Thanks for the compliment. I get the majority of my information from my advisor who is the original lens designer for the SCALPEL. As far as your questions:
They can not use field emission because, for one, it is too sensitive to contamination from gases, therefore, it can't be used easily on a high throughput line. There are some other reasons to this too, but I can't remember them all, right now. The main limitation is the low-flux sources. Remember, in resist lithography, you want to have a high flux of particles (photons, electron, etc.) to impinge on the resist to expose it.
As far as the space-charge effects, you have to remember that SCALPEL operates in a transmission mode for the mask and needs a high accelerating voltage then (about 100kV). This then reduces the time of flight and therefore the space-charge effects by quite a bit (electrons are relatively far apart). So, with that said, if I remember right, the type of filament that they are using is a heated one, but it is not a normal sharp one. It is actually a large flat surface. It is a polished flat to the (001) surface, single crystal of LaB6 (lanthinum hexaboride) with a 2.5mm diameter (SPIE vol. 3155, p. 2 (1997)). So as you can tell, they have reinvented the gun on this to produce the flux that they need on the sample to expose the resist.
No, they don't use a raster technique. This would never work for simple speed of production issues. They use a similar technique to traditional lithography. They use a plane wave electron beam (same as for UV) upon the mask. This beam then goes through optics (electron magnetic lenses) and the image of the mask is refocused on the wafer, and exposes a layer of resist that is on the surface (just like UV litho). However, in this technique, you are using something that has a smaller resolution and therefore can make smaller features. No-one that I know of is seriously thinking that a beam-etching technique will ever work because of speed issues. There are some other pluses and negatives to this technique, but I spell them out in my other post (Electron Lithography 101).
Okay, for all of you out there that would like to know a little more about this "new" technique, I will fill you in on some of the details. First of all Electron Beam Lithography (EBL) has many advantages over conventional photon lithography.
1. Inorder to get the resolutions required in the future, photon lithography would have to go to X-rays that have a high enough brightness (i.e. You need a syncrotron X-ray source on site). For EBL, you just need a large source filament.
2. Masks for X-rays would need to be the same size as the actual features because there is still not a good method to make images out of X-rays so they use a shadowing technique. Not the case for EBL. Electrons use magnetic lenses to focus and have been used and designed for years. This actually allows you to build the mask in seperate parts and have the electron beam deflection put it all together for you as if it was all together.
3. Stepper motors don't need to be quite as acurate on positioning. This is because you can put in a simple feedback unit that examines where you are projecting on the surface of the wafer and deflection coils can position the beam exactly. This means that you can do lithography while the wafer is still moving! You couldn't do this in your wildest dream with X-rays.
4. Electrons have a very small wave-length at the acceleration voltages used (on the order of picometers). However, the real limitation for EBL is not the wavelength by lens abberations (pick up a good optics book) as well as space-charge effects (this happens because you are using a charged particle and they repel each-other giving a bluring effect). Even with all of this, some predict that you could get resolutions "easily" to the 10nm scale in lithography. No, we can't do atom manipulation with this technique.
5. No this technique does not use a focused beam technique (similar to scanning transmission electron microscopy), but it uses a plane-wave electron beam so that you can expose large areas at once (similar to stardard transmission electron microscopy), allowing for higher through-put.
Probably the major disadvantage for EBL right now is that we need more sensitive resists. The brightness of the EBL is still low compared to UV photon lithography, but I know of several groups that have come a long way with this one.
As another side note to this, Lucent Tech. has an EBL system just about at proof of concept called SCAPEL. Hope this clears up a few of the wrong ideas and helps people understand what this is all about.
Okay, I know that I will probably get majorly flamed for posting anything like this, but here it goes. We know that there are big problems with censorware, but parents still have a right and a legal responsibility to know what their childern are up to. As an example: my son when 16 gets drunk and crashes the car hurting a person. Who is finacially responsible? Me. My son may lose his license, but some states are thinking of prosecuting the parents in things like this if the person dies (some even have laws).
So what does this have to do with the internet? Well what if my child was involved in sharing and view child pornography (illegal), I as the parent need to know and be involved, but what if he does this not on our home computer that I monitor the usage of, but at the library that does not filter? I can't do anything, because I won't know.
So, an alternative is the following: if you want to check-out a book at the library, you need a library card. So, if you want to "check-out" material on the internet you also need a library card. You scan it into the system and it then logs your activity. Now here is the new idea (I think), when you child set up the account, you had to be present and give an email address to you only (or opt to have a log you could come in and see). That way when your child is done with the browsing, a log is emailed to you. You could even add in a "censor"-like feature that just highlighted those in the list that might be "questionable" (if the parent requests that on the web-browsing form), but allowed him/her to see everything.
Why do it this way? Well, I agree that this type of responsiblity lies with the parent (speaking as one) and that if my child were to be viewing things that were questionable (or even trying to) I would like to know about it so we could sit down and discuss what is going on. Plus, if my child were looking up info on, say, sex-education, it would remind me that maybe I have delayed that talk a little too long.
So why even do anything at all? Well, in a debate on an issue where emotionally people are screaming for something to be done, if you have 2 options: first one, to censor, and the second to do nothing. Then people will be likely to vote for the censoring. But, if you have an different option that does take action, but does not infring on freedoms then you can get people to stop, analyze the two options and hopefully make a better choice. And something needs to be "done" because people are demanding it.
If this has been proposed before in its entirity then I am sorry for wasting you time, but I would like to see comments on this and how this would stand up to all viewpoints. The purpose of this post is to see if there are other options to the situation at hand that can satisfy both side's needs.
Exactly. I don't want to be critical here, but the reporter did what reporter do, blew it out of proportion with out knowing what they were talking about. As those who may be lucky enough to impliment the manufaturing of such devices, we need to remember that there are some very large physical barriers that still need to be overcome before anything like this could be made.
1. The central atom is moved around and extracted by the STM tip, so if a device is going to use this we have to some how miniturize an STM like tip to mecanically remove atoms and place them when needed, most likely, one per elliptical ring. This would be a Nobel level achievement in and of itself! My opinion is that a mechanical (yes this is mechanical because it require physical movement) device would not be practical, but I would love to be proved wrong on this. I personally see a structure like this being used to resonate wave states generated by an applied voltage, thus allow for more a more quickly cycled device.
2. Another concern is stability. They had to operate at 4K in order to prevent thermal fluctuation to destroy the device. Personally, I don't want something that is 4K on my shirt. Also, how will the quantum states change (the miarge image) once the device has been embedded to protect the device from the environment (scratching, bumping, etc.), and once embedded can the atoms still be moved around.
3. One more major issue is how to make these devices. They made it atom by atom. How could this be done on the 10^9 or 10^12 scale of devices needing to be produced every day? Can this be cost effectively done? If it can't, then it will never reach us the consumer.
These are questions that need to be answered along with many more before we can ever use such devices practically. This is definitely a neat discovery, however, there are much bigger barriers than this to overcome if we are ever going to get this type of technology to the level where everyone can have one at a resonable cost and have it last long enough to justify spending the money. This represent the equivalent of another baby-step in the direction of getting such devices publically available. So, we need the mentioned IBM group and other groups to keep up the great work to help us break down some of these other barriers.
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They can not use field emission because, for one, it is too sensitive to contamination from gases, therefore, it can't be used easily on a high throughput line. There are some other reasons to this too, but I can't remember them all, right now. The main limitation is the low-flux sources. Remember, in resist lithography, you want to have a high flux of particles (photons, electron, etc.) to impinge on the resist to expose it.
As far as the space-charge effects, you have to remember that SCALPEL operates in a transmission mode for the mask and needs a high accelerating voltage then (about 100kV). This then reduces the time of flight and therefore the space-charge effects by quite a bit (electrons are relatively far apart). So, with that said, if I remember right, the type of filament that they are using is a heated one, but it is not a normal sharp one. It is actually a large flat surface. It is a polished flat to the (001) surface, single crystal of LaB6 (lanthinum hexaboride) with a 2.5mm diameter (SPIE vol. 3155, p. 2 (1997)). So as you can tell, they have reinvented the gun on this to produce the flux that they need on the sample to expose the resist.
No, they don't use a raster technique. This would never work for simple speed of production issues. They use a similar technique to traditional lithography. They use a plane wave electron beam (same as for UV) upon the mask. This beam then goes through optics (electron magnetic lenses) and the image of the mask is refocused on the wafer, and exposes a layer of resist that is on the surface (just like UV litho). However, in this technique, you are using something that has a smaller resolution and therefore can make smaller features. No-one that I know of is seriously thinking that a beam-etching technique will ever work because of speed issues. There are some other pluses and negatives to this technique, but I spell them out in my other post (Electron Lithography 101).
1. Inorder to get the resolutions required in the future, photon lithography would have to go to X-rays that have a high enough brightness (i.e. You need a syncrotron X-ray source on site). For EBL, you just need a large source filament.
2. Masks for X-rays would need to be the same size as the actual features because there is still not a good method to make images out of X-rays so they use a shadowing technique. Not the case for EBL. Electrons use magnetic lenses to focus and have been used and designed for years. This actually allows you to build the mask in seperate parts and have the electron beam deflection put it all together for you as if it was all together.
3. Stepper motors don't need to be quite as acurate on positioning. This is because you can put in a simple feedback unit that examines where you are projecting on the surface of the wafer and deflection coils can position the beam exactly. This means that you can do lithography while the wafer is still moving! You couldn't do this in your wildest dream with X-rays.
4. Electrons have a very small wave-length at the acceleration voltages used (on the order of picometers). However, the real limitation for EBL is not the wavelength by lens abberations (pick up a good optics book) as well as space-charge effects (this happens because you are using a charged particle and they repel each-other giving a bluring effect). Even with all of this, some predict that you could get resolutions "easily" to the 10nm scale in lithography. No, we can't do atom manipulation with this technique.
5. No this technique does not use a focused beam technique (similar to scanning transmission electron microscopy), but it uses a plane-wave electron beam so that you can expose large areas at once (similar to stardard transmission electron microscopy), allowing for higher through-put.
Probably the major disadvantage for EBL right now is that we need more sensitive resists. The brightness of the EBL is still low compared to UV photon lithography, but I know of several groups that have come a long way with this one.
As another side note to this, Lucent Tech. has an EBL system just about at proof of concept called SCAPEL. Hope this clears up a few of the wrong ideas and helps people understand what this is all about.
So what does this have to do with the internet? Well what if my child was involved in sharing and view child pornography (illegal), I as the parent need to know and be involved, but what if he does this not on our home computer that I monitor the usage of, but at the library that does not filter? I can't do anything, because I won't know.
So, an alternative is the following: if you want to check-out a book at the library, you need a library card. So, if you want to "check-out" material on the internet you also need a library card. You scan it into the system and it then logs your activity. Now here is the new idea (I think), when you child set up the account, you had to be present and give an email address to you only (or opt to have a log you could come in and see). That way when your child is done with the browsing, a log is emailed to you. You could even add in a "censor"-like feature that just highlighted those in the list that might be "questionable" (if the parent requests that on the web-browsing form), but allowed him/her to see everything.
Why do it this way? Well, I agree that this type of responsiblity lies with the parent (speaking as one) and that if my child were to be viewing things that were questionable (or even trying to) I would like to know about it so we could sit down and discuss what is going on. Plus, if my child were looking up info on, say, sex-education, it would remind me that maybe I have delayed that talk a little too long.
So why even do anything at all? Well, in a debate on an issue where emotionally people are screaming for something to be done, if you have 2 options: first one, to censor, and the second to do nothing. Then people will be likely to vote for the censoring. But, if you have an different option that does take action, but does not infring on freedoms then you can get people to stop, analyze the two options and hopefully make a better choice. And something needs to be "done" because people are demanding it.
If this has been proposed before in its entirity then I am sorry for wasting you time, but I would like to see comments on this and how this would stand up to all viewpoints. The purpose of this post is to see if there are other options to the situation at hand that can satisfy both side's needs.
1. The central atom is moved around and extracted by the STM tip, so if a device is going to use this we have to some how miniturize an STM like tip to mecanically remove atoms and place them when needed, most likely, one per elliptical ring. This would be a Nobel level achievement in and of itself! My opinion is that a mechanical (yes this is mechanical because it require physical movement) device would not be practical, but I would love to be proved wrong on this. I personally see a structure like this being used to resonate wave states generated by an applied voltage, thus allow for more a more quickly cycled device.
2. Another concern is stability. They had to operate at 4K in order to prevent thermal fluctuation to destroy the device. Personally, I don't want something that is 4K on my shirt. Also, how will the quantum states change (the miarge image) once the device has been embedded to protect the device from the environment (scratching, bumping, etc.), and once embedded can the atoms still be moved around.
3. One more major issue is how to make these devices. They made it atom by atom. How could this be done on the 10^9 or 10^12 scale of devices needing to be produced every day? Can this be cost effectively done? If it can't, then it will never reach us the consumer.
These are questions that need to be answered along with many more before we can ever use such devices practically. This is definitely a neat discovery, however, there are much bigger barriers than this to overcome if we are ever going to get this type of technology to the level where everyone can have one at a resonable cost and have it last long enough to justify spending the money. This represent the equivalent of another baby-step in the direction of getting such devices publically available. So, we need the mentioned IBM group and other groups to keep up the great work to help us break down some of these other barriers.