<azonenberg_lab> Time to start tonight's experiments
<azonenberg_lab> Step 1: measure etch rate of my film in SC2
<azonenberg_lab> 5 seconds its gone
<azonenberg_lab> lol
<azonenberg_lab> guess 60 was a bit much...
<azonenberg_lab> And just ran another test - photoreist over Cu over Ta2O5
<azonenberg_lab> Successful patterning of Cu with 5 sec in SC2
<azonenberg_lab> Waiting for the hot plate to warm up so i can see how well the Cu + photoresist works as a hardmask for HF
<azonenberg_lab> Well, metal patterning is now a solved problem :)
<azonenberg_lab> And no matter how this current experiment turns out its the closest i've ever gotten to reliable Si wet etching
<azonenberg_lab> its just a matter of tuning layer thicknesses now
<azonenberg_lab> the process works great
<CIA-67> homecmos r105 | trunk/lithography-tests/labnotes/azonenberg_labnotes.txt | Today's lab notes
<azonenberg_lab> It pretty much worked - the Cu delaminated slightly due to undercut but a thinner oxide layer should fix it
<azonenberg_lab> Pattern transferred from mask to photoresist reduced 10x, then to evaporated Cu, then to Ta2O5, then to Si
<azonenberg_lab> Now its just a matter of getting sharper edges, better adhesion, etc
<azonenberg_lab> Right now i dont feel comfortable calling 20 microns my achievable feature size, 30-40 is more like what i can actually do with the current process
<azonenberg_lab> my finer features didnt quite resolve
<azonenberg> This is the second test die I ran today
<azonenberg> Features were narrowed due to overetch of the hardmask
<azonenberg> But overall it was my most successful run to date
<azonenberg> And shows potential for improvement
<azonenberg> I want to try some tests on <110> in the next few weeks and try doing through-wafer KOH etches
<azonenberg> lekernel: Did you see my die shot from last night?
<azonenberg> Had some slight undercut of the mask but it was largely successful :)
<bart416> pictures!
<azonenberg> Uploading now
<azonenberg> Slow cable is slow :P
<azonenberg> I dont have time to select and downsample so i have to do the raw camera-res jpegs
<azonenberg> A quarter gig of data (my last three lab sessions didnt get uploaded until now) at 1 Mbps or even a bit less...
<bart416> Anyway, I'm off for a few hours
<azonenberg> k
<kristianpaul> where are the pictures..
<kristianpaul> ?¿
<azonenberg> Just finished uploading, sec
<azonenberg> http://colossus.cs.rpi.edu/~azonenberg/images/homecmos/2011-07-22/S7301536.JPG is 400x of the die copyright halfway through processing
<azonenberg> The yellow-green is around 200nm of tantalum oxide over silicon
<azonenberg> red-orange is 200nm of evaporated copper with photoresist over it
<azonenberg> this is after the first wet etch
<azonenberg> The oxide layer was too thick ( i need to try 100nm next time) so the HF undercut the maks a little, note the copper/photoresist in the background fell off due to undercut
<azonenberg> But the oxide is still present over most places it should be (though a little thin)
<azonenberg> http://colossus.cs.rpi.edu/~azonenberg/images/homecmos/2011-07-22/S7301551.JPG is a 40x die overview after the final KOH wet etch and mask strip (so what you're seeing is all Si except for a bit of some brownish precipitate in the lower parts of the etched areas)
<azonenberg> And http://colossus.cs.rpi.edu/~azonenberg/images/homecmos/2011-07-22/S7301553.JPG is 400x (a bit blurred but you can clearly see the angled sidewalls of the holes since this is <100> Si)
<kristianpaul> 551 looks a bit messy compared to 536
<kristianpaul> but of course, is all Si :-)
<kristianpaul> this is taking using metallurgical microscope, right?
<azonenberg> Yes
<azonenberg> And yes, i am still working on getting better results
<azonenberg> The problem is that the Ta2O5 was too thick so the HF undercut the Cu hardmask
<azonenberg> I need to use a thinner oxide layer and maybe a little more Cu
<azonenberg> But overall it worked surprisingly well
<kristianpaul> indeed, well if you take look back to previos results of course !
<azonenberg> Lol yeah
<azonenberg> This was the first die i actually took all the way through the process that even sort of worked
<azonenberg> So now its just a matter of tuning it to give better results
<azonenberg> I plan to do prep (Ta2O5 + Cu deposition) on a quarter of a <110> wafer in the next week or two
<azonenberg> so i can try some vertical etches
<azonenberg> wants a comb drive :)
<azonenberg> lekernel_: How far do you think i am from a working comb drive now? I have silicon patterning mostly worked out, i can deposit dielectric (Ta2O5 is actually a high-K material), and I can deposit metal if i borrow time on the evaporator
<azonenberg> Think end of summer to end of the calendar year is feasible?
<nathan7> azonenberg: :o
<azonenberg> nathan7: :o at what?
<nathan7> :o at it all
<kristianpaul> wellcome solrize , check the paper http://colossus.cs.rpi.edu/~azonenberg/papers/litho1.pdf