By D.Sc.(Tech.) Heikki Holmberg, senior development manager technology, Okmetic Oy 

The MEMS industry has huge growth potential. Will MEMS fabrication act as a bottleneck to continued expansion or a critical conduit to achieving that potential? Slow development cycles, multiple fabrication platforms and high cost for small R&D volumes are barriers to rapid development of new products. Understanding the special features of MEMS fabrication — with its many ecosystem options — will help your company to navigate successfully these challenges as you more quickly develop new and unique products.

The sheer diversity and varying requirements of MEMS devices and the one product, one process approach are the root causes of most MEMS fabrication challenges. While a single approach will not suit all companies, forming an ecosystem that leverages different companies’ expertise is one of the best ways to address these challenges. However, knitting together this ecosystem is difficult because having multiple partners in the mix only works if the entire supply chain follows common basic design rules and a common top-level technology development roadmap. Because establishing these commonalities takes time and effort, many large- and medium-sized companies prefer to own their supply chain, regardless of the costs. In contrast, emerging companies that cannot support heavy capital investments in new equipment will inevitably find foundries that have all the equipment in place — as well as a wide variety of MEMS processes — a more attractive option. As you embark on a MEMS fabrication journey, which options should you consider to stay ahead of the pack?

Finding ecosystem partners

Since there are so many different technology choices that make process integration difficult in MEMS fabrication, technology know-how is the key to developing unique products in time. If you are not able to own your supply chain, you must find ecosystem partners whose expertise both matches and complements your technology (Table 1).

Supply Chain Option	Option 1	Option 2	Option 3	Option 4	Option 5
Company Expertise	Fully owned component supply chain.	Outsourced assembly and ASIC design only.	Outsourced MEMS-fabrication by pure-play MEMS foundry.	Outsourced MEMS-fabrication and MEMS design by MEMS foundry.	Purchased ready-made MEMS chips.
MEMS chip fabrication	2	1	3	2	3
MEMS chip design + testing	2	1	1	2	3
ASIC design	2	3	2	1	2
Assembly	2	3	2	2	1
System-level know-how of the component	2	2	2	2	1

Table 1: Ecosystem choices as a function of company expertise. 1=Excellent fit 2=Good fit 3= Ok fit.

You must also understand how your company can add value — either directly to the end-product or to the other partners in the ecosystem. Above all, there must be trust among partners. A lack of mutual trust will lead to inadequate information-sharing and cumulative knowledge-gathering — slowing problem-solving and/or causing excessively long development cycles.

Option 1: Own your supply chain

While few companies can support Option 1 — having the whole supply chain in-house (like Bosch or STMicroelectronics) — the benefits are many: all know-how will be contained within the company, IP is easy to protect, and supply-chain management is simpler. However, this model demands a significant investment in tools and, in the long run, substantial effort and money to remain technologically competitive in each part of the supply chain.

Option 2: Outsource the ASIC

You might opt for a fully owned supply chain — outsourcing only ASIC fabrication and possibly ASIC design and assembly. This option requires significant expertise in MEMS technology, freeing you from the limitations of a fabless operation model as you gain more control of MEMS fabrication processes. It also offers more IP protection than you would have with a foundry.

While the disadvantages of Option 2 are similar to the fully owned supply chain model, you can mitigate them by outsourcing part of the MEMS chip fabrication supply chain or outsourcing some development to wafer supply companies that can handle the customer-designed embedded structures inside the wafer and/or multi-stack wafer packages. Outsourcing will shorten the process flow and reduce the amount of capital required for growth. A third outsourcing option is to farm out especially difficult or incompatible steps, delivering multiple benefits such as access to better materials, including specialized polymers – which are typically more expensive than silicon – and precious metals, such as gold or platinum, which can contaminate equipment during thin-film deposition processes.

Options 3-4: Foundry models

While more companies still own the whole supply chain or outsource the ASIC portion of their device than use MEMS foundries, the MEMS foundry solution is still an especially good option for cost-conscious companies. If you cannot afford the substantial investment needed for new tools and/or advanced materials or your product requires rapid scaling-up because of short lifecycles, you should explore foundry solutions. There are two main types: pure-play foundries (Option 3) and a foundry with design services and its own IP (Option 4). Option 3 offers no design services, nor does it provide its own designs. It is an excellent choice for a MEMS design-based company lacking its own MEMS fabrication line. However, if your company lacks in-depth knowledge of MEMS design, Option 4 will give you design support and possibly some IP as well.

Option 5: Buy the MEMS

Option 5 is to buy ready-made MEMS chips and use them as the foundation to build your component. This is solid choice if your company is high in the value chain or has system-level expertise.

In the future, MEMS ecosystem players will win by offering both design-library development and a supporting portfolio of MEMS process design kits — just as the IC industry now does. This winning approach will significantly shorten the MEMS product-design cycle – from idea to process development and finished product – and will ultimately change the rules of the game for the MEMS fabrication industry.

About the author

Based in Vantaa, Finland, D.Sc.(Tech.) Heikki Holmberg develops new business opportunities for Okmetic’s high-performance silicon wafers. He also manages Okmetic’s research portfolio, including European Union- and nationally funded research projects.

For more information, visit: https://www.okmetic.com/