Open Fabs

[jim bell]

----- Original Message -----
 From: Zenaan Harkness <zen at freedbms.net>

On 7/29/15, wirelesswarrior at safe-mail.net <wirelesswarrior at safe-mail.net> wrote:


>> For CPunks what's needed is a DIY Electron Beam Litho apparatus. Its
>> basically an electron microscope in reverse. For relatively simple chips it
>> could be more than adequate as its possible eliminates the need and
>> complexity, chemistry, etc. for masks and can perform most all process
>> functions (doping, implantation, etc.) and attain feature sizes commensurate
>> with current foundary tech. AFAIK, its possible to build from used
>> e-microscopes though maintaining calibration and linarity is something best
>> learned in a working environment at someone else's expense. :) One of the
>> main shortcomings of EBL is its low production  rate since all features must
>> be developed by "writing" them, like an old stylevector display, on the
>> substrate.

>Whereas with "photon lithography" (terminology?) a light source covers
>an area (of the mask?) which is then lens-focused down to the
>appropriate scale (eg 24nm) onto the silicon and etc physical layer?
>Firstly is this minimal understanding correct?
That's the way things were about 25 or so years ago.  Wafers with photoresist were exposed with machines using UV, which over the years used ever-decreasing  wavelengths of UV, in equipment:436. 365nm, and 248nm, eventually reaching 193 nanometer UV.  In the 1970's, entire wafer-masks (which covered the entire wafer) were used.  This became impractical as feature-sizes were reduced.  Step-and-repeat devices ("wafer-steppers) https://en.wikipedia.org/wiki/Stepper   then allowed exposure of a much smaller portion of a wafer.  (these eventually used mirrors, rather than lenses, because it is hard to process UV in a solid lens.)   
However, because the wavelength of light eventually became a large portion of the size of a chip feature (a line or a space) it was increasingly difficult to 'draw' the picture necessary to expose the resist on the wafer.  Due to many ever-more-heroic technologies, it eventually became possible to use 293 nanometer wavelength to expose features far smaller than the wavelength itself, which would have been considered phenomenal in the 1970's.  These days, EUV ("extreme ultraviolet") has been used for ever more small features.   https://en.wikipedia.org/wiki/Extreme_ultraviolethttps://en.wikipedia.org/wiki/Extreme_ultraviolet_lithography   EUV is strongly absorbed by air, so such exposure is typically done in a vacuum.

>Secondly is there any potential areal electron emission device (as
>opposed to point electron emission device) comparable to current litho
>tech (areal photon emission)?
None that I'm aware of.  But EUV will take over from electron-beam:  The latter is quite slow, and typically has been used mostly for making masks.

  
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