成果報告書詳細
管理番号20120000000888
タイトル*平成23年度中間年報 次世代パワーエレクトロニクス技術開発(グリーンITプロジェクト) 次世代SiC電力変換器基盤技術開発
公開日2012/8/2
報告書年度2011 - 2011
委託先名技術研究組合次世代パワーエレクトロニクス研究開発機構
プロジェクト番号P09004
部署名電子・材料・ナノテクノロジー部
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)事業目的、概要
本技術開発では、材料特性に優れたSiC半導体の結晶基板(ウエハ)評価から、デバイスモジュール開発、さらにSiCパワーデバイスを用いたデータセンタ用高効率サーバ電源、太陽光発電用高効率パワーコンディショナの機器・システムの実証に至る研究開発を以下の通り行う。
革新的電力変換器を実現するために、高温環境においても超低オン抵抗を有する次世代SiCパワースイッチングデバイスに必要な革新的デバイス構造/高耐圧デバイス化プロセス、高信頼化技術を開発する。次世代パワーデバイスを利用した革新的電力変換器設計技術と高温実装技術等を開発し、それらを取り入れた電力変換器の高出力パワー密度性能の検証を行う。
英文要約Title:Future Power Electronics Technology Development/(FY2009-FY2012)FY2011 Annual Report. 3. Future SiC Power Converter Technology:

We have developed 250 cc, 10 kW inverter using SiC power devices. To fully utilize the advantages of SiC power devices, it is necessary to reduce the inductance of the power module. This was done by using a ceramic substrate with a current return layer, attaining a low inductance of 5 nH. The low inductance greatly reduced the surge voltage at the switching transient. The cooling performance of the inverter was designed so that its driving temperature becomes 220 ?C at an output power of 10 kW using thermal fluid simulation. A continuous switching test equivalent to motor driving output power of 10 kW showed that the high output power density of 40 kW/L can be achieved.
A compact EMI filter was specially designed and elaborated to reduce noise emitted from our inverter. We found that the inverter equipped with this filter can fully satisfy a criterion specified in IEC61800-3 category C3 even in switching at 50 kHz.
SiC device shows a lower switching loss property. Therefore, its high frequency operation surely results in miniaturization of LC filter components. A DC chopper using an all-SiC module was also fabricated and compared in power loss with the use of the previously reported Si-IGBT+SiC-SBD hybrid module. It was found that all-SiC module can make it possible to switch even at a frequency of 100 kHz.
Highly reliable SiC die attachment systems using eutectic Au-Sn (m.p. = 280°C) and Au-Ge (m.p. = 356°C) solders were well fabricated on Cu-SiN substrates. Reliability test results revealed that both die attachment systems using either Au-Sn or Au-Ge could withstand storage for > 3000 hours at 250°C and thermal cycle stress of > 1500 cycles between ?40°C and 250°C. Additionally, a new die attachment using eutectic Zn-Al solder (m.p. = 356°C) was investigated. Superior wettability, reproducibility and reliability were achieved in the soldering process.
For the purpose of increased reliability of the joint of SiC chip to the Cu-SiN substrate, the effectiveness of introducing TaN diffusion barrier (DB) was evaluated. Samples with TaN DB which were storage for 1500 hours at 330°C showed 56 MPa for the die shear strength. The sample without DB and without storage showed 20 MP and 60 MPa, respectively. This indicates their high temperature reliability. Cu-Sn diffusion bond was tested as a new joint technology. Cu-Sn is one of the candidates for transient liquid phase sintering process. Cu-Sn was melted at 260°C in the first heat cycle. But it was not melted afterward. The excellent strength property of 40 MPa was confirmed at 300°C. In order to analysis turn-off surge voltage behavior of SiC power devices, the circuit model of SiC SBD has been proposed. The proposed model has a good agreement between simulation and experimental results and also shows the effect of dynamic junction capacitance characteristic of SiC SBD.
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