High resolution interferometric metrology for patterned wafers

Shouhong Tang; Klaus Freischlad; Petrie Yam

doi:10.1117/12.735121

10 September 2007 High resolution interferometric metrology for patterned wafers

Shouhong Tang, Klaus Freischlad, Petrie Yam

Proceedings Volume 6672, Advanced Characterization Techniques for Optics, Semiconductors, and Nanotechnologies III; 667208 (2007) https://doi.org/10.1117/12.735121
Event: Optical Engineering + Applications, 2007, San Diego, California, United States

Abstract

The precision metrology of patterned wafer is increasingly demanded by the semiconductor device manufacturers. The most common methods include scanning probe microscopy (SPM) techniques such as stylus profilometry and Atomic Force Microscopy (AFM). These methods acquire data by contacting the surface over a sequence of one-dimensional scans. While high lateral resolution can be achieved in this way, such processes are time-consuming and can have the potential to deform the surface under test. An alternative non-contact interferometric method is presented here. The method uses the white-light interferometry (WLI) to provide wafer topography quickly in a direct three-dimensional format. The improved measurement throughput suggests that it is feasible to use this method for production monitoring. Most commercial interferometers with WLI are capable of measuring opaque surfaces with sub-nanometer precision. The described method extends this capability to determine the top surface topography of structured surfaces in the presence of varying phase shifts on reflection. The phase shift on reflection may be due to the material properties of bulk surfaces, single or multi-layer film stacks on a substrate, or other micro-structures on the wafer. Furthermore, this method simultaneously or separately provides additional parameters of the test piece e.g. layer thickness and/or material refractive index for film stacks, or line width and structure depth of micro-structures. The measurement results on various types of the wafer surfaces will be presented in this paper.

Citation Download Citation

Shouhong Tang, Klaus Freischlad, and Petrie Yam "High resolution interferometric metrology for patterned wafers", Proc. SPIE 6672, Advanced Characterization Techniques for Optics, Semiconductors, and Nanotechnologies III, 667208 (10 September 2007); https://doi.org/10.1117/12.735121

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