International Electron Devices Meeting—IEDM 2015


Gary M. Dolny at Bodo’s Power Systems

Gary M. Dolny

The 2015 International Electron Devices Meeting, IEDM, took place at the Washington D.C. Hilton Hotel from December 7-9, 2015.  The conference was preceded by day-long short courses on Sunday, December 6 and a program of 90-minute tutorials on Saturday, December 5. IEDM is sponsored by the Electron Devices Society of the Institute of Electrical and Electronics Engineers (IEEE) and is considered the premier forum for reporting breakthroughs in the technology, design, manufacturing, physics and the modeling of semiconductors and other electronic devices. This year’s conference was attended by nearly 1400 scientists and engineers from around the world representing all areas of micro and nanoelectronics.

The conference technical program consisted of 226 papers chosen from 588 submissions, as well as a rich offering of other events, including evening panel discussions, special focus sessions, IEEE awards and an entrepreneurial luncheon sponsored by IEDM and IEEE Women in Engineering.  The low percentage of acceptances guarantees a program of high quality presentations.

“From its inaugural meeting until today, the IEDM conference has been the place where breakthroughs that drive the electronics industry forward are unveiled,” said Mariko Takayanagi, IEDM 2015 Publicity Chair and Senior Manager at Toshiba. “For example, at the IEDM in 1975 Intel’s Gordon Moore gave a talk that refined his earlier prediction of transistor scaling into what has since become known as Moore’s Law. That tradition of attracting the best speakers and a large, diverse audience from around the world continues, with a focus this year on devices intended to support the Internet of Things and other emerging areas of importance that depend upon advances in semiconductor technology.”

The power semiconductor industry was well represented at this year’s IEDM with several conference sessions devoted to topics of interest to the field.  Power devices were also the subject of one of the conference’s Special Focus sessions entitled “Advances in Wide Bandgap Power Devices”.  These Special Focus sessions consist of a series of invited talks by top experts in the field and are intended to highlight areas of increasing technical and commercial importance.

The technical presentations showed a clear consensus that wide-bandgap materials, especially gallium nitride, are the future of the power semiconductor industry. High electron-mobility transistors (HEMTs) made from GaN were shown to have great potential for reducing conduction and switching losses in power applications although some technical hurdles still remain.  These include issues with material quality, reliability, cost, and the difficulties associated with producing true enhancement mode devices. 

Several presentations discussed the phenomena of current collapse and dynamic on-resistance.  

These are manifest as a decreased output current and increased on state resistance after reverse bias due to the presence of electron traps.  A research group from Fujitsu, Japan, showed that a novel double-layer silicon nitride passivation technique was effective in alleviating these problems resulting in basic reliability for commercial products [1].  A team led by the Massachusetts Institute of Technology, USA, drew a similar conclusion, and indicated that with proper device passivation stable devices can be achieved [2].  Additional work by On Semiconductor, Belgium, University of Bristol, UK, and University of Padova, Italy, studied the impact of buffer layer leakage on the intrinsic reliability of 650V GaN HEMTs[3].  They showed dynamic Ron to be highly voltage dependent and could be completely suppressed under certain bias conditions.

HRL Laboratories, USA, presented a study on increasing the switching frequency of GaN HFET DC-DC converters.   They showed that in hard switched applications the performance benefits of GaN may be outweighed by the cost and reliability risks of the new technology [4].  They further concluded that at 600V, GaN offers more value in softswitched applications compared to Si, and could open new markets that cannot be addressed by conventional Si devices.  Using a figure of merit analysis they predicted that GaN ICs in 400V soft-switched converters could achieve frequencies beyond 100MHz.

A group from Taiwan Semiconductor Manufacturing Corporation, Taiwan presented next generation CMOS compatible GaN-on-Si transistors [5].  They demonstrated enhancement-mode HEMTs from 100V to 650V fabricated on GaN-on-Si wafers. Their devices showed good performance in converter applications and have passed industrial reliability qualification, including 1000 hours of high-temperature reverse bias stress.

Although most of the presentations focused on GaN, silicon carbide also received attention.  A group from ST Microelectronics, Italy, noted that SiC devices have been in the market for several years and have demonstrated excellent performance and reliability [6].  The SiC devices are expected to dominate the high-power applications.

Looking even further into the future, a group from Tottori University, Japan, presented a study of avalanche breakdown in diamond for power device applications [7].  They concluded that the material could potentially have advantages in future high-power, high-temperature applications.  

2015 was the final year that IEDM will be held in Washington DC.  After rotating between Washington D.C. and San Francisco, CA for more than twenty years, starting in 2016 the conference will be permanently held in San Francisco.  Next year’s IEDM will be held from December 5-7 at the Hilton San Francisco Union Square, San Francisco CA, USA.  Additional information is available on the conference website http://ieee-iedm.org.

Gary Dolny can be contacted at [email protected].

Source: Bodo's Power Systems, February 2016