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Electronics => Beginners => Topic started by: haxtormoogle on March 11, 2014, 01:00:42 am

Title: Silicon wafer testing?
Post by: haxtormoogle on March 11, 2014, 01:00:42 am

I am trying to figure the best method for detecting what type of silicon wafers I have, along with what type of coating some of them have. Most are polished rejects with tiny scratches / defects in the surface.

(http://wtfmoogle.com/wp-content/uploads/2014/03/IMG_1324-300x225.jpg)
(http://wtfmoogle.com/wp-content/uploads/2014/03/IMG_1325-300x225.jpg)

Any suggestions / ideas?

http://wtfmoogle.com/?p=3612 (http://wtfmoogle.com/?p=3612)
Larger photos on my website of a few of the neat wafers.

Title: Re: Silicon wafer testing?
Post by: T3sl4co1l on March 11, 2014, 04:48:35 am

Probe the surface (standard meter probes, make sure they're pointy enough to make contact, in case the surface is passivated or whatever).  Check resistance (first to see if you are making contact, but also to get some idea of the doping -- by my understanding, light P doping is pretty common, but YMMV).  Then measure voltage while holding a hot soldering iron (or other heat source) near one probe.  The voltage will go positive or negative on the order of 10s of mV.  Which sign the heated side exhibits determines the doping polarity.  I forget which... JFGI. ;)

Tim

Title: Re: Silicon wafer testing?
Post by: Refrigerator on March 11, 2014, 10:16:27 am

You could locate the pins and maybe make a little test jig with little connectors coming down on the wafer.