Crossbar, Inc., a start-up company, unveiled a new Resistive RAM (RRAM) technology that will be capable of storing up to one terabyte (TB) of data on a single 200mm2 chip. A working memory was produced array at a commercial fab, and Crossbar is entering the first phase of productization. “We have achieved all the major technical milestones that prove our RRAM technology is easy to manufacture and ready for commercialization,” said George Minassian, chief executive officer, Crossbar, Inc. The company is backed by Artiman Ventures, Kleiner Perkins Caufield & Byers and Northern Light Venture Capital.

The technology, which was conceived by Professor Wei Lu of the University of Michigan, is based on a simple three-layer structure of silver, amorphous silicon and silicon (FIGURE 1). The resistance switching mechanism is based on the formation of a filament in the switching material when a voltage is applied between the two electrodes. Minassian said the RRAM is very stable, capable of withstanding temperature swings up to 125°C, with up to 10,000 cycles, and a retention of 10 years. “The filaments are rock solid,” he said.

Crossbar has filed 100 unique patents, with 30 already issued, relating to the development, commercialization and manufacturing of RRAM technology.

After completing the technology transfer to Crossbar’s R&D fab and technology analysis and optimization, Crossbar has now successfully developed its demonstration product in a commercial fab. This working silicon is a fully integrated monolithic CMOS controller and memory array chip. The company is currently completing the characterization and optimization of this device and plans to bring its first product to market in the embedded SOC market.

Sherry Garber, Founding Partner, Convergent Semiconductors, said: “RRAM is widely considered the obvious leader in the battle for a next generation memory and Crossbar is the company most advanced to show working demo that proves the manufacturability of RRAM. This is a significant development in the industry, as it provides a clear path to commercialization of a new storage technology, capable of changing the future landscape of electronics innovation.”

FIGURE 1. The resistance switching mechanism of Crossbar’s technology is based on the formation of a filament in the silicon-based switching material when a voltage is applied between the two electrodes.

Crossbar technology can be stacked in 3D, delivering multiple terabytes of storage on a single chip. Its simplicity, stackability and CMOS compatibility enables logic and memory to be integrated onto a single chip at the latest technology node (FIGURE 2).

Crossbar’s technology will deliver 20x faster write performance; 20x lower power consumption; and 10x the endurance at half the die size, compared to today’s best-in-class NAND Flash memory. Minassian said the biggest advantage of the technology is its simplicity. “That allowed us in three years time to get from technology understanding, characterization, cell array and put a device together,” he said.

Minassian said RRAM compares favorably with NAND, which is getting more complex and expensive. “In 3D NAND, you put all of these thing layers of top of each other – 32 layers, or 64 or 128 in some cases – then you have to etch them, you have to slice them all at once and the equipment required for that accuracy and that geometry is very expensive. This is one of the reasons that 3D has been very difficult for NAND to be introduced.” With the Crossbar approach, “you’re always dealing with three layers. It’s much easier to stack these and it gives you a huge density advantage,” Minassian said.

“The switching media is highly resistive,” explains Minassian. “If you try to read the resistance between top and bottom electrode without doing anything, it’s a high resistance. That’s the off state. To turn on the device, we apply a positive voltage to the top electrode. That ionizes the metal on the top layer and puts the metal ions into the switching media. The metal ions form a filament that connect the top and bottom electrode. The moment they hit the bottom electrode, you have a short, which means that the top and bottom electrode are connected which means they have a low resistance.” The low resistance state is the on state. He said that although silver is not commonly used in front-end CMOS processing, the RRAM memory formation process is a back-end process. “You produce all your CMOS and then right before the device exits the fab, you put the silver on top,” he said. The silver is deposited, encapsulated, etched and then packaged. “That equipment is available, you just have to isolate it at the end,” Minassian said.

FIGURE 2. Crossbar’s simple and scalable memory cell structure enables a new class of 3D RRAM which can be incorporated into the back end of line of any standard CMOS manufacturing fab.

The approach is also CMOS compatible, with processes used to fabricate the memory layers all running at less than 400°C. “This allows you to not only be CMOS compatible, but it allows you to stack more and more of these memory layers on top of each other,” Minassian said. “You can put the logic, the controllers and microprocessors, next to the memory in the same die. That allows you to simplify packaging and increase performance.”

Another advantage compared to NAND is that the controllers used to address the cells can be less complicated. Minassian said that in conventional cells, 30 electrons are required to produce 1 Volt. “If you shrink that to a smaller node, the number of electrons is less. Fewer electrons are much harder to detect. You need a massive controller that does error recovery and complex coding so if the bits are changed, it can still provide you the right program to execute.” Also, because the Crossbar RRAM is capable of 10,000 write cycles, less complicated controllers are needed. Today’s NAND is capable of only 1000 write cycles. “If you write information 1000 times, that cell is destroyed. It will not contain or maintain the information. You have this complex controller that keeps track of how many cells have been written, how many times, to make sure all of them are aged equally,” Minassian said.

Non-volatile memory, expected to grow to become a $60 billion market in 2013, is the most common storage technology used for both code storage (NOR) and data storage (NAND) in a wide range of electronics applications. Crossbar plans to bring to market standalone chip solutions, optimized for both code and data storage, used in place of traditional NOR and NAND Flash memory. Crossbar also plans to license its technology to SOC developers for integration into next-generation systems-on-chips (SOC).

Michael Yang, Senior Principal Analyst, Memory and Storage, IHS, said: “Ninety percent of the data we store today was created in the past two years. The creation and instant access of data has become an integral part of the modern experience, continuing to drive dramatic growth for storage for the foreseeable future. However, the current storage medium, planar NAND, is seeing challenges as it reaches the lower lithographies, pushing against physical and engineering limits. The next generation non-volatile memory, such as Crossbar’s RRAM, would bypass those limits, and provide the performance and capacity necessary to become the replacement memory solution.” •

P. Singer

The Semiconductor Industry Association (SIA) announced that worldwide sales of semiconductors reached $74.65 billion during the second quarter of 2013, an increase of 6 percent from the first quarter when sales were $70.45 billion. This marks the largest quarterly increase in three years. Global sales for June 2013 hit $24.88 billion, an increase of 2.1 percent compared to June 2012 and 0.8 percent higher than the May 2013 total. Regionally, sales in the Americas jumped 8.6 percent in Q2 compared to Q1 and 10.6 percent in June 2013 compared to June 2012, marking the region’s largest year-over-year increase of 2013. All monthly sales numbers are compiled by the World Semiconductor Trade Statistics (WSTS) organization and represent a three-month moving average.

“There’s no question the global semiconductor industry has picked up steam through the first half of 2013, led largely by the Americas,” said Brian Toohey, president and CEO, Semiconductor Industry Association. “We have now seen consistent growth on a monthly, quarterly, and year-to-year basis, and sales totals have exceeded the latest industry projection, with sales of memory products showing particular strength.”

Quarterly sales outperformed the World Semiconductor Trade Statistics (WSTS) organization’s latest industry forecast, which projected quarter-over-quarter growth of 4.6 percent globally and 3.4 percent for the Americas (compared to the actual increases of 6 percent and 8.6 percent, respectively). Total year-to-dates sales of $145.1 billion also exceeded the WSTS projection of $144.1 billion. Actual year-to-date sales through June are 1.5 percent higher than they were at the same point in 2012.

Regionally, sales in June increased compared to May in the Americas (3.5 percent), Asia Pacific (0.4 percent), and Europe (0.1 percent), but declined slightly in Japan (-0.9 percent). Compared to the same month in 2012, sales in June increased substantially in the Americas (10.6 percent), moderately in Asia Pacific (5.4 percent), and slightly in Europe (0.8 percent), but dropped steeply in Japan (-20.8 percent), largely due to the devaluation of the Japanese yen.

“While we welcome this encouraging data, it is important to recognize the semiconductor workforce that drives innovation and growth in our industry,” continued Toohey. “A key roadblock inhibiting our innovation potential is America’s outdated high-skilled immigration system, which limits semiconductor companies’ access to the world’s top talent. The House of Representatives should use the August recess to work out their political differences on this issue and return to Washington next month ready to approve meaningful immigration reform legislation.” •

Light and proximity sensors in mobile handsets and tablets are set for expansive double-digit growth within a five-year period, thanks to increasing usage by electronic giants Samsung and Apple. Light and proximity sensors can detect a user’s presence as well as help optimize display brightness and color rendering.

Revenue for the sensors is forecast to reach $782.2 million this year, up a prominent 41 percent from $555.1 million in 2012, according to insights from the MEMS and Sensors Service at information and analytics provider IHS. The market is also expected to grow in the double digits for the next three years before moderating to a still-robust eight percent in 2017. By then, revenue will reach $1.3 billion, as shown in the figure on page 10.

“The continued growth of the smartphone and tablet markets serve as the foundation of a bright future for light sensors,” said Marwan Boustany, senior analyst for MEMS & sensors at IHS. “Market leaders in these areas are driving the growth, with Apple pioneering their adoption and Samsung later taking the lead in their usage.”

Sensor segments
There are three types of light and proximity sensors: ambient light sensors (ALS) that measure the intensity of the surrounding light enveloping a cellphone or tablet to adjust screen brightness and save battery power; RGB sensors that measure a room’s color temperature via the red, green and blue wavelengths of light to help correct white balance in the device display; and proximity sensors that disable a handset’s touch screen when it is held close to the head, in order to avoid unwanted input, and also to turn off the light in the display to save battery power.

Overall, the compound annual growth rate for the sensors from 2012 to 2017 equates to 19 percent.

Driving this growth is the shift in use from ALS to RGB in mid- to high-end smartphones; the growing deployment of proximity sensors with gesture capabilities compared to just simple proximity sensors; and the price premiums associated with such changes in usage.

Aside from their most conspicuous use in wireless communications typified by handsets and tablets, light sensors are also utilized in various other applications. These include consumer electronics and data processing for devices like televisions, laptops and PC tablets; the industrial market for home automation, medical electronics and general lighting; and the automotive space for vehicle displays and car functionalities like rain sensors.

Samsung and Apple are leaders in sensor use
Both Samsung and Apple have made use of light and proximity sensors in recent years, helping the sensor market grow in no small measure.

In 2010, Apple included an RGB and proximity sensor for its iPhone 4 and an RGB sensor in its iPad, even though the sensors were subsequently dropped in the iPhone 4S, iPhone 5 and later iPads. Apple let go of the sensors, which were made available at that time in a combination—or combo package—in favor of discrete solutions consisting of individual proximity as well as ALS sensors for its products. While combo sensors offer the convenience of a single configured package and sourcing from a single supplier, discrete solutions can offer flexibility in the choice of sensor.

Samsung, meanwhile, has gone on to use light and proximity sensors in even larger quantities than Apple. Last year Samsung included an RGB, proximity and infrared (IR) combo sensor, for both its Galaxy SIII smartphone and flagship Galaxy Note 2 device that the company termed as a “phablet.” This year, Samsung deployed a discrete RGB sensor in its latest smartphone, the Galaxy S4, switching from a combo package due to lack of availability of a combo sensor with gesture capability. Samsung’s move toward using RGB sensors in its high-end handsets currently sets the tone for the RGB sensor market given Samsung’s high unit sales. Such a move by the South Korean maker is expected to open the door for other brands to also include RGB sensors in their handsets and tablets, IHS believes.

The new gesture functionality, such as that found in the Galaxy S4, will see especially vigorous growth in the years to come, with revenue enjoying an astonishing 44 percent compound annual growth rate from 2013 to 2017. Maxim Integrated Solutions of California provides the discrete gesture solution for the Galaxy S4, but Japan’s Sharp will be producing a combo sensor product with gesture capabilities by September this year.

Sensor suppliers and buyers tussle
Samsung and Apple are the top buyers of light sensors, accounting for more than 50 percent of light sensor revenue last year. Samsung pulled away from Apple after impressive 90 percent growth in sensor purchases between 2011 and 2012, compared to Apple’s 54 percent growth rate of spend during the period.

This is due to Samsung’s shift toward RGB sensors in its Note 2 and SIII devices, which command higher average selling prices. In third place after Samsung and Apple is a collective group of original equipment manufacturers from China. Included here are global players with significant name recognition like Huawei Technologies, ZTE and Lenovo, as well as a multitude of lesser-known companies such as Coolpad and Xiaomi.

Meanwhile, the top sensor suppliers are Austrian-based ams via its Taos unit in Texas, which supplies to Apple; and Capella Microsystems from Taiwan, the top light sensor supplier to Samsung. Together the two manufacturers furnish more than half of the light sensor market. Other important sensor makers are Avago Technologies from California and Sharp from Japan.

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