| ashaw | azonenberg, are you there? | 01:00 |
|---|---|---|
| azonenberg | ashaw: back | 01:15 |
| azonenberg | Was on campus | 01:15 |
| ashaw | no probs. | 01:15 |
| azonenberg | Whats up? | 01:16 |
| ashaw | I am thinking about using LDI to image the surface of an IC. | 01:19 |
| azonenberg | As in you want to do laser direct-write lithography for making an IC? | 01:19 |
| azonenberg | Very feasible as long as you can align it, which is tricky | 01:19 |
| azonenberg | I'd suggest doing it for mask fab and then contact alignment of the mask | 01:19 |
| ashaw | I have been thinking, why not use a UV laser and have a Blu-ray like controll | 01:21 |
| azonenberg | Well, the hard part is how to tell where you're pointing the laser | 01:22 |
| azonenberg | before firing it and exposing whatever is under it | 01:22 |
| ashaw | not really | 01:22 |
| azonenberg | you suggest just doing a low-power pulse in a corner? | 01:23 |
| azonenberg | In any case, i think it's very doable | 01:23 |
| azonenberg | i seriously planned to do the exact same thing myself | 01:23 |
| azonenberg | just been too busy to make it happen | 01:23 |
| ashaw | no - I suggest using an electron beam to put tracking marks on the edge and then plating them with a metal | 01:23 |
| azonenberg | If you have e-beam | 01:24 |
| azonenberg | why not use ebeam for everything? | 01:24 |
| ashaw | I suppose | 01:24 |
| azonenberg | Since ebeam is pretty easy to use for low-power imaging and high-power litho | 01:24 |
| azonenberg | Turning a SEM into an e-beam direct write system is a solved problem | 01:24 |
| azonenberg | several companies sell conversion kits | 01:24 |
| azonenberg | they can even still image | 01:24 |
| ashaw | can you use a STM to image? | 01:26 |
| azonenberg | Yes, but i dont know if you can make one do lithography | 01:27 |
| azonenberg | and scanning probe techniques are much slower than scanning-beam systems like SEM | 01:27 |
| ashaw | I know. | 01:30 |
| azonenberg | I mean, there are so many tools i eventually want to have in my lab lol | 01:30 |
| ashaw | as I | 01:30 |
| azonenberg | its all a matter of deciding which ones to build/buy first | 01:30 |
| ashaw | yeah | 01:30 |
| azonenberg | Now that i have Ethernet working on PIC32s i can make networked lab equipment | 01:30 |
| azonenberg | I'm planning to build an ethernet-controllable spin coater in the fairly near future | 01:31 |
| azonenberg | gotta pick out a good motor and do some CAD work | 01:31 |
| ashaw | how about using a single pulse on one corner to create the beam | 01:31 |
| azonenberg | To do alighnment you'd need at least two marks | 01:31 |
| ashaw | sorry the tracking generator | 01:31 |
| ashaw | no. | 01:31 |
| azonenberg | you need to know scale, theta, and position | 01:31 |
| ashaw | I would not | 01:31 |
| azonenberg | no way you can get that without at least two | 01:32 |
| ashaw | I just need one | 01:32 |
| ashaw | and then rotate it | 01:32 |
| azonenberg | not sure i understand what you're planning | 01:32 |
| azonenberg | in any case, the easiest technique IMO | 01:32 |
| azonenberg | is to make the laser direct write be unaligned | 01:32 |
| azonenberg | just write onto a mask blank | 01:32 |
| azonenberg | develop and etch the mask (probably sputtered metal on a microscope slide) | 01:33 |
| azonenberg | Then use the resulting chrome-on-glass mask in a contact aligner, which would be pretty easy to build | 01:33 |
| ashaw | Interesting. | 01:35 |
| ashaw | however, I still need scale | 01:35 |
| azonenberg | I'd do a single initial calibration | 01:37 |
| azonenberg | and then just assume it's accurate | 01:37 |
| azonenberg | recalibrate periodically | 01:37 |
| azonenberg | as in, write two lines X distance apart | 01:37 |
| azonenberg | where X is nominally, say, 100um | 01:38 |
| ashaw | So what do we know about the disk? | 01:38 |
| azonenberg | then take a photo with a calibrated camera and measure | 01:38 |
| ashaw | we know it's rotation velocity | 01:38 |
| azonenberg | Bluray disks are polar coordinates | 01:38 |
| azonenberg | and have tracking metadata already etched into them | 01:38 |
| azonenberg | this will be cartesian | 01:38 |
| azonenberg | on a blank substrate | 01:38 |
| ashaw | no, I will write in polar | 01:38 |
| azonenberg | Oh | 01:38 |
| azonenberg | Mine will be cartesian | 01:38 |
| azonenberg | i envision reusing the diode but otherwise doing totally my own structure | 01:38 |
| ashaw | What type? | 01:40 |
| ashaw | I too will only use the diode, I do not think the structure can be controlled well enough | 01:42 |
| ashaw | My intent is to use a 2in wafer, spinning at 10k rpm | 01:43 |
| ashaw | and image using a set of fibe beams with a high NA | 01:44 |
| ashaw | lenses on the end. | 01:44 |
| ashaw | spaced on the axis of rotation 100 um apart | 01:44 |
| ashaw | approx. | 01:45 |
| ashaw | azonenberg | 01:45 |
| ashaw | ? | 01:46 |
| kanzure | patron saint of lithographers? | 01:47 |
| ashaw | hey what? | 01:47 |
| kanzure | just reading the backlog | 01:47 |
| ashaw | who is? | 01:48 |
| kanzure | /kick ashaw | 01:48 |
| ashaw | why? | 01:48 |
| azonenberg | Back | 01:49 |
| azonenberg | So let me see if i understand your plan | 01:49 |
| azonenberg | 10k rpm is pretty high, for starters | 01:49 |
| ashaw | not really. | 01:49 |
| azonenberg | So you want to have a single diode going into a set of optical fibers? | 01:49 |
| ashaw | no, multiple diodes | 01:49 |
| azonenberg | That's a LOT of power | 01:49 |
| kanzure | in molecular biology labs you regularly get up to >50k rpm | 01:50 |
| azonenberg | for a silicon wafer, i mean | 01:50 |
| azonenberg | most spin coaters run at like 3-5k | 01:50 |
| azonenberg | But for a 2" it should be fine | 01:50 |
| azonenberg | i'd be cautious about an 8" or larger that fast | 01:50 |
| ashaw | yeah | 01:50 |
| azonenberg | anyway so ONE bluray diode is overpowered for litho | 01:50 |
| ashaw | I mainly want a high linear velocity | 01:50 |
| azonenberg | they're meant to actually heat and burn the metal on the disk | 01:50 |
| ashaw | I will only run it a very low power | 01:51 |
| azonenberg | You'll have to | 01:51 |
| ashaw | it is more for control | 01:51 |
| azonenberg | otherwise you'll overexpose hugely and heat it | 01:51 |
| ashaw | I want to controll each laser seperately | 01:51 |
| azonenberg | My thinking was to have a single diode | 01:51 |
| azonenberg | x/y mirror for fine alignment | 01:51 |
| azonenberg | (within one die) | 01:51 |
| azonenberg | then a mechanical stage for die-to-die stepping | 01:51 |
| ashaw | x/y mirror? how are you moving it? | 01:52 |
| azonenberg | Open question, probably light show galvos | 01:52 |
| azonenberg | then feed the resulting pattern through a reducing lens | 01:52 |
| azonenberg | I'm far from sure of what i'm doing here | 01:52 |
| fenn | light show galvos have terrible spatial resolution | 01:54 |
| azonenberg | fenn: 100um would be enough | 01:54 |
| azonenberg | if i was able to then reduce optically | 01:54 |
| ashaw | you cannot. | 01:54 |
| ashaw | you have a problem | 01:55 |
| azonenberg | In any case, i had some other ideas | 01:55 |
| azonenberg | one was to bounce the beam off a DLP micromirror array | 01:55 |
| ashaw | You need a high numerical aperature | 01:55 |
| ashaw | That was my first Idea | 01:55 |
| fenn | i think you want to move the diode image around with flying optics, if you're going the continuous (vector drawing so to speak) way | 01:55 |
| azonenberg | fenn: Again, open question | 01:55 |
| fenn | DLP's are great, A+ | 01:55 |
| azonenberg | this is on the tools-to-build-eventually list | 01:55 |
| azonenberg | not on the tools-under-current-development list | 01:56 |
| fenn | also you can fake it with LCD's if you don't mind waiting a long time | 01:56 |
| ashaw | What tools are you building currently | 01:56 |
| azonenberg | I just crossed "fume hood" off my list | 01:56 |
| azonenberg | "proper spin coater" is next up | 01:56 |
| azonenberg | as in, one that isnt made of 2x4s and filling my entire hood | 01:56 |
| azonenberg | this one will be much smaller, mostly metal construction | 01:56 |
| azonenberg | and have proper feedback-loop speed control | 01:56 |
| fenn | use a juiceman jr. | 01:56 |
| azonenberg | i want it controllable over ethernet | 01:57 |
| azonenberg | the plan is for all of my tools to be networked | 01:57 |
| azonenberg | so i can download process recipes from my laptop onto it | 01:57 |
| azonenberg | and then just click "run" | 01:57 |
| fenn | i had the same dream... once | 01:57 |
| azonenberg | I already have a PIC32 receiving UDP packets and decoding them | 01:57 |
| kanzure | hey wait. | 01:58 |
| kanzure | azonenberg: http://gnusha.org/skdb/ | 01:58 |
| azonenberg | and i know how to generate PWM for motor driving | 01:58 |
| fenn | PWM is easy compared to decoding ethernet | 01:59 |
| azonenberg | fenn: http://pastebin.com/fbWrjrdA | 01:59 |
| azonenberg | that was a day or two ago | 01:59 |
| fenn | most microcontrollers have PWM hardware built in | 01:59 |
| azonenberg | The "read ethernet" is a solved problem | 01:59 |
| azonenberg | i just have to put that and a PWM controller on one board | 01:59 |
| azonenberg | add some kind of optical encoder for speed feedback | 02:00 |
| azonenberg | and do mechanical design for the chuck etc | 02:00 |
| kanzure | no really, check the link | 02:00 |
| azonenberg | i did | 02:00 |
| ashaw | so after the spin coater, perhaps a CMP machine? | 02:01 |
| kanzure | ok my work here is done | 02:01 |
| azonenberg | ashaw: contact mask aligner is likely to come first | 02:01 |
| Sync | closed loop speed control seems to be overkill, you don't have the load changing around alot | 02:01 |
| azonenberg | Sync: but i need precise ramp rate contorl | 02:01 |
| azonenberg | i need constant accel/decel | 02:02 |
| azonenberg | and without knowing the mass of the load thats hard unless you have closed loop feedback | 02:02 |
| ashaw | are we going to work on whole wafers here.\ | 02:02 |
| azonenberg | in any case a CMP system would be a pretty simple mod of the spin coater | 02:02 |
| azonenberg | ashaw: I'd like to eventually but for now most of my work is done at the die level | 02:03 |
| Sync | well, you know the mass pretty well | 02:03 |
| azonenberg | since wafers are pricey | 02:03 |
| azonenberg | ashaw: so contact mask aligner is high on the todo list | 02:03 |
| kanzure | why not dlp | 02:03 |
| ashaw | how much are wafers? | 02:03 |
| azonenberg | in the longer term a stepper | 02:03 |
| ashaw | The problem kanzure is the optics. | 02:04 |
| azonenberg | ashaw: on the order of $25-50 depending on size, one vs two side polish, etc | 02:04 |
| ashaw | how much is unpolished? | 02:04 |
| azonenberg | Dirt cheap, i got an entire boat of 25x solar grade unpolished from ebay for $50 | 02:04 |
| ashaw | as wafers? | 02:05 |
| azonenberg | Yes | 02:05 |
| ashaw | what size | 02:05 |
| ashaw | ? | 02:05 |
| azonenberg | 4 inch N type | 02:05 |
| ashaw | defect level? | 02:05 |
| azonenberg | http://www.ebay.com/itm/25-FZ-Silicon-Wafers-Wafer-100mm-4-diameter-NEW-cassette-/180798982562?pt=LH_DefaultDomain_0&hash=item2a187589a2 | 02:05 |
| azonenberg | thats the spec | 02:05 |
| azonenberg | I bought a cassette from that seller | 02:06 |
| azonenberg | i've used two or three so far | 02:06 |
| azonenberg | as mechanical dummies for testing spin coating | 02:06 |
| azonenberg | as "cookie sheets" for heating single dies in the oven | 02:06 |
| azonenberg | etc | 02:06 |
| ashaw | Why not make a CMP machine as a top priority then | 02:06 |
| azonenberg | Because i usually work with single dies, not full wafers, so cost of silicon is minimal | 02:07 |
| azonenberg | http://www.mtixtl.com/siwafer1002diax027mmt1spptypebdoped.aspx | 02:07 |
| azonenberg | that is enough for like a hundred experiments | 02:07 |
| azonenberg | most of my dies are 2-3mm square | 02:07 |
| azonenberg | If i were to do CMP, it'd be for a different reason | 02:07 |
| azonenberg | namely, copper damascene | 02:07 |
| ashaw | I think CMP is going to really make things easier | 02:08 |
| azonenberg | ashaw: it's a valuable process to develop, i dont deny that | 02:09 |
| azonenberg | I just dont think its top priority | 02:09 |
| ashaw | perhaps. | 02:10 |
| azonenberg | It depends, in part, on what you're trying to do | 02:11 |
| azonenberg | for starters | 02:11 |
| azonenberg | CMOS or MEMS? | 02:11 |
| azonenberg | My current process is targeting MEMS | 02:11 |
| ashaw | I think that with a Doubled BD-R laser and spin imaging we could get a 180nm process | 02:11 |
| azonenberg | ashaw: I'm very interested lol | 02:12 |
| ashaw | I am trying to target CMOS | 02:12 |
| azonenberg | My current roadmap goes out to about 750nm | 02:12 |
| azonenberg | 20um is the smallest i've done reliably and i've hit 5um experimentally but not with good yield | 02:12 |
| ashaw | I want to do it with 10k in equipmemnt | 02:12 |
| azonenberg | Well, I like it lol | 02:12 |
| azonenberg | The first thing is particle contamination | 02:13 |
| azonenberg | at 180nm its nontrivial | 02:13 |
| ashaw | what is the process you are having the most problems with | 02:13 |
| azonenberg | So far, it's simply that i cannot make a mask small enough | 02:13 |
| ashaw | Yeah we will need a whole clean environment. | 02:13 |
| azonenberg | i can reduce my 200um mask by 10x = 20um features reliable | 02:13 |
| azonenberg | and by 40x = 5um but my 40x objective has a defect on it | 02:13 |
| azonenberg | so i cant get good results | 02:13 |
| kanzure | what is your current reducing optics like? | 02:13 |
| azonenberg | Microscope objective | 02:14 |
| azonenberg | the illuminator, though, is a halogen lamp | 02:14 |
| azonenberg | as a result the FOV is small and it needs a really long exposure | 02:14 |
| azonenberg | Both of those could be fixed if i built a LDI system for making masks | 02:14 |
| azonenberg | then used high intensity UV tubes for a contact exposure | 02:14 |
| azonenberg | Which is why once i get the spin coater built, LDI and contact aligner are next on the TODO | 02:14 |
| azonenberg | fume hood was first as photoresist fumes can be a little nasty | 02:15 |
| azonenberg | i have a spin coater but its so big it barely fits in the hood | 02:15 |
| azonenberg | and obstructs airflow | 02:15 |
| azonenberg | so i get vapors leaking out | 02:15 |
| azonenberg | the new one will be a lot smaller | 02:15 |
| ashaw | well for mask creation I cannot see a better technique than using a BD-R on a sputter coating of tungsten | 02:26 |
| ashaw | and then ablating the tungsten | 02:27 |
| azonenberg | why tungsten in particular? | 02:27 |
| azonenberg | and why ablation vs lithography (which needs a lower power dose and gives cleaner edges) | 02:27 |
| ashaw | nothing, actually any material | 02:27 |
| ashaw | no reason at all actually | 02:28 |
| ashaw | How long are you prepared to wait for a mask | 02:30 |
| azonenberg | A while, even overnight would be fine if the equipment wqasnt expensive to run | 02:30 |
| azonenberg | But vibration would be a concern at those feature sizes | 02:31 |
| azonenberg | you'd need to find some way of damping it | 02:31 |
| ashaw | where are the vibrations coming from? | 02:33 |
| azonenberg | Um, everwhere | 02:33 |
| azonenberg | people walking by | 02:33 |
| azonenberg | cars outside | 02:33 |
| azonenberg | HVAC system | 02:33 |
| ashaw | on what time scale? | 02:33 |
| azonenberg | several Hz | 02:33 |
| ashaw | above 100k? | 02:33 |
| azonenberg | no, single Hz | 02:33 |
| azonenberg | like, maybe 0.1 - 10 | 02:33 |
| azonenberg | even at 400x with a microscope you can see the image shaking if its not on a realy stable mount | 02:34 |
| ashaw | then just compensate the lithography | 02:34 |
| azonenberg | and at 1000x when people walk by it's nearly impossible to see anything | 02:34 |
| ashaw | Why not suspend the entire aparatus on an air bearing | 02:36 |
| ashaw | and use a wireless adaptor | 02:37 |
| azonenberg | Again, there are a lot of possibilities | 02:37 |
| ashaw | for the signal | 02:37 |
| azonenberg | in fact, many commercial anti-vibration tables are based on air bearings | 02:37 |
| azonenberg | the SEM at my school's cleanroom uses one for example | 02:37 |
| azonenberg | But it adds to the cost and development complexity | 02:37 |
| azonenberg | Not saying you cant do it, i'm all for it | 02:37 |
| azonenberg | But i also want to point out potential problems in advance | 02:37 |
| ashaw | I like that. | 02:38 |
| ashaw | allways important | 02:38 |
| ashaw | we also need an ultra high purity water generator | 02:40 |
| azonenberg | Again i'm doing MEMS, not CMOS, so i've been fine with regular distilled water from a pharmacy | 02:40 |
| azonenberg | didnt need to do DI on site | 02:40 |
| ashaw | yeah | 02:41 |
| cheater_ | why are air bearings superior to magnetic bearings? | 11:10 |
| cheater_ | you'd think a couple of electromagnets would be easy enough to cobble together | 11:10 |
| Sync | you do not need advanced control circuits | 11:12 |
| ashaw | and there is no possible stable magnetic bearing in a still system | 11:22 |
| ashaw | so the bearing is by nature a dynamic system | 11:22 |
| Sync | the amd diffusion plant in dresden did some major effort to get the vibration out of their building | 11:23 |
| ashaw | it is really important | 11:23 |
| ashaw | as at that level micro-vibrations are huge | 11:23 |
| Sync | I don't work with that fine structures at the moment | 11:24 |
| ashaw | not YET | 11:26 |
| ashaw | we'll get there | 11:26 |
| ashaw | so talking about the equipment problem. | 11:26 |
| Sync | no, I won't, I don't need to :P | 11:26 |
| ashaw | Why? | 11:27 |
| Sync | I manufacture fets in my sidejob at the university | 11:27 |
| Sync | they won't get smaller because they will not work as good then | 11:27 |
| ashaw | aaah | 11:27 |
| ashaw | hehehe | 11:27 |
| ashaw | you will not use smaller microstructures on your fet | 11:27 |
| Sync | okay "make" is a bit overstating it | 11:27 |
| ashaw | to reduce capacitance and such | 11:28 |
| Sync | I yell at the ion implanter and hope it does what I want | 11:28 |
| Sync | this is not an issue | 11:28 |
| ashaw | kihihihi | 11:28 |
| Sync | we develop ion sensitive fets | 11:28 |
| Sync | for measuring pH values | 11:28 |
| ashaw | oh cool | 11:29 |
| ashaw | which uni might I ask? | 11:29 |
| Sync | hannover, germany | 11:29 |
| ashaw | oh cool | 11:30 |
| ashaw | are you a stdent or a resercher?// | 11:30 |
| Sync | I'm a student | 11:30 |
| ashaw | Bachelor, Masters or PhD? | 11:31 |
| Sync | first semester bachelor ;) | 11:31 |
| ashaw | hehe, Just finished my 1st year | 11:51 |
| --- Sat Feb 18 2012 | 00:00 | |
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