High-resolution optical metrology

Recent advances in optical imaging techniques have unveiled new possibilities for optical metrology and optical-based process control measurements of features in the 65 nm node and beyond. In this paper we discuss methods and applications that combine illumination engineering and structured targets which enable sensitivity to nanometer scale changes using optical imaging methods. These methods have been investigated using simulation tools and experimental laboratory apparatus. The simulation results have demonstrated substantial sensitivity to nanometer changes in feature geometry. Similar results have now been observed in the laboratory. In this paper we will show simulation data to motivate the use of low numerical aperture and structured illumination optical configurations. We will also present the basic elements and methods which we are now using in the design of an optical tool specifically designed for these types of measurements. Target configurations which enhance the scattered electromagnetic fields will be shown along with experimental verification of the methodology. The simulation and experimental apparatus is used to explore and optimize target geometry, optical configurations, and illumination structure for applications in both critical dimension and overlay metrology.

[1]  Edward Kornegay,et al.  Overlay Metrology: Recent Advances and Future Solutions | NIST , 2001 .

[2]  Richard M. Silver,et al.  Comparison of edge detection methods using a prototype overlay calibration artifact , 2001, SPIE Advanced Lithography.

[3]  Egon Marx,et al.  New method to enhance overlay tool performance , 2003, SPIE Advanced Lithography.

[4]  Jeremiah R. Lowney,et al.  Scanning electron microscope analog of scatterometry , 2002, SPIE Advanced Lithography.

[5]  Charles N. Archie,et al.  Correlating scatterometry to CD-SEM and electrical gate measurements at the 90-nm node using TMU analysis , 2004, SPIE Advanced Lithography.

[6]  Mark P. Davidson.  Analytic waveguide solutions and the coherence probe microscope , 1991 .

[7]  Mario Dagenais,et al.  Focus and edge detection algorithms and their relevance to the development of an optical overlay calibration standard , 1999, Advanced Lithography.

[8]  Egon Marx,et al.  Comparison of measured optical image profiles of silicon lines with two different theoretical models , 2002, SPIE Advanced Lithography.

[9]  Charles N. Archie,et al.  Reducing measurement uncertainty drives the use of multiple technologies for supporting metrology , 2004, SPIE Advanced Lithography.

[10]  Jaime D. Morillo,et al.  Simultaneous critical dimension and overlay measurements on a SEM through target design for inline manufacturing lithography control , 2004, SPIE Advanced Lithography.

[11]  Joerg Bischoff,et al.  Comparison between rigorous light-scattering methods , 1997, Advanced Lithography.

[12]  E. Marx,et al.  Integral equation for scattering by a dielectric , 1984 .

[13]  Alexander Starikov,et al.  Accuracy of overlay measurements: tool and mark asymmetry effects , 1992 .

[14]  G. G. Stokes.  "J." , 1890, The New Yale Book of Quotations.