STMicroelectronics Reaches New Milestone in MEMS Sensor Manufacturing Process
MEMS (Micro-Electro-Mechanical Systems) sensor manufacturing technology has reached a new milestone. STMicroelectronics (ST) announced the successful combination of the advantages of surface-micromachining and bulk-micromachining processes to develop THELMA60, a new generation proprietary MEMS process that is both cost-effective and highly precise. It is already being used in the production of accelerometers and gyroscopes, and is expected to significantly improve the price-performance ratio of MEMS components and open up new application markets.
Benedetto Vigna, Executive Vice President and General Manager of the Analog, MEMS, and Sensors Group at STMicroelectronics, stated that the company's latest THELMA60 surface-micromachining process will usher in a new era in the development of inertial sensors. In the past, many demanding applications requiring high-sensitivity sensing—such as implantable medical devices and high-end sensors used in aerospace systems and seismic exploration—could only be manufactured using bulk-micromachining technology. Now, the advent of the THELMA60 surface-micromachining process will reverse this situation, making the sensors used in these applications more cost-effective.
Vigna further pointed out that after revolutionizing the consumer inertial sensor market, STMicroelectronics will use this innovative technology to change the landscape of the high-end sensor application market. Currently, several designs have successfully adopted the THELMA60 surface-micromachining process and have begun mass production.
In the past, when semiconductor manufacturers mass-produced three-dimensional MEMS components such as accelerometers, gyroscopes, microphones, and pressure sensors, they primarily relied on two processes: surface micromachining and bulk micromachining. The former is considered to have higher cost-effectiveness, while the latter is mostly used to mass-produce sensors requiring higher sensitivity and precision.
Jean-Christophe Eloy, President and CEO of market research firm Yole Développement, analyzed that many semiconductor companies have attempted to adapt the bulk-micromachining process—which is suitable for producing high-precision, high-sensitivity sensors—to meet the demands for higher mass production efficiency in the growing IoT, consumer electronics, and mobile markets, but all have failed. STMicroelectronics' THELMA60 surface-micromachining process breaks through this bottleneck.
It is understood that the size of the mass of the movable structure in a MEMS component is closely related to sensing sensitivity. Generally speaking, the surface-micromachining process forms an epitaxial layer about 25 micrometers thick on a silicon wafer, which serves as the mass of the MEMS component's movable structure; meanwhile, the bulk-micromachining process builds microstructures directly on the silicon substrate, resulting in a thicker mass for the movable structure, thus offering better sensitivity and precision.
STMicroelectronics' THELMA60 surface-micromachining process increases the thickness of the aforementioned epitaxial layer to 60 micrometers, thereby achieving a level of sensitivity that previously only sensors made with bulk-micromachining processes could demonstrate. (Source: Nov 17, 2014, Micro-Electronics)
Intensifying Competition in the MEMS Market
The battle in the MEMS market is intensifying. Targeting IoT opportunities, both veterans and newcomers in the MEMS chip market are actively launching offensives to seize various sensor application territories. Among them, major Integrated Device Manufacturers (IDMs) are fiercely competing for multi-functional integrated (Combo) solutions, such as 6-axis or 9-axis sensors; meanwhile, new entrants from Taiwan and mainland China are targeting the massive demand for accelerometers and magnetometers in low- to mid-range products, rapidly ramping up production.
Max Lai, General Manager of iSentek, stated that driven by consecutive waves of design demand from mobile and IoT devices, the shipment volume of MEMS sensors is continuously expanding. This encourages existing IDMs to heavily expand their next-generation motion sensor product lineups and accelerate development toward more forward-looking, single-chip Combo sensor designs. At the same time, it is attracting many emerging fabless MEMS companies from Taiwan and mainland China to grab a slice of the pie, causing the MEMS market competition to rapidly heat up.
In fact, IDMs such as STMicroelectronics and Bosch Sensortec, along with InvenSense—whose technical capabilities are quite comparable—began laying the groundwork for highly integrated, small-sized, and low-power IoT MEMS System-in-Package (SiP) technologies as early as 2013. This sparked a design craze for 6-axis (accelerometer plus magnetometer or gyroscope) and 9-axis solutions. Recently, Bosch Sensortec and STMicroelectronics introduced new-generation single-chip processes and various R&D achievements in environmental sensors, which are expected to accelerate the realization of 9-axis MEMS System-on-Chip (SoC) solutions.
In addition to the Combo technology race sparked by major manufacturers, MEMS newcomers are also emerging to seize the market. This includes Taiwanese companies like Richtek, iSentek, Sitronix, and mCube, as well as mainland Chinese companies like MEMSIC and QST, all actively using cost-effective accelerometers and magnetometers to capture territory in the low- to mid-priced mobile and IoT device markets.
Max Lai further analyzed that because accelerometer technology and the market are already quite mature, the focus of competition among manufacturers lies in price. As for magnetometers, the current state is one of fierce contention, with various companies possessing certain performance and cost competitiveness; thus, it is the most intensely fought battleground. In the future, once mobile devices and IoT applications incorporate advanced functions such as Augmented Reality (AR) and Indoor Navigation, magnetometer developers will need to significantly improve product precision and reduce sizes to firmly establish a foothold in the market.
Fude Yuan, Senior Principal Engineer at iSentek, revealed that currently, only magnetometer suppliers like AKM, Yamaha, and iSentek can develop magnetometers with dimensions as small as 1.2 mm × 1.2 mm. This forms a technological barrier and is expected to accelerate vendor consolidation. Regarding magnetometer precision, future AR will demand accuracy with less than a 1% margin of error, which will pose a severe challenge to traditional Hall Sensor designs. Consequently, this is expected to drive the rise of manufacturers adopting new technologies, leading to a shift in market share dynamics.
Fude Yuan emphasized that in response to the strict precision requirements for magnetic sensing in next-generation mobile and IoT devices, iSentek has developed an exclusive patented miniature sensor structural design and utilizes two-directional magnetic setting technology to significantly improve product precision and anti-interference capabilities. This is expected to gradually carve into the market share of established magnetometer suppliers. (Source: Nov 10, 2014, Micro-Electronics)