Automated SEM Metrology of Wafers Printed Using a SCAA Mask

摘要

The massive amount of data necessary to qualify a new 100nm generation technology can be efficiently collected using an automated CD-SEM and analyzed using Klarity ProData. By comparing the linewidths, space widths, and pitches printed in resist with different focus, exposure dose, and numerical aperture with the measured reticle parameters, one can determine optimal processing conditions and the required biasing rules for the new technology. The Sidewall Chrome Alternating Aperture Mask (SCAA Mask), a next generation alternating Phase Shift Mask (alt-PSM) structure, is especially suitable for this as all relevant mask features are visible from the top surface which, however, is not planar and thus can confuse optical mask inspection tools. Resist patterns with line-space pitches from 220nm to 800nm and isolated lines (approximately 20,000 values) - as well as the reticle - were measured using a KLA-Tencor 8250 CD-SEM and analyzed with ProData. At the isofocal dose, the 70nm line - 150nm space reticle pattern printed with equal 110nm lines and spaces at NA=0.63 on a Canon FPA-5000 ES3 248nm step and scan tool, with a process window that overlapped those of less dense ～100nm features.