Re: Home-made SSI chips

Hi all!

> Please don't laugh.. I'm serious. > > After having made PCB's with the photographic-like technique, and > being very pleased with the resolution I've been able to achieve, > I was wondering what would it take to make my own SSI chips? > > Of course I'm not talking about 90 nM resolution.. but something > like 0.1 millimeters (at best). I have a 2400²dpi laser printer. > > How does one make a transistor? Is this technology reachable from > the (enthusiast) hobbyst? Where could I find the necessary materials? >

While I admire your enthusiasm, it is highly unlikely that you can build, even low resolution, integrated circuits without a fairly large capital investment (probably a minimum of tens, if no hundreds, of thousands of dollars). The process requires a number of steps, each of which reqires specialized equipment, high purity (possibly poisonous) materials and a high degree of accuracy and precision.

Here is a web page that gives a quick overview of the IC manufacturing process:

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If you would like an interesting and challenging next step in your hobby, you could either 1) try making multi-layer circuit boards, or

2) start working with FPGAs.

Multi-layer circuit boards will move you a step closer to the IC manufacture process (ICs require several layers to be built up on a silicon wafer: at least, for PNP type devices, a P-type substrate, a set of N-type regions in the substrate, another set of P-type regions in the N-type regions, an insulating layer on top of the entire thing and, finally, a metal interconnect layer between PNP devices).

FPGAs give you the chance to construct actual chips that can compete with relatively modern custom devices (you can get, with carefull design, devices operating in the tens of megahertz). While this has little to do with the physical challenges of building ICs, it gives you the chance to experience some of the logical design challenges.

Reply to
Jeffrey Dutky
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Interesting :) So you say that I'm now a step closer to manufacturing my own IC's ? Cool :) Just kidding, but seriousely, I builld multilayer PCB's at home on a regular basis using my homebrew through hole plating machine.

Markus

Reply to
Markus Zingg

Don't tease :) Tell us more?

Mike Harding

Reply to
Mike Harding

Ok, you asked for it :)

A while ago, I put a little quick hack kind of homepage online showing the station. I should update the pages to show the latest developements. Time did not permitted this yet, but it's still better than nothing.

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A through plating machine is what you primarely need to create multilayer boards. It's of course also a great thing to have for double layers if you have lot's of holes and vias as it's often the case. The process of creating multilayers then (somewhat oversimplified to be short) boils down to first creating the inner layer but withouth any drilling, then glueing the outer layers onto the inner layer, drilling and through hole plate the whole stack. Then expose and etch the outer layers, apply a solder stop laminate if requiered. The process is the same for 6 layers but of course takes another aditional glue etc. step. Drilling is always done as the last step after glueing layers. You will need to work with photoresist laminates cause through plating on precoated material is not possible

- and - the holes must be covered during the final etching stage of the outer most layers or else the through hole plating will be etched away. Actually, using photoresist laminates is fun and fairly easy once you know how to do it. A nice side effect of the laminates is that you can create even finer artwork with them. The quality and look and feel of the resulting PCB can't be distinguished from those made in a board house if things are done propperly and provided you also laminate a solder stop mask onto the final PCB. I use those homebrew PCB's primarly for prototypes cause this is a huge timesaver and - provided you have some reasonably anual volume of boards you need - actually also the cheapest way to get (multilayer) PCB's (as a rough estimate, calculate ~$1.5 per square inch). A four layer pcb takes aproximately 5 hours until it's ready. The speed is influenced by the fact wether you have a CNC drill or not ( I don't). Having one will speed up things by ~1 hour. This is of course a rough estimation for PCB's that are reasonably sized (i.e. 4x6.5").

Btw, building a simple CNC drill is my next project that I will start as soon as time permits. I mostly want one to reduce the risk of creating an unuseable PCB by a drill error after 3 hours of work and - of course - it's also not so funny to hand drill > 200 holes.

Markus

Reply to
Markus Zingg

I am impressed sir. And after reading you more detailed account of multi-layer circuit board production, I think you may be a lot closer to building ICs than at first appeared. You still need to deal with the caustic/ultrapure/high-temperature chemical problem, but you probably have the other problems licked (I'm not sure how similar the photoresist you are using is to what is required for IC manufacture, but you are certainly on the right track).

The alignment and optics should be too big a problem: you should be able to use standard photographic equipment for the optics, and the alignment is just a matter of patience (especially if you are willing to ruin a high proportion of your wafers).

The checmical problems (obtaining silicon wafers and the oven in which to bake them to produce doped and insulating layers) are just a slight matter of money. I'd bet you could find some nice, bench-top, top stuff in any scientific supply catalog. I'm pretty sure the oven needs to be able to sustain a vaccuum, so no simple consumer device will substitute.

Another problem would be disposal of the byproducts: these things are TOXIC and probably tightly regulated by your local government. It's bad enough if you just want to do photography or auto repair.

-- Jeff Dutky

Reply to
Jeffrey Dutky

Hi Jeffrey

And I'm more than surprized to hear this. I never would have spend one single thought in producing home brew IC's and I'm sure I'm not going to try this in the forseable future. I'm really happy for the moment to have found a way to produce multilayer PCB's "at will" cause this is a huge time and money saver. Also I'd like to point out that I do this exclusively to produce prototypes.

Thanks for your information anyways and who knows, maybe you have just placed a virus in my brain :)

Markus

Reply to
Markus Zingg

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