METROLOGY APPARATUS BASED ON HIGH HARMONIC GENERATION AND ASSOCIATED METHOD

摘要

In a first aspect of the invention, there is provided a metrology apparatus for measurement of a target formed on a substrate by a lithographic process, the metrology apparatus comprising: a radiation source operable to provide first radiation; a configured solid high harmonic generation medium being configured to receive and be excited by said first radiation to generate high harmonic second radiation from an output surface of the configured solid high harmonic generation medium; and a detection arrangement operable to detect said second radiation, at least a portion of which having been scattered by said target; wherein said configured solid high harmonic generation medium is configured to shape the beam of said second radiation and/or separate said first and second radiation. In a second aspect of the invention, there is provided a configured solid high harmonic generation medium comprising an axicon shape operable to impart an annular profile onto first radiation received at an input surface; and concentric circular grooves on an output surface such that high harmonic second radiation generated at said output surface resulting from excitation by said first radiation is focused on and/or propagates along an optical axis of the configured solid high harmonic generation medium. In a third aspect of the invention there is provided, a metrology method for measuring a target formed on a substrate by a lithographic process comprising: exciting a configured solid high harmonic generation medium with first radiation, to generate high harmonic second radiation from an output surface of the configured solid high harmonic generation medium and to shape the beam of said second radiation and/or separate said first radiation and said second radiation; and detecting said second radiation, at least a portion of which having been scattered by said target. In a fourth aspect of the invention, there is provided a configured solid high harmonic generation medium comprising an input surface operable to receive a first radiation; and an output surface operable to emit a high harmonic second radiation resulting from excitation by the first radiation.