DescriptionExtreme ultraviolet (EUV) lithography light sources are aimed to emit light in a narrow wavelength band (in-band: 13.5 nm ± 1%) that is matching the spectral transmission of the optics and sensitivity of the photoresist. On the other hand, these sources also emit radiation outside the desired wavelength band, extending into the deep ultraviolet (DUV) and visible/IR range. The out-of-band radiation can have significant side effect such as contrast loss in the exposed photoresist or heat load on the delicate optics. Moreover, spectral characteristics of the in-band and out-of-band ranges contain a wealth of information about the conditions of the plasma. A broadband spectral diagnostic can be a vital tool in assessing the side effects of the out-of-band radiation and optimizing the plasma conditions towards higher in-band and lower out-of-band emission. Here we present spectral measurements of an EUV lithography source in the EUV and DUV/visible wavelength ranges using a transmission grating spectrometer. The spectrometer is based on a set of free-standing transmission gratings that can be reconfigured to record EUV and DUV/visible bands without breaking the vacuum. The recorded spectra can be immediately related to specific charge states in the plasma allowing optimization of the source conditions.
|Period||6 Nov 2017 → 8 Nov 2017|
|Event title||EUV Source Workshop 2017: null|
|Degree of Recognition||International|