Critical dimension small angle X-ray scattering measurements of FinFET and 3D memory structures

Charles Settens; Benjamin Bunday; Brad Thiel; R. Joseph Kline; Daniel Sunday; Chengqing Wang; Wen-li Wu; Richard Matyi

doi:10.1117/12.2012019

10 April 2013 Critical dimension small angle X-ray scattering measurements of FinFET and 3D memory structures

Charles Settens, Benjamin Bunday, Brad Thiel, R. Joseph Kline, Daniel Sunday, Chengqing Wang, Wen-li Wu, Richard Matyi

Proceedings Volume 8681, Metrology, Inspection, and Process Control for Microlithography XXVII; 86810L (2013) https://doi.org/10.1117/12.2012019
Event: SPIE Advanced Lithography, 2013, San Jose, California, United States

Abstract

We have demonstrated that transmission critical dimension small angle X-ray scattering (CD-SAXS) provides high accuracy and precision CD measurements on advanced 3D microelectronic architectures. The competitive advantage of CD-SAXS over current 3D metrology methods such as optical scatterometry is that CD-SAXS is able to decouple and fit cross-section parameters without any significant parameter cross-correlations. As the industry aggressively scales beyond the 22 nm node, CD-SAXS can be used to quantitatively measure nanoscale deviations in the average crosssections of FinFETs and high-aspect ratio (HAR) memory devices. Fitting the average cross-section of 18:1 isolated HAR contact holes with an effective trapezoid model yielded an average pitch of 796.9 ± 0.4 nm, top diameter of 70.3 ± 0.9 nm, height of 1088 ± 4 nm, and sidewall angle below 0.1°. Simulations of dense 40:1 HAR contact holes and FinFET fin-gate crossbar structures have been analyzed using CD-SAXS to inquire the theoretical precision of the technique to measure important process parameters such as fin CD, height, and sidewall angle; BOX etch recess, thickness of hafnium oxide and titanium nitride layers; gate CD, height, and sidewall angle; and hafnium oxide and titanium nitride etch recess. The simulations of HAR and FinFET structures mimic the characteristics of experimental data collected at a synchrotron x-ray source. Using the CD-SAXS simulator, we estimate the measurement capabilities for smaller similar structures expected at future nodes to predict the applicability of this technique to fulfill important CD metrology needs.

Citation Download Citation

Charles Settens, Benjamin Bunday, Brad Thiel, R. Joseph Kline, Daniel Sunday, Chengqing Wang, Wen-li Wu, and Richard Matyi "Critical dimension small angle X-ray scattering measurements of FinFET and 3D memory structures", Proc. SPIE 8681, Metrology, Inspection, and Process Control for Microlithography XXVII, 86810L (10 April 2013); https://doi.org/10.1117/12.2012019

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