Automotive Drives MEMS and Power
By Ben Lee and Mike Rosa
There’s no question that smartphones require a large number of MEMS sensors and power devices. However, as smartphone growth shows signs of a slowdown due to market saturation, where is the next big growth area?
The consensus among leading analysts points toward automobiles. It’s clear that electronics content in automobiles has grown substantially in the past few years. Gartner analyst Jim Hines estimates that the electronics content of automobiles will reach $350 per vehicle this year, up from about $250 in 2000. Gartner sees a 6.4 percent CAGR in automotive semiconductor revenues between 2012 and 2018.
This growth is expected to increase exponentially as more and more sensors, power devices, and other electronic components make their way into automobile systems. The Consumer Electronics Show (CES) in Las Vegas early this year showcased car manufacturer exhibits featuring multiple forms of electronics-based technology. While autonomous drive was huge at CES, there were also demonstrations of readily available capabilities such as sensors that detect when a driver is intoxicated or drifting across driving lanes, and systems that provide pre-crash warnings.
The automotive field is quickly becoming an alliance of carmakers and technology vendors. In March, General Motors bought Cruise Automation, a San Francisco-based startup that offers an autonomous drive system that can be installed on existing vehicles. The reported acquisition price was a billion dollars for the three-year-old, 40-person company. Recently, Ford created a new business unit, Ford Smart Mobility, in Palo Alto, California, as part of its strategy to tap into Silicon Valley’s engineering talent to expand into self-driving vehicles, mobility and vehicle connectivity.
These applications are leading device makers into new territories. At the March 2016 Compound Semiconductor International Conference (CS) in Brussels, Belgium, leading power device companies and suppliers stressed the need for more innovative advancements in power devices to support the transition to 5G wireless for instantaneous communication with automobiles and other products.
Vehicles already consume a significant fraction of both power and MEMS devices, and healthy growth is expected.
The automotive sector comprises approximately 26% of the total MEMS and Sensors market. The volume of sensors in conventional cars, and then autonomous cars, is expected to grow an average of 16% annually over the next fifteen years, according to market research firm Yole Développement (Lyon, France).
In the power market, automotive devices accounted for about 18 percent of the total 2014 power device market of $11.5 billion, according to Yole. By 2020, the power device sector is expected to total $17.2 billion, with electric vehicles and hybrids (EV/HEV) leading a resurgence of growth in the sector.
The automotive revolution goes far beyond replacing a gas engine with an electric motor. Market research firm IHS Technology’s teardown analysis of the infotainment and instrumentation systems on the Tesla Model S, for example, reveals many similarities in content and design with that of a tablet or smartphone.
Tesla also is active in Advanced Driver Awareness and Safety (ADAS) features. For instance, the company’s cars produced after June 2015 are capable of receiving a software update that gives the car autonomous driving capabilities. The software upgrade costs $6,000, and some are calling it the most expensive in-app purchase available.
Industry stalwart automakers are taking ADAS seriously as well. In a presentation to a recent MEMS industry group in Napa, California, one GM executive said he was among a Pony Express-like team that had travelled in one of the company’s prototype fully-autonomous cars from the East to the West coasts of the United States.
ADAS is not science fiction; many forms of self-driving are happening now. ADAS uses a combination of advanced sensors stereo cameras and long/short-range radar, combined with actuators, control units, and integrating software to enable cars to monitor and respond to their surroundings. For example, LIDAR, a combination of “light” and “radar” which measures distance by illuminating a target with a laser is key to ADAS.
Some ADAS solutions are currently available, notably lane-departure warning systems, adaptive cruise control, back-up alerts, and parking assistance, while other advanced autonomous driving capabilities will arrive in the near future. Beyond ADAS, sensory-based management systems on cars are handling everything from the condition of the engine and power train to communications, location services, body fatigue and, most importantly, driver safety.
New MEMS Sensors
While existing sensors such as pressure, temperature, gas sensing, inertial, optical, and ultrasonic will still be utilized in cars, specific types of sensors that support functions such as safety or autonomous driving are needed.
For companies such as Applied Materials, the challenge lies in developing the films and processes to be used to enable the next generation of MEMS and sensor technologies for application not only in ADAS but the growing list of existing applications in automobiles. These include engine management sensors (for harsh environments), gas sensors (inside and outside the cabin, including in and around the engine and exhaust) and others.
Inside the cabin, for example, automotive companies would like to offer new voice control functions, which in turn require MEMS microphones with signal-to-noise ratios in the 60-70 db range. This requirement is driving cantilever-based MEMS microphone designs, among other innovations, which require process innovations. Customers are doing demonstrations of these new microphones now, and at least one company plans to be in production with a comb-finger-based capacitive microphone.
Automotive Process Requirements
Power devices come in different voltage ranges, with electric vehicles requiring power devices in the medium voltage range of 300 volts to 1,200 volts (locomotives, for example, require higher-voltage power devices, in the range of 1.7 to 6.5kV). Yole predicts that insulated-gate bipolar transistor (IGBT) devices in the low- to medium-voltage range, driven by growth in electric vehicles and hybrids, will grow faster than the overall semiconductor market.
Building advanced power device structures requires enhancements in semiconductor processing equipment. For example, epitaxial silicon grown in an Applied Materials high growth rate (HGR) epi chamber enables uniform, ultra-pure, low defect silicon needed for precise control of series resistance, or Rds(on). Since voltage handling requirements in power devices can exceed 1000V, the epitaxial layer can vary from as little as 5µm to as much as 100µm or more. As a result, Applied’s HGR epi chamber, which grows epi 50 percent faster than previous offerings, is gaining traction with customers.
Similarly, an Applied Materials high deposition rate (HDR ) PVD reactor deposits thick Al on the order of 3-6µm+ in order to handle current and voltage as well as heat dissipation requirements. Applied’s HDR Al chamber deposits Al at 2.3µm per minute, without defects and cracks. Unique epi doping steps are required to get certain electrical properties in IGBT devices, for example.
The move toward more ADAS capability in automobiles will drive the need for faster (instantaneous communication with data and safety systems, for example) and more efficient (ultra-fast on-off switching and minimal power consumption) power devices. And while chip designers will continue to push the limits of existing silicon-based technology, hurdles will need to be overcome in bringing in the next era of wide band gap (GaN and SiC) power devices that enable performance beyond silicon.
These changes have significant implications for the processing of GaN and SiC devices, encompassing epi, etch, defect and inspection, doping and anneal steps.