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Foundries and MEMS: Manufacturability is Not Enough

August 1, 2005 By: Jim Knutti Sensors



 

After a lingering fallout period the MEMS-based sensor industry is now back on a reasonable growth track, with significant advances and manufacturability improvement in MEMS-based products outside the proven sectors. Sensing and actuation for industrial and biomedical applications in particular hold major promise. But whether these efforts come to fruition depends on several key factors, one of the most important of which is foundry business model and cost.

 

Foundries: What Went Wrong?

 

Looking back at the past few years of foundry experience, were the shutdowns the result of economic changes and cash shortages throughout the supply chain? While admittedly money was tight and coming from the top down, fabless developers were optimistic. Many of them did indeed secure interest and commitments from potential customers. So what went wrong? While in some cases the designs (especially in the telecom sector) were far too complex to be reliable given manufacturing capability of the time, the failed foundries had a few traits in common.

They tried to appeal to a broad base of developers. As MEMS engineers are aware, MEMS devices can depend on a wide range of processes, with an enormous number of variables. The devices that were already on the market had been commercialized only after years of process refinement and test. R&D teams typically need extensive amounts of time to reach conclusions about the physics of the processes and materials, and the causes of failure. Tests demonstrate that even one device manufactured using a single material such as polysilicon may require marked variations in process, depending on the source of the polysilicon and the deposition method.

The failed commercial foundries tried to address multiple product opportunities across multiple markets and multiple processes, with the result that their R&D time and even prototype manufacturing variables increased exponentially. For smaller foundries, this was the kiss of death.

They lacked experience with high volumes and cost-cutting methods. The operators of these independent foundries, many of whom began in academic R&D, had little experience with high-volume production and cost-cutting expertise necessary for typical infrastructure and optimizations required for mass manufacture. The prevailing attitudes were based on "find a process and they will come," with little regard for how components would fit into existing designs and what the customer was willing to pay.

In the case of RF MEMS, some large-volume consumer equipment manufacturers were seeking MEMS-based components at a price range of $0.10 in volumes of 10 million or more. This figure was to include packaging and test! Clearly, the requirements were beyond the range of smaller fabs, dooming the broad-based business model.

 

A New Foundry Business Model

 

In assessing the independent foundries that survived, we can begin to see the formation of a foundry business model that may predominate—at least until the industry can lay a stronger foundation with standard material definitions and some form of semi-standard processes. In particular, while the remaining designers and manufacturers have learned their lesson and have made strides in design for manufacturability and reliability, these qualities alone are no longer enough to persuade volume OEMs to make what is perceived as a frightening jump into replacement technology, even for simple discrete components.

These integrators do, of course, perceive the benefit of the technology and are intent on offering their customers significant value. The question is not if, since MEMS is an increasingly proven technology, but when. Yet, since 2000 these mainstream equipment suppliers—many of whom are virtually giving away technology such as standard cell phones—have become accustomed to squeezing their component suppliers to a bare minimum to realize better margins.

Given such stringent requirements, independent foundries have a crucial role in making innovative MEMS products technically and financially attractive to the mainstream market. This role, while not easy, is a natural fit for foundries, since batch-produced MEMS can facilitate size reduction and cost savings at the same time. Achieving size and unit cost goals in a timely and cost-effective manner, however, is a solution that not all foundries can offer.

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