Nano Process & Device Lab.
What is Extreme Ultraviolet?
1 m
100 nm
IR
10 nm
X-ray
UV
DUV
10 eV
F2 157 nm
Soft X-ray
EUV
SiL
1 eV
0.1 nm (1 Å )
1 nm
Ck Ok
100 eV
EUV 13.5 nm
ArF 193 nm
KrF 248 nm
I-line 365 nm
G-line 436 nm
Reflective
Refractive
Optics
Optics
1 keV
SiK
Hard X-ray
CuK
10 keV
100 keV
Schematic design of BIM & PSM
Conventional
binary intensity mask (BIM)
Attenuated
Phase-shift mask (PSM)
Attenuated phase-shift mask (PSM)
What is the mask shadowing effect?
 The illumination beam is shadowed by edge of absorber
 The effective mask CD is changed.
 Printed pattern biased.
What is the photon shot noise effect?
 The statistical fluctuations between photon and photo resist (PR)
 Exposure dose & Diffraction Intensity ratio → number of quanta
 Small number of quanta → Large shot noise effect
 More serious for EUV lithography.
 Results in degradation of CDU, LER(CER)
So, we propose an attenuated Phase Shift Mask (PSM)!
 40.5nm absorber stack (26.5nm of TaN / 14nm of Mo)
 ~6% reflectivity at absorber stack and 180° phase shift
 Mitigate mask shadowing effect
 Mitigate photon shot noise effect
Schematic image of the
proposed attenuated PSM
Thank you for listening