Vol.3 No.4 2011

5/72

Research paper : R&D of SiC semiconductor power devices and strategy towards their practical utilization (K. Arai)−246−Synthesiology - English edition Vol.3 No.4 (2011) switching in wide blocking voltage range (MOS-FET and junction FET) will alleviate the limitations of the silicon power device. The power loss during device operation can be reduced by low on-resistance and high-speed switching, and with the downsizing and simplification of the heat dissipation structure (heat release fin or fan) as well as downsizing of the passive components through use of high-frequency, significant cost reduction can be expected for power electronics equipment such as inverters, and this will eventually lead to energy saving. The increased power density (or the downsizing) of the electric power converter is an important index in introducing the converter to society, and has been indicated in the roadmap (Fig. 2). In addition, the high blocking voltage, high-temperature operation, and high breakdown resistance of the SiC power device are expected to allow pioneering new fields of power electronics application. To “achieve the ubiquitous power electronics” that support thorough energy saving, the practical utilization of the SiC device is expected to play an extremely important role.2.2 Goals during the ETL period (1993~2000)Material research should not stop at the search in the style of the material science, but should aim for the practical utilization by clarifying the principle superiority through creation of actual devices in a wide sense. The potential of SiC, GaN, and diamond as devices were carefully reviewed, and the research subjects and the goals were narrowed down. The goal was set “to show that SiC possessed principle superiority in the power device application against current silicon in the wide band gap semiconductors, and also to show that SiC has a leading edge compared to other wide ・ Demonstration of application to equipment (joint research with industries)・ Establishment of wafer venture (LLP)・ Concurrent development of GaN devices・ Participation of experienced people from industries・ Construction of device fabrication line ・ Clarification of possibility of SiC power devices and equipment (wafer quality, low-loss and reliability of devices, increased power density of equipment)・ Concurrent development of demonstration, core, and pioneering researches・ Total solution strategy (concurrent development of wafer ‒ device ‒ equipment)・ Construction of SiC basic technology in Japan・ NEDO project starts・ Clarification of goal →Power device・ Industrial Transformation Research Initiative (manufacturing line for SiC device prototype) (FY 2008~2011)・ Development of Basic Technology for Future Power Electronics (FY 2009~2012)・ “Development of Basic Technology for Power Electronics Inverter” (FY 2006~2008)・ 3 topics subcontracted to AIST (module, power supply, system) (FY 2002, 2004, 2003~2006 respectively)・ 2 topics in open proposal for energy saving (FY 2003~2005)・ Development of Basic Technology for Ultralow Loss Power Device (FY 1998~2002)・ Survey (FY 1994~1995) and leading research (hard electronics) (FY 1996~1997)Energy Semiconductor Electronics Research Laboratory, AIST (2008.4~)Power Electronics Research Center, AIST(2001.4~2008.3)Material Science Dept., ETL(1993~2001.3)・ International exchange and collaborationOrganizationMain activityGoalMain resultNotesTable 1 Flow of the activities GaNHetero-epitaxial substrateLow-loss, high-frequency, high-current horizontal device (HEMT)SiCLarge bulk substrateLow-loss, high blockingvoltage, high-currentvertical device(MOSFET, JFET)VS : Saturated drift velocityEB : Breakdown fieldMJ=(EB・ VS)2/4π2Figure of merits for semiconductors: (Johnson index)Diamond 5.6GaN 2.63C-SiC 3.06H-SiC 3.04H-SiC 3.5Si 0.3[MV/cm]Shielding unnecessaryCooling unnecessaryControl of various enginesControl and monitoring of nuclear powerGeothermal use, fossil fuel explorationSpace explorer, satellitesRadiation use (medical, SOR)Satellite communication, broadcast (solidification of traveling wave tube)Multimedia (mobile communication base station)Global network of electric powerNext-generation high-speed traffic systemElectric vehicleDownsizing power supply for office appliancesUltrahigh-frequencyoperationUltralow loss2000600300DiamondSiC GaN Si 1101001000Ultrahigh-temperatureoperationBreakdown fieldFig. 1 Hard electronics (the world of wide-bandgap semiconductors)In the wide bandgap semiconductor, the dielectric breakdown field is large and the saturated mobility rate is also large. Therefore, the figure of merits of the semiconductor is one digit greater compared to the silicon semiconductor devices. The on-loss (current-conducting loss) of the SiC power device is estimated to be 1/200 of the Si device.

※このページを正しく表示するにはFlashPlayer9以上が必要です