Spectrophotometric method for measuring the groove depth of calibration reflection gratings
Tóm tắt
A method for measuring the groove depth of calibration gratings is proposed which is based on measuring the spectral dependence of the the zero-order reflection diffraction efficiency. The errors of the method are determined by three main factors: the shift of the maxima of the spectrum due to the wall slope of the grating grooves, the error in setting the wavelength of the spectrophotometer, and the divergence of the light beam in the setup. It is shown theoretically that the measurement error is in the range of 0.25–1%, depending on the fabrication technology of the grating and measuring equipment. The method was tested experimentally using commercial calibration gratings. The range of applicability of the method is discussed in terms of the geometrical parameters of the microstructure of reflection gratings and the characteristics of the spectrophotometer used.
Tài liệu tham khảo
Optical Shop Testing, Ed. by D. Malacara (Wiley and Sons, New York, 2007).
E. V. Sysoev, I. A. Vykhristyuk, R. V. Kulikov, et al., “The Interference Microscope, Profilometer,” Avtometriya 46(2), 119–128 (2010) [Optoelectron., Instrum. Data Porcess. 46 (2), 198–205 (2010)].
J. W. Gate, “Fringe Spacing in Interference Microscopes,” J. Sci. Instrum. 33(12), 507 (1956).
C. J. R. Sheppard and K. G. Larkin, “Effect of Numerical Aperture on Interference Fringe Spacing,” Appl. Opt. 34(22), 4731–4734 (1995).
Dimensional Products—Groove Depth Standards (Quartz), http://www.vlsistandards.com/products/dimensional/step.asp?SID=100.
L. Koenders, WGDM-7: Preliminary Comparison on Nanometrology, Nano2: Groove Depth Standards. Final Report (Physikalisch-Technische Bundesanstalt, Braunschweig, 2003).
Nanoscale Calibration Standards and Methods: Dimensional and Related Measurements in the Micro- and Nanometer Range, Ed. by G. Wilkening and L. Koenders (Wiley-VCH, 2005).
Test Structures — TGZ Series, http://www.spmtips.com/tgz.
L. L. Doskolovich and V. A. Soifer, “Multi-Order DOE,” in Diffraction Computer Optics, Ed. by V. A. Soifer (Fizmatlit, Moscow, 2007), pp. 254–297 [in Russian].
Yu. A. Bystrov, E. A. Kolgin, and B. N. Kotletsov, Process Control of Sizes in the Microelectronic Fabrication (Radio i Svyaz’, Moscow, 1988) [in Russian].
A. R. Hind and L. Chomette, “The Determination of Thin Film Thickness Using Reflectance Spectroscopy,” http://www.chem.agilent.com/Library/applications/uv90.pdf.
A. G. Poleshchuk, “Diffractive Light Attenuators with Variable Transmission,” J. Modern Opt. 45(7), 1513–1522 (1998).
International Intellectual Group, Inc., http://www.pcgrate.com.
M. J. Weber, Handbook of Optical Materials (CRC Press, 2003), pp. 325–333.