by Paula Doe, Contributing Editor
Packaging and test equipment for MEMS could be as much as a $2 billion potential opportunity, as the devices move into high-volume consumer applications.
Booming demand for MEMS systems in consumer applications means the MEMS market is seeing unit growth of more than 25% a year, reports Yole Developpement. But those high volume consumer markets come with consumer product price pressures as well, notes managing director Jean-Christophe Eloy. “That means overall MEMS prices will likely fall 6%-7% each year,” says Eloy.
Most opportunity for cost reduction looks to be from packaging and test, which Eloy reports still accounts for 40%-50% of the cost of a typical MEMS device, and is particularly problematic for consumer devices. Cost pressures are driving a move from ceramic to plastic packaging, to wider use of wafer-level packaging, and away from wafer stacking to reduce the number of wafers used. The market remains extremely fragmented, with most device makers still making their own custom test equipment. But it’s a potentially significant business. With at least 30% of the revenue of the projected $7.6 billion MEMS market this year going to packaging and testing expenses, that means a potential $2 billion opportunity.
One option to significantly cut packaging costs is wafer level test, so only the known good die are packaged. But physical testing of MEMS devices’ proper response to sound, pressure, vibration and the like before packaging has typically been problematic. The MEMUNITY international network of test engineers and scientists is working on developing and sharing solutions to this problem, based on using a wafer prober to do the loading, aligning, contacting and mapping, and adding modules to apply temperature or motion or sound or pressure. “When we began to offer MEMS test, customers kept asking about applying non-electrical stimuli and measuring non-electrical results,” says Frank-Michael Werner, business manager, SUSS MicroTec Test Systems GmbH (Dresden,, Germany). “We found there was nothing available on the market.” So SUSS and the test house DELTA (Hørsholm, Denmark) got EU funding to develop a prober-based modular MEMS test system. Afterwards, they set up a user group as a way to make the results available to the MEMS community. Now the organization, open to all, holds regular seminars in Europe to exchange information and continue development.
“More and more things are coming together,” says Werner, noting the group now has field-installed test set-ups for pressure sensors, silicon microphones, inertial sensors, micro mirrors and micro bolometers. Recent developments from the MEMUNITY community include a membrane-test system that applies an electrostatic stimulus to the device under test and measures the resulting motion with a laser-Doppler vibrometer, and cryogenic and vacuum test systems, such as the high-vacuum wafer-level test system at IMEC used for reliability testing of RF-MEMS devices.
Another option for cutting test costs is higher throughput, where SPEA (Volpiano, Italy) says it can get significant improvement by integrating its high speed pick and place system with electrical test and with physical test –with a multi-axis rate table for accelerometers, or an acoustic chamber for microphones for an integrated MEMS test cell.. “We’ve put the rate table in our pick and place machine,” says Dave Webb. “So it can move in ways that resemble real life.” He says this increases throughput by true parallel, multisite batch testing of devices.. Webb says the equipment is in use at big MEMS makers in Europe, where the Italian company is more well known for its MEMS and semiconductor test offerings. Though mostly known in the US for its board testers, SPEA is expanding its semiconductor and MEMS business here as well, through SPEA America offices outside Dallas, in Tyler, Texas.
Costs can also be reduced by reducing breakage and contamination of fragile MEMS structures that have to be open to the environment by dicing the wafers without saws or slurry, proposes Disco Corp. Instead the company focuses a laser beam inside the wafer. The laser doesn’t have enough energy to effect the wafer as it passes through, but at the small spot where it’s focused, it vaporizes the silicon, and the vapor expands to create a stress that breaks the wafer in a line along the cleavage plane. Then simply stretching the tape on the taped wafer gently separates the die.
The majority of silicon microphone makers are now testing or using the technology, says Scott Sullivan, chief technologist of Disco HI-TEC America. The current alternative, he notes, is conventionally dicing the taped wafer with a saw, and then manually pulling the dice apart. “As wafers get thinner and thinner, there are more and more challenges to using a traditional dicing saw, and this may be a solution,” says Sullivan.
MEMS events at SEMICON West
These and other key industry players will update show goers on significant recent developments in the MEMS market, the progress of new volume consumer applications, and the impact on equipment and materials suppliers Tuesday at the Emerging Markets TechXpot in Moscone West.