All,
One of the difficult engineering problems for maskless lithography is throughput. So maybe the first task for a guy looking further into this is compute what the expected throughput will be of the maskless lithography system one wants to develop.
The first thing to do is determine how many pixels you want to use for printing a minimum width feature. If you stick to use one pixel for a minimum feature width and the layer is for example polysilicon you will be limited in the variation you can make of width, length and pitch of the poly lines.
If this is done one knows how much area will be covered by the resolution of the selected projection system and thus how many images are needed to cover a full waver.
Finally step is to determine how many images per second one can print, including alignment after each position change and this will determine the time it will take to print a full waver.
An alternative is to use such a litho system to make your own masks and use these then for printing wafers.
greets,
Staf.
Paul Gerhardt schreef op di 14-01-2020 om 22:59 [+0800]:
DLP/DMD is promising. I'd also say check out the short throw laser projectors - in particular the new Xiaomi 4k model has native 0.5um pitch, 5000 lumens and only costs ¥10999rmb/€1433 for CNY specials - it uses ALPD 3.0 though as I understand it Appotronics came out with an even newer 4.0 spec in 2018:
http://www.appotronicsusa.com/alpd_technology.html-pmg
Hello.
On 1/14/20 11:08 AM, David Lanzendörfer wrote:
>> I guess that is both a very ambitious but at the same time very tempting
>> project. Looking forward to seeing self-made litho steppers pop up in
>> hackspaces ;D
> Exactly. Yes.
:-)
> We can use a DMD[1] which already can go down to 500nm, as I've seen
> recently[2], assuming, we get the lens system right.
A issue I see here is the pattern structure of DMDs. Between all the
small mirrors are always even smaller gaps.
If we like to draw a bar, eg. poly or whatever
(ASCII-Art)
------------------------- -----
^
|
v
------------------------- -----
the mirrors are with a gap instead
+-------+ +-------+ -----
| mirror| |mirror | ^
| | gap | | |
| | | | v
+-------+ +-------+ -----
|<----->|
???
This means that it becomes difficult to "stitch" two mirrors gap-less.
For human eyes it does not matter, the eyes does not see the pixel /
pattern structure. But I guess, the photo resist will see 'em - so we
have to tricked them out somehow.
Can we use here diffraction?
Or we already need double-pattering here?
Regards,
Hagen.
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