Optical scatterometry of subwavelength diffraction gratings: neural-network approach.

Optical scatterometry is a method for the on-line measurement of the geometry of a diffraction grating, which is deduced from diffraction-pattern data. We demonstrate the use of a neural network as a promising method for performing an accurate quantitative characterization of the geometry. As an example, we show the deduction of the geometry of a grating with subwavelength grooves with a rms accuracy of 1.9 degrees for the slope of the groove walls, 0.7 nm for the linewidth, and 1.0 nm for the groove depth.

[1]  Joerg Bischoff,et al.  Photoresist metrology based on light scattering , 1996, Advanced Lithography.

[2]  David M. Haaland,et al.  Etch depth estimation of large-period silicon gratings with multivariate calibration of rigorously simulated diffraction profiles , 1994 .

[3]  Nicholas George,et al.  Neural networks applied to diffraction-pattern sampling. , 1994, Applied optics.

[4]  C. A. Hobson,et al.  Diffraction pattern analysis for automatic defect classification in manufactured electronic assemblies , 1994, Electronic Imaging.

[5]  Joseph B. Kruskal,et al.  Reactive ion etching profile and depth characterization using statistical and neural network analysis of light scattering data , 1993 .

[6]  Donald R. Hush,et al.  Using scattered-light modeling for semiconductor critical dimension metrology and calibration , 1993, Advanced Lithography.

[7]  J. McNeil,et al.  Linewidth measurement of gratings on photomasks: a simple technique. , 1992, Applied optics.

[8]  J. Kruskal,et al.  Use of light scattering in characterizing reactively ion etched profiles , 1991 .

[9]  James D. Keeler,et al.  Layered Neural Networks with Gaussian Hidden Units as Universal Approximations , 1990, Neural Computation.

[10]  Kurt Hornik,et al.  Multilayer feedforward networks are universal approximators , 1989, Neural Networks.

[11]  T. Gaylord,et al.  Zero-reflectivity high spatial-frequency rectangular-groove dielectric surface-relief gratings. , 1986, Applied optics.

[12]  T. Gaylord,et al.  Rigorous coupled-wave analysis of planar-grating diffraction , 1981 .

[13]  Daniel Maystre,et al.  Inverse scattering method in electromagnetic optics: Application to diffraction gratings , 1980 .

[14]  A. Roger,et al.  Grating profile reconstruction by an inverse scattering method , 1980 .

[15]  L. Botten,et al.  Groove depth determination using a laser for sinusoidal groove gratings. , 1977, Applied optics.

[16]  E. Oja,et al.  Neural networks – advantages and applications , 1994 .

[17]  John R. McNeil,et al.  SCATTEROMETRY APPLIED TO MICROELECTRONICS PROCESSING. PART II , 1993 .

[18]  D. Greenberg,et al.  The impact of electron transport regimes on the linearity of AlGaAs/n+-InGaAs HFETs , 1993 .

[19]  G. Wallraff,et al.  NEW SINGLE-LAYER POSITIVE RESISTS FOR 193- AND 248-NM LITHOGRAPHY USING METHACRYLATE POLYMERS , 1993 .