| azonenberg_lab | Running experiments on evaporated copper now | 01:04 |
|---|---|---|
| azonenberg_lab | First step was the "Scotch tape test" on a glass sample, it failed miserably | 01:05 |
| azonenberg_lab | almost complete delamination | 01:05 |
| azonenberg_lab | Next will be seeing how it handles HF | 01:05 |
| azonenberg_lab | i've heard some people say they think it passivates, others say it will etch | 01:06 |
| azonenberg_lab | lekernel: Know anything about the behavior of Cu in HF? | 01:28 |
| azonenberg_lab | Will it etch, passivate, not react at all? | 01:28 |
| CIA-67 | homecmos r104 | trunk/lithography-tests/labnotes/azonenberg_labnotes.txt | Today's lab notes | 02:55 |
| azonenberg | http://i.imgur.com/ximLl.jpg | 03:09 |
| azonenberg | 100x view of evaporated copper on wafer | 03:10 |
| azonenberg | after spin coating in PR, exposing, developing, and wet etching in SC2 | 03:10 |
| azonenberg | After stripping resist; http://i.imgur.com/WZDVv.jpg | 03:10 |
| azonenberg | Colors are a bit off | 03:10 |
| azonenberg | But the yellow is copper and the background is silicon | 03:10 |
| azonenberg | I wonder if 60 sec in SC2 is too much | 03:11 |
| azonenberg | The film is very thin, after all | 03:11 |
| azonenberg | Maybe i want to water it down... | 03:11 |
| azonenberg | Yeah, its waaay too much | 03:53 |
| azonenberg | Etch Rates for Micromachining Processing - Part II, IEEE MEMS journal | 03:54 |
| azonenberg | gives etch rate for a similar FeCl3 based etchant as 3900nm/min | 03:54 |
| azonenberg | I'm using HCl : H2O2 but in PCBs they etched at about the same rate | 03:54 |
| azonenberg | Which means my film (rough guesstimate 200nm) would be etched throuhg in 5 sec | 03:54 |
| azonenberg | And then 12x overetched :P | 03:55 |
| nathan7 | azonenberg: :o | 07:26 |
| Laurenceb | HF is acid | 12:40 |
| Laurenceb | it should etch copper | 12:41 |
| lekernel | Laurenceb, not all acids etch copper, e.g. hydrochloric acid does not | 13:37 |
| lekernel | HF, I don't know | 13:37 |
| lekernel | Laurenceb, also, you have passivation phenomena with some strong acids... for example pure sulfuric acid does not etch copper, but diluted sulfuric acid does (iirc) | 13:38 |
| lekernel | azonenberg: see http://www.dtic.mil/cgi-bin/GetTRDoc?AD=AD288458&Location=U2&doc=GetTRDoc.pdf | 13:39 |
| lekernel | "In the manufacture and storage of hydrogen fluoride and its aqueous solution, i.e., hydrofluoric acid, equipment made of copper and its alloys is used" | 13:39 |
| lekernel | so it most probably does not ;) | 13:40 |
| bart416 | For HF storage, just use teflon | 13:40 |
| lekernel | that's a 1962 document | 13:40 |
| lekernel | and the question isn't how to store HF but whether it can be used to etch copper | 13:41 |
| nathan7 | lekernel: In the presence of Cu(2+) it does | 13:43 |
| nathan7 | ahem, Cu²z | 13:43 |
| lekernel | HF or HCl? | 13:44 |
| lekernel | and I guess that's a chain reaction? | 13:44 |
| azonenberg | Well thats good because it means i can use evaporated copper as a hardmask for HF etching | 15:04 |
| azonenberg | I just might need a little bit more than i used for this deposition run | 15:04 |
| azonenberg | This might finally solve my patterning problems | 15:07 |
| azonenberg | Spin coat TaCl5, bake to oxidize | 15:08 |
| azonenberg | Evaporate Cu | 15:08 |
| azonenberg | Spin coat photoresist, develop, wet etch Cu hardmask in dilute SC2 | 15:08 |
| azonenberg | Etch Ta2O5 through Cu with hot HF | 15:08 |
| azonenberg | Strip Cu in SC2 | 15:08 |
| azonenberg | Etch Si through Ta2O5 with KOH | 15:08 |
| azonenberg | So i'd have *three* levels of masking | 15:09 |
| azonenberg | But in theory it should work | 15:09 |
| azonenberg | My last run seems to have had adhesion issues with the Cu, thats my only concern | 15:22 |
| azonenberg | Wondering if it wasnt pure enough / I didnt clean the surface adequately | 15:22 |
| azonenberg | but when i tried HF etching a glass substrate with Cu over it, the Cu floated off | 15:23 |
| azonenberg | Not damaged, but it was undercut | 15:23 |
| bart416 | Well, HF tends to do that azonenberg | 16:44 |
| azonenberg | bart416: Yeah, i was hoping the Cu would actually mask it | 16:44 |
| azonenberg | Need to figure out if i just etched too long or what | 16:44 |
| azonenberg | I only need to go down around 100nm | 16:44 |
| bart416 | For etching glass I'd just use regular photoresist to be honnest | 16:55 |
| azonenberg | bart416: Doesnt work | 17:01 |
| azonenberg | My resist allows F- to diffuse through it | 17:02 |
| bart416 | auch :( | 17:02 |
| azonenberg | you get etching of the substrate with intact photoresist over it | 17:02 |
| azonenberg | At least, thats my working hypothesis | 17:03 |
| azonenberg | all i know for sure is what actually happens | 17:03 |
| azonenberg | not how | 17:03 |
| azonenberg | So my newly modified process calls for ten different operations to pattern one bulk-etch mask level into a piece of silicon lol | 20:00 |
| azonenberg | Spin coat TaCl5, bake | 20:02 |
| azonenberg | Evaporate Cu | 20:02 |
| azonenberg | Spin coat photoresist, soft bake | 20:02 |
| azonenberg | Expose, develop, hard bake | 20:02 |
| azonenberg | Wet etch Cu in dilute SC2 | 20:02 |
| azonenberg | Strip PR in acetone | 20:02 |
| azonenberg | Wet etch Ta2O5 through Cu with HF | 20:02 |
| azonenberg | Strip Cu in SC2 | 20:03 |
| azonenberg | Wet etch Si in KOH | 20:03 |
| azonenberg | Strip Ta2O5 in HF | 20:03 |
| nathan7 | SC2? | 20:03 |
| azonenberg | Standard Clean 2, the second of two cleaning solutions in the RCA clean | 20:03 |
| azonenberg | 1 part HCl : 1 part 30% H2O2 : 6 parts water | 20:03 |
| azonenberg | I use a slightly different mixture due to lack of 30% peroxide, i use 1 part conc HCl to 6 parts 3% H2O2 | 20:04 |
| azonenberg | A little less of an oxidizer but its pretty close, just slightly slower etch rate on some materials | 20:04 |
| nathan7 | mhm | 20:35 |
| nathan7 | azonenberg: ebay has 30% H2O2 | 20:35 |
| azonenberg | nathan7: Not saying it cant be obtained | 20:36 |
| azonenberg | But i dont have it | 20:36 |
| azonenberg | It also decomposes fast enough i dont want to order it | 20:37 |
| nathan7 | Not terribly fast | 20:37 |
| nathan7 | Just keep it in the dark and don't keep it with metal | 20:37 |
| azonenberg | In any case, cant do too much moe work until sunset in the USA | 20:39 |
| azonenberg | more* | 20:39 |
| azonenberg | silly photoresist and my lack of a darkroom... | 20:39 |
| nathan7 | lol | 20:40 |
| bart416 | H202 lasts quite a while if you keep it in the right bottles | 21:23 |
| bart416 | As long as you don't expose it to much light and avoid heating it it'll last years | 21:27 |
| azonenberg | bart416: 3% or 30%? | 21:35 |
| bart416 | Both | 21:35 |
| azonenberg | And i'd use an opaque plastic or brown glass bottle under a shelf | 21:35 |
| azonenberg | at 75F | 21:35 |
| nathan7 | Put it in the lab freezer! | 21:36 |
| bart416 | ^that | 21:36 |
| azonenberg | nathan7: Dont have one (working at least) | 21:36 |
| bart416 | put it in a fridge | 21:36 |
| bart416 | I mean, it's not like it's really all that toxic | 21:36 |
| bart416 | Unless if you intend to drink it | 21:36 |
| azonenberg | On general principle i keep lab stuff well separated from food / living spaces | 21:36 |
| nathan7 | H2O2 is nontoxic | 21:37 |
| nathan7 | just oxidising | 21:37 |
| bart416 | Just keep it in a labeled teflon bottle | 21:38 |
| bart416 | And put it somewhere in a cool cupboard | 21:38 |
| bart416 | that's my storage procedure for 10% H202 and up | 21:38 |
| bart416 | As long as you stay under 50% that should be safe | 21:39 |
| azonenberg | 50%? Lol | 21:39 |
| azonenberg | I'm not working with rocket fule here | 21:39 |
| azonenberg | fuel* | 21:39 |
| bart416 | It's only qualified as rocket fuel starting from 65% or something like that | 21:40 |
| bart416 | lol | 21:40 |
| azonenberg | Lol, 50 is still quite possibly explosive | 21:40 |
| bart416 | Nah, 50% is still safe if you don't heat it | 21:40 |
| nathan7 | or stir it with silver spoons | 21:44 |
| nathan7 | or silver powder | 21:44 |
| nathan7 | really high-surface area silver powder | 21:44 |
| nathan7 | that still gets a nice fizz out of 3% | 21:44 |
| azonenberg | lol :P | 21:45 |
| azonenberg | how about 50nm nanopowder? :p | 21:45 |
| azonenberg | boom | 21:45 |
| bart416 | nathan7, don't try to feed it iron either :p | 21:47 |
| bart416 | And never ever try to feed it alkali metals | 21:47 |
| nathan7 | ;D | 21:47 |
| azonenberg | Alkali metals... | 21:47 |
| bart416 | you know, if you throw a block of potasium in water it reacts violently eh... | 21:47 |
| azonenberg | Rubidium plus 50% H2O2 | 21:47 |
| nathan7 | azonenberg: I dissolved 97/3 Sn/Ag solder in HCl(aq) | 21:48 |
| bart416 | Now try throwing it in high concentration hydrogen peroxide | 21:48 |
| bart416 | I'll stand back a bit :P | 21:48 |
| nathan7 | ;D | 21:48 |
| bart416 | Violent is an understatement | 21:48 |
| bart416 | Its a damned depth charge >_> | 21:48 |
| azonenberg | lol | 21:49 |
| nathan7 | bart416: better, put a tube to the bottom | 22:01 |
| nathan7 | make sure it's dry inside | 22:01 |
| nathan7 | and drop the K in | 22:01 |
| nathan7 | then quickly remove the tube | 22:01 |
| nathan7 | the K will be at the bottom | 22:01 |
| azonenberg | lol | 22:01 |
| bart416 | nathan7, heh we had another method | 22:02 |
| bart416 | we put the potasium in a one of those large plastic canisters you can buy chemicals in | 22:02 |
| azonenberg | And puncture the lid? | 22:02 |
| bart416 | attach a brick to it | 22:03 |
| bart416 | attach fireworks with fuses that work under water to the lid | 22:03 |
| nathan7 | :> | 22:03 |
| azonenberg | ... | 22:03 |
| bart416 | and throw it in the river | 22:03 |
| azonenberg | So you use a small charge to blow the lid off | 22:03 |
| nathan7 | azonenberg: where are you located? | 22:03 |
| bart416 | yes | 22:03 |
| azonenberg | nathan7: USA | 22:03 |
| nathan7 | azonenberg: Yes, where USA? | 22:03 |
| azonenberg | Near Albany | 22:03 |
| nathan7 | State? | 22:03 |
| azonenberg | why you ask? | 22:03 |
| azonenberg | NY | 22:04 |
| nathan7 | You<->ozonenerd distance | 22:04 |
| azonenberg | Oh | 22:04 |
| azonenberg | Where's he at? | 22:04 |
| nathan7 | ah, that's far | 22:04 |
| nathan7 | Florida | 22:04 |
| azonenberg | Lol | 22:04 |
| azonenberg | Yeah, 500 miles ish? | 22:04 |
| azonenberg | maybe a bit more? | 22:04 |
| nathan7 | americaland is big. | 22:04 |
| bart416 | I'm bored | 22:17 |
| --- Sat Jul 23 2011 | 00:00 | |
Generated by irclog2html.py 2.9.2 by Marius Gedminas - find it at mg.pov.lt!
