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E-beam Lithography - Making Tiny Things with Electron Microscope

Jun 10, 2021
Hello today I want to talk about eben

lithography

which uses an

electron

microscope

to not only take pictures of small

things

but also make them to record this video a few weeks ago when I was at home but now I'm back at school so Electron

beam

lithography

, which will be a voiceover, is truly amazing and is used in industry to create features down to five nanometers and below. A normal

electron

microscope

scans a focused electron

beam

onto a sample and to To put it very simply, it detects what bounces and this. It is able to image much more

things

than optical microscopes because the wavelength of an electron is very small compared to that of light, but in EB lithography you are using exactly the same hardware but in reverse, so so instead of imaging or

making

the sample and We use the scanned coils inside the microscope to control the beam and draw with it in X and Y and create the sample that we would like to make, so the first thing we need to do is control the do in x.
e beam lithography   making tiny things with electron microscope
And so the fundus microscope has these connections to an external scanning controller and you can give it 10 volts or so on the X and Y connections and it will bend the beam to its maximum deflection. It has a third one which is an external scan. and I can, I don't have the connector for this, so I just added these BNC. Next I had to build the computer driver or computer interface for this, so I use 2 12-bit Dax, which turned out to not be enough. it had a current output so there is a trans impedance amplifier that provides a plus and minus 10 volt output to control the microscope which is controlled by a CPL D and an Arduino with a USB connection to the PC, now that we can control the beam, the interesting problem arises. of turning it on and off, so if you were to draw this with pencil and paper, it would be the equivalent of being able to draw something very fine and detailed without even lifting the pencil from the paper, so it's like an engraving of a sketch.
e beam lithography   making tiny things with electron microscope

More Interesting Facts About,

e beam lithography making tiny things with electron microscope...

It's very useful but not great so they normally use a beam suppressor and this can be electrostatic or magnetic so it's some plates or some electromagnets that are placed inside the column of electrons so when you apply two to them voltages or current, it will become very out of focus. the beam or simply deflect it to the side or pinch it so that it effectively turns off the sample so that it does not hit or the beam does not hit the sample. The mine didn't work perfectly, but it's at least a test. concept so I'll show you what I started doing and get better at this hopefully when I come back for winter break maybe I started by

making

a high voltage power supply because I was going to use the Electrostatic Method so I built this little box here.
e beam lithography   making tiny things with electron microscope
It has two ranges that can output 0 to 90 volts or 0 to 4 kV and has a B and a C on the back that go to the PC scan controller to power the HP power supply. and well that was pretty good, the electronics could have been a little faster, but this is where the real problem came, it was my hardware, so I just folded this really bad piece of cable and stuck it in the camera right on top of the sample, so This is really far from ideal. Typically, these beam flashers are high up in the column rather than in the sample chamber.
e beam lithography   making tiny things with electron microscope
This was definitely just a quick proof of concept, but the idea is that the beam passes through the ring that I bend on that copper wire and what I apply a high positive voltage to, the negatively charged beam of electrons is attracted to this copper wire. copper, so it is highly focused and there is no longer a focus point to expose the resistor. It works quite well, as you can see here in the image obtained. on the microscope and I can adjust the high voltage on this beam, the image will go in and out and the current measured in a sample goes up and down.
Here's a look at the back of my microscope. I keep adding small boxes, detectors and amplifiers. for all these projects and it's getting really out of hand, I mean, it's a total disaster back here, there's definitely a fire hazard. I counted for fun, there are about 45 outlets chained together on the same circuit, so we're good to go after getting a good vacuum cleaner. I'll go to the microscope and break up a silicon wafer so I can clean it with standard products like acetone and alcohol and then we'll apply a photoresist in a minute here that will expose on the microscope so well that I'm cleaning.
I'll talk for a second about resistance. There are usually specialized resistors that are sensitive to electron beam wavelengths because photoresistor is commonly only sensitive to UV rays, but I couldn't get my hands on any of these special B resistors, so I started. I was playing around and didn't expect anything to come out of this but there is a very common resistor called Su-8 and it's mainly used for UV of course but I had some lying around and heard some stories about I think it's being used in Germany , like in the 80s, exposed with an X-ray source, so this is a similar wavelength.
I guess I told you you might as well try it, so I put some on the wafer and stuck it to the microscope. and I was surprised by the first results, so this su H is sensitive to many wavelengths from about 400 nanometers and below up to UV and then apparently EB as well and I also don't have the right developer, so this was also in What crazy, why not? It's worth a try. I exposed or developed it with acetone, which should never work, but it actually turns out that if you spray it very quickly with acetone, the development takes a second or two and is actually quite repeatable, so our sample is ready to use.
I melted it into this brass specimen pedestal for my microscope. Attach it with double-sided conductive tape and screw it into this little bracket. The same method is to place it in the microscope as in my previous videos. an airlock loading lock area that is inserted into the first pump and there is a valve that opens between that and then it is pushed into the actual sample chamber, so the view you will see in a minute is a bit hard to get. I have a position. the camera is fine but what you are seeing now is that the sample at the bottom is rising, the coil in the middle is the beam suppressor and what is at the top is the pole piece which is where it emerges from the electron beam since the beginning of Trani electronics. with the scan controller and then with the high voltage power supply box, after that image will be obtained normally with the microscope and then we have to adjust the current of the probe, so some experiments have to be done to achieve this match and get the correct exposure, so adjust it to get the correct emission current that I want, about 0.03 micrograms and then we'll enable the external scan control, turn off the lights or add a dramatic effect and then we can start doing the stuff right now, the images are exported from Inkscape and then converted to g code and sent to the arduino via grbl where they are buffered and sent to the CPL D, eventually the CPL D or FPGA will have USB directly, you will be able to send all the program in which the buffer will be stored. memory and is sent with a very high bandwidth to the microscope, but that is version 2.
Now I have to develop it as I said before. We'll be using acetone, which isn't ideal, but I thought it actually works well. I'll get on a plate and prepare my chemicals because the developing time is very short, just a few seconds. I have to have some water ready right away so I can wash it and stop the etching time and when should you use deionized water or distilled water, so let's put some acetone in, wait and wash it quickly, it's a very scientific process, As you can see, we're going to inspect it next, so I'm going to throw it under the microscope.
The most convenient was this way for the tester, so turn on the light and that's it. Put it in there, so in the video it shows pictures of some things I did. I haven't had much time to mess with this and obviously there is a lot of room for improvement. The beam like only works partially. You can see these lines. like chains connecting everything, you can also see all these points inside that bear when you zoom in and that's because the 12 bit DAC I chose isn't enough and it's a digital scan driver so that's it for this one video, I'll probably do more on this. topic but I hope you learn something and thanks for watching

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