High NA-EUV Lithography
Zeiss is beginning production of their High NA-EUV systems for ASML.
“High NA” means high numerical aperture, which is a measure of the angular range from which an optical system can pick up light. For context High NA has numerical aperture of 0.55, whereas current EUV NA is 0.33
A 66% improvement.
That’s a feature density improvement of 1.67^2=2.789 so a near tripling of transistor density per unit area. It brings the critical dimension down to 8nm from 13nm.
Q: How did Zeiss achieve this?
A: With great difficulty.
• The projection optics system is 40,000 parts and around 12 tonnes.
• The illumination system is 25,000 parts and is 6 tonnes.
• The machine that manufacturers these mirrors is based in Germany, and consists of 100,000 parts and is 150 tonnes, the machining chamber itself is a 5m x 5m x 10m vacuum chamber.
The mirrors are machined for 3 months[!] to achieve a precision equivalent to 1mm deviation over an area the size of the Pacific Ocean.
It’s worth noting here that theoretical maximum NA = 1.0
Hyper NA (>0.7 and achieved using 8 mirrors) is expected the enter production 2032 - 2035.
That brings the critical dimension down to around 6nm and that might be the end, a single silicon atom is 0.23nm so the precision would be +/- 24 atoms.
Fun note… there is a category of lathes and machine tools called “ultra-precision” and these have axis resolutions of 1-2nm and can produce contoured shapes to 25nm accuracy.
You can buy “ultra-precision” machines, grinding machines for optical equipment have incredibly precise axis control because surface asperity on a mirror is visible to the eye.
B23B is the IPC/CPC class, and it teaches some interesting niche stuff (tells you where the future is going, even with trade secrets omitted).