Patent ID: 8194322
Filing Date: 2012-06-05
Classification: B82Y,G02B,G03F,G21K

Abstract:
1. A multilayer-film reflective mirror, comprising: a base; and a multilayer film formed on the base, the multilayer film comprising multiple layer pairs, each layer pair comprising a respective first layer and a respective second layer, the first and second layers being laminated together in an alternating manner; first and second regions of the multilayer film that reflect extreme ultraviolet light; a first group of layer pairs disposed in each of the first and second regions and having a first periodic length; a second group of layer pairs disposed over the first group in the first region, the second group having a second periodic length less than the first periodic length; and a third group of layer pairs disposed over the first group in the second region, the third group having a periodic length substantially equal to the first periodic length, wherein the first and second regions have similar reflectance, within a specified tolerance level, to an operational wavelength of incident light as the first region produces reflected light exhibiting a respective phase change with respect to the incident light having the operational wavelength, compared to the second region, wherein the first and second regions collectively define a mirror surface that exhibits smooth and continuous transitions in surface shape from first regions to second regions and from second regions to first regions, and wherein phase-changes in boundaries defined by first and second regions are smoothly and continuously distributed.