Spectro-photoelastic imaging of local strain fields in semiconductor devices

Research Project

Project/Area Number	17K05040
Research Category	Grant-in-Aid for Scientific Research (C)
Allocation Type	Multi-year Fund
Section	一般
Research Field	Crystal engineering
Research Institution	Kyoto Institute of Technology
Principal Investigator	Fukuzawa Masayuki 京都工芸繊維大学, 情報工学・人間科学系, 准教授 (60293990)
Project Period (FY)	2017-04-01 – 2021-03-31
Project Status	Completed (Fiscal Year 2020)
Budget Amount *help	¥4,810,000 (Direct Cost: ¥3,700,000、Indirect Cost: ¥1,110,000) Fiscal Year 2019: ¥910,000 (Direct Cost: ¥700,000、Indirect Cost: ¥210,000) Fiscal Year 2018: ¥1,040,000 (Direct Cost: ¥800,000、Indirect Cost: ¥240,000) Fiscal Year 2017: ¥2,860,000 (Direct Cost: ¥2,200,000、Indirect Cost: ¥660,000)
Keywords	結晶評価 / 残留歪み / デバイス局所歪み / 光弾性法 / 光弾性
Outline of Final Research Achievements	A scanning spectro-polariscope (SSP) and a near-infrared imaging polariscope with a scanning mechanism of the light incident angle (NIRIP+) have been developed to quantitatively characterize only local strain fields in semiconductor devices. Since they are designed to be applicable in 6-inch semiconductor substrates as it is even after device fabrication, local strain fields inside and outside the device can be examined without their partial relief by dicing or scraping. The NIRIP+ enabled us to selectively detect strain-induced birefringence in commercial off-axis SiC substrates by eliminating the effect of natural birefringence. By combining the NIRIP+ map with the photo-elastic coefficients of SiC crystal obtained experimentally by a simple load test, selective and quantitative imaging of local strain fields was achieved in commercial SiC substrates and devices. The SSP also enabled us to achieve quantitative imaging of local strain field in the Si devices before its dicing.
Academic Significance and Societal Importance of the Research Achievements	本研究成果の学術的意義は、半導体デバイス中の局所歪み場を大面積で可視化した点にある。X線回折やRaman 散乱では、測定領域の制限からダイシング後の小片しか評価できず、局所歪みの一部は緩和されていたが、本研究によって、局所歪みを緩和させずに評価できるようになった。デバイス高品質化への貢献が期待でき、プロセスシミュレーションとの直接比較も可能となる。本研究成果の社会的意義は、光弾性法の応用範囲が大きく拡大した点にある。装置構成が簡便で、X線回折やRaman 散乱とは用途が補完関係にあるため、基礎研究だけでなく、商用基板やデバイスの開発・生産における評価・検査装置としての応用も有望である。