Byungmin Yoo1,3, Dong Gon Woo3, Young Woong Kim2,3, Young Ju Jang1,3, Seong Ju Wi2,3 and Jinho Ahn1,2,3*

1 Division of Nanoscale Semiconductor Engineering, 2 Division of Materials Science and Engineering, 3 EUV-IUCC (Industry University Collaboration Center)

Hanyang University, 222 Wangsimni-ro, Seongdong-gu, Seoul 04763, Korea

INTRODUCTION

EXPERIMENT

RESULTS & DISCUSSION

SUMMARY & CONCLUSION

7-11 June 2020, Online2020 EUVL Workshop

<Optic system of EUV ptychography microscope>

❑ EUV ptychography microscope

<EUV ptychography microscope>

❑ Imaging method - ptychography

<Convolution of probe and object function>

<Optical microscope image of

contaminated EUV pellicle

(red box: through-pellicle imaging region)>

❑ Through-pellicle imaging with the contaminated pellicle

➢ Particles smaller than 5 μm also can cause EUV random scattering and loss, but do not affect the

final wafer patterns due to focus-out in the image plane

<(a) Optical microscope image of contaminated EUV pellicle, (b) and (c) Results of through-pellicle imaging>

<Comparison of defect review results between optical microscope (left) and EUV ptychography microscope (right)

(a) 50 x 50 μm2 x 500 nm, (b) 30 x 30 μm2 x 500 nm, (c) 20 x 20 μm2 x 500 nm, (d) 15 x 15 μm2 x 500 nm>.

❑ Programed defect review of EUV pellicle

⚫ Particle defects are programmed with the various sizes on the EUV pellicle to evaluate EUV ptychography

microscope’s defect detectability

⚫ EUV ptychography microscope can identify the particle defect which is tens of micrometers in size

<Comparison of reconstructed mask image and intensity

profile (a) Without pellicle, (b) With contaminated pellicle>

100 um

100 um

100 um

(a) (b)

(c)

100 um

(d)

10 x 10 μm2 size particle

Focal

mirror

Plane

mirror

CCD detector

Fast

shutter

<EUV distribution before through the pellicle (left) and after through the pellicle (right)>

➢ Mask patterns imaging is deteriorated by EUV random scattering and loss from 10 x 10 μm2 size

particles on the EUV pellicle

⚫ EUV ptychography microscope is an actinic inspection tool using high-order harmonic generation (HHG)

source and ptychographic imaging method

⚫ The optic system of EUV ptychography microscope is designed to emulate EUV scanner’s oblique

illumination

⚫ The numerical aperture(NA) of EUV ptychography microscope is about 0.125 and the resolution is

about 53.74nm

<EUV generation of EUV ptychography microscope>

<Solution for probe instability> <Solution for position inaccuracy error>

⚫ Input probe information is replaced with real probe measurement data to reduce error from probe instability

⚫ Relative shift error between input and actual position can be compensated by using an annealing algorithm

<Numerical aperture and resolution of

EUV ptychography microscope>

Object functionProbe function Diffraction pattern

⚫ Ptychography which is one of the coherent diffractive imaging (CDI) technique reconstructs the mask image

from the captured diffraction pattern with redundancy

⚫ In ptychography, PIE can obtain more accurate object information and more wider field of view than other

CDI methods by calculating the complex function of the probe function and the object function separately

<Formula of PIE’s object update function><Schematic view of ptychographical iterative engine

(PIE)>

⚫ EUV ptychography microscope using high-order harmonic generation (HHG) source and ptychographic

imaging method has been developed as an actinic inspection tool of EUV mask and pellicle

⚫ The defect detectability of EUV ptychography microscope is confirmed by defect mapping

⚫ If there is a particle that larger than 10 μm on the EUV pellicle, it can cause the final wafer patterning

deterioration

⚫ The feasibility of EUV ptychography microscope for EUV pellicle qualification and defect review is

demonstrated