Anyone remember Anamartic? They tried to develop DRAM arrays, but they also included on-wafer testing. They allocated some wafer tiny space to test logic that tested everything on the wafer in parallel, with a simple chained GO/NO-GO comms bus spiralling out to connections at the edge.
Time and cost saving were pretty good, probably patent issues stopped everyone using the technique. Guess it also would've meant chip designers listening to the needs of the test department, that would be a first, hey?
Easiest with digital, but some analog testing can be done, also, and since that takes much longer the benefits are greater from parallel testing.
Probably the killer was it makes step-and-repeat more difficult.
I don't see this technology going beyond RFID chips. It's a good idea to test the RFID chips they way they are used. Other devices require more power than can be provided wirelessly. They also require the bond pads and it would take up too much space to add the RF receiver to power the chip.
If pushed well ( e,g. by DARPA ) this could be the beginning of something big and may change things radically beyond just Test of simple RFID wafers. For potential check out work done at Sun before Oracle bought it.
It is had for me to see what product lines this technology would be excel on. Low power RFID chips are small, cheap and packaging dead chips can eat at already slim margins. Still, improving yield and eliminating test strikes me as the intuitive route to reducing cost on mature products. This technique would have to operate in a high GHzrange given the antenna size.
@PeterClarke: this topic has been researched for a while now and I hope the work above can be transferred to a production environment. That is where the proof lies ultimately.
Just curious, what is the time interval between the step & repeat cycles? I would imagine there has to be couple of orienting beams in the probing array to align at each die site. It would be interesting to know how long does it take for each cycles? Not to mention the overall cost of the EMWS probe card assembly.
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