Fig. 1. Schematic of EUV optics system and mask. (a) EUV optics system; (b) EUV mask

Fig. 2. Schematics of DEE optimization method. (a) Initial status; (b) optimization of edge pixels; (c) optimization of outer edge pixels; (d) status after optimization

Fig. 3. Comparison of initialization methods

Fig. 4. Difference between pattern edges and resist pattern contour at each position

Fig. 5. Flowchart of mask optimization based on ADEE

Fig. 6. Illumination source

Fig. 7. Simulation results of line-space pattern. (a) Aerial image; (b) calculation errors of pxSDM1 and pxSDM2

Fig. 8. Variation of aerial image error with pixel number

Fig. 9. Target patterns. (a) Pattern 1; (b) pattern 2

Fig. 10. Aerial images of two initial mask patterns obtained by different methods. (a)(e) RCWA; (b)(f) pxSDM1 without upsampling; (c)(g) pxSDM1 with upsampling; (d)(h) pxSDM2

Fig. 11. Comparisons of resist patterns and target patterns. (a)(c) Initial resist patterns; (b)(d) resist patterns after mask defocus

Fig. 12. Optimized masks and resist patterns of pattern 1. (a)(b) Optimization results of DEE method; (c)(d) optimization results of ADEE method

Fig. 13. Optimized masks and resist patterns of pattern 2. (a)(b) Optimization results of DEE method; (c)(d) optimization results of ADEE method

Fig. 14. Convergence curves. (a) Pattern 1; (b) pattern 2