27 August 1999 COCOS oxide film characterization and monitoring
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Abstract
COCOS, corona oxide characterization of semiconductor, metrology provides for fast and economic non-contact characterization of oxide properties in IC fab lines. The technique employs the repeated application of corona charge in sequence with contact potential difference, CPD, measurements to obtain flatband, Tox, Cox, Dit, and other characteristics of the SiO2 - Si system. Following a brief discussion of the underlying physical principles, specific examples of process induced defects and properties identified by the COCOS method will be presented. For example, process integrity monitoring is demonstrated with a process-tube sealing problem revealed by the correspondence between percent-thickness- uniformity and flatband data when oxide thickness varied by only a few angstroms. Characteristics of oxides annealed in a hydrogen containing ambient to remove damage are presented as examples of integration and process improvement efforts. Interface trap spectroscopy results using the new technique show that the anneal has a varied effect on traps depending on their position in the bandgap designated by the value of the surface barrier voltage. Such parametric data is rapidly obtained from re-usable monitor wafers run along with product, which results in increased equipment utilization. These and other encouraging results suggest that the COCOS methodology may enable the development of a better understanding of the key relationships between process conditions and the material properties produced by them.
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Andrew M. Hoff, Andrew M. Hoff, Damon K. DeBusk, Damon K. DeBusk, Robert W. Schanzer, Robert W. Schanzer, } "COCOS oxide film characterization and monitoring", Proc. SPIE 3884, In-Line Methods and Monitors for Process and Yield Improvement, (27 August 1999); doi: 10.1117/12.361336; https://doi.org/10.1117/12.361336
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