On the wide application of MEMS sensors

The full name of MEMS is a micro-electro-mechanical system that utilizes traditional semiconductor processes and materials, and integrates micro-sensors, micro-actuators, micro-mechanics, signal processing and control circuits, high-performance electronic integrated devices, interfaces, communications, and power supplies. Device or system. With a small size, low cost, and integration features.

MEMS working principle diagram

1

MEMS sensor applications

In addition to smart phones, MEMS sensors will be widely used in AR/VR, wearable and other consumer electronics, smart driving, smart factories, smart logistics, smart home, environmental monitoring, smart medical and other Internet of Things.

1, wearable device applications

Taking the millet bracelet as an example, ADI's MEMS acceleration and heart rate sensors are used to achieve exercise and heart rate monitoring. Inside the Apple Watch, in addition to MEMS accelerometers, gyroscopes, and MEMS microphones, pulse sensors are used.

2, VR applications

VR devices need to be accurate enough to determine the speed, angle, and distance of the head's rotation. The use of MEMS accelerometers, gyroscopes, and magnetometers is one of the most important solutions, and it almost becomes the standard for VR devices. Oculus Rift, HTC Vive, and PlayStation VR all use MEMS accelerometers and gyroscopes. Future VR devices may also use MEMS eye tracking technology.

3, drone applications

UAV flight attitude control technology, MEMS sensors have a display space. With accelerometers and gyroscopes, angle changes can be calculated and positions and flight attitudes can be determined. MEMS sensors can work in all kinds of harsh conditions while obtaining high-precision output. The application of MEMS accelerometers and gyroscopes on drones can be described as brilliant.

4, car networking applications

Car networking is a major area for the development of the Internet of Things. Smart cars are the core of car networking and are in rapid development. In the era of smart cars, active safety technologies have become an emerging area of ​​concern and need to improve existing active safety systems such as rollover and stability control (ESC), which requires MEMS acceleration sensors and angular velocity sensors to sense Test body posture.

Speech will become an important way for people and smart cars to interact. MEMS microphones will usher in new opportunities for development. MEMS sensors have many applications in the automotive field, including airbags (high-g accelerometers for frontal crashworthy airbags and pressure sensors for side airbags), and automotive engines (intake manifolds for detecting intake air volume) Absolute pressure sensor and flow sensor) etc.

5, automatic driving applications

The rise of automatic driving technology further promoted the entry of MEMS sensors into cars. Although the GPS receiver can calculate its own position and speed, when the GPS signal is poor (underground garage, tunnel) and the signal is disturbed, the navigation of the car will be affected, which is a fatal flaw for automatic driving. Using MEMS gyroscopes and accelerometers to obtain speed and position (angular velocity and angular position), any fine movements and tilting attitudes of the vehicle are converted into digital signals that are passed to the trip computer via the bus. Even at the fastest speed, MEMS accuracy and response speed can be adapted. Thanks to the development of silicon micro-machining, wafer bonding and other technologies, the accuracy has risen to 0.01.

6, industrial applications

MEMS makes the sensor small and intelligent, and MEMS sensors will be promising in the smart industrial era. MEMS temperature and humidity sensors can be used to detect environmental conditions. MEMS accelerometers can be used to monitor the vibration and rotation speed of industrial equipment. High-precision MEMS accelerometers and gyroscopes provide precise position information for navigation and rotation of industrial robots.

2

Main MEMS sensor types and suppliers

There are a wide variety of MEMS sensors. The main MEMS sensors include motion sensors, pressure, microphones, environments, and optical sensors. The motion sensors can be classified into gyroscopes, accelerometers, and magnetometers.

1, MEMS motion sensor

MEMS motion sensors mainly include three categories: accelerometers, gyroscopes, and magnetometers. Accelerometers and gyroscopes can be integrated into six-axis inertial sensors. Magnetometers and accelerometers are integrated into electronic compasses (e-compasses), accelerometers, and gyroscopes. The magnetometer can be integrated as a 9-axis sensor.

Inertial sensors (accelerometer + gyroscope) manufacturers are: STMicroelectronics (ST), Asahi Kasei Microelectronics (AKM), InvenSense, Robert, Bosch and so on.

The electronic compass (magnetometer + accelerometer) manufacturers include: Asahi Kasei Microelectronics (AKM), Yamaha (Alpha), Alps Electric, and MEMSIC (acquired by Huacan Optoelectronics in July 2016).

2, MEMS microphone manufacturers

3, MEMS pressure sensor manufacturers

4, MEMS environmental sensors

Environmental sensors can be subdivided into gas, temperature and humidity sensors. MEMS temperature sensors can be used wherever temperature needs to be detected.

MEMS humidity sensors have been widely used in industries such as industrial control, meteorology, agriculture, and mine detection.

MEMS gas sensors are mainly used to detect the composition and concentration of the target gas.

5, MEMS biosensor

MEMS biosensors are currently in the early stages of development. MEMS biosensors are devices that use biomolecules to detect biological reaction information and are listed as one of the five major medical inspection technologies in the new century. They are products of modern biotechnology, microelectronics, and chemistry. In the future, MEMS biosensors will have broad space for development in the fields of medicine, food industry, and environmental monitoring.

3

MEMS industry chain

MEMS is a complex multidisciplinary system. The entire industry chain involves design, manufacturing, packaging and testing, software and application solutions. The upstream of the MEMS industry chain is responsible for the supply of MEMS device design, materials, and production equipment. Midstream manufactures and manufactures MEMS devices and downstream uses MEMS devices to manufacture terminal electronic products.

The entire industry chain of MEMS is complex and involves a large number of manufacturers. China's design, manufacture, and packaging and testing companies are actively deploying MEMS, and a complete MEMS industrial chain has been formed.

1. Global MEMS Manufacturers

The world's top ten MEMS manufacturers include Bosch, STMicroelectronics, Hewlett-Packard, Texas Instruments, Canon, InvenSense, Avago, Qorvo, Knowles Electronics, Panasonic, and others. Among them, BOSCH firmly occupies the top position in the industry because of its dual layout in automotive electronics and consumer electronics, and its revenue accounts for about one-third of the total revenue of the top five companies.

Most of the major manufacturers in the MEMS industry are mainly Fabless, such as Floormaster, HP, and Canon. At the same time, there are also IDM vendors who are vertically involved in all aspects of the entire industry chain. Bosch and ST, for example, have their own wafer foundry production lines.

2, MEMS OEM

There are two main types of MEMS foundry: MEMS foundry provided by IDM vendors, MEMS foundry provided by independent foundries, and independent foundries including integrated circuit foundries and pure MEMS foundries. In recent years, MEMS device manufacturers in the Fabless model have developed rapidly. Independent MEMS foundries are striving to find standardized processes to increase economies of scale, reduce manufacturing time, and reduce costs. As a result, independent MEMS foundries have grown rapidly, but IDM OEMs still Leading position in the market.

Currently, IDM vendors that provide MEMS OEMs mainly include STMicroelectronics, Sony, and Texas Instruments. TSMC is currently the world's largest independent MEMS foundry. The world's leading pure MEMS foundries include Silex Microsystems, Teledyne DALSA, and Asia Pacific Microsystems. X-FAB, Innovative Micro Technology, etc., domestic SMIC, Huahong Hongli, and Shanghai Advanced Semiconductor also have the ability to produce MEMS.

3, MEMS packaging test

At present, international manufacturers with MEMS packaging and testing capabilities mainly include Riyueguang, Anfu, Xipin, and Licheng Technology. Domestically, there are Huatian Technology, Changjiang Electronics Technology, and Jingfang Technology. Although domestic MEMS front-end manufacturing still lags behind international manufacturers, domestic packaging technology has started earlier, and the back-end packaging of domestic MEMS industry chain is relatively complete.

There are many differences between the packaging technology and the IC package, and the requirements for the enterprise are very high. As we all know, the price of MEMS devices has dropped very quickly. At present, the packaging cost in some MEMS devices even accounts for 40% to 60% of the total price. How to achieve low-cost packaging is a great challenge for manufacturers of packaging and testing.

After more than forty years of development, micro-electromechanical systems (MEMS) have become one of the major scientific and technological fields in the world. It involves various disciplines and technologies such as electronics, mechanics, materials, physics, chemistry, biology, medicine, etc. It has broad application prospects.