On-Wafer Testing Verifies IC Performance and Process Yield

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  • Author: Gary Breed
More than ever,RF, microwave, optical and high-speed digital prod-ucts are being developed with custom, semi-cus-tom or application-specif-ic integrated circuits as the primary active device. To verify that these devices work as designed, the first testing is performed by probing the new devices directly on the wafer, before dicing and packaging. On-wafer testing of devices operating at GHz frequencies presents a unique set of chal-lenges, compared to basic DC or low frequency functional testing. The two primary issues are the performance of probe itself, and calibra-tion of the test system. Of course, issues that affect all wafer probing systems are also of concern. These include reliable contact of the probe tip to the wafer test points, accurate positioning of the probes, plus capturing and storing measurement data.