Shrinking trends in the semiconductor industry are forcing probing pads to be reduced accordingly. Consequently, Cascade Microtech has made significant technological advancements to its popular line of Infinity probes, offering finer pitches (down to 50 ¦Ìm), smaller contact area and higher frequency operation (up to 220 GHz).

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Besides density, silicon CMOS and silicon germanium (SiGe) technologies have enabled smaller and faster devices that require engineers to test and validate performance up to 220 GHz and beyond. The high-performance waveguide series of Infinity probes ensures accurate and repeatable measurements to 220 GHz with pitches ranging from 50 to 150 μm. Bias tee options are also available. These probes are frequently used for semiconductor process characterization and test of ultra-high frequency interconnects and devices such as amplifiers, mixers, oscillators, multipliers and switches used in automotive collision avoidance systems, satellite telecommunications, radio astronomy, spectroscopy, surveillance, and medical imaging.

The Infinity probe combines Cascade Microtech's proprietary thin-film technology with coaxial technology to offer high performance with respect to return loss, attenuation and crosstalk specifications. The microstrip transmission lines on the Infinity probe's thin-film tips confine fringing fields more tightly than conventional flexible coplanar tips, and the resulting improved field confinement reduces unwanted couplings to nearby devices or other probe tips, thus increasing RF measurement accuracy. A precision RF connection to aluminum pads on a wafer is much more difficult than connection to gold pads used in other technologies, said the manufacturer. According to Cascade Microtech, the Infinity probe's high performance on aluminum pads is achieved by optimizing the key probe factors that affect contact resistance: tip contact area, force applied, tip metallurgy and scrub. The force delivery of the Infinity probe is such that only a small horizontal motion (scrub) is necessary to break through the aluminum oxide to make contact with the pad. This, coupled with the probe's non-oxidizing tips, ensures minimal pad damage and superior contact on silicon devices with pads as small as 25 μm x 25μm.

The Infinity probe is available in 40 GHz, 50 GHz, 67 GHz, 110 GHz, 140 GHz, 170 GHz and 220 GHz versions, and comes in 50 ¦Ìm, 75 ¦Ìm, 100 ¦Ìm, 125 ¦Ìm, 150 ¦Ìm, 200 ¦Ìm or 250 ¦Ìm pitches. Pricing for the Infinity probe starts at $895.