FEI ion beam cuts imaging time for MEMs, 3D chips

High-end focused ion beam (FIB) tools have long served chip developers by cutting cross-sections that provide comprehensive views of advanced processes reaching nanoscale levels. Users however have observed that dissecting the micron- and millimeter-scale features of MEMS chips and 3D stack chips such as through-silicon vias (TSVs) with these FIB tools could take as long as 12hrs. FEI Co. believes it has found a solution, announcing it has refined the FIB for 3D and MEMS chips.

"MEMS devices and next-generation packaging features, such as TSVs for memory-on-logic devices, are too small for mechanical manipulations, but too big for focused ion beams," said Peter Carleson, product marketing manager at FEI. "Features measuring 100s of microns can takes hours, but by redesigning the Vion to handle higher currents, we can work at these larger scales."

FEI claims its newly redesigned Vion plasma focused ion beam (PFIB) tool can cut the time to image MEMS and 3D chip features by 20x, down from more than 10hrs to under 40mins for TSVs. The new tool can reveal in minutes semiconductor features that range in size from 30nm to 1mm, compared to existing FIBs that work at down to 5nm, according to the firm.

"The increased milling speed provided by FEI's Vion PFIB system lets us perform analysis in minutes, as opposed to several hours on a conventional FIB," said Peter Ramm, head of the department for device and 3D integration at Fraunhofer.

Used for failure analysis of micron-scale features of both packaging and MEMS devices, the new Vion FIB is the first FEI tool to incorporate plasma source technology. Plasma enables it to quickly perform cross-sectional analysis by using more than a microamp of beam current, compared to nano amps used for traditional FIBs with liquid metal ion sources.

Besides dissecting 3D stacked chips and MEMS devices, the Vion PFIB system can be used in failure analysis of bumps, wire bonds, and other package-level tests and modifications.

- R. Colin Johnson
??EE Times