Cascade Microtech : Parametric Process Monitoring

It should come as no surprise to anyone in the semiconductor industry that the maniacal march down the geometry roadmap that drives us is also touching the parametric market. Pad sizes in the scribe line have been getting smaller for years as dicing technology has allowed for ever more narrow scribes. Pad sizes have recently got even smaller when several tester companies came out with 100-channel capability. Many of the top 10 Semiconductor companies customers wanted that extra data and moved from 20 and 40 pads in a single line to two lines of 50, pushing pad sizes down to 30 µm. We are now starting to get requests down to 20 µm, which is on our roadmap for 2017. To make matters worse, most companies want to have a buffer zone and don't want to see probe marks within 2-4 µm of the pad edge. At that size, we have to start thinking about the overall accuracy budget required to hit something that small. The elements of that budget include not only the tip face size, which of course gets bigger as the probe tip wears out, it also includes the positional accuracy of its placement on the membrane, the accuracy of the probe station, the accuracy of the pad location, and the length of the scrub. And don't even get me started if you want to do this over any significant temperature range!

I have great faith in the human imagination and creativity to find ways to solve this ever more difficult challenge but one has to wonder how expensive it will become when customers need to buy new, more accurate probe stations and probes with very, very small tips. No doubt the need for parametric process monitoring is going to continue and likely become more important as those processes get more complex. So I guess we'd better get those creative juices flowing. 20 µm, and probably even smaller, pads are coming and the prize will go to the companies that figure out the most effective way to touch them. I'm confident that Cascade Microtech is up for the challenge.

Please share your thoughts on what the future holds?

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