28 May 2003 Optical emission endpoint optimization in the tetra etch chamber for production of embedded phase-shift photomasks
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Proceedings Volume 5148, 19th European Conference on Mask Technology for Integrated Circuits and Microcomponents; (2003) https://doi.org/10.1117/12.515073
Event: 19th European Conference on Mask Technology for Integrated Circuits and Microcomponents, 2003, Sonthofen, Germany
Abstract
The Etec Systems TetraTM photomask etch system is currently used to etch attenuated phase shift photomasks. Currently, MoSiON is a common film used for phase shifting. Either chrome or re sist can be used as a mask for etching this film. Because the quartz substrate etches with the same chemistry commonly used to etch MoSiON, precise endpoint control is necessary to meet the phase targeting requirements to create this type of phase-shifting mask. This paper will address techniques used to obtain precise endpoint control ofthe MoSiON-quartz boundary. Endpoint control is required for the precise phase targeting of 1 800 ± 1 .5° needed for advanced subwavelength patterning technologies. In this paper, optical emission spectroscopy is used to characterize and monitor chrome etch processes on the Etec Systems TetraTM photomask etch chamber. Changes in process conditions have been captured by time-averaged optical emission traces. Using multi-wavelength optical emission spectroscopy data collected during MoSiON etching, a fingerprint ofthe plasma can be taken. The fingerprint is used to detect changes in emission lines during the etch and determine the best wavelength for endpoint detection. Secondly, this paper will examine numerical methods ofendpoint optimization, including averaging, smoothing and derivative techniques.
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Cynthia B. Brooks, Scott Anderson, Rex B. Anderson, Corey Collard, Jason Clevenger, Nicole L. Sandlin, Melisa J. Buie, "Optical emission endpoint optimization in the tetra etch chamber for production of embedded phase-shift photomasks", Proc. SPIE 5148, 19th European Conference on Mask Technology for Integrated Circuits and Microcomponents, (28 May 2003); doi: 10.1117/12.515073; https://doi.org/10.1117/12.515073
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