U.S. CitiesCity-Data Forum Index
Go Back   City-Data Forum > General Forums > Science and Technology
 [Register]
Please register to participate in our discussions with 2 million other members - it's free and quick! Some forums can only be seen by registered members. After you create your account, you'll be able to customize options and access all our 15,000 new posts/day with fewer ads.
View detailed profile (Advanced) or search
site with Google Custom Search

Search Forums  (Advanced)
Reply Start New Thread
 
Old 08-24-2010, 09:17 AM
 
Location: U.S.A.
3,306 posts, read 9,006,224 times
Reputation: 2919

Advertisements

When performing photolithography to make microelectronic circuits we come across the standing wave effect in the exposed then developed photoresist. Obviously the result of this effect is dictated by the source's wavelength but it makes me wonder... Do photons follow a sinusoidal path? Does the answer lie within the explanation of wave-particle duality?

To me it seems obvious that the photons would travel a path like that however its probably not as simple as I think.

Here is an example...



As you can see the waves are formed on the sidewalls of the patterned resist. The coherency of these steppers is quite amazing!
Reply With Quote Quick reply to this message

 
Old 08-24-2010, 05:20 PM
 
Location: Westwood, MA
3,443 posts, read 4,348,222 times
Reputation: 4428
Quote:
Originally Posted by Lux Hauler View Post
When performing photolithography to make microelectronic circuits we come across the standing wave effect in the exposed then developed photoresist. Obviously the result of this effect is dictated by the source's wavelength but it makes me wonder... Do photons follow a sinusoidal path? Does the answer lie within the explanation of wave-particle duality?
You're making it more complicated than it really is--light is classically a wave and you're seeing something consistent with the classical approach. If you saw anything that showed quantum effects you would need the wave-particle duality, but there is no indication of photons.
Reply With Quote Quick reply to this message
 
Old 08-24-2010, 08:18 PM
 
Location: Virginia
33 posts, read 55,425 times
Reputation: 45
Quote:
Originally Posted by jayrandom View Post
You're making it more complicated than it really is--light is classically a wave and you're seeing something consistent with the classical approach. If you saw anything that showed quantum effects you would need the wave-particle duality, but there is no indication of photons.
I don't know how photolithography works, but if it's a single beam of light at a fixed frequency exposing a light-sensitive surface, I don't see a reason for a sinusoidal pattern to show up. Maybe you're thinking of the double slit experiment in which interference fringes show up with both slits open. But with a single slit, as would be the case with a single focused beam, there is no interference pattern.

However, I doubt if what the OP is seeing is due to any quantum effect. It's more likely to be a modulation effect on the mechanism pointing the beam.
Reply With Quote Quick reply to this message
 
Old 08-24-2010, 08:21 PM
 
Location: U.S.A.
3,306 posts, read 9,006,224 times
Reputation: 2919
Quote:
Originally Posted by jayrandom View Post
You're making it more complicated than it really is--light is classically a wave and you're seeing something consistent with the classical approach. If you saw anything that showed quantum effects you would need the wave-particle duality, but there is no indication of photons.

I think thats what I was told before but I don't understand. The sidewall of the photoresist literally has the wavelength etched into the side of it. That means light physically passed through the resist along that path. I guess what I picture is photons leaving the barrel of a gun and traveling a sinusoidal path as opposed to a straight one. And I guess you are trying to say that there are no photons rather there is just a static wave.

Whenever I see a little flash video of a propagating light wave they always animate it as the phase constantly moving and the speed of the phase change is the speed of light. However as is seen in the photoresist the light does not travel that way otherwise the sidewalls would not be scalloped in accordance to the wavelength, they would just be flat... do you sort of see my confusion?
Reply With Quote Quick reply to this message
 
Old 08-24-2010, 08:27 PM
 
Location: U.S.A.
3,306 posts, read 9,006,224 times
Reputation: 2919
Quote:
Originally Posted by Nesper View Post
I don't know how photolithography works, but if it's a single beam of light at a fixed frequency exposing a light-sensitive surface, I don't see a reason for a sinusoidal pattern to show up. Maybe you're thinking of the double slit experiment in which interference fringes show up with both slits open. But with a single slit, as would be the case with a single focused beam, there is no interference pattern.

However, I doubt if what the OP is seeing is due to any quantum effect. It's more likely to be a modulation effect on the mechanism pointing the beam.
Classical photolithography on its most basic level is pretty much shining light through a mask (pattern containing quartz glass) and onto a substrate coated with photoresist. With positive resist the regions exposed to light will be developed away. The light sources used in these cases emit have output peaks at very specific wavelengths. So ideally just one wavelength is emitted from the source.

The kicker is that the light's incident angle to the resist is ideally 0 degrees so I don't really understand how an interference pattern can be generated vertically.
Reply With Quote Quick reply to this message
 
Old 08-24-2010, 10:33 PM
 
Location: Virginia
33 posts, read 55,425 times
Reputation: 45
Quote:
Originally Posted by Lux Hauler View Post
Classical photolithography on its most basic level is pretty much shining light through a mask (pattern containing quartz glass) and onto a substrate coated with photoresist. With positive resist the regions exposed to light will be developed away. The light sources used in these cases emit have output peaks at very specific wavelengths. So ideally just one wavelength is emitted from the source.

The kicker is that the light's incident angle to the resist is ideally 0 degrees so I don't really understand how an interference pattern can be generated vertically.
Well, whatever the process is, you need at least two light paths from the same source to get interference patters. A single path will not do it. Does the mask include the equivalent of narrow parallel slits that allow the light to pass through adjacent slits, thus interfering with itself?

If not, perhaps it's just some simple vibration that allows the light beam to have a sinusoidal pattern.
Reply With Quote Quick reply to this message
 
Old 08-25-2010, 04:11 AM
 
Location: Westwood, MA
3,443 posts, read 4,348,222 times
Reputation: 4428
I thought it was pretty clear from the name that you've set up a standing wave in the photoresist from the combination of the incident and wafer-reflected light. This phenomenon can be eliminated or reduced by including an anti-reflection coating on the wafer, below the photoresist. The light needs to be monochromatic and a plane wave for this to happen, but that appears to be the case in a deep UV stepper.

Chris Mack, Gentleman Scientist
Reply With Quote Quick reply to this message
 
Old 08-25-2010, 08:33 AM
 
Location: Virginia
33 posts, read 55,425 times
Reputation: 45
Quote:
Originally Posted by jayrandom View Post
I thought it was pretty clear from the name that you've set up a standing wave in the photoresist from the combination of the incident and wafer-reflected light. This phenomenon can be eliminated or reduced by including an anti-reflection coating on the wafer, below the photoresist. The light needs to be monochromatic and a plane wave for this to happen, but that appears to be the case in a deep UV stepper.

Chris Mack, Gentleman Scientist
Bingo
Reply With Quote Quick reply to this message
 
Old 09-03-2010, 03:42 PM
 
Location: U.S.A.
3,306 posts, read 9,006,224 times
Reputation: 2919
So if one photon were emitted from the source and we were able to track its movement would it or would it not move along a sinusoidal path? And also if we were to look straight down on the photon with it moving directly away from us, what dictates the rotational orientation of it's path?
Reply With Quote Quick reply to this message
 
Old 09-03-2010, 05:15 PM
 
1,241 posts, read 1,008,840 times
Reputation: 806
Quote:
Originally Posted by Lux Hauler View Post
So if one photon were emitted from the source and we were able to track its movement would it or would it not move along a sinusoidal path? And also if we were to look straight down on the photon with it moving directly away from us, what dictates the rotational orientation of it's path?
From what I understand, and please correct me if I am wrong, but the trajetory of a single electron is "particle like" and that is why we can direct it at a phosphorescent material on a screen. Both the electron and the photon present the duality behavior, and that is that they have both behaviors, like a particle and a wave.

I know that a laser is a stream of photons, and a photon is the smallest unit of electromagnetic radiation, we can emit single photons, like particles, and have them behave like any particle having mass, aiming it at a target. This to me says that the particle moves in a straight line, but the "Color" or spectrum/wavelength of the particle is also measurable, and that to me is that it is behaving like a wave.
Reply With Quote Quick reply to this message
Please register to post and access all features of our very popular forum. It is free and quick. Over $68,000 in prizes has already been given out to active posters on our forum. Additional giveaways are planned.

Detailed information about all U.S. cities, counties, and zip codes on our site: City-data.com.


Reply
Please update this thread with any new information or opinions. This open thread is still read by thousands of people, so we encourage all additional points of view.

Quick Reply
Message:

Over $104,000 in prizes was already given out to active posters on our forum and additional giveaways are planned!

Go Back   City-Data Forum > General Forums > Science and Technology
Similar Threads
Follow City-Data.com founder on our Forum or

All times are GMT -6.

2005-2018, Advameg, Inc.

City-Data.com - Archive 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35 - Top