Nano-level defect detection technique of sapphire substrate for LED with wide-field view laser microscope

2018 Fiscal Year Final Research Report

• Project/Area Number: 16K14144
• Research Category: Grant-in-Aid for Challenging Exploratory Research
• Allocation Type: Multi-year Fund
• Research Field: Design engineering/Machine functional elements/Tribology
• Research Institution: Niigata University
• Principal Investigator: Nitta Isami 新潟大学, 自然科学系, 教授 (30159082)
• Research Collaborator: Tsukiyama Yosuke ; Kanno Akihiro
• Project Period (FY): 2016-04-01 – 2019-03-31
• Keywords: 設計工学 / 機械機能要素 / トライボロジー / レーザ走査 / 欠陥検査

Outline of Final Research Achievements

With the increasing precision of equipment, the technology for producing high-precision smooth surfaces has become important. In sapphire wafers used for LED fabrication, flaw detection is an urgent issue because fine polishing flaws affect the performance. At present, flaw detection is performed using multiple large-scale inspection devices. In this study, it was investigated whether nano-level flaw inspection can be performed with a relatively small-sized device named a wide-field laser microscope with a field of view 400 times wider than that of a normal microscope. As a result, it showed that it was possible.

Free Research Field

機械工学

Academic Significance and Societal Importance of the Research Achievements

欠陥検査では，ラインセンサやCCDカメラ等を用いるのが一般的であり，多方面に利用されている．現在，欠陥検出への要求は対象欠陥の微小化と，検査領域の広範囲化がある．この2つの要求は相反するものであり，微小な欠陥検出のために光学系の倍率を上げると，観察領域は狭くなる．他にも，フィルムやガラスなどの薄い透明体に対しては，照明系の選択も難しくなり，従来のカメラ型システムが不得意な分野であり，新たな手法の提案が待たれている．
本研究では既開発の広視野レーザ顕微鏡がnmレベルの微細欠陥を検出できるかを調べた．その結果，サファイアガラスとSiウエハに作製した数nmの浅い欠陥でも検出できることを示した．