metrology by pupil imaging mike adel, march 2014
TRANSCRIPT
Outline
The pupil Animal kingdom
Optics
Pupil imaging Optical architecture
The Fourier domain
Overlay metrology by pupil imaging What is overlay?
Target architecture
Quantification
6 confidential
Field imaging architecture
Illumination
Field
Stop
Fiber from
sourceImage Sensor
Objective
Target
BS
Mirror
pupil
7 confidential
Pupil imaging architecture
IFS
Fiber from
source
CFS
Pupil image Sensor
Objective
Target
BS
Apodizer (spatial filter)
Mirror
Apodizer (spatial filter)
What is overlay metrology and why is it important?
Very Tight (Ångstrom level) Position Control
Sca
nn
er w
avel
eng
th [
nm
]
9
Overlay metrology is enabled by quantification of symmetry breaking.
Field imaging Pupil imaging
Pupil image
-F0 F0
Rotational Symmetry Translational Symmetry
Summary
The pupil has many meanings and uses in optics.
The pupil is also a location in the optical path which enables the image to be viewed in the Fourier domain.
Overlay metrology is enabled by pupil imaging of overlaid periodic structures.
Translational offsets between periodic structures are required in order to quantify symmetry breaking in the pupil image.
-F0 F0I+I_I0
0
0.2
0.4
0.6
0.8
1
0 50 100 150 200 250 300 350 400 450 500 550 600
Wavelength (nm)
Rel
ativ
e In
ten
sity
EUV
Shorter wavelength = higher resolutionEvolution of lithography light sources
Tungsten filamentlight source & power
supply ~$500Circa 1965
I-Line
H-Line
G-Line
Mercurylamp & power supply ~$5kCirca 1985
UPExcimer Laser & beamline ~$500kCirca 2005
ArF
KrF
13.5
EUV light source~ 5m$?Circa 2015?
What happens in
the meantime?