of micrometres. And the measurement task could be categorized as one dimensional (1D), two dimensional (2D), two and half dimensional (2.5D) and true three dimensional (3D) measurements.

With a brief overview of techniques such as scatterometry, optical microscopy and scanning electron microscopy, the presentation will focus on atomic force microscopy (AFM), which is capable of measuring micro and nanostructures directly, accurately, (almost) non-destructively and in 3D. Several AFMs developed at PTB will be detailed, for instance a metrological large range AFM with a capable measurement volume of 25 mm x 25 mm x 5 mm (x, y, z) coupled with homodyne laser interferometers for traceable nanoscale dimensional metrology. A newly developed 3D-AFM which is capable of performing true 3D measurements of nano structures by applying flared AFM tips. A novel AFM probe, referred to as the assembled cantilever probe (ACP) will also be introduced. It is capable of performing measurements at the sidewalls of micro and nanostructures directly. In addition, the development of a micro/nano coordinate measuring machines (CMM) will be presented.

Transfer artifacts and writing standards for micro- and nanoscale dimensional metrology will be briefly introduced. Versatile measurement examples will be demonstrated.

Dr. Gaoliang Dai is currently a research scientist and the head of the working group of „mask metrology“ at the Physikalisch-Technische Bundesanstalt (PTB). His main areas of research cover the dimensional metrology of micro- and nanostructures. He is responsible for developing the high accurate metrological SFM, metrological large range SFM, 3D-AFM and micro/nano CMM at PTB. Gaoliang gained a BSc, an MSc and a PhD in optical engineering from the Tsinghua University, P. R. China. He was a R&D engineer in the Physik Instrument (PI) GmbH & Co till the year 2001. He has authored over 70 technical publications in the field of micro- and nanometrology.

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