Deposition- controlled uniformity of multilayer mirrors

Alan F. Jankowski; Daniel M. Makowiecki; M. A. McKernan; R. J. Foreman; R. G. Patterson

doi:10.1117/12.23175

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1 February 1991 Deposition- controlled uniformity of multilayer mirrors

Alan F. Jankowski, Daniel M. Makowiecki, M. A. McKernan, R. J. Foreman, R. G. Patterson

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Proceedings Volume 1343, X-Ray/EUV Optics for Astronomy, Microscopy, Polarimetry, and Projection Lithography; (1991) https://doi.org/10.1117/12.23175
Event: 34th Annual International Technical Symposium on Optical and Optoelectronic Applied Science and Engineering, 1990, San Diego, CA, United States

Abstract

The widely used physical vapor deposition techniques to produce multilayer x-ray optics with uniform layer pair spacings (<1% variation) over large areas (> 10cm x 10 cm) have all been limited by the geometry of the vapor source. Magnetron sputtering sources, geometrically a convolution of point sources in a circular or rectangular array, provide uniformly thick regions of coating only within the boundaries of the erosion track. To maximize uniformity over large regins requires target materials equally as large, proving a costly proposition. Electron beam or molecular beam sources are similarly limited by the size of the melt pooi or effusion cell diameter. For ion beam deposition, spatial divergence from typical ion sources results in coating thickness variations of 5%or more for large areas as previously described. To minimize the ultimate expense of designing a necessarily large, single deposition source to provide a small thickness variation (without the use of compensating substrate motion or elaborate shielding over the deposition sources), several small sources arranged in an appropiate array may provide a viable alternative. To this end, the use of a linear array of one-inch magnetron sources has proven effective. Material has been deposited within the limitations of 1.5% thickness variation, along the axis of a linear gun array, over 15cm in length. The feasibility of using two linear arrays of magnetron sources is investigated to prepare large area multilayer mirrors with minimal layer pair spacing variations. Such a deposition system also allows for gradually varying the layer pair spacings across the surface of an optic, in a designed manner, which proves useful for focusing applications.

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Alan F. Jankowski, Daniel M. Makowiecki, M. A. McKernan, R. J. Foreman, and R. G. Patterson "Deposition- controlled uniformity of multilayer mirrors", Proc. SPIE 1343, X-Ray/EUV Optics for Astronomy, Microscopy, Polarimetry, and Projection Lithography, (1 February 1991); https://doi.org/10.1117/12.23175

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