Fig. 1. Schematic diagrams of X-ray microscopes. (a) Scanning transmission X-ray microscope^[2]; (b) full-field transmission X-ray microscope^[3-4]

Fig. 2. Micrographs of all successfully fabricated critical components in X-ray microscopes by author’s team^[43-47]

Fig. 3. Technical roadmap of focusing/imaging zone plate lenses proposed by authors’ group from 2013 to 2022

Fig. 4. Comparison of proximity effect correction^[45]. (a) Uniform spatial distribution of charge dose without proximity effect correction (PEC), calculated by BEAMER; (b)(c) distorted outer zones in PMMA after electron beam lithography (EBL) without PEC; (d) non-uniform spatial charge dose distribution after PEC; (e)(f) resultant zones in PMMA after EBL with distortion; (g) outer zones in Au after Au electroplating

Fig. 5. Simulated profiles of outer zones with 100 nm resolution in 1.5 μm thick PMMA (shaded area) obtained by LAB software^[45]. (a) Simulated profiles without PEC, showing unclear zones in PMMA and without reaching depth of 1.5 μm; (b) simulated profiles with PEC by adding extra zone outside outermost zone, showing all unclear zones with depth of 1.5 μm

Fig. 6. SEM micrographs^[45]. (a) 100 nm resolution zone plate with 2 μm wide additional zone outside outmost zone for distance of 2 μm;(b)(c) uniform exposure of outermost zones

Fig. 7. SEM micrographs showing successfully fabricated 70 nm resolution zone plate with large aspect ratio after proximity effect correction of pattern method^[45]

Fig. 8. Different zone shapes and zone-widths in three different regions in zone plate ( patterns in stripes are zones generated by BEAMER software)^[46]

Fig. 9. Three different charge distributions in PMMA with 620 nm depth obtained by three different PEC methods^[46]. (a) Without PEC; (b) PEC by BEAMER and TRACER; (c) local PEC in three different regions in zone plate

Fig. 10. Three different simulated profiles obtained by using LAB software^[46] . (a) Over exposed outcome for zones in centre and in middle of zone plate without proximity effect correction; (b) significant deviations in profiles between zones and unwanted zone spread are obtained by using the commercial BEAMER and TRACER for PEC; (c) deviations in profiles between zones are after PEC by manual zone method

Fig. 11. Three different replicated profiles in PMMA by EBL with three different charge distortions^[46]. (a1)(a2) Without PEC; (b1)(b2) PEC for whole zone plate; (c1)(c2) PEC for local PEC

Fig. 12. Successfully fabricated 50 nm zone plates by EBL with local PEC^[46]. (a)--(c) Soft X-ray lens; (d)--(f) hard X-ray lens

Fig. 13. 30 nm zone plate formed by DC electroplating of Au^[47]. (a) EBL pattern of 30 nm zone plate; (b)(c) micro crystals formed by DC electroplating; (d) setup of DC electroplating

Fig. 14. Successfully fabricated 30 nm soft X-ray zone plate lens by EBL combined with pulsed Au electroplating^[47]

Fig. 15. Fabricated Siemens Stars with 50 nm resolution and high aspect ratio by EBL and Au electroplating. (a)(b) Replicated patterns in 1.2 μm thick PMMA by EBL; (c)--(e) successfully fabricated Siemens star with 50 nm resolution and 1 μm height (aspect ratio of 20∶1)

Fig. 16. 30 nm resolution Siemens star fabricated by EBL combined with Au electroplating (height at 30 nm wide tips is 600 nm, and aspect ratio is 20∶1)^[47]

Fig. 17. Demonstration of 50 nm resolution imaging by soft X-ray lens^[46]. (a) SEM micrograph of 50 nm resolution Siemens star fabricated by author’s team; (b)(c) imaging results of Siemens star obtained by 50 nm resolution zone plate

Fig. 18. Demonstration of 50 nm resolution imaging by hard X-ray lens^[46]. (a) SEM micrograph of 50 nm resolution Siemens star commercially supplied; (b) 50 nm resolution imaging of Siemens star by hard X-ray zone plate; (c) enlarged area in center of image (white line is scaling bar of 200 nm)

Fig. 19. Photos of in-house developed scanning transmission X-ray microscope on soft X ray beamline of BL08U1-A (706 eV) in Shanghai Synchrotron Radiation Facilities (SSRFs)

Fig. 20. Demonstration of 30 nm resolution imaging by soft X-ray lens^[47]. (a) SEM micrographs of 30 nm resolution zone plate fabricated by author’s team; (b)--(d) soft X-ray imaging photos when magnification increases from left to right, showing 30 nm line in center of each photo