Fabrication of nanoscale patterns in lithium fluoride crystal using a 13.5 nm Schwarzschild objective and a laser produced plasma source

Xin Wang; Baozhong Mu; Li Jiang; Jingtao Zhu; Shengzhen Yi; Zhanshan Wang; Pengfei He

doi:10.1063/1.3665970

Fabrication of nanoscale patterns in lithium fluoride crystal using a 13.5 nm Schwarzschild objective and a laser produced plasma source

Rev Sci Instrum. 2011 Dec;82(12):123702. doi: 10.1063/1.3665970.

Authors

Xin Wang¹, Baozhong Mu, Li Jiang, Jingtao Zhu, Shengzhen Yi, Zhanshan Wang, Pengfei He

Affiliation

¹ Key Laboratory of Advanced Micro-structured Materials, MOE, Department of Physics, Institute of Precision Optical Engineering, Tongji University, Shanghai 200092, China.

PMID: 22225219
DOI: 10.1063/1.3665970

Abstract

Lithium fluoride (LiF) crystal is a radiation sensitive material widely used as EUV and soft x-ray detector. The LiF-based detector has high resolution, in principle limited by the point defect size, large field of view, and wide dynamic range. Using LiF crystal as an imaging detector, a resolution of 900 nm was achieved by a projection imaging of test meshes with a Schwarzschild objective operating at 13.5 nm. In addition, by imaging of a pinhole illuminated by the plasma, an EUV spot of 1.5 μm diameter in the image plane of the objective was generated, which accomplished direct writing of color centers with resolution of 800 nm. In order to avoid sample damage and contamination due to the influence of huge debris flux produced by the plasma source, a spherical normal-incidence condenser was used to collect EUV radiation. Together with a description of experimental results, the development of the Schwarzschild objective, the influence of condenser on energy density and the alignment of the imaging system are also reported.