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Solid State Watch: May 20-26, 2016

Tuesday, May 31st, 2016
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RF and MEMS Technologies to Enable the IoT

Friday, October 24th, 2014


By Ed Korczynski, Sr. Technical Editor, Solid State Technology and SemiMD

The “Internet of Things” (IoT) has been seen as the next major market that will demand high volumes of integrated circuits (IC). The IoT can be loosely defined as a network of small, low-cost, ubiquitous electronic devices where sensing data and communicating information occurs without direct human intervention. Each device would function as a “smart node” in the network by doing some low-level signal processing to filter signals from noise, and to reduce the bandwidth needed for node-to-node communications. The nodes will need to communicate up to some manner of a “cloud” for secure memory storage and to bounce actionable information down to humans.

Figure 1 shows a conservative forecast of the global IoT market that was recently published by IDC. IDC expects the worldwide IoT installed base to experience a compound annual growth rate (CAGR) of 17.5% from 2013 to 2020, starting from 9.1 billion smart nodes installed at the end of 2013 and growing to 28.1 billion units by 2020.

FIGURE 1: Forecast for global IoT applications revenue 2013-2020. Note that smart node “intelligent systems/devices” provide the foundation for this huge growing market. (Source: IDC)

Due to the anticipated elastic-demand for IoT devices that would come from cost reductions, the forecasts for the number of IoT nodes ranges to 50 billion or even 80 billion by the year 2020, as documented in the recent online Pete’s Post “Don’t Hack My Light Bulb, Bro”. The post also provides an excellent overview of recent discussions regarding the host of additional technology and business challenges associated with the enterprise infrastructure and security issues surrounding the integration of vast streams of new information.

As shown in Figure 1, the smart nodes form the foundation for the whole IoT. Consequently, the world will need low-cost high-volume manufacturing (HVM) technologies to create the different functionalites needed for smart nodes. Sensor- and logic-technologies to enable IoT smart nodes will generally evolve from existing IC applications, while R&D continues in Radio Frequency (RF) communications and in Micro Electro-Mechanical Systems (MEMS) energy harvesting.

RF Technology

IoT smart-nodes will use wireless RF technologies to communicate between themselves and with the “cloud.” In support of rapid growth in the 71-86 GHz RF “E-band” telecom backhaul segment—which transports data from cell sites in the peripheral radio access network (RAN) to the wireless packet core—Presto Engineering recently announced a non-captive production-scale testing service for 50µm-thin gallium arsenide wafers.

Silicon-On-Insulator (SOI) substrate supplier Soitec has excellent perspective on the global market for RF chips, since it’s High-Resistivity SOI (HR-SOI) wafers are widely used in commercial fabs. Bernard Aspar, senior vice president and general manager of the Communications and Power business unit of Soitec, explained to SemiMD in an exclusive interview why the market for RF chips is growing rapdily. RF front-end module unit sales are forecasted to increase at a CAGR of ~16% over the period of 2013-2017, while the area of silicon needing to be delivered could actually increase at ~30% CAGR. RF chips are increasing in average size due to the need to integrate multiple standards for wireless communications and multiple antenna switches. “The first components to be integrated in silicon were the antenna switches, moving from 70% on GaAs in 2010 to more than 80% on SOI in 2014,“ said Aspar.

Soitec claims that >80% of smart-phones today use an RF chip built on a wafer from the company, based on sales last year of >300k 200mm HR-SOI wafers. Due to anticipated future growth in RF demand, the company has plans to eventually move HR-SOI production to 300mm diameter wafers. Most of the anticipated demand will be for the company’s new variant of HR-SOI called eSI (“enhanced Signal Integrity”previously called “Trap Rich”) with a measured effective resistivity as high as 10 kOhm-cm for improved device performance.

This high-resistivity characteristic, which is conserved after a full CMOS process, translates to very low RF insertion loss (< 0.15 dB/mm at 1 GHz) and purely capacitive crosstalk similar to quartz substrates. HR-SOI substrates in general demonstrate reduced harmonics compared with standard SOI substrates, and the eSI wafers reduce harmonics to the point that they can be considered as lossless. Soitec was recently given a Best Partnership Award by Sony Semiconductor for supplying RF substrates.

“We’re also adding value to the substrate because it allows for simplification of the fab processing,” said Aspar. The eSI wafers enable much higher linearity and isolation, helping designers to address some of the most advanced LTE requirements at competitive costs. These substrates also provides benefits for the integration of passives, such as the quality factor of spiral inductors or tunable MEMS capacitors.

Vibrational Energy Harvesting

IoT smart nodes will need electrical power to function, and batteries that must be replaced or charged by an external source create issues for ubiquitous always-on small devices. In principle the ambient energies of the environment can be harvested to power smart nodes, and to do so we may consider using thermoelectric, photovoltaic, and piezoelectric properties of thin-films. Thermoelectric and photovoltaic devices both require somewhat specialized ambients for efficient energy harvesting, while piezoelectric devices can extract energy from subtle vibrations almost anywhere in the world (Fig. 2).

FIGURE 2: Schematic cross-section of piezoelectric cantilever with end mass, depicted in connection to an energy-harvesting circuit. (Source: Science)

Researchers in the Energy Harvesting and Mechatronics Research Lab at Stony Brook University, New York, recently published an excellent overview of the potential for 1 W to 100 kW piezoelectronic energy harvesting in building, automobiles, and wearables electronics in the Journal of Intelligent Material Systems and Structures 24(11) 1405-1430. However, the largest forecasted growth in the IoT is for small devices that would consume µW to mW of active power.

For low-cost and low-power consumption, the logic chips for IoT smart nodes are expected to be made using a 65nm “trailing edge” fab process. For example, CAST Inc. has developed a 32-bit BA20 embedded processor core that can deliver 3.41 CoreMarks/MHz at a maximum frequency of 75 MHz. Using TSMC’s 65nm Low Power fab process, it occupies only 0.01 mm2 of silicon area while consuming 2 µW/MHz. Thus, at maximum speed the chip core would consume just 150µW.

MicroGen Systems, Inc. (MicroGen) is a privately held company developing thin piezoelectric energy harvesters, based on technology from Cornell University’s NanoScale Science and Technology Facility. Founded in 2007, MicroGen has headquarters and R&D in the Ithaca and Rochester, NY areas, and volume manufacturing with X-FAB in Itzehoe, Germany. Figure 3 shows one of the company’s ~100 mm2 area chips featuring an aluminum nitride (AlN) peizoelectric thin-film on a cantilever that produces alternating current (AC) electricity in response to external vibrations. Different cantilever designs allow for harvesting energy from either single-frequency or broadband vibrations. At resonance the AC power output is maximized, so it can be ~100 µW at 120Hz and 0.1g, or ~900 µW at 600Hz and 0.5g.

FIGURE 3: BOLT™-R0600 energy-harvesting chip without packaging. The green-silver trapezoidal area is a 25-100µm thick cantilever (with several thin-film layers including an AlN piezoelectric) attached to grey rectangular end mass (silicon). A fixed-frequency device, at resonance of ~600Hz it can produce ~900 µWatts of AC power. (Source: MicroGen Systems)

For any piezoelectric energy harvester there are basic materials properties that must be optimized, including the piezoelectric strain constant as well as the electromechanical coupling factor of the thin-film to the moving mass. Lead-zirconium-titanate (PZT) has been the most studied piezoelectric thin-film due to high strain constant and ability to couple to a substrate though the use of buffer layers.

S. H. Baek, et al. showed “Piezoelectric MEMS with Giant Piezo Actuation” in Science 18 November 2011, Vol 344 using lead-manganese-niobate with lead-titanate (PMN-PT) layers epitaxially grown on a strontium-titanate (STO) buffer layer over 4°-off-axis(001)Si. Figure 4 shows both the transverse piezoelectric coefficient (C/m2) and the energy-harvesting figure of merit (GPa) for this and other thin-films. Note that to acheive stable “giant” piezoelectric effects the PMN-PT layer had to be grown epitaxially with precise control over the STO grain orientation.

FIGURE 4: Transverse piezoelectric coefficient (C/m2) and the energy-harvesting figure of merit (GPa) for PMN-PT (“this work”) and other piezoelectric thin-films. (Source: Science)


The Week in Review: February 14, 2014

Friday, February 14th, 2014

Worldwide silicon wafer revenues declined by 13 percent in 2013 compared to 2012 according to the SEMI Silicon Manufacturers Group (SMG) in its year-end analysis of the silicon wafer industry. Worldwide silicon wafer area shipments increased 0.4 percent in 2013 when compared to 2012 area shipments.

Silicon wafer area shipments in 2013 totaled 9,067 million square inches (MSI), slightly up from the 9,031 million square inches shipped during 2012. Revenues totaled $7.5 billion down from $8.7 billion posted in 2012. “Annual semiconductor silicon shipment levels have remained essentially flat for the past three years,” said Hiroshi Sumiya, chairman of SEMI SMG and general manager of the Corporate Planning Department of Shin-Etsu Handotai Co., Ltd. ”However, industry revenues have declined significantly for the past two years.”

Rudolph Technologies, Inc. announced this week the sale of its first NSX 320 TSV Metrology System to CEA-Leti, a research organization based in Grenoble, France, which, in the frame of the Nanoelec Research Technology Institute (Nanoelec RTI) program, is developing three-dimensional integrated circuit (3DIC) technologies that use through silicon vias (TSVs) to conduct signals among vertically-stacked chips. The new NSX 320 TSV system includes integrated 3D metrology that enables specialized measurements critical to the TSV process.

Honeywell announced today that it has introduced new RadLo low alpha plating anodes based on proprietary technology to help reduce alpha particle radiation that can lead to data errors in semiconductors. The new plating anodes for semiconductor packaging wafer bumping applications expand Honeywell’s RadLo offerings and employ proprietary Honeywell metrology and refining techniques.

At this week’s International Solid State Circuits Conference (ISSCC2014), imec and Holst Centre, together with Olympus, demonstrated a low-power single channel implantable electrocardiography (ECG) acquisition chip with analog feature extraction, which enables precise monitoring of the signal activity in a selected frequency band. Leadless Pacemakers with ultra-small size and ultra-low power consumption are emerging, improving analysis and clinical research of the intra-cardiac rhythm, and as a result, improving patients’ quality of life. The new low-power ECG acquisition chip advances the state-of-the-art by consuming only 680nA when all features are active, and also provides competitive performance, such as input SNR>70dB, CMRR >90dB, PSRR >80dB without any external passive components. By equipping an ultra-low power analog feature extractor, the new chip is capable of assisting digital signal processor platforms for the implementation of low-power heartbeat detection algorithms.

SPTS Technologies, a supplier of advanced wafer processing solutions for the global semiconductor industry and related markets today announced the opening of a new office in Korea. The new SPTS Korea office is situated in Pangyo and will be the central base of operations for sales, field process and engineering staff. The new facility will also carry essential and critical spares inventory to support SPTS’ system installed base.

Fujitsu Laboratories Ltd. and imec Holst Centre this week announced that they have developed a wireless transceiver circuit for use in body area networks (BAN) for medical applications that adheres to the 400 MHz-band  international standard. While the subject of high expectations for medical applications, wireless monitoring of brainwaves or other vital signs has in the past required over a dozen milliwatts (mW) of electric power. Now, however, by optimizing the architecture and circuitry, Fujitsu Laboratories and imec Holst Centre have succeeded in reducing the electric power requirements of wireless transceiver front-ends, to just 1.6 mW when receiving data and 1.8 mW when transmitting.