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A new approach to testing ICs with MEMS

By Raymond W. Grimm [Nidec SV TCL]
T he expansion of 5G/Internet Flexible and customizable MEMS

of Things (IoT) and the
i n c r e a s i ng n u m b e r o f probe technology
One of semiconductor’s leading
semiconductors in automobiles, homes technologies, microelectromechanical
and other emerging technologies has systems (MEMS), can be found in
made it more important than ever that nearly all new technology products from
the equipment entrusted to test these navigation, microphones, and medical
integrated circuits (ICs) works effectively devices to everything else in between. For
and efficiently right out of the box. And IC test, MEMS-based probe cards have
if all of that was not enough, every new become the breakout stars and are the
chip design now includes some type of fastest growing product segment. Because
high-speed and high-power requirement of the significant increase in the complexity
for test. The speed and efficiency of test of test, the number of probes required on a
is becoming more and more critical as probe card has gone from 4,000-5,000 just Figure 1: Image of a MEMS probe array.
modern tech devices that are in constant a few years ago, to upwards of 60,000 now
communication with one another must be (Figure 1). In comparison to traditional
more accurate and in sync. vertical probe technology and buckling
As IC technology continues its beam-style probes, MEMS probes provide
evolution, the semiconductor industry several added benefits aside from the
has been driven by increasingly smaller miniature size, process control capability,
nodes, from 20nm just a few years ago, and fine pitch.
to 7, 5, and 3nm technologies today. The Although MEMS probe cards have
proliferation of 2.5/3D and advanced been steadily growing in popularity, until
packaging technologies have also now, standard MEMS probes have lacked
fueled chip complexity significantly. the flexibility and customization options
Increasing IC density has given rise to required to meet the testing requirements
ultra-complex probe cards with higher of chips that are continuously shifting
parallelism, increased pin counts, and towards higher functionality in a smaller
more integrated test, which require size. Over the past few years, we have Figure 2: SEM image of the MEMSFlex™ probe.
multiple power domains along with put focus on, and a significant investment With the new probe design, the
matched electrical characteristics from in, a more innovative MEMS probe, a “always on” contact with the space
site to site. These developments have solution that can repeatedly adapt to transformer allows for consistent
made IC test extremely challenging both effectively probe the current ICs on the electrical contact. The probe design
mechanically and electrically, ramping market and the next generation of devices. also supports higher current carrying
up the necessity for advanced probe Patent-pending MEMSFlex™ probes capabilities and a more consistent
card design and manufacturing. Test have an advanced 3D design featuring force over the life of the probe card,
hardware solutions must now also be a fine MEMS spring from an electro- af ter hu nd red s of t hou sa nd s, or
easily replicated, repeatable, and easily formed Ni-pipe and are fully customizable even millions of touchdowns. With
repaired. To meet the tough testing for force, length, overdrive, tip style and the probe head structure, we have
challenges of today’s and tomorrow’s rotation control. These MEMS-based probe enhanced the alignment, which helps
complex devices, probe card technology cards can be optimized to the customer’s our customers realize touchdowns
must also advance to meet the dynamic specific testing requirements and are ideal that are precise and consistent with no
test demands of chips packed with for targeted applications such as wafer- lateral deflection, producing a smaller
technology. Suppliers of probe cards must level chip-scale packaging (WLCSP), flip scrub over traditional vertical probes.
continuously research and develop ways chip, Cu pillar, solder bump, pad, and now, Because of that, planarity and yield are
to produce innovative probe cards that radio frequency (RF). The flexibility of the also improved.
can effectively validate an IC’s reliability new probe design (Figure 2) also makes Utilizing a continuous, automated
before that IC is installed into an end- it possible to probe bumps and pads on MEMS manufact uring process, a
product, whether it is an automotive the same IC with one probe head, probe wide array of custom pin pitches and
safety feature, or a critical component of in trenches, or other unique structures specifications can be supported within a
the latest smartphone. developed by our end users. short cycle. Unlike other MEMS probe

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