MEMS technology has become widely popular in sensors for measuring motion, acceleration, and inclination. MEMS sensors offer multiple-axis response with high resolution and low power consumption in a single package. Thanks to the extreme precision and large-scale manufacturing process at the Company’s state-of-the-art 8-inch manufacturing line, ST’s MEMS components can be fabricated with very close tolerances at very competitive costs.

In the consumer market, MEMS accelerometers enable the cost-effective creation and success of various motion-activated devices. The sensors can add an intuitive man machine interface to a mobile phone, MP3/MP4, PDA, or game controller, linking the user’s wrist, arm, and hand movements to interact with applications, navigate within and between pages, move characters in a PC game and many more. Another typical MEMS application is the data integrity protection in portable devices. In case of a free fall or other abnormal movement, a , MEMS sensor promptly instructs the system to stop all reading and writing operations, and move the magnetic head on the hard disk drive to a safety position.

MEMS can be also used in ‘dead-reckoning’ systems to back up a GPS signal inside buildings and in urban areas, by monitoring motion and distance traveled and correcting digital-compass readings in the absence of the GPS signal. ST accelerometers are also integrated as vibration detectors in today‘s electronic home appliances, such as washing machines or dryers, to alert users to unbalanced loads and to protect against excessive wear of parts, before a failure occurs.

ST experts believe that further integration of different sensor functions in one package will lead to an overall system performance improvement, utilizing ST’s experience in design and packaging to support the customers’ needs.

Silicon micromachining has been successfully applied in developing various thermofluidic MEMS devices. ST has been a long-time supplier of thermally operated inkjet print heads to a major inkjet printer manufacturer. The print head contains a chip with hundreds of microscopic channels connected to corresponding miniature ink-filled chambers. The heating elements and the control circuitry, formed in the same chip, vaporize and propel the tiny ink bubbles onto the paper.

Similarly, silicon’s electrical and thermal properties are utilized in ST´s groundbreaking Lab-on-Chip, which is able to replace expensive and time-consuming laboratory analysis with cost-effective, disposable tools. ST’s In-Check™ product platform is the first biochip for amplifying and microarray-detecting of DNA samples by precisely controlled heating. Since silicon has very good thermal properties and allows electronic temperature controls on the same chip, the Lab-on-Chip heats and cools DNA sample so precisely that the analysis is more accurate and specific. MEMS miniature geometries also save costs by consuming less power and using smaller quantities of costly reagents, compared with conventional diagnostic systems.

STMicroelectronics has identified and addressed several issues that are critical for mass deployment of MEMS in a broad range of applications. In order to accelerate time-to-market and achieve economies of scale, standardizing the core technology is critically important. At the forefront of the necessary standardization efforts, the Company has developed THELMA (Thick Epitaxial Layer for Microactuators and Accelerometers), a 0.8-micron, surface micro-machining process, combining variably thick and thin polysilicon layers for structures and interconnections, respectively. Aside from THELMA, ST´s goal is to establish two additional micro-machining standards, offering enough flexibility to satisfy diverse market needs.

One of ST’s micro-machining processes allows integrating a cavity into monocrystalline silicon and thus producing an ultra-compact pressure sensor. This technology provides advantages in term of size and performance, resulting in a thinner and smaller device with higher robustness thermal stability and reliability.

MEMS are leaving the labs and revolutionize the industry by exploiting both the unique electrical and outstanding mechanical properties of silicon. STMicroelectronics is well-positioned to play a major role in this process, with its impressive range of MEMS process, product and application IP (Intellectual Portfolio) and sound business cases, together with successful standardization efforts, aimed at achieving the economies of scale and winning customer confidence, critical in stimulating market demand for applications of this sophisticated technology.

November 2006