Harder Uv Source For Lithography

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Discussion Overview

The discussion revolves around the development of an extreme UV light source for semiconductor lithography, specifically focusing on the feasibility of a 30nm wavelength source. Participants explore the implications of wavelength choice, light intensity, and the associated costs, while considering the technical challenges in lithography processes.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • Marc Schaefer proposes a 30nm wavelength light source, questioning whether shorter wavelengths would be advantageous despite concerns about fluorescence affecting lithography.
  • Some participants suggest that the light source is not the primary bottleneck in lithography, pointing to issues with lenses and optical proximity correction (OPC) algorithms as more significant challenges.
  • There is a discussion about the current use of excimer lasers at 193nm and the stress this places on lenses, with some arguing that shorter wavelengths could alleviate these issues.
  • One participant mentions the need for improved algorithms to handle the increasing computational demands of smaller feature sizes in IC fabrication.
  • Another participant notes that while shorter wavelengths could reduce lens requirements, they would necessitate a complete retooling of existing systems.
  • Discussion includes consideration of wavelengths like 13.5nm or 11nm for future sources, highlighting challenges with material opacity at these wavelengths and the efficiency of mirrors.
  • Marc expresses doubt about contributing anything new to the topic, indicating a sense of resignation regarding the feasibility of his ideas.

Areas of Agreement / Disagreement

Participants exhibit disagreement regarding the primary challenges in lithography, with some asserting that the light source is not the bottleneck, while others emphasize the importance of wavelength and light intensity. The discussion remains unresolved on the optimal approach to improving lithography techniques.

Contextual Notes

Participants reference the limitations of current technologies, including the computational demands of OPC and the physical constraints of lenses at shorter wavelengths. There are also mentions of the economic implications of developing new light sources.

Enthalpy
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Hello semiconductor technologists!

I'm thinking at a source of extreme UV for semiconductor lithography, so what would be your wishes, as compared to the first figures that emerge from my rantings?

I take 30nm wavelength. Would less be better? I fear fluorescence hampers lithography.

Right now I estimate half a watt of light is produced, continuous and monochromatic and coherent, initially in a narrow beam of small divergence. Could that be enough?

This absolute silver bullet would cost several millions. Is that any worry?

Thanks!
Marc Schaefer, aka Enthalpy
 
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Enthalpy said:
Hello semiconductor technologists!

I'm thinking at a source of extreme UV for semiconductor lithography, so what would be your wishes, as compared to the first figures that emerge from my rantings?

I take 30nm wavelength. Would less be better? I fear fluorescence hampers lithography.

Right now I estimate half a watt of light is produced, continuous and monochromatic and coherent, initially in a narrow beam of small divergence. Could that be enough?

This absolute silver bullet would cost several millions. Is that any worry?

Thanks!
Marc Schaefer, aka Enthalpy

I don't think your post translated very well. Is this question for your work, where you are putting together an IC fabrication line? Or are you thinking of putting together a small IC fabrication setup as a hobby (and have the several million dollars to spend on it)?
 
Enthalpy said:
Hello semiconductor technologists!

I'm thinking at a source of extreme UV for semiconductor lithography, so what would be your wishes, as compared to the first figures that emerge from my rantings?

I take 30nm wavelength. Would less be better? I fear fluorescence hampers lithography.

Right now I estimate half a watt of light is produced, continuous and monochromatic and coherent, initially in a narrow beam of small divergence. Could that be enough?

This absolute silver bullet would cost several millions. Is that any worry?

Thanks!
Marc Schaefer, aka Enthalpy

The technical bottleneck in practice isn't the light source. The bottlenecks are the lens and the OPC patterning of the masks. Besides, the trend is increased reticle size so a narrow beam isn't necessarily a good thing.

If you really want a silver bullet (and we're talking pie-in-the-sky anyway) you should invent a much faster e-beam lithography technique.

Or, figure out an OPC algorithm that doesn't require a supercomputer to calculate in a reasonable time.
 
Thank you!

The light source isn't the bottleneck? I thought channels 22nm long were patterned with excimer lasers at 193nm wavelength or a bit less, and this fundamentally unhealthy situation puts stress on the lenses. Shorter waves shall ease this.

http://en.wikipedia.org/wiki/Excimer_laser#Major_applications
corresponds to what I read here and there.

A narrow beam is easily broadened.
 
Enthalpy said:
Thank you!

The light source isn't the bottleneck? I thought channels 22nm long were patterned with excimer lasers at 193nm wavelength or a bit less, and this fundamentally unhealthy situation puts stress on the lenses. Shorter waves shall ease this.

http://en.wikipedia.org/wiki/Excimer_laser#Major_applications
corresponds to what I read here and there.

A narrow beam is easily broadened.

Nope. Not the bottleneck. Of course all aspects of the system need to be improved but the killers are the lens and the OPC. Right now it takes something like a CPU-century to calculate OPC for a typical mask.
 
Ask someone else for the computer. It boils down to assembling many Cpu or Gpu, I'm not that interested.

The lens is difficult because the half-wave is too big for the small pattern features. This also leads to shorter and shorter waves, and fiddlings like double exposure, but no progress has been made since the excimer lasers, and indeed IC shrink ever slower.

Such things tell a lot about the present cost and power of light sources:
http://www.cymer.com/XLR600ix/
it doesn't look cheap neither, but it produces 90W at 193nm.
 
Last edited by a moderator:
Enthalpy said:
Ask someone else for the computer. It boils down to assembling many Cpu or Gpu, I'm not that interested.

The lens is difficult because the half-wave is too big for the small pattern features. This also leads to shorter and shorter waves, and fiddlings like double exposure, but no progress has been made since the excimer lasers, and indeed IC shrink ever slower.

Such things tell a lot about the present cost and power of light sources:
http://www.cymer.com/XLR600ix/
it doesn't look cheap neither, but it produces 90W at 193nm.

Well, I would say that it boils down to improving the algorithms, since if you shrink down the process the compute problems grows faster than our ability to assemble gpu clusters.

True, a shorter wavelength UV source would relax requirements on the lens, but would also require retooling the whole system. Could work, though!
 
Last edited by a moderator:
Found some answers.

-----

All actors consider wavelengths like 13.5nm or 11nm for the next sources.

The synchrotron and undulator I considered is already an old idea, the current advances being fluorescence in various forms, which provides more power than the half-watt typical of synchrotrons and undulators.

Lenses are a difficulty at 13.5nm (100eV!) because materials are opaque. Mirrors aren't much better, achieving 50% reflectivity at normal incidence.

-----

I wanted to give the accelerating cavities the same wavelength as the undulator, and now I'm confident this already exists.

I wanted to add a Perot-Fabry cavity around the undulator to increase the output power. This has been considered but is difficult at such a wevelength because neither mirrors nor light guides are efficient.

Apparently I won't bring anything new nor useful in this topic and give it up.
 

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