25-08-2017, 09:32 PM
Extreme Ultra-Violet Lithography
[attachment=50353]
Why EUV?
Minimum lithographic feature size =
k1: “Process complexity factor” – includes “tricks” like phase-shift masks
λ: Exposure wavelength
NA: Numerical aperture of the lens – maximum of 1 in air, a little higher in immersion lithography (Higher NA means smaller depth of focus, though)
Why EUV? Why not the next excimer line?
Hg (G line) @ 436nm Hg (H line) @ 405nm Hg (I line) @ 365nm
KrF Excimer @ 248nm ArF Excimer @ 193nm ?
157nm lithography based on the fluorine excimer laser has been largely shelved, which leaves 193nm with extensions for production
Below that, no laser line has the required output power
Excimer-based steppers expose 109 steps per 300mm wafer, and produce >100 wafers per hour – exposure times ~ 10-20ns
Additionally, fused silica and atmospheric oxygen become absorptive by 157nm – so even incremental decreases in wavelength start to require a major system overhaul
Current Lithographic Technology
Lenses are very effective and perfectly transparent for 193nm and above, so many are used
A single “lens” may be up to 60 fused silica surfaces
System maintained at atmospheric pressure
Lens NA ~0.5-0.85
Up to 1.1 for immersion
Exposure field 26x32mm
Steppers capable of >100
300mm wafers per hour
at >100 exposures per
wafer
Plasma Radiation Source
The only viable source for 13.5nm photons is a plasma
Powerful plasma required – temperature of up to 200,000oC, atoms ionized up to +20 state
Plasma must be pulsed – pulse length in pico- to nanosecond range
Conclusion
Will 193nm ever die?
As recently as 2003, EUV was “the only viable solution” for the 45nm node
Now Intel wants EUV for the 32nm node, but it may be pushed back more:
“In a nutshell, many believe that EUV will NOT be ready for the 32-nm node in 2009. Some say the technology will get pushed out at the 22- nm node in 2011. Some even speculate that EUV will never work.”
My opinion: never say “never” about this industry…
A lot of work remains: increase output power of 13.5nm source, increase NA of reflective lenses, increase lifetime of collector optics (decrease cost of ownership)
But the potential payoff is sufficient that we will make it work
[attachment=50353]
Why EUV?
Minimum lithographic feature size =
k1: “Process complexity factor” – includes “tricks” like phase-shift masks
λ: Exposure wavelength
NA: Numerical aperture of the lens – maximum of 1 in air, a little higher in immersion lithography (Higher NA means smaller depth of focus, though)
Why EUV? Why not the next excimer line?
Hg (G line) @ 436nm Hg (H line) @ 405nm Hg (I line) @ 365nm
KrF Excimer @ 248nm ArF Excimer @ 193nm ?
157nm lithography based on the fluorine excimer laser has been largely shelved, which leaves 193nm with extensions for production
Below that, no laser line has the required output power
Excimer-based steppers expose 109 steps per 300mm wafer, and produce >100 wafers per hour – exposure times ~ 10-20ns
Additionally, fused silica and atmospheric oxygen become absorptive by 157nm – so even incremental decreases in wavelength start to require a major system overhaul
Current Lithographic Technology
Lenses are very effective and perfectly transparent for 193nm and above, so many are used
A single “lens” may be up to 60 fused silica surfaces
System maintained at atmospheric pressure
Lens NA ~0.5-0.85
Up to 1.1 for immersion
Exposure field 26x32mm
Steppers capable of >100
300mm wafers per hour
at >100 exposures per
wafer
Plasma Radiation Source
The only viable source for 13.5nm photons is a plasma
Powerful plasma required – temperature of up to 200,000oC, atoms ionized up to +20 state
Plasma must be pulsed – pulse length in pico- to nanosecond range
Conclusion
Will 193nm ever die?
As recently as 2003, EUV was “the only viable solution” for the 45nm node
Now Intel wants EUV for the 32nm node, but it may be pushed back more:
“In a nutshell, many believe that EUV will NOT be ready for the 32-nm node in 2009. Some say the technology will get pushed out at the 22- nm node in 2011. Some even speculate that EUV will never work.”
My opinion: never say “never” about this industry…
A lot of work remains: increase output power of 13.5nm source, increase NA of reflective lenses, increase lifetime of collector optics (decrease cost of ownership)
But the potential payoff is sufficient that we will make it work