Nanoscale resolution Full Field imaging with extreme ultraviolet light

1
Nanoscale resolution Full Field imaging with
extreme ultraviolet light

• C. S. Menoni, C.A. Brewer, F. Brizuela, P.
  Wachulak, D.H. Martz, M.C. Marconi, J.J. Rocca
  
• NSF ERC for Extreme Ultraviolet Science and
  Technology and
• ECE Department, Colorado State University
• W. Chao, E. H. Anderson, and D. T. Attwood
• NSF ERC for Extreme Ultraviolet Science and
  Technology
• and Center for X-ray Optics, LBNL
• A. V. Vinogradov and I. A. Artioukov
• P. N. Lebedev Physical Institute, Russia
• Y. P. Pershyn and V. V. Kondratenko
• National Technical University KhPI, Ukraine

2
Extreme ultraviolet light sees smaller
features, writes smaller patterns
3
EUV/SXR microscopes provide high-resolution
capabilities and unique advantages for
nanoscience and nanotechnology applications
? wavelength of illumination NA numerical
aperture of the objective k1 illumination and
test specific constant
SXR microscopy can potentially resolve full-field
images with 10-100x smaller features than
conventional visible microscopy.
Panoramic view of Beamline 6.1.2, the home of a
transmission full-field imaging x-ray microscope
(XM-1), at the ALS at E.O. Lawrence Berkeley
National Laboratory. (Image downloaded at
http//www-als.lbl.gov/als/)
Investigate electromigration in IC interconnects
Image biological cells
W. Chao, et al., Nature Vol. 435, 1210-1213
(2005)
Images downloaded at www-cxro.lbl.gov
3
4
Compact EUV/SXR sources make full-field
microscopy more accessible
Source HHG Wavelength 13.6 nm Resolution 200
nm Exposure time 4 minutes Sample diatoms M.
Weiland et al., (2005)
Source plasma Wavelength 2.48 nm Resolution
sub 30 nm Exposure time 5 minutes Sample in
image diatom P.A.C. Takman et al. (2007)
Source SXR lasers
Early work in transmission Wavelength 4.48 nm
(NOVA laser) Resolution 75 nm Exposure time
single 200 picosecond pulse Sample gold
pattern on Si3N4 substrate L.B. Da Silva et
al. (1992)
Source compact laser Wavelength 13.9
nm Resolution 200 nm Exposure time single
picosecond pulse Sample Cr/Si multilayer Kishimot
o et al. (2003)
Early work in reflection Wavelength 18.2
nm Resolution 700 nm Exposure time 8
shots Sample gold squares on a glass
substrate D.S. DiCicco et al. (1992)
5
High brightness compact EUV lasers enable
nanoscale experiments on a table top
OUTLINE

• Imaging at ?13 nm in transmission configuration

• Imaging at ?46.9 nm in transmission and
  reflection configurations

54 nm spatial resolution
38 nm spatial resolution
6
Compact ?46.9 nm microscope
Transmission mode configuration
7
Microscope illumination source worlds most
compact capillary discharge 46.9 nm EUV laser
12 Hz rep. rate , 0.15 mW average power
Laser Output Characteristics

• gt 10 microjoule /pulse
• 0.15 mW average power
• 12 Hz repetition rate
• Pulse duration 1.5 ns
• ??/? lt 1 x 10-4

S. Heinbuch Optics Express vol. 13, 4050 (2005)
8
Microscope optics reflective Condenser and
Fresnel zone plate objective
Si/Sc multilayer coated Schwarzschild Condenser
Free standing Fresnel Zone Plate Objective
Zone Plate Parameters
Specifications Diameter M1 D1 50 mm Diameter
M2 D2 10.8 mm Focal distance f 27 mm Num.
Aperture NA 0.18 Throughput 16.
Designed and fabricated at Lebedev Physical
Inst.- KhPI-Ukrane
Fabricated by electron beam lithography at CXRO
E. H. Anderson, IEEE JQE vol. 42, 27 (2006)
I.A. Artioukov, Opt. Lett. Vol. 30, 2451, (1995)
9
Spatial resolution is proportional to the width
of the outermost zone
?r width of the objective zone plates
outermost zone k1 constant that is dependent on
the coherence of the system and the particular
resolution test
D. T. Attwood, Soft X-rays and Extreme
Ultraviolet Radiation
9
10
Resolution The constant k is test and
illumination dependent
k1
0.3 ltk lt0.5 (Grating test- half period)
Coherence parameter m NAC/NAO
All tests are equivalent when the imaging system
is incoherent
J. M. Heck, D.T. Attwood, et al., J. X-ray Sci.
Tech. 8, 95 (1998)
10
11
46.9 nm EUV microscope fits on an optical table

• Compact microscope incorporates
• Controlled positioning of EUV optics
• Visible optical microscope aids in alignment
• Remote imaging acquisition operation

12
Freestanding dense line grating are imaged to
build the modulation transfer function

• Test sample
• Transmission gratings with half periods of 400
  - 54 nm
• Samples are freestanding ? 100 sample contrast

Image intensity lineout
EUV/SXR image obtained with ? 46.9 nm microscope
M 26.5
300 nm
400 nm
150 nm
200 nm
?r 120 nm zone plate, 20 seconds
12
13
Single shot EUV/SXR images with ?r 70nm zone
plate and 11.25 x 11.25 nm2 pixel size
EUV image of 70 nm half-period grating
Modulation Transfer Function
SEM image of 70 nm half-period grating
13
14
Latest result EUV single shot transmission
image of carbon nanotubes
Image of Carbon nanotubes with nominally 80 nm
diameters

• Very compact microscope
• At-wavelength resolution
• Single nanosecond exposure

14
15
Large field of view images of a semiconductor
chip microscope images semiconductor chip
46.9 nm laser
CCD
Objective zone plate ?r200 nm
CCD
Schwarzschild Condenser
46.9 nm laser
Test Pattern at 45º
16
Versatile, compact 46.9 nm microscope yields
excellent quality images of integrated circuits
EUV Image of metal pattern on Silicon
EUV Image of polysilicon lines on Silicon
?r200 nm Exposure time 20 sec _at_ 3Hz Spatial
resolution 120 nm
17
Full field 13 nm microscope operates in
transmission mode

• Condenser zone plate
• ?r 100 nm

Objective zone plate ?r 80 nm ?r 50 nm
18
EUV Lasers pumped by a 5-10 Hz, 1 J Short Pulse
Table-top TiSapphire laser System
Laser average power ?2 uW Pulsewidth 5 ps
J.J. Rocca et al., Opt. Lett. Vol. 30, 2581
(2005) Y. Wang et al., Phys. Rev. A 72, 5
(2005)
19
?13 nm imaging system offers Large Field of View
EUV Image of radial test pattern ?r80 nm
objective lens - 20 sec exposure
60 nm half-period lines are resolved
15 ?m
20 ?m
20
Half period spatial resolution of the ?13.2 nm
microscope is better than 38 nm
EUV Images of dense line patterns ?r50 nm, 20
sec exposure
70 Intensity Modulation of 38 nm 11 lines
indicates spatial resolution is better than 38
nm
G. Vaschenko, et al Optics Letters, vol 31, 1214
(2006)
System Resolution limit also confirmed with Image
Analysis Algorithm P. Wachulak submitted to
JOSA B
21
Summary

• Table-top EUV laser-based imaging systems are new
  tools for nanoscience and nanotechnology
• NANOSCALE IMAGING
• Compact laser based 46.9 nm microscope
• Experimentally determined the modulation transfer
  functions for objective zone plates with ?r 200
  nm, 120 nm, and 70 nm
• Achieved near-wavelength 54 nm spatial resolution
• Acquired single shot images, providing nanosecond
  temporal resolution
• Imaged with a single shot nominally 80 nm
  diameter carbon nanotubes
• Capable of imaging nanostructures in reflection
  mode.
• Full field microscope 13.2 nm microscopes
  achieves 38 nm resolution

Carmen.Menoni_at_Colostate.edu
22
EUV Laser and Imaging and Ablation Teams