Zoneplate lenses for EUV microscopy. EUVL workshop 2009 Iacopo Mochi, Kenneth A. Goldberg, Erik H. Anderson, Sungmin Huh

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1 Zoneplate lenses for EUV microscopy EUVL workshop 2009 Iacopo Mochi, Kenneth A. Goldberg, Erik H. Anderson, Sungmin Huh

Iacopo Mochi, Kenneth A. Goldberg, Erik H. Anderson Lawrence Berkeley National Laboratory IMochi@lbl.gov, KAGoldberg@lbl.gov, EHAnderson@lbl.gov Sungmin Huh SEMATECH Sungmin.Huh@SEMATECH.

2 Iacopo Mochi, Kenneth A. Goldberg, Erik H. Anderson Lawrence Berkeley National Laboratory Sungmin Huh SEMATECH Contents Zoneplates Theory Chromatic aberration and order sorting Off-axis zoneplate Actinic Inspection Tool: a practical example Aberrations and zoneplate aligent Illumination and stray light Image samples 3

$Zoneplates focus light using diffraction r r n r n 2 f n f 4N r 2 n 2$ 22 r High quality zone plates of 12 outer zone widths have been

process. (W. Chao, J. Kim, S. Rekawa, P. Fischer, and E.

3 Zoneplates focus light using diffraction r r n r n 2 f n f 4N r 2 n Rayleigh resolution f (on-axis zoneplates) 1.22 r High quality zone plates of 12 outer zone widths have been successfully fabricated using a novel electron beam lithographic process. (W. Chao, J. Kim, S. Rekawa, P. Fischer, and E. Anderson, "HSQ Double Patterning Process for 12 Resolution X-Ray Zone Plates," J. Vac Sci Tech. B (submitted).) 4

$aberration Multiple diffracted orders *Performance of actinic EUVL mask imaging$

4 Zoneplates are small Affordable ($50k) Highly customizable Multiple configurations Small flare* 130 µm 12 inches Small useful field of view Intrinsic chromatic aberration Multiple diffracted orders *Performance of actinic EUVL mask imaging using a zoneplate microscope, Kenneth A. Goldberg, et al., Proc. SPIE 6730, 67305E (2007) 5

adjustments** Improved optical stability **K. A. Goldberg, I. Mochi, S.

5 Chromatic aberration: a liability turned into an asset f f 0 0 N zones EUV lasers*: 20,000 Monochromator : 1450 Focus change with small wavelength adjustments** Improved optical stability **K. A. Goldberg, I. Mochi, S. Huh, SPIE 7271, 72713N-1-8 (2009). *F. Brizuela et al, Opt. Lett. 34, (2009). 6

6 Through focus image series with wavelength change

7 Through focus image series with wavelength change

8 Through focus image series with wavelength change

9 Through focus image series with wavelength change

10 Through focus image series with wavelength change

11 Through focus image series with wavelength change

12 Through focus image series with wavelength change

$Zoneplates diffract light into focused$ efficiency m 1/4 1 m 2 2 0 m = 0 m odd

13 Zoneplates diffract light into focused and diverging beams Diffraction order efficiency m 1/4 1 m m = 0 m odd m even -1th order Zero order -3th order -5th order Focal length f m f m 1th order Zero order 3th order 5th order 14

14 Order sorting with off-axis zoneplates D x Parent zoneplate center f 15

15 Order sorting with off-axis zoneplates x D Parent Zoneplate f NA 2 r NA _off sin arctan 2x 2 f D arctan x f sin arctan x f 2 arctan 2x 2 f D 16

16 The SEMATECH Berkeley Actnic Inspection Tool: an EUV zoneplate microscope for mask inspection Wavelength = 13.4 ± 0.01 (tunable) From synchrotron NA = (0.35 x4) (0.30 x4) (0.25 x4) Magnification = Si 3 N 4 17

17 LBNL 5 µm 7/15/09 EUV Litho Global Foundries MET 10

µm (object space) Aberration control Wavefront error (λ RMS) λ/4 λ/5 λ/7 λ/10 λ/20 Strehl Ratio 0.35 0.55 0.75 0.

18 µm (object space) Aberration control Wavefront error (λ RMS) λ/4 λ/5 λ/7 λ/10 λ/20 Strehl Ratio µm (object space) µm (object space) I. Mochi et al., Improving the performance of the actinic inspection tool with an optimized aligent procedure, Proc. SPIE 7271, (2009). 19

19 µm (object space) Aberration control Wavefront error (λ RMS) 5 µm µm (object space) 20

20 Zoneplate aligent Scattering Surface Reflective Surface Zoneplate aligned and centered 21

21 30 µm Dark field effects AIT image Zoneplate B NA 0.25 (4x) Bright field Dark field 22

22 Patterned objects can cause background light We reduce stray light scattered from the pattern on the reticle by shrinking the illumination area Periodic pattern Illumination footprint q Image p Incoming beam Reticle Object 23

23 Patterned objects can cause background light We reduce stray light scattered from the pattern on the reticle by shrinking the illumination area Periodic pattern Illumination footprint q Image p Incoming beam Reticle Object 24

24 When the zoneplate is correctly aligned... Here are some of the latest images collected with the AIT 25

25 LBNL 5 µm 7/15/09 EUV Litho Global Foundries MET 10

26 LBNL 1 µm 80 lines 20 (4x) 2 µm 7/15/09 EUV Litho Global Foundries MET 10

27 LBNL 1 µm 75 lines (4x) 2 µm 7/15/09 EUV Litho Global Foundries MET 10

28 LBNL 1 µm 70 lines 17.5 (4x) 2 µm 7/15/09 EUV Litho Global Foundries MET 10

29 LBNL 1 µm 65 lines (4x) 2 µm 7/15/09 EUV Litho Global Foundries MET 10

30 Zoneplates come in exotic flavors Phase control Illumination uniformity improvement Aberration correction C. Chang et al., Optics Letters / Vol. 31, No. 10, (2006) A. Sakdinawat and Y. Liu, Optics Letters / Vol. 32, (2007). A. Sakdinawat and Y. Liu, Opt. Express 16, (2008). 31

31 Acknowledgments The authors gratefully thank all the members of the Center for X-Ray Optics at LNBL and particularly Weilun Chao, Anne Sakdinawat, Simi George and Patrick Naulleau. Special thanks to Bruno LaFontaine (Global Foundries) who gave us permission to show the images presented in this talk. 32

k λ NA Resolution of optical systems depends on the wavelength visible light λ = 500 nm Extreme ultra-violet and soft x-ray light λ = 1-50 nm

k λ NA Resolution of optical systems depends on the wavelength visible light λ = 500 nm Extreme ultra-violet and soft x-ray light λ = 1-50 nm Resolution of optical systems depends on the wavelength visible light λ = 500 nm Spatial Resolution = k λ NA EUV and SXR microscopy can potentially resolve full-field images with 10-100x smaller features