Vol.6 No.3 2014

Research paper : Development of diamond-based power devices (S. SHIKATA et al.)−153−Synthesiology - English edition Vol.6 No.3 (2013) as main defect types and rough defect density are being discerned,[35][36] and detailed investigation of defects’ influence to the device characteristics is being done. We aim to achieve the practical vertical structure device and the verification of several to 100 A devices.For transistors, many researches have been studying diamond to achieve high speed and high frequency application using the lateral device structure.[37]-[39] However, vertical device structure with high breakdown voltage and high output current is mandatory for the power device, and it is necessary to speed up research based on past findings. We plan to investigate the superiority quantitatively, including the technology to achieve cooling free operation at high temperature through device implementation.Table 1 shows the roadmap of the wafer and device created through surveying industry and academia, based on the technological strategy map of METI. For wafers, the supply system for 2-inch wafers is built jointly with companies to help promote the device research at the companies and universities. Also, the developments of practical wafers such as low-resistance and low-defect wafers are planned. For devices, the researches for low-defect epitaxial growth and ②High performance, high output diode③Low resistance wafer②Low defect waferLow defect < 1000/cm2Practical use of diode4 inch device grade2 inch device grade3 inch device gradeNEDO Project②Low defect waferLow defect < 5000/cm26 inch4 inch①Low-defect epiUsage expansion6 inch, 8 inch device grade①Wafer manufacturing technology for R&DCopypn junction④Large surface areaLarge CVD device, processing, etc.Refractory electrodeVertical structureOperation at 250 ℃High voltageHigh current density1 kA/cm2ReliabilityTechnology for large diameter applicationProduction technology / cost decrease・Achievement of high performance (usage deployment)・Achievement of low costPower module verification③Transistor developmentCooling system-free technology・Achievement of high performance (usage deployment)・Achievement of low costSynthesis & processing base for 2 inch waferPractical use of power module3 inchStart supply of 2 inchDiffusion to other countriesWaferDevice2 inch wafer developmentDevice performance verificationIndustry → civilian, Transportation20402030202020152010 year5000 2000 1000 500 200 100 50 20 10 5 2 1 SiSiC10 20 50 100 200 500 1 k 2 k 5 k 10 k 100 10 1 0.1 0.01 In wheelInside range of diamondIn motorOutside range of diamondSmall, high outputExample: High voltage SBD for train Wind power generation, etc. Downsizing distribution system・Nuclear power plant・Space developmentOperating temperature (C)Radiation dose (Gy)600500400300200100DiamondHigh-temperature operationRadiation resistance(4) Others(1) Cooling system free, ultra downsizing(2) High current density(3) High voltage, high current densityPower density (W/cm3)103104106107108109105Power sourceMotorHigh output marketMedium output marketLow output marketRated voltage (V)Trunk line power systemDistribution systemTrainsVesselsSW power sourceServer WSAC adapterElectrical appliancesEVHEVGeneral-useCommunication devicesDistributed industryElectrical components of automobilesOffice & home appliancesRated current (A)Pulse power sourceBooster circuitTable 1. Roadmap for the diamond power device and waferFig. 13 Prospect of diamond power device application


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