Posts Tagged ‘SEM’

Lock Picking and SEM

spoolpinBack in October, Pumping Station: One hosted an event called Locktoberfest, an annual event run by the Chicago chapter of TOOOL (The Open Organisation Of Lockpickers.) It features, well, lockpicking, beer, and brats. (The beer is necessary to relax one’s hands. Really. I mean it.) A number of nationally known people came out to Chicago for this, including Deviant Ollam and Babak Javadi.

Lock picking involves manipulating small components. Small metal components, which are conductive, and would image well in a scanning electron microscope. And it just so happens that we’re probably the only hackerspace with a working SEM.

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15

12 2013

Silicon ReSEMblance

Every year, the UIUC chapter of ACM has an student-run conference called Reflections|Projections . One (rather excellent) speaker at the 2013 conference was the well-spoken (and wickedly-smart) Todd Fernandez¬†, who spoke about the state of the semiconductor integrated circuit industry. As a nice bonus for those brave souls who asked, or answered, a question during his talk, he was giving out junked silicon wafers. Not being much of a brave soul myself, but realizing that the wafer would make for an awesome sample in our now-functioning Scanning Electron Microscope (SEM), I answered a question about Moore’s Law and scored a wafer.

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Here’s a picture of a similar wafer we had on hand (Not the one we put in the SEM. We shattered that one.)

Saving you a trip to Wikipedia: the wafers are slices of an impressively large and pure single crystal of silicon (known as a boule) on which semiconductor devices (such as transistors) are fabricated. These devices are usually incredibly tiny and incredibly numerous.

What happens after that is that the SEM rasters a beam of electrons across the surface of the wafer sample and, in this particular case, utilizes its ability to detect secondary electrons kicked off the wafer by the beam. Because the surface is the important part and because the SEM’s resolution is so amazing, before we mounted the sample, we had to sterilize it in an acetone bath suspended in the space’s ultrasonic cleaner.

 

Now the cool part. Because, if you look at the picture below, you can easily see leads on the wafer that are 4 microns in width (and resolve gaps between the leads that are 2 microns wide). For reference’s sake, the diameter of a human hair is given as 100 microns on average. And that is awesome.

sem003

Many thanks to the exceptional Ryan Pierce, who helped me with this every step of the way.

 

-Jerry Lebedowych

22

11 2013

SEM, EDX and fun with liquid nitrogen

Our scanning electron microscope came with an Oxford Isis EDX detector that we were told was non-functional. After a little poking around, I discovered that the replacement power supply which supposedly didn’t work was shipped from London, where the default power is 240V. After changing the voltage, the computer suddenly recognized the electronics, and it passed all the self tests. That looked like a good sign, so the next step was to acquire liquid nitrogen, which is needed to cool the detector.

Fortunately, one of our members owns NFC, a company that, among other things, sells liquid nitrogen. He loaned us a dewar of LN2 so we could test it out. After transporting it back to the space, I asked Everett to watch from a safe distance and let me know if anything was spilling while I filled the dewar attached to the SEM. He took some video of the process. The plastic funnel I used was cracking as I was pouring, which in hindsight wasn’t that great of an idea, so maybe we need to find another solution here….

YouTube Preview Image

The detector took over an hour to cool down, but ultimately it worked beautifully! I kicked up the energy of the electron beam to 20 keV which excited the atoms in the sample to give off characteristic X-rays. The EDX unit measured the energy spectrum of the X-rays given off, and was able to suggest possible elements that have those peaks, which I could then label. The next day Susan Young, the microscopist who used this SEM when it was at its former home, came to the space to give me some advice on the EDX and the sputter coater.

At center is an aluminum sample stub, with a square of copper tape and a strip of carbon tape. The SEM is imaging an area showing all three surfaces.

At center is an aluminum sample stub, with a square of copper tape and a strip of carbon tape. The SEM is imaging an area showing all three surfaces.

After calibrating the detector on a copper target, I then tried imaging a sample that consists of an aluminum sample stub, copper foil, and carbon tape, that has some of each of these exposed. I’ve labeled three peaks for copper, one for aluminum, one for carbon, and one for oxygen. The peak at 0 is just an artifact of the detector. Here is a movie of the X-ray peaks building as the detector collects data:

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Here is the complete spectrum:

EDXSpectrum

The EDX detector has the ability to determine not just what is in a sample, but where it occurs in the sample. I did this by defining energy windows, above. One for carbon, one for one of the copper peaks, and one for aluminum. Each time the EDX detects an X-ray whose energy falls within one of the bands, the EDX sends a pulse on one of several channels to the SEM. The SEM operates in X-ray mapping mode and, because it knows the beam’s position when the pulse is received, it makes a dot on a color coded map showing where that element occurs. This map is an overlay on the secondary electron image of the sample.

EDXMap

The aluminum peak is colored cyan, which dominates the upper left part of the sample. Magenta corresponds to the copper peak, which appears primarily on the lower left. Orange represents carbon. The detector didn’t detect that much of the carbon peak (seeing as it’s the smallest of the three), but orange dots are clearly visible on the right hand side. The surface in the middle is the edge of the copper tape, but it is almost vertical relative to the electron beam, so it doesn’t seem to be giving off many X-rays.

All in all, this is seriously cool technology.

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21

07 2013

Pictures from the Scanning Electron Microscope

A few nights back, Brian and I took some images from the SEM. We exported them into TIF format, and then copied them via Sneakernet, a.k.a. using 3.5″ floppy disks and a portable USB floppy reader. I converted them into .png files. Click them for full 1024×768 resolution, the limit of the Leica image capture board. I’m very happy with how they turned out.

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09

04 2013

Scanning Electron Microscope Update

SEM and RyanBack in January, we got word that Philip Strong, a past member of PS:One, worked for a company that needed to get rid of a working scanning electron microscope and was considering donating it to PS:One. While we have an existing SEM in the space (a Leica S440, owned by JP, a member), this one supposedly was fully functional, had documentation, and we could get some help from the microscopist, Susan Young, who used it. Of course we were interested!

On Monday the 18th, I learn that yes, the donation was approved, but with a catch: It had to be moved on Saturday the 23rd! Read the rest of this entry →

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27

03 2013