24 May 2004 Alignment offset analyzer against wafer-induced shift (WIS)
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Abstract
In lithography, the alignment error can be categorized into three factors. The first factor is called as Tool Induced Shift (TIS). The second is Wafer Induced Shift (WIS) and the third is the interaction between TIS and WIS. About TIS, we have defined a new evaluation criterion. About WIS, we have shown an error analyzer to quantify and compensate the alignment error using Atomic Force Microscope (AFM) and optical simulation. We have called this analyzer as 'Alignment Offset Analyzer'. This analyzer has the following features. The topography of an alignment mark and resist surface on the alignment mark are measured individually by the AFM. The two topography data are wrapping over in a signal simulator. Using the wrapped topography, an alignment signal and an alignment measurement offset are calculated. Since the alignment offset can also be calculated before exposure sequence, the alignment offset can be inputted to exposure tool without send-ahead wafers. This time we report the accuracy of the Alignment Offset Analyzer. The alignment offset measured by an exposure tool and the calculated one above mentioned showed a good agreement, and the difference was several nm.
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Takahiro Matsumoto, Hideki Ina, Koichi Sentoku, "Alignment offset analyzer against wafer-induced shift (WIS)", Proc. SPIE 5375, Metrology, Inspection, and Process Control for Microlithography XVIII, (24 May 2004); doi: 10.1117/12.534757; https://doi.org/10.1117/12.534757
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