#homecmos IRC log for Saturday, 2011-07-23

azonenberg_labTime to start tonight's experiments02:24
azonenberg_labStep 1: measure etch rate of my film in SC202:24
azonenberg_lab5 seconds its gone02:32
azonenberg_labguess 60 was a bit much...02:33
azonenberg_labAnd just ran another test - photoreist over Cu over Ta2O503:10
azonenberg_labSuccessful patterning of Cu with 5 sec in SC203:10
azonenberg_labWaiting for the hot plate to warm up so i can see how well the Cu + photoresist works as a hardmask for HF03:10
azonenberg_labWell, metal patterning is now a solved problem :)04:09
azonenberg_labAnd no matter how this current experiment turns out its the closest i've ever gotten to reliable Si wet etching04:29
azonenberg_labits just a matter of tuning layer thicknesses now04:29
azonenberg_labthe process works great04:29
CIA-67homecmos r105 | trunk/lithography-tests/labnotes/azonenberg_labnotes.txt | Today's lab notes05:16
azonenberg_labIt pretty much worked - the Cu delaminated slightly due to undercut but a thinner oxide layer should fix it05:16
azonenberg_labPattern transferred from mask to photoresist reduced 10x, then to evaporated Cu, then to Ta2O5, then to Si05:17
azonenberg_labNow its just a matter of getting sharper edges, better adhesion, etc05:17
azonenberg_labRight 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 process05:17
azonenberg_labmy finer features didnt quite resolve05:17
azonenbergThis is the second test die I ran today05:55
azonenbergFeatures were narrowed due to overetch of the hardmask05:56
azonenbergBut overall it was my most successful run to date05:56
azonenbergAnd shows potential for improvement05:56
azonenbergI want to try some tests on <110> in the next few weeks and try doing through-wafer KOH etches05:56
azonenberglekernel: Did you see my die shot from last night?13:52
azonenbergHad some slight undercut of the mask but it was largely successful :)13:52
azonenbergUploading now13:53
azonenbergSlow cable is slow :P13:56
azonenbergI dont have time to select and downsample so i have to do the raw camera-res jpegs13:57
azonenbergA quarter gig of data (my last three lab sessions didnt get uploaded until now) at 1 Mbps or even a bit less...13:58
bart416Anyway, I'm off for a few hours14:05
kristianpaulwhere are the pictures..16:25
azonenbergJust finished uploading, sec16:27
azonenberghttp://colossus.cs.rpi.edu/~azonenberg/images/homecmos/2011-07-22/S7301536.JPG is 400x of the die copyright halfway through processing16:27
azonenbergThe yellow-green is around 200nm of tantalum oxide over silicon16:27
azonenbergred-orange is 200nm of evaporated copper with photoresist over it16:28
azonenbergthis is after the first wet etch16:28
azonenberghttp://colossus.cs.rpi.edu/~azonenberg/images/homecmos/2011-07-22/S7301542.JPG is 100x after the second wet etch16:28
azonenbergThe 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 undercut16:29
azonenbergBut the oxide is still present over most places it should be (though a little thin)16:29
azonenberghttp://colossus.cs.rpi.edu/~azonenberg/images/homecmos/2011-07-22/S7301547.JPG is 400x after stripping the Cu / PR16:29
azonenberghttp://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)16:31
azonenberghttp://colossus.cs.rpi.edu/~azonenberg/images/homecmos/2011-07-22/S7301552.JPG is 100x16:31
azonenbergAnd 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)16:31
kristianpaul551 looks a bit messy compared to 53616:37
kristianpaulbut of course, is all Si :-)16:37
kristianpaulthis is taking using metallurgical microscope, right?16:42
azonenbergAnd yes, i am still working on getting better results16:45
azonenbergThe problem is that the Ta2O5 was too thick so the HF undercut the Cu hardmask16:45
azonenbergI need to use a thinner oxide layer and maybe a little more Cu16:45
azonenbergBut overall it worked surprisingly well16:46
kristianpaulindeed, well if you take look back to previos results of course !16:47
azonenbergLol yeah16:47
azonenbergThis was the first die i actually took all the way through the process that even sort of worked16:47
azonenbergSo now its just a matter of tuning it to give better results16:47
azonenbergI plan to do prep (Ta2O5 + Cu deposition) on a quarter of a <110> wafer in the next week or two16:47
azonenbergso i can try some vertical etches16:47
Action: azonenberg wants a comb drive :)16:49
azonenberglekernel_: 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 evaporator17:28
azonenbergThink end of summer to end of the calendar year is feasible?17:29
nathan7azonenberg: :o17:59
azonenbergnathan7: :o at what?18:23
nathan7:o at it all18:32
kristianpaulwellcome solrize , check the paper http://colossus.cs.rpi.edu/~azonenberg/papers/litho1.pdf18:32
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