<azonenberg>
And once i do that, my first project will be a filament evaporator for thin-film deposition
<solrize>
hmm
<azonenberg>
Since my current process requires evaporated copper
<azonenberg>
And i'm currently borrowing time on an evaporator in one of the labs on campus to do process development
<azonenberg>
But i want to replace it with a homebrew unit soon (like end of year ish)
<solrize>
wow
<solrize>
where are you?
<azonenberg>
RPI
<azonenberg>
first year PhD student
<azonenberg>
though i started the project while an undergrad
<solrize>
neat
<azonenberg>
Yesterday I did a pretty successful run using a triple-level mask process (photoresist over evaporated copper over sol-gel tantalum oxide) for wet etching patterns into Si
<azonenberg>
I had some undercut, which could be fixed by thinning the oxide layer, and some uneven exposure of the photoresist pattern (I still havent had the time to order a proper illuminator so i'm still using the mag-lite from the paper)
<azonenberg>
So i didnt quite hit the 20 micron target, but my bigger features (maybe 30-50um across) resolved fine
<azonenberg>
And this is something i can work with, most of my previous runs failed horribly :P
<azonenberg>
As a side effect i also demonstrated 20um patterning in evaporated copper, which can easily be shrunk to 10 or less based on the look of things
<azonenberg>
That process worked beautifully
<azonenberg>
The etch time was like five seconds :P)
<azonenberg>
My first try at it used 60 sec and undercut severely
<lekernel>
The first image is of an IC that had way too much current passed through it. We expected to see just the usual destroyed substrate but instead were surprised to see this nice little fiber of silicon oxide that grew out the unfortunate device. The device became hot enough to actually oxidize the silicon and cause the fiber to grow instead of just explode. Shades of the movie "Alien".
<lekernel>
"a propellant throughput capability exceeding 100 kg/kW". looks rather good, no?
<lekernel>
but "the pre-prototype HiPEP produced 670 mN of thrust at a power level of 39.3 kW ". uhm ...
<bart416>
ion thrusters in the atmosphere just seem like a bad idea
<bart416>
What you should really ask is if it works on oxygen and nitrogen
<bart416>
If the answer is yes, it should work in the earth atmosphere anyway
<lekernel_>
why are they a bad idea?
<lekernel_>
I don't see a problem with striking an ECR plasma of oxygen or nitrogen, but the increased pressure might be a problem
<lekernel_>
you can make such a plasma with an electrodeless system, so reactivity isn't even an issue (except that you might end up with toxic nitrous oxides in our case)
<bart416>
Well, air humidity might make the electric field problematic
<lekernel_>
ECR uses only microwaves
<lekernel_>
there are no multi-dozen-kV electrodes involved
<bart416>
oh, then it might just work
<bart416>
the general issue with ion thrusters is the way the charge gradient is created
<lekernel_>
yes, the idea is that ECR could make air fairly conductive, so this becomes less of a concern
<azonenberg>
Well, I think i have a pretty good idea of where to proceed from here
<azonenberg>
Gonna try and set up another session on the evaporator and do some through-wafer etching
<azonenberg>
The substrate for this run will be a quarter of a 2-inch <110> SSP wafer, coated in a thin layer of Ta2O5 after an RCA clean
<azonenberg>
And here i was thinking i'd never use all of the ten 2-inch cassettes i bought
<azonenberg>
Once you start cleaving wafers and want to store the halves and quarters separately since they were all processed differently...
<bart416>
top gear is on
<bart416>
jeremy clarkson driving wrecking equipment
<azonenberg>
wants e-beam direct write in his living room
<azonenberg>
doesnt expect to get it for another 5-10 years at best
<azonenberg>
Tired of guessing at layer thicknesses
<azonenberg>
Some time in a week or two i want to cross-section a few of my samples and see
<azonenberg>
My processes are decently repeatable, I can see the thicknesses are even because its all the same color
<nathan7>
Hi azonenberg
<azonenberg>
But without knowing the refractive index etc I have no idea what the actual value is
<azonenberg>
And knowing the index for bulk material doesnt usually help with thin films :P
<azonenberg>
hi
<nathan7>
e-beam, the whiteboards?
<azonenberg>
I'd love to be able to do ebeam but its a ways out
<azonenberg>
When i build and/or buy (eventually i want both a nice commercial one plus a homebrewed one just for the fun of it) a SEM i plan to equip it to do ebeam
<nathan7>
oh, electron beam
<azonenberg>
Specifically, electron beam direct-write lithography
<nathan7>
COOL
<azonenberg>
You do a raster scan of the electron beam onto a polymer that functions like a photoresist (normally some kind of doped PMMA i think)
<azonenberg>
then develop it just like PR
<azonenberg>
Its typically used for making photomasks
<nathan7>
interesting, interesting
<azonenberg>
Since you generally dont get precision alignment capability with it
<azonenberg>
But you can make a mask and then stick that in a stepper, contact aligner, etc
<bart416>
I'm going to etch wafers using the LHC
<azonenberg>
lol :p
<bart416>
I fear it might not meet the required energy to etch the wafer though
<azonenberg>
Hmm, what other famous images would work nicely as test patterns besides the companion cube?
<azonenberg>
Thinking of nyan cat
<azonenberg>
its already pixelated
<azonenberg>
other suggestions? Has to fit into a 500 lambda disk
<azonenberg>
with no features smaller than 5 lambda
<azonenberg>
iow, you can make features with dimensions 5, 6, 7, ... 500
<bart416>
nyan cat would make you look like a fury though
<bart416>
maybe something symbolic
<azonenberg>
I've been doing companion cubes for too long
<azonenberg>
And i want to stay with the trend of memes
<azonenberg>
Make it look like a typo
<azonenberg>
I'm setting up this super-complex lab for making MEMS but somewhere along the line an extra letter got added :P
<azonenberg>
In all seriousness the dots on his back are perfect for testing point resoluition