a small-pixel CCD project

[John Geary]

Posted to CCD-world:
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At 03:11 PM 1/8/98 -0300, you wrote:

>Our interest in joining a collaboration on the 1Kx4Ks could be enormous
>or low depending on the details.  We are desperate to get good
>spectroscopic CCDs.  I am waiting to see how various current CCD
>devlopment projects pan out at EEV, SITe, and LBL (hi-rho).  I have
>been nursing the idea of trying to organize a consortium to make the
>ultimate spectroscopic CCD, if these don't come close enough to our
>performance requirements.  
>
>Excellent blue response and noise is a must, with good dark current and
>CTE too, of course.
>
>3K by 1K ~15um pixel CCD would be ideal.   A pair of 1Kx4K 8 um
>buttable CCDs would cover slightly more than 2/3 of the spectral range
>and all of the spatial.  We have another camera where a
>single CCD binned to 2K by 500 is perfect.  Presumably 8um pixels
>binned by two will eliminate the resolution loss in the blue that we
>suffer with our current 15 um Lorals.  The lower full well of the 8 um
>pixels wont matter much since we are talking spectroscopy.  We would
>prefer to put the serial register on the long dimension but I guess
>this is not in the plans.
>
>What is the expectation for noise?  I don't have a chance of raising
>money unless we can safely acheive 3 e- or better.  We really want
>something like 1.5e- for which we would prefer a high output node
>sensitivity but we could live with a skipper with a read noise of 3 e-
>before skipping.

As always, there is a lot to digest in your messages.  Let me attack to core
first.  We don't know what the unltimate noise will be, but the supplier is
Sarnoff, which does not have any very-low-noise experience at all.  I would
say it is super unlikely that these devices would get below the 6-10e range
of ordinary (old-style) CCD amps.  Not good spectroscopic candidates, but OK
for the direct photography envisioned for this project.

>How about more details on QE?  Are we talking about a Lesser-thinned
>and UV flooded chip?

Sarnoff's process is very much different - boron implant with thermal
anneal.  Good, but not the 95+% sort of QE that ML can produce (but oh so
slowly, and expensively).

>When you say "Schmidt camera" do you mean spectrograph camera or wide
>field imager.....It would be nice to know if "the project you know of"
>shares similar objectives to us.  Are we allowed to know of them too?

Wide field.  The group is at Yale (Baltay et al.)

>Does the cost include thinning & packaging?   How much if any
>screening/testing?

Two wafer runs, thinned, tested, and packaged.  Total is $400k and Yale has
$300k in pocket.

>Yeild of 20-25 devices:  is this thinned and packaged?!  That would be
>an incredible bargain for 100K.  We've never had a foundry run that has
>been that successful, so I will meet considerable scepticism unless
>they can provide a plausible justification for this yeild.

These devices are not that big, so yield should be quite good.  Sarnoff has
been thinning devices for 20 years and they really know how to do it their way.

--JG

P.S.  Any recent news on Ricardo's boy?


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