Accurate surface profilometry of ultrathin wafers

Weeks, A.E., Litwin, D., Galas, J., Surma, B., Piatkowski, B., MacLaren, D.A. and Allison, W. (2007) Accurate surface profilometry of ultrathin wafers. Semiconductor Science and Technology, 22(9), pp. 997-1002. (doi: 10.1088/0268-1242/22/9/004)

Abstract

Geometric characterization of 50 mm diameter, 50 µm thick single-crystal Si(1 1 1) wafers has been performed using complementary methods: industry-standard capacitance measurements of warp and total thickness variation (TTV), and a technique we term scanned chromatic confocal profilometry (SCCP). We compare the measurements made by the two techniques and demonstrate the limitations of capacitance measurements when applied to ultrathin wafers. The two-dimensional SCCP measurements are shown to enhance the description of wafer thickness variations beyond that generated by the standard test method. We discuss a Fourier transform-based analysis and show it to be useful in wafer quality assessment. Adding a summary of spatial frequencies in a wafer's thickness map to the conventional measures of warp and TTV provides a more complete summary of the salient features of a wafer's geometry.

• Item Type: Articles
• Status: Published
• Refereed: Yes
• Glasgow Author(s) Enlighten ID: MacLaren, Professor Donald
• Authors: Weeks, A.E., Litwin, D., Galas, J., Surma, B., Piatkowski, B., MacLaren, D.A., and Allison, W.
• Subjects: Q Science > QC Physics
• College/School: College of Science and Engineering > School of Physics and Astronomy
• Journal Name: Semiconductor Science and Technology
• ISSN: 0268-1242
• Published Online: 06 August 2007