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Vacuum Fab Room

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Following on from an annotation in the linked post.

If dust is a problem in cleanrooms (for microprocessor fabrication), simply run them under a fairly hard vacuum. Dust particles of any size will settle out in a rapid and Newtonian way under vacuum and, with no air currents to disturb them, would stay put instead of wafting their motey ways onto the wafers.

The human operators are already in bunny suits with filtered air, so a pressure suit wouldn't be too far out of the question and, in any case, human operators will be less and less required.

MaxwellBuchanan, Jul 07 2012

Suggested by: NexGen_20Clean_20Room
[MaxwellBuchanan, Jul 07 2012]


       I'm not sure about the state of the art in chip fabs, but as of a decade or so ago, several processes still involved liquid. Definitely for board fabs solder pastes and adhesives are common. These would not do so well in vacuum.
MechE, Jul 08 2012

Cuit_au_Four, Jul 08 2012

       [mechE] you're probably right.   

       The alternative, then, is to stick with atmospheric pressure but to spin the whole facility up to about 50G. Then dust particles may settle out even in air. Of course, the people would need a little training.
MaxwellBuchanan, Jul 08 2012

       [CaF] has the key point here, I think.   

       That said, I don't think we're talking about assembling mother (or any other close relative) boards - we're talking specifically about "printing" the microprocessor chips themselves.
Custardguts, Jul 08 2012

       Precisely so. I have seen movies of fab rooms, and they always seem to have people moving stacks of wafers from machine to machine, but I find it hard to believe that this is still the case.
MaxwellBuchanan, Jul 08 2012

       //Like a vacuum will suddenly make solder float away// I think the point was that solder would tend to boil in a vacuum. Whether that is true or not, I am unsure.
MaxwellBuchanan, Jul 08 2012

       //Are you getting confused with zero G ?//   

       No, I'm talking about the rate of evaporation (or for pastes, differential evaporation) that would render various solvents, adhesives, and similar very difficult to use.   

       //but I find it hard to believe that this is still the case//   

       That I know to still be the case. Everything in scoring and making the dies can be automated, but transferring the wafers and handling filled spools of the finished product is still largely manual.
MechE, Jul 08 2012

       ...Yeah, but your poor vacuum pumps are going to hate you for producing atmosphere. Just think of how long it's going to take to pull back down to pressure once you flash off a couple litres of toluene or trike or whatever you're using. Gah!!
Custardguts, Jul 09 2012

       An alternative would be to have a normal air-filled, positive-pressure clean room but to fill it with air from tanks of liquified air.
hippo, Jul 09 2012

       //fill it with air from tanks of liquified air//   

       I don't think there's a problem in getting dustless air into the room - filters are very effective. The problem, I presume, is that activities within the room generate some irreducible amount of dust, which wafts around before being pulled out by the filter system.
MaxwellBuchanan, Jul 09 2012

       Had better moor this facility tightly to Earth, otherwise it might float away like a proverbial vacuum blimp. Otherwise, [+]; robots can work in vacuum and solder is not used in ultraclean rooms anyway.
sqeaketh the wheel, Jul 09 2012

       Solder isn't, but I'm pretty sure various cleaning solvents are.   

       Also it just occurred to me that some operations in clean rooms that produce debris are kept clean in laminar flow hoods. Which means air flow.
MechE, Jul 10 2012

       Soldering would surely work better in a vacuum. Oxidation would be reduced, and it wouldn't precipitate much extra evaporation.
spidermother, Jul 10 2012

       The issue isn't solder itself (although evaporation of different fractions while in a liquid state would be a problem), but solder paste. Again not relevant for die fab, but the paste is used in board level fab because it dispenses easily. Trying to use that in a vacuum would cause all sorts of problems.
MechE, Jul 10 2012


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