By Paula Doe, Contributing Editor
A crowd of Japanese suppliers are gambling that rising demand for MEMS devices for high volume products is about to spur a real volume market for production tools and services. There are now 20 Japanese companies offering microelectromechanical foundry services and 12 supplying MEMS etching equipment, according to a recent report from PennWell partner Nikkei Microdevices. Even Tokyo Electron is offering MEMS design, simulation, and prototyping services.
With 5-6 million cell phones/year potentially using accelerometers, and 60 million cars using airbag, tire pressure and assorted other sensors, Dainippon Printing and Ulvac report some MEMS devices are moving to high enough volume demand to support a shift from 100mm and 150mm substrates to 200mm wafers, potentially cutting costs to further increase demand. Both companies also are counting on these increasing volumes in ambitiously raising their sales targets to the US$40-$60 million range for their MEMS businesses this year.
Dainippon Printing has moved beyond prototyping services at its MEMS foundry, adding 200mm capacity to offer volume production capability, and announced a sales target of some 6 billion yen ($58 million) for the business in fiscal 2005. The company has started offering design services as well, noting an increase in interest in MEMS products from users not knowledgeable about the production process. First touted product design is a 0.9 sq. mm piezoresistive accelerometer that cuts costs significantly by cutting the required silicon real estate down to 10%-20%. Ulvac also has added 200mm MEMS foundry capacity, as has Kyodo International.
So far systems makers have been making most of the world’s MEMS devices to add value to their own products, not chipmakers selling the devices alone (see chart). In Japan, as elsewhere, some of these companies are selling unused capacity on their production lines in the foundry market (Omron, Olympus, Matsushita Denko).
Japan’s major chipmakers are notably absent from Yole Developpement’s listing of the top 30 MEMS suppliers, but some do have MEMS foundry programs (Hitachi, Renesas) or have converted aging semiconductor lines to MEMS production (Oki Electric). Also jumping on the bandwagon are trading companies (Marubeni Solutions) and startups (MEMS Core). The rest of the list of Japanese MEMS foundries includes, besides TEL, Ulvac, and DNP, the diverse companies Adamant Kogyo, C. Itoh Mechatronics, Nippon MEMS, Nippon Precision Circuit, and Hitachi Metals.
Among the crowd of equipment makers chasing the market for deep-trench silicon etchers for the MEMS market, Ulvac is pushing a new technology that it says eliminates the sidewall notching of the standard Bosch approach. Its sales target is an ambitious 50 units this first year, at some 75 million yen ($720,000) each, for a $36 million business.
Deep-trench silicon etchers from Surface Technology Systems that dominate 80% of the market, and most others in common use, use inductively coupled plasma etching based on technology originally developed by Robert Bosch GmbH. That approach alternates the SF6 etch step with passivation with C4F8, and can etch deep aspect ratio features at up to 30 microns/min. But the alternating cycles do create a pattern of notches in the sidewalls.
Ulvac instead relies on a magnetic neutral loop discharge approach also used for quartz etching. The method wraps a coil around a tubular vacuum chamber and applies a high-frequency magnetic field to create a doughnut-shaped plasma. It uses a physical process akin to sputtering for the passivation film, instead of depositing it by chemical reaction, so both etching and passivation can be done at the same time in a continuous process. Since the steps don’t alternate, no notching occurs; nor is there any problem with the deposition gas remaining at the bottom of the holes or building up deposits in the chamber. The company says the etching rate is about the same 20 microns/min, with 5 times better resist sensitivity, so the trenches can be made deeper.
Anelva also has a new tool that does not use the Bosch technology or require the passivation step. It relies instead on capacitively coupled plasma. The approach ramps frequency up from the usual 13.6MHz to 60MHz when applying the magnetic field, increasing plasma energy to speed up etching to 10-20 microns/min, without sidewall problems.
Sumitomo Precision sells a version of Surface Technology Systems’ Bosch-type etcher in Japan, Canon distributes Alcatel Micromachines’ tool, and Samco International has a Bosch version of its own. Shinko Seiki and Panasonic Factory Solutions sell their own inductively coupled plasma tools not based on the Bosch technology, as does Unaxis.
Finally, hoping to challenge Coventor in the market for MEMS design tools is the MEMS-ONE project of the Micro Machine Center consortium, based on Mizuho Information and Research Institute technology, from the former Fuji Research Institute. Developers claim the consortium-funded tool will be cheaper and more reliable than its commercial competitor. Coventor says the market for MEMS design tools will likely grow faster than the MEMS device market, potentially doubling to $140 million by 2006.