3D00400 - SEMI 3D4 - Guide for Metrology for Measuring Thickness, Total Thickness Variation (TTV), Bow, Warp/Sori, and Flatness of Bonded Wafer Stacks

 1  Purpose1.1  This Guide provides a description of tools that can be used to determine these key parameters before, during, and after the process steps involved in wafer bonding. Control of parameters such as bonded wafer stack (BWS) thickness, total thickness variation (TTV), bow, warp/sori, and flatness, is essential to successful implementation of a wafer bonding process. These parameters provide meaningful information about the quality of the wafer thinning process (if used), the uniformity of the bonding process, and the amount of deformation induced to the wafer stack by the bonding process. TTV is also critical in certain bonded wafer manufacturing process steps, since non-planarity can lead to problems in subsequent processing steps, including lithographic overlay and intermittent electrical contact between metal layers in the bonded wafers.2  Scope2.1  This Guide provides examples of the capabilities and limitations of various measurement technologies applicable to BWS as we