SUPER HIGH VERTICAL RESOLUTION NON-CONTACT 3D SURFACE PROFILER BY FOCUS VARIATION WITH WHITE LIGHT INTERFEROMETRY
Takashi Nishikawa
Abstract:
This system is developed as a focus variation microscopic system with great versatility and high vertical resolution. Conventional focus variation microscopic systems cannot measure surface topography of smooth surfaces such as a glass surface because the surface has no texture to get effective point focus sharpness. This system can obtain very high point focus sharpness by operating a 3x3x3 voxel operator, we call ‘the Digital Stylus’, to fringe images which are generated by the two beam interferometric objective lens. Furthermore a new algorithm to decide the position of focal point, we call ‘the APF: Approaching Function’ method, is introduced. The decision of the focal position for each pixel is made by Newton’s method with this APF. As 1 picometer is set for the truncation error of Newton’s method the system can calculate the surface topography with 1 picometer vertical resolution. The traceability of surface topography data using an 8 nm Standard Step Height Sample certified by NIST is shown in this paper. Sample data of a super smooth SiC wafer are also presented. This system allows us to get surface topography data by scanning once while other White Light Interferometry Systems require many scans for averaging to reduce the system noise. Not only will it measure super smooth surfaces but also very rough surfaces such as a ceramic bump without any changes of system configuration or parameters. This system will contribute significantly to the efficiency of the study of materials science.
Keywords:
surface profiler, focus variation, white light interferometry, approaching function, SiC wafer
Download:
IMEKO-TC14-2014-29.pdf
DOI:
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Event details
IMEKO TC:
TC14
Event name:
TC14 LMPMI Symposium 2014
Title:

11th Symposium on Laser Metrology for Precision Measurement and Inspection in Industry

Place:
Tsukuba, JAPAN
Time:
03 September 2014 - 05 September 2014
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