Ultra-high accuracy thermal expansion measurements with PTB's precision interferometer

Demands on dimensional stability and on the detailed knowledge of thermal expansion properties of 'high-tech' materials are growing considerably. One application is the further development of photolithography towards EUV?lithography where it is very important to know the thermal expansion properties of the substrates used for the masks but also for the mirrors used as main optical components. This paper describes the recent state of length/thermal expansion measurements with PTB's precision interferometer. The measurements are based on the observation of the absolute length of gauge-block-shaped or cylindrically material samples as a function of temperature using phase stepping interferometry. As reported earlier, in the precision interferometer alignment errors and errors involving the assignment of the sample's position within the camera pixel array are reduced to a negligible level [1, 2]. As a further improvement, in this paper corrections for the temperature-dependent effect of platen flexing are suggested. Measurement examples are shown to demonstrate CTE-measurement capabilities with uncertainties in the range of 10?9 K?1 or less.

[1]  Rene Schoedel,et al.  Methods to recognize the sample position for most precise interferometric length measurements , 2004, SPIE Optics + Photonics.

[2]  Giovanni Bianchini,et al.  Interferometric dilatometer for thermal expansion coefficient determination in the 4–300 K range , 2006 .

[3]  S. Bennett,et al.  An absolute interferometric dilatometer , 1977 .

[4]  René Schödel,et al.  Highest-accuracy interferometer alignment by retroreflection scanning. , 2004, Applied optics.

[5]  K P Birch,et al.  Intercomparison of Interferometric Dilatometers at NRLM and NPL , 1991 .

[6]  J. W. Berthold Iii,et al.  Ultraprecise measurement of thermal coefficients of expansion. , 1970, Applied optics.

[7]  R. W. Evans,et al.  A review of measurement techniques for the thermal expansion coefficient of metals and alloys at elevated temperatures , 2001 .

[8]  R. Schodel.  Investigation of thermal expansion homogeneity by optical interferometry , 2005, SPIE Optical Metrology.

[9]  G Galzerano,et al.  International comparison of two iodine-stabilized frequency-doubled Nd:YAG lasers at λ = 532 nm , 2000 .

[10]  G. Bönsch,et al.  Hochgenaue Temperaturmessung mit Thermoelementen (High-precision Temperature Measurements with Thermo Couples) , 2001 .

[11]  A. Chtcherbakov,et al.  Multiplexed fibre Bragg grating Fabry–Perot interferometers for measuring the coefficients of thermal expansion of anisotropic solids , 2006 .

[12]  Naofumi Yamada,et al.  Ultra-precise thermal expansion measurements of ceramic and steel gauge blocks with an interferometric dilatometer , 2000 .

[13]  Jennifer E. Decker,et al.  Considerations for the evaluation of measurement uncertainty in interferometric gauge block calibration applying methods of phase step interferometry , 2004 .

[14]  H. Preston‐Thomas,et al.  The International Temperature Scale of 1990 (ITS-90) , 1990 .

[15]  R. Schoedel.  Accurate extraction of thermal expansion coefficients and their uncertainties from high precision interferometric length measurements , 2005, SPIE Optics + Photonics.

[16]  R B Roberts,et al.  Absolute dilatometry using a polarization interferometer , 1975 .

[17]  Johannes Suska,et al.  DESIGN NOTE: An interferometric device for precise thermal expansion measurements on bar-shaped materials , 1999 .

[18]  Andrew B Lewis,et al.  Measurement of length, surface form and thermal expansion coefficient of length bars up to 1.5 m using multiple-wavelength phase-stepping interferometry. , 1994 .

[19]  Rene Schoedel,et al.  Precise interferometric measurements at single-crystal silicon yielding thermal expansion coefficients from 12° to 28°C and compressibility , 2001, Lasers in Metrology and Art Conservation.