P. A. Rosenthal and E. T. Yu
Department of Electrical and Computer Engineering and Materials Science and Engineering Program
University of California San Diego, La Jolla, CA. 92093-0407

As MOS transistor device dimensions decrease to the 0.1 mm gate length regime, the need for quantitative charge carrier profiling in both the vertical and lateral directions becomes critical for advances in process and device simulation and production. The 1997 National Technology Roadmap for Semiconductors (NTRS) states that appropriate tools for this endeavor will have spatial resolution < 10 nm, high quantification accuracy (5%), and high sensitivity over a dynamic range of 10¹⁴-10²⁰ cm^-3. These requirements push the practical limits of other techniques such as secondary ion mass spectroscopy (SIMS), spreading resistance profiling, and dopant-selective etching, which lack the requisite spatial resolution and/or reproducibility. Additional metrology methods are therefore required. Several techniques based on scanning probe microscopy have emerged as powerful tools suitable for characterization of  2-D dopant profiles in current and future ULSI materials and devices. This talk will focus on three of these techniques: nano-spreading resistance profiling¹, scanning capacitance microscopy², and scanning Kelvin probe force microscopy³. Each of these techniques will be examined highlighting applications to 2-D dopant profiling on cross-sections of test and actual device structures. Comparisons will be made between the techniques, with emphasis on the NTRS criteria.

References:

1) P. Dewolf, T. Clarysse, W. Vandervorst, L. Hellmans, Ph. Niedermann, and W. Hänni, J. Vac. Sci. Tech. B. 16(1), 355 (1998).

2) G. Neubauer, A. Erickson, C. C. Williams, J. J. Kopanski, M. Rodgers, and D. Adderton, J. Vac. Sci. Tech. B. 14(1), 426 (1996).