Direct bonding of widegap semiconductors and diamond for high-efficiency devices and investigation of bonding interface characteristics

2019 Fiscal Year Final Research Report

• Project/Area Number: 18K19034
• Research Category: Grant-in-Aid for Challenging Research (Exploratory)
• Allocation Type: Multi-year Fund
• Review Section: Medium-sized Section 30:Applied physics and engineering and related fields
• Research Institution: Osaka City University
• Principal Investigator: Shigekawa Naoteru 大阪市立大学, 大学院工学研究科, 教授 (60583698)
• Co-Investigator(Kenkyū-buntansha): 嘉数 誠 佐賀大学, 理工学部, 教授 (50393731) ; 梁 剣波 大阪市立大学, 大学院工学研究科, 准教授 (80757013)
• Project Period (FY): 2018-06-29 – 2020-03-31
• Keywords: ダイヤモンド / ワイドギャップ半導体 / 直接接合 / 熱処理効果

Outline of Final Research Achievements

Diamond FETs were successfully fabricated by growing diamond epi layers on single crystal diamonds directly bonded to Si substrates and performing device process, which indicated that the directly-bonded interfaces are equipped with enough thermal tolerance from the practical viewpoint. GaN epi layers were successfully bonded to diamonds. The bonding interfaces revealed a thermal tolerance at 600 degrees Celsius. TEM observation of GaN/diamond junctions revealed that the intermediate layer formed at bonding interfaces got thinned by annealing. Al and Cu were also bonded to diamonds. The bonding interfaces revealed the thermal tolerance up to temperatures close to the metling points of metals.

Free Research Field

半導体デバイス

Academic Significance and Societal Importance of the Research Achievements

接合直後のダイヤモンドと異種材料（GaN、金属）の直接接合界面が準安定状態にあることを示すとともに、ダイヤモンド／Si界面において、界面の耐熱性の起源を示唆する結果を得た。ダイヤモンド／GaN界面がGaN素子作製プロセスに必要な耐熱性を有することを示し、従来技術を凌ぐ高熱伝導率GaN素子を実現可能であることを明らかにした。