Re: reflection microscopy of integrated circuit

Posted by Shalin Mehta on
URL: http://confocal-microscopy-list.275.s1.nabble.com/reflection-microscopy-of-integrated-circuit-tp2492030p2507889.html

Hi Doug,
  I have never worked with such samples, but read some papers. I shall send them to you off list.
At visible wavelengths the silicon acts as a nearly perfect reflector.
Therefore, one would expect that when you acquire a z-stack you get pixel-data which is convolution of the PSF and the true surface profile. Out of curiosity, can you see anything beneath the surface?

You may suspect that the light-path (e.g. pinhole location) is not perfectly aligned and hence giving artifacts.
If the z-stack doesn't seem to show true surface profile and appears artifactual, you might want to put a mirror on the stage and take a z-stack. If light-path is aligned properly it should give you strong single peak when the objective is focused exactly at the surface of the chip.

Best
Shalin

On Wed, Mar 18, 2009 at 10:37 PM, <[hidden email]> wrote:

I’ve only had one response and I could really use some help.

Thanks.

Doug

 

From: Confocal Microscopy List [mailto:[hidden email]] On Behalf Of [hidden email]
Sent: Friday, March 13, 2009 3:32 PM
To: [hidden email]
Subject: reflection microscopy of integrated circuit

 

Always something new when you run a core facility…

 

There’s a lab on my campus that works with CCD chips to make cameras for big telescopes.  Since they do their own backthinning, they want to inspect the chips.  They approached me about doing reflection mode confocal.  The person I’m working with has a degree in optics, which has made the training easy.  My problem is that I’m a biologist, not a materials science person, and other than some quick instructions on how to set up the Zeiss LSM 510 for reflection mode, I really feel at a loss.

 

We did some imaging today and I’m not sure how to interpret what we’re seeing.  What should be slight “bumps” look more like “pits”.  Also, I’m seeing what looks like (for lack of a correct technical term) linear diffraction from the chip surface.  In fact, when you looked at some of our “pits” from the side, they looked a lot like the top half of a PSF.

 

Is there anyone out there with some experience with this type of sample that could give me a few pointers?  If there’s a review article you can refer me to, that would be great too.

 

Thanks.  Enjoy Pi Day tomorrow (3.14)!

 

Doug

 

 

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