Important point

guiding_light

2nd July 2006 - 02:39 PM

http://www.cs.vu.nl/~nsilvis/microeng.pdf

See Figure 3. Secondary electrons limit effective resolution to 40 nm, for an idealized 0-nm resolution lithography process.

Guest

3rd July 2006 - 12:10 PM

QUOTE

Secondary electrons limit effective resolution to 40 nm, for an idealized 0-nm resolution lithography process.

Does this make any sense? Thought sub-40 nm features were quite common actually.

3rd July 2006 - 12:27 PM

It's been pretty well-known, that secondary electrons (defined usually as electrons with energies <50 eV, generated by other radiation) were the key exposing agents in electron-beam and X-ray lithography. So it all depends on how large the cloud of secondary electrons is from the beam incidence point. The reference shows it can extend as far as ~40 nm just from the contamination fingerprint.

plasma_guy

3rd July 2006 - 01:26 PM

QUOTE

Does this make any sense? Thought sub-40 nm features were quite common actually.

Starting with a 100 nm litho CD, you can trim the photoresist feature down to 50 nm by etch. For a 70 nm litho CD, probably can get down to 30 nm.

Just by looking at the final feature size, you can't necessarily guess correctly the actual steps used to make it.

plasma_guy

3rd July 2006 - 01:33 PM

Maybe the secondary electrons can help explain line-edge roughness (a real big problem)?

guiding_light

3rd July 2006 - 10:49 PM

QUOTE

Does this make any sense? Thought sub-40 nm features were quite common actually.

The secondary electron resolution limit is ~40 nm, although whatever primary radiation you use is supposed to be less.

When you dissolve PMMA or other resist, you can ideally stop the process at the right point to get the feature size desired. But how sure can you be of the secondary electron distribution each time?

guiding_light

4th July 2006 - 12:15 AM

QUOTE

Maybe the secondary electrons can help explain line-edge roughness (a real big problem)?

Very likely.

original link

5th July 2006 - 02:34 PM

http://www.iop.org/EJ/abstract/0957-4484/17/6/001

original link

6th July 2006 - 12:25 AM

http://adsabs.harvard.edu/abs/2006Nanot..17.1543S

Nanotechnology, vol. 17, pp. 1543-1546 (2006).

(Article seems to be difficult to access online)

guiding_light

6th October 2006 - 01:09 PM

A secondary electron generates an uncertain and unknown number of chemical reaction products (e.g., acids) as it slows down and scatters.

On the other hand, a non-ionizing UV photon does not have this problem. One photon is absorbed to produce the acid or other photochemical product.

PhysOrg scientific forums are totally dedicated to science, physics, and technology. Besides topical forums such as nanotechnology, quantum physics, silicon and III-V technology, applied physics, materials, space and others, you can also join our news and publications discussions. We also provide an off-topic forum category. If you need specific help on a scientific problem or have a question related to physics or technology, visit the PhysOrg Forums. Here you’ll find experts from various fields online every day.