The scanned-probe microscope as nano-metrology tool

Metrology is an essential requirement in the microelectronics industry. As features in computing and memory devices (and also in the flat-panel, hard disc, and CD/DVD industries) reach farther into the nanoscale, their metrology becomes increasingly difficult. Scanned--probe microscopes (SPMs) offer potential solutions. SPMs can produce images with resolution down to the atomic level. However, because of inherent nonlinearities, conventional SPMs possess poor \underline {metrology }capabilities. Nanometrology requires closed-loop scanning, high throughput, and long-term stability, with subnanometer lateral and vertical resolution and extreme scan flatness over 100s of $\mu $m. We have developed metrology scanners suited for high-precision scanning and positioning applications. They have ultralow out-of-plane motion error ($<$1 nm over 100 $\mu $m scan area). A DSP-based controller enhances the scanner performance. Advanced control algorithms improve dynamic characteristics of the system significantly by reducing phase lag and settling time. The motion control system routinely achieves sub-nanometer resolution and accuracy with high working bandwidth and long-term stability. Using the performance of these metrology scanners we propose a vision of a complete SPM-based CD metrology tool that will enable nanometrology of future generations of electronic devices.