成果報告書詳細
管理番号20110000001691
タイトル*平成22年度中間年報 「省エネルギー革新技術開発事業/挑戦研究/冷却フリー・大出力ダイヤモンドパワーデバイスの研究開発」
公開日2012/2/17
報告書年度2010 - 2010
委託先名独立行政法人産業技術総合研究所 独立行政法人物質・材料研究機構 国立大学法人大阪大学
プロジェクト番号P09015
部署名省エネルギー部
和文要約和文要約等以下本編抜粋:1. 研究開発の内容及び成果等 (1)高耐圧デバイス開発 ア)縦型デバイスプロセス開発 (産総研 分担) パワーデバイスの動作層であるp-ドリフト層を低欠陥で成長することは、大面積デバイスを動作させる最重要課題である。通常の材料では高濃度層(この場合p+コンタクト層)上にドリフト層を成長させるが、ダイヤモンドの場合結晶の結合エネルギーが極端に大きくドリフト層に多数の欠陥が生成する。このため、我々は低欠陥のドリフト層成長を最優先にし、縦型構造を実現するためには、ドリフト層成長後にコンタクト層を成長する逆転構造の実現をポイントとして開発を進めた。この場合基板側をショットキーまたはコンタクト層/オーミック部を開口する複雑なデバイスプロセスとそれに伴う成長技術が必要になる。H21年度はこの縦型構造を実現するためのドライエッチング技術/開口技術などのプロセス要素技術を開発し、開口部100μmφの開口プロセスを可能にした。H22年度ではこれを受けて、前処理及びエッチング条件の最適化を行い、デバイスプロセス全体の技術を確立し、p-ドリフト層、p+コンタクト層成長、ショットキー、オーミック電極形成して、デバイスとしての動作まで実施した。なお、エッチング前の諸コンタミの除去を行うことの可能なアッシング装置(AIST10-2)を導入した。
英文要約Title: Development of Cooling System Free High Power Diamond Power Diode (FY2009-2011) FY2010 Annual Report
1) High breakdown voltage diode: To utilize p+ contact/ p- drift layer on insulating diamond substrate to realize vertical structure diamond power diode, the fabrication process is developed by using ICP dry etching method. For high breakdown voltage device, the Field Plate (FP) structure is also designed by simulation and found that maximum electric field can be deduced to less than 1/3 of the conventional structure. Using these technologies, the high voltage (1.8kV) vertical structure device was developed using Al2O3 insulator as FP. For the high performance device, high quality epitaxial layer is of primary importance. For this purpose, we have launched the crystal analysis. Very high stress region of compressive and tensile is observed by Raman peak shift imaging for the dislocation center called “Band A”, which is estimated as 45 deg mixed dislocation. From the analysis of reverse current-voltage characteristics it was revealed that poor diodes can be categorized into two groups; one is continuous increase due to crystalline defects and the other saturates at a certain current level that comes from the imperfection of metal/semiconductor interfaces. 2) High current density diode: Theoretical calculation for the on resistance and breakdown voltage is carried out for the punch through type vertical structure diode, and the drift layer doping concentration and its thickness are optimized associated with p+ series resistance, that is experimentally verified. The vertical device was developed and high current density up to 800A/cm3 was measured at 250C operation. Newly-proposed tungsten carbide showed good stability for high current injection of 1000A/cm2 and high temperature stability at 400℃. Pealing of electrodes observed at higher injection of >1kA/cm2 might come from mechanical deterioration caused by local heating of injection. 3) Diode dynamic operation: For high temperature operation without cooling system, the Jisso technologies are of importance. For this purpose, 250C durable package was designed and fabricated using Al2O3 ceramic and FeNiCo metal and tested for high voltage and high current density operation. IV characteristics were evaluated from RT to extremely high ambient temperature with the package. CV characteristics, influences of pulse duty for forward conduction, self-heated up phenomenon with conduction and switching loss, heat radiation were also measured. The switching characteristics of the device was characterized and evaluated with the use of Si MOSFET. The switching response of the diamond Schottky barrier diode was performed on the basis of double pulse method. The forward conduction current, reverse blocking voltage, dv/dt and di/dt were tested as the parameter of switching characteristics, and fast switching and no reverse recovery feature of majority carrier device was clarified for the diamond device.
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