| azonenberg_work | Testing lift-off patterning of Cr tomorrow, finally confirmed my lab time | 21:17 |
|---|---|---|
| azonenberg_work | followed by several deep wet etches | 21:17 |
| mrdata | cool | 21:19 |
| azonenberg_work | If this works i'll be doing through-silicon vias/trenches this weekend | 21:21 |
| azonenberg_work | IDK if i can hit a 25:1 aspect ratio (20 um hole 500um deep) but i should be able to hit 5:1 at least | 21:21 |
| azonenberg_work | meaning a 100um square hole 500um deep | 21:22 |
| azonenberg_work | i'll also be testing wafer thinning | 21:25 |
| azonenberg_work | do a ~400um deep etch in the center of a die | 21:26 |
| azonenberg_work | then flip over and do another etch on the front with my features | 21:27 |
| azonenberg_work | Hmm, so here's my thought | 21:34 |
| azonenberg_work | Take half a wafer and spin coat in PR | 21:34 |
| azonenberg_work | Expose and develop a contact mask with die-separation lines on it | 21:34 |
| azonenberg_work | Evaporate Cr over the lines | 21:35 |
| azonenberg_work | lift off in acetone | 21:35 |
| azonenberg_work | Now i have a micron of Cr over my dies and nothing in the trenches | 21:35 |
| azonenberg_work | The next step is to KOH etch the entire wafer until i'm around 100um deep | 21:35 |
| azonenberg_work | (the back side would also be Cr coated) | 21:36 |
| azonenberg_work | So now i have hardmask over both sides of the wafer except in the kerf areas | 21:36 |
| azonenberg_work | which are etched ~100um deep | 21:36 |
| mrdata | neat | 21:37 |
| azonenberg_work | At this point I spin coat PR and lay down a second contact mask | 21:37 |
| azonenberg_work | This one is a rectangle in the center of each die | 21:37 |
| azonenberg_work | Also coat the back side of the wafer in resist so i dont damage the Cr there | 21:38 |
| azonenberg_work | Etch in HCl until the Cr is removed from the center areas | 21:38 |
| azonenberg_work | Then KOH etch until the dies are separated | 21:38 |
| azonenberg_work | At this point i have a bunch of ~3mm square dies with square outlines | 21:38 |
| azonenberg_work | in the middle of the top is a 400um deep rectangular hole | 21:39 |
| azonenberg_work | maybe 1-2mm square | 21:39 |
| azonenberg_work | I then flip the dies over | 21:39 |
| azonenberg_work | one at a time, spin coat in PR | 21:40 |
| azonenberg_work | expose projection mask with comb drive pattern over the center | 21:40 |
| azonenberg_work | develop, HCl etch | 21:40 |
| azonenberg_work | then KOH a third time (leaving the 400um trench on the underside unmasked) | 21:40 |
| azonenberg_work | the two etches will meet 50um into the die | 21:40 |
| azonenberg_work | leaving me with free-standing features in a 50um silicon plate | 21:41 |
| azonenberg_work | with a nice thick 500um ring around it for mechanical support | 21:41 |
| azonenberg_work | If successful, that's all of the bulk micromachining needed for my comb drive | 21:41 |
| azonenberg_work | i just have to grow thermal oxide, evaporate metal, and pattern the M1 mask | 21:42 |
| mrdata | still, seems like a lot of steps | 21:43 |
| azonenberg_work | lol, it is | 21:43 |
| mrdata | how many layers is the resulting circuit? | 21:44 |
| azonenberg_work | This is for MEMS | 21:44 |
| azonenberg_work | it'd be one metal layer over 3D silicon geometry | 21:44 |
| mrdata | ok | 21:44 |
| azonenberg_work | i'll do a CAD model later today and post a render | 21:44 |
| azonenberg_work | Right now, going afk as my battery is about dead:p | 21:45 |
| uneducatedsavant | how do memristors work? | 21:48 |
| uneducatedsavant | how do they actually change resistance? | 21:49 |
| mrdata | if you wnt them to be useful, you should be able to set their resistance many times | 21:50 |
| mrdata | but, i dontknow much about memristors exactly | 21:50 |
| uneducatedsavant | yeah it has something to do with filament formation | 21:53 |
| uneducatedsavant | but i'm not sure how those filaments form | 21:53 |
| uneducatedsavant | or what the filaments are made of | 21:53 |
| uneducatedsavant | is it metal? | 21:53 |
| uneducatedsavant | hmm i wish i knew someone who could help me understand. it's very interesting | 21:54 |
| azonenberg | Back | 22:39 |
| azonenberg | I dont understand memristance myself but there was someone here who wanted to do work on them | 22:39 |
| azonenberg | i forget who it was | 22:39 |
| --- Fri Oct 21 2011 | 00:00 | |
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