They messed up the double patterning story so the whole thing seems shaky.
The pre-elongation rounding is unavoidable.
20:1 sounds nearly vertical like conventional etching though.
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AMAT cuts EUV costs
- Thread starter Arthur Hanson
- Start date
The pre-elongation rounding is unavoidable.
20:1 sounds nearly vertical like conventional etching though.
The 20:1 is horizontal in this case. It seems likely both the plasma flow and the chemistry (both plasma and resist) has been tweaked to get there.
What did they mess up in the double patterning? If you are creating a layer with 1D structures and your goal is to avoid tip to tip distance limitations, this allows you to sidestep that. The only gotcha would be if the litho-friendly geometry would be short enough to give a shadow, but that seems like a rule the EDA can handle with marginal effect on density.
Unless TSMC provisioned for it years in advance and designed the layers that are only just barely double patterned for an easy swap to single exposure, it cannot be done after the fact economically. Given the fact TSMC reduced the number of EUV double patterned layers with N3 and N3E over time, it seems plausible they didn't make these provisions due to being a bit too bullish on the economics they could achieve with their current lithographic capabilities.
The SALELE approach has been around for a while, so tip-to-tip is not handled like that.
In fact, the starting tips are still round, there would still be expansion other than longitudinal.
It's seems more presented as being an alternative to High-NA EUV, when actually they are competing against cutting. But in fact, ovals don't have a well-defined CD to base on. Straight features have the edge which can be preserved.
The lower metals, vias had much smaller pitch, so were not single patterned. The middle layers appear to have been converted to single, maybe relaxed pitch or simpler layout.
Given that rounded features are more sensitive to such random deformation errors, since the edge plays a larger role, it would seem to aggravate the issue.
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Sorry for my lack of technical knowledge but what do you mean by cutting?
First printing straight lines, then cutting them (blocking some portions from etching) into individual shorter strips. The strips are guaranteed straight.
Robert Maire
Moderator
A bit of marketing hyperbole...just a selective etch tool..not a "patterning" tool...not enabling, just cheaper...only replaces some, limited double patterning..similar to other existing technology...can only "etch" what EUV "patterns"......https://conta.cc/3YmtxFk
That was my point (although it was probably poorly articulated). The lower metals were already locked in stone and the middle layers got hasty conversions to larger pitchs. If TSMC planned to insert this tool into their process flow to replace double patterned layers with LEE layers on N3E, I don't think we would be seeing such a substantial density hit. But who knows I could totally be off base here and maybe that is exactly what happened.
Maybe they are using paternshapping for lower metal vias (if that is even plausible for this technology)? Unless my understanding of the tech is wrong, I assume you can use it for removing bridge defects even with birectional rules given how short that etch probably is relative to a pattern shaping etch? Put another way maybe the bridges are small enough that the ion ribbon can cut it and scan past before it meaningfully upsets the intended pattern shape. But that is way beyond my knowledge so I am curious what you think of my hairbrained idea?
TSMC also touched upon this idea (US20210096473). For obstructed trenches maybe the descums might already be targeted? But not for merged trenches.
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We now have actual results/SEMs in the wild for AMAT's ion beam dry etcher.
Would be interesting to see cross-sections.
Profile control for slanted etching - Oxford Instruments Plasma Technology
Profile control for slanted etching Ion beam etching technology is one of the well-known techniques in forming slanted gratings. Oxford Instruments Plasma Technology has developed a technology to allow optical designers to achieve a large uniform processing area over 200 mm wafers for angles...
nanovactech.com
Actually, the idea of using tilted etching/deposition (i.e., shadow effect) to correct the post-lithography misalignment and tune the pattern CD had been proposed and patented a long time ago (2010). It mainly works for correctting the translational overlay error, but not functional for other types of overlay error (e.g., rotation or thermal expansion). A geometrical CD tuning model was also reported and published by PKU researcher in SPIE Advanced Lithography back in 2013. An AMAT engineer did approach the author after his oral presentation, but AMAT never mentioned the PKU pioneer work.
US Patent # 7700444: Post-lithography misalignment correction for multiple patterning, 2010.
P. Zhang, Y. Chen, “Cut-process overlay yield model for self-aligned multiple patterning and a misalignment correction technique based on dry etching,” Proc. of SPIE, Vol. 8685, 86850K, 2013.