Category Archives: Thin Film Batteries

September 21, 2009 – MIT researchers say carbon nanotubes formed into tiny springs can store as much energy, pound-for-pound, as lithium-ion batteries, and offer better durability and reliability.

Based on two papers — a theoretical analysis in the June issue of the journal Nanotechnology, and a laboratory demonstration in the September issue of the Journal of Micromechanics and Microengineering — indicate that carbon nanotube springs could store more than 1000× more energy for their weight than steel springs, and comparable to state-of-the-art lithium ion batteries.

Two key differences indicate springs’ advantage over traditional batteries: they can deliver store energy either in a rapid, intense burst, or slowly and steadily; and their stored energy doesn’t leak out over time.

Applications for such CNT springs could be emergency backup power supplies that go years untouched until needed without testing or replacement; portable devices in place of gasoline engines; or sensors in harsh environments where conditions like temperature or pressure extremes (e.g., boreholes for oil wells) would affect performance of traditional battery technology. First uses are likely in larger systems, not MEMS devices, since storage and release of energy in such springs is of a mechanical nature and not necessary to convert into electricity, notes MIT prof. and co-author Carol Livermore, in a statement.

Next steps in the work are to test actual performance over time, to confirm the CNT springs can charge and recharge without performance loss, and more research and engineering to determine how close devices using them could come to theoretically possible high energy density. Current CNT growth methods need to be improved to make more desirable highly concentrated CNT bundles with longer, thicker fibers, instead of the CNT fibers joined in parallel made in initial lab tests.

June 26, 2009: KLD Energy Technologies is launching US sales of an electric scooter based on an transmissionless motor system that uses a nanocomposite material to boost energy efficiency.

The firm’s “Neue” motor, which it says can reach speeds of up to 65mph (Twice that of other electric motors) and a range of 100mi on a standard lithium battery, is built on a nanocrystalline composite material that the company says conducts energy up to 10× more efficiently than iron-core motors (2500Hz vs. 250Hz), with no need for additional cooling systems.

With a high frequency and low RP the motor does not require a transmission, and enables the scooter to achieve speeds and performance levels comparable to gas-powered vehicles, the firm says.

Base price for the scooter is $3288, plus a $500 reservation; deliveries are slated to start in 3Q10.

May 18, 2009: Altair Nanotechnologies Inc. (Altairnano), a provider of energy storage systems for clean, efficient power and energy management, and Amperex Technology Ltd. (ATL), which designs and manufactures of lithium-ion battery cells for mobile devices, have entered into a joint development agreement to accelerate the commercialization of next-generation high-performance lithium-titanate battery cells.

Under terms of the agreement, Altairnano and ATL will provide respective technical resources to focus on the engineering, design and testing of the next-generation of rechargeable cells, according to a news release.

The cells are the core technology supporting Altairnano’s energy storage and battery systems designed for electrical grid stability, renewable energy integration, and transportation applications.

The joint development agreement is an integral component of Altairnano’s product roadmap and accelerated commercialization strategy for the company’s advanced energy storage solutions. This initiative seeks to improve cell performance by increasing cell energy and power density.
Increased density, coupled with Altairnano’s distinctive performance capabilities, will further enhance the value and market adoption of the company’s energy storage systems, the company said.

“ATL, utilizing world-class manufacturing techniques and industry-leading expertise in battery cell development, views its association with Altairnano as furthering its goal of working with key companies in the energy storage system market to take advantage of the resulting synergies,”
said Dr. Robin Zeng, president and CEO at ATL, in a prepared statement.

“We are very pleased to be working with Altairnano to accelerate commercialization of next-generation lithium-titanate batteries. The association with Altairnano will provide additional inroads to the global market in energy storage.”

Initial availability of these cells and advanced energy storage systems and batteries featuring the company’s next generation of advanced lithium-titanate cells is anticipated by the end of 2009.

“We’re excited to partner with a recognized world leader in advanced cell design and manufacturing,” said Dr. Terry Copeland, president and CEO, Altairnano, in a prepared statement. “Strategic alignment with ATL strengthens Altairnano’s position to meet growing global market demands for utility-scale energy storage systems and for EV, HEV and PHEV battery applications.”

April 16, 2009: A123 Systems, whose nanophosphate formula is an important ingredient in its Li-ion batteries, has received more than $100 million in tax credits from the state of Michigan.

The tax credits are part of a push by Michigan Gov. Jennifer Granholm to make the state a center for automotive battery manufacturing. The Massachusetts-based company will open a new production plant in suburban Detroit.

The announcement came shortly after Chrysler chose A123 as its supplier of lithium-ion batteries for electric vehicles expected to reach the market in 2010.

April 3, 2009: For the first time, MIT researchers have shown they can genetically engineer viruses to build both the positively and negatively charged ends of a lithium-ion battery.

The new virus-produced batteries have the same energy capacity and power performance as state-of-the-art rechargeable batteries being considered to power plug-in hybrid cars, and they could also be used to power a range of personal electronic devices, said Angela Belcher, the MIT materials scientist who led the research team.

The new batteries, described in the April 2 online edition of Science, could be manufactured with a cheap and environmentally benign process: The synthesis takes place at and below room temperature and requires no harmful organic solvents, and the materials that go into the battery are non-toxic.

In a traditional lithium-ion battery, lithium ions flow between a negatively charged anode, usually graphite, and the positively charged cathode, usually cobalt oxide or lithium iron phosphate. Three years ago, an MIT team led by Belcher reported that it had engineered viruses that could build an anode by coating themselves with cobalt oxide and gold and self-assembling to form a nanowire.

In the latest work, the team focused on building a highly powerful cathode to pair up with the anode, said Belcher, the Germeshausen Professor of Materials Science and Engineering and Biological Engineering. Cathodes are more difficult to build than anodes because they must be highly conducting to be a fast electrode, however, most candidate materials for cathodes are highly insulating (non-conductive).

To achieve that, the researchers, including MIT Professor Gerbrand Ceder of materials science and Associate Professor Michael Strano of chemical engineering, genetically engineered viruses that first coat themselves with iron phosphate, then grab hold of carbon nanotubes to create a network of highly conductive material. (The virii were a common bacteriophage, which infect bacteria but are harmless to humans.)

Because the viruses recognize and bind specifically to certain materials (carbon nanotubes in this case), each iron phosphate nanowire can be electrically “wired” to conducting carbon nanotube networks. Electrons can travel along the carbon nanotube networks, percolating throughout the electrodes to the iron phosphate and transferring energy in a very short time.

The team found that incorporating carbon nanotubes increases the cathode’s conductivity without adding too much weight to the battery. In lab tests, batteries with the new cathode material could be charged and discharged at least 100 times without losing any capacitance. That is fewer charge cycles than currently available lithium-ion batteries, but “we expect them to be able to go much longer,” Belcher said.


A display of MIT’s virus-built battery (the silver-colored disc), being used to power an LED. (Source: MIT)

The prototype is packaged as a typical coin cell battery, but the technology allows for the assembly of very lightweight, flexible and conformable batteries that can take the shape of their container.

Last week, MIT President Susan Hockfield took the prototype battery to a press briefing at the White House where she and US President Barack Obama spoke about the need for federal funding to advance new clean-energy technologies.

Now that the researchers have demonstrated they can wire virus batteries at the nanoscale, they intend to pursue even better batteries using materials with higher voltage and capacitance, such as manganese phosphate and nickel phosphate, said Belcher. Once that next generation is ready, the technology could go into commercial production, she said.

January 19, 2009: Worldwide nanotechnology thin film lithium-ion batteries are poised to achieve significant growth as units become more able to achieve deliver of power to electric vehicles efficiently, according to a new report by Electronics.ca Publications.

The market research network predicts the market for thin-film lithium-ion batteries will reach $9.1 billion by 2015, from $911 million in 2008.

According to the study, economies of scale leverage the lithium-ion battery nanotechnology advances needed to make lithium-ion batteries competitive. Unlike any other battery technology, the report said, thin-film solid-state batteries show very high cycle life. Using very thin cathodes batteries have been cycled in excess of 45,000 cycles with very limited loss in capacity. After 45,000 cycles, 95% of the original capacity remained.

Then there is the problem of translating the evolving technology into manufacturing process. What this means is that the market will be very dynamic, with the market leaders continuously being challenged by innovators, large and small that develop more cost efficient units. Systems integration and manufacturing capabilities have developed a broad family of high-power lithium-ion batteries and battery systems.

Electric Vehicles depend on design, development, manufacture, and support of advanced, rechargeable lithium-ion batteries. Batteries provide a combination of power, safety and life. Next-generation energy storage solutions are evolving as commercially available batteries. Lithium-ion batteries will play an increasingly important role in facilitating a shift toward cleaner forms of energy.

December 30, 2008: Ener1 Inc., which develops nanotech-based batteries and fuel cells, will switch the listing of its common stock from NYSE Alternext U.S. to the Nasdaq after the close of 2008, according to a company news release. The company’s shares will trade on Nasdaq on January 2, 2009 and will continue to be listed under the symbol HEV.

This decision was reached “after careful consideration of capital market alternatives and analysis of the electronic market model, which provides added visibility to our investors,” said Charles Gassenheimer, Ener1’s chairman and chief executive. “We believe that NASDAQ’s electronic multiple market maker structure will provide our company with enhanced exposure and liquidity, at the same time providing investors with the best prices, the fastest execution and the lowest cost per trade.”

Ener1 develops and manufactures compact, high performance lithium-ion batteries to power the next generation of hybrid and electric vehicles. In addition to battery technology, Ener1 develops commercial fuel cell products through its EnerFuel subsidiary and nanotechnology-based materials and manufacturing processes for batteries and other applications through its NanoEner subsidiary.

Dec. 22, 2008 – In the end, all it took was an extra greenback to tip the scales for Panasonic’s pursuit of Sanyo.

After rebuffs from a key Sanyo shareholder for what were thought as lowball offers (first ¥120/share, then ¥130/share), Panasonic apparently now has a green light from all three top shareholders with a gently sweetened ¥131/share offer — which was actually below Sanyo’s share price as of Saturday (¥136/share). All three top Sanyo stakeholders — Sumitomo Mitsui Banking, Daiwa Securities, and now Goldman Sachs — apparently have accepted the new bid. The Nikkei daily noted that Goldman Sachs apparently didn’t need much to tip its opinion in favor of selling its stake, having been forced to reevaluate its opinion of Sanyo’s long-term viability as a solo enterprise given plunging earnings for electronics firms — and the fact that Goldman itself posted a $2B quarterly loss over the weekend, the first since its 1999 IPO.

The preferred shares held by the three firms, equal to about 70% of the company’s ownership, will be converted to common stock in early 2009 for roughly ¥567B, and Panasonic is expected to push to convert Sanyo into a wholly owned subsidiary. The firm also is likely to sell about ¥400B worth of bonds to help finance the deal, and invest another ¥100B into Sanyo for capex and operations, reports the paper. After alignment, the firms expect to achieve about ¥40B in “synergy” at the operating-level profit from energy-related operations alone, plus another ¥40B for other operations, overlaps, and cost-cutting, reports the paper.

The Nikkei Veritas adds that Panasonic’s financial muscle helped push this deal through, with a >¥100B pipeline stuffed with planned investments including plants for plasma and LCD panels and lithium-ion batteries, plus additional projected investments for Sanyo’s battery technology. But the Nikkei daily notes that Panasonic has its work cut out to figure out how to restructure Sanyo’s money-losing operations in semiconductors and white goods, areas with some overlap between the two firms.

Meanwhile, three years after their initial investments, Goldman, Daiwa, and Sumitomo Mitsui will have achieved about a 23% annualized return on their initial investments (¥125B, ¥125B, and ¥50B, respectively), notes the Nikkei daily.

And while the two firms dig into strategies and “synergy” efforts, the move is likely to have a broader influence for electronics industry M&A, notes the Nikkei daily. Japanese production of electronic devices surged from ~¥11T in 1980 to ¥26T in 1990, but has since stalled back down to ¥20T, according to the paper, citing statistics from the Ministry of Economy, Trade and Industry (METI). Yet despite the slump, nine domestic firms are still battling one another: Panasonic, Sony, Sharp, and Sanyo in home electronics; Hitachi, Toshiba, and Mitsubishi Electric in electrical machinery; and NEC and Fujitsu in telecom equipment. For example, eight firms in Japan are fighting over a cell phone market with 50M units and most are swimming in red ink; meanwhile Nokia sells 400M units/year and has 12% margins, the paper notes. Other sectors are likely to see consolidation too — LCD TV sales will drop 16% in 2009, according to US firm DisplaySearch, while Gartner sees a -16.3% plunge in chip sales in 2009 following a -4.4% decline in 2008.

by Dick James, senior technology adviser, Chipworks

Editor’s Note: Each day during IEDM, Chipworks’ Dick James will share his thoughts on what he saw as the best presentations.

It’s hard to discuss the Monday morning plenary sessions without getting a bit linear. First up was Peter Fromherz from the Max Planck Biochemistry Institute in Munich, talking about interfacing chips with brain cells. That sort of topic usually makes my eyes roll up, but he actually had some good pragmatic stuff. Question: How do you monitor brain cells without affecting them? Answer: Lay them on a transistor gate so that the voltage pulses turn the transistor on, and measure the response.

Similarly, to put a voltage pulse into a cell without contaminating it, you lay it on a capacitor with a physiologically inert HfO2 or TiO2 dielectric, and pulse the capacitor. The actual link between the cell and the inorganic devices relies on the response of the ions within the electrolyte containing the cell and device, influencing the ion channels that are the communication media of nerve cells. All the semiconductors have a passivation layer so that the electrolyte does not affect the chips.

Fromherz had an impressive video of a slice of brain laid over an array of transistors, showing how a pulse at one point influenced the neurons and was transmitted through the tissue, its movement monitored by the transistor array. A bit simplistic — as well as a bit gruesome — but a good example of how basic research could lead to the prosthetics of the future. The blind may yet see, if this kind of experiment pays off.

Stefan Lai, formerly of Intel, then Ovonyx, and now independent, gave a review of non-volatile memories, working his way through NOR and NAND flash to cross-point memories such as the SanDisk/Matrix, to his recent phase-change memories and IBM’s Millipede MEMS-based system. Asked when PCM would appear in a real product, he declined to comment — but given the list of pros and cons (mostly cons) for PCM he had shown earlier, it doesn’t look any time soon.

As the session stretched into numb-bum time (there are no morning or afternoon breaks at IEDM, and three hours is a long time to sit in a conference room), Tatsuo Saga of Sharp gave a good review of the PV options (though at times a little sales-pitchy and promotional). One surprising stat: some of the more complex solar cells are now closing in on 40% conversion efficiency.

Having just installed geothermal heating at home, he had me thinking about solar PV as well — not an obvious thing for Canada where I live, but Ottawa is actually south of a lot of the installations in Germany, which has gone gung-ho for renewable energy of all sorts. Unfortunately, now that fossil fuel prices have fallen off a cliff, the economics have changed and the payback time will be a lot longer — exactly what torpedoed the solar movement back in the ’80s.

On the way out of the hall for lunch I crossed paths with Stanley Wolf, author of what is still the most comprehensive set of reference books for the industry, “Silicon Processing for the VLSI Era” — now a slightly quaint title, since time has gone by since they were first launched. I mention this because Stan is thinking of updating volume 1, last revised in 2000, and needless to say quite a lot has happened since then in chip processing. Keep an eye on his Lattice Press Web site to see when the new version comes up.

Afternoon sessions

The conference proper started in the afternoon with the usual irritating plethora of parallel sessions. The AMD/IBM/Freescale alliance gave a paper on embedded carbon-doped epitaxial source/drains to stress nMOS transistors (paper 3.1), which gave a decent 9% Ion increase over the equivalent device using nitride + memorized stress. Unfortunately good epi growth requires low-doped drain extensions, so there is still work to do to get the technique integrated, increased series resistance is not a price we want to pay.

This was followed (3.2) by an examination by Fujitsu of the mechanism of the stress memorization techniques (SMT). The gate polysilicon is amorphized by implantation, then capped with nitride. During the source/drain anneal the amorphized silicon expands as it re-crystallizes, but since it is constrained by the cap and sidewall spacers (SWS), compressive vertical stress is applied to the channel underneath. After the anneal the nitride cap is removed, and a conventional contact etch-stop liner (CESL) used to apply lateral tensile stress. We tend to think of nMOS stress as only needing to be tensile, but in the z-direction it’s compressive stress that helps for both nMOS and pMOS.


Figure 1: Effect of channel stress on nMOS & pMOS transistors. [1]

As part of the investigation, arsenic and phosphorus source/drain implants were tried, and oxide and nitride sidewall spacers. As would be expected, the harder nitride SWS is more effective at applying stress to the channel, and possibly the greater atomic mass of the arsenic increases the expansion tendency of the gate polysilicon.


Figure 2: Effect of SMT on electron mobility. [2]

Then we got into one of those timing clashes that IEDM is notorious for — two interesting papers in different sessions at the same time! Both by Intel, as it happened, one on CMP and the other on the use of (110) silicon — I picked CMP, since the Intel 45nm metal gate structure would not have been manufacturable without a highly tuned CMP capability.

That was the message from Joe Steigerwald (2.4), and it jives with our analysis when we looked at the structure. CMP is used to polish back the surrounding dielectric to expose the sacrificial poly gates (POP step), to polish down the final metal fill and electrically isolate the metal gates, and of course for all the copper levels in the BEOL. This is complicated, and arguably helped, by the density of the real and dummy gates — see our pictures below.


Figures 3-4: Intel’s metal gates in cross-section and plan-view. (Source: Chipworks)

If you look at the structure, we can see that under-polish at the POP step will not expose the poly for removal, and over-polish could get into the raised epi pMOS source/drains. Similarly under-polish at the metal removal could leave gates shorted together, and affect the contact etch yield, and over-polish will leave them too thin and high-resistance, especially pMOS if too much of the Al-Ti fill is removed. One thing not mentioned is the thin layer of AlTiO on the top of the gates, presumably a side-effect of the CMP — or are they using E-CMP (electrochemical CMP)?

The standing-room only paper of the afternoon was an invited paper given by Yi Cui of Stanford, on nanowire batteries — they are doing some really interesting work on using silicon nanowires to replace graphite as the anode in lithium-ion batteries. Bulk silicon has good performance, but limited surface area, and expands too much as charge is stored to be a practical device. With nanowires there is of course much greater surface area, and room for the nanowires to expand. The bottom line is that there is potentially as much as ten times as much charge storage capacity as the equivalent conventional Li-ion battery. They are also working on LiMn2O4 nanorods to improve cathode performance, and getting encouraging results. After the plenary session on solar, which requires the extensive use of batteries if you want to go off-grid, this paper appeared to strike a chord with attendees; there was great enthusiasm for this work.

In the evening was the reception, a good chance to catch up with colleagues, and confirm that engineers and scientists are the same as normal folks — give them food and wine, and you need ear protection after a while! — D.J.

References

[1] S. Thompson, et al, A 90-nm logic technology featuring strained-silicon; IEEE Transactions on Electron Devices; Volume 51, Issue 11, Nov. 2004, pp. 1790 — 1797.
[2] T. Miyashita et al, “Physical and Electrical Analysis of the Stress Memorization Technique (SMT) using Poly Gates and its Optimization for Beyond 45nm High Performance Applications,” Proc. IEDM 2008, pp. 55-58.

DICK JAMES is a 30-year veteran of the semiconductor industry and the senior technology analyst for Chipworks, an Ottawa, Canada-based specialty reverse engineering company that gets inside technology and takes apart ICs and electronics systems in order to provide engineering information for its customers. Contact him at 3685 Richmond Road, Suite 500, Ottawa, ON, K2H 5B7, Canada; ph 613/829-0414, fax 613/829-0515, [email protected], www.chipworks.com.

December 2, 2008: The University of Colorado has been awarded U.S. Patent number 7,426,067 “Atomic layer deposition on micro-mechanical devices,” which has been exclusively licensed to ALD NanoSolutions, Inc.

ALD NanoSolutions is focused on commercializing its nano-coating processes, called Particle ALD and Polymer ALD, and is targeting collaborative research agreements with domain partners for the discovery and validation of innovative composite materials in selected industries.

This patent describes a method and technology for conformal coating Micro/Nano Electro Mechanical Systems (MEMS/NEMS) by atomic layer deposition (ALD) for a wide variety of purposes, including hermetic sealing, reducing stiction, surface change control, creating biocompatible films, optical properties control, chemical corrosion protection layers, and electrically insulating layers. The patented technologies, methods and materials can be used to fine tune the properties and function of MEMS/NEMS, allowing new application opportunities and/or superior lifetime reliability.

ALD NanoSolutions, also announced that it has received a $100,000 Phase I Small Business Technology Transfer (STTR) grant from the U. S. Department of Energy, titled “Novel ALD-Coated Nanoparticle Anodes for Enhanced Performance Lithium-Ion Batteries”. This award, will develop nanomaterial technology to enable advanced Li-ion batteries with improved stability and performance.

“In order to realize the promise of novel electrode nanomaterials, ALD coatings are needed to passivate these particulate electrode materials with conformal ultrathin films. Such novel nano-engineered electrodes will address not only capacity retention and power issues, but also the safety problems associated with Li-ion batteries,” said Karen Buechler, president of ALD NanoSolutions, in a statement.