Quantitative analysis of hydrogen in SiO2/SiN/SiO2 stacks using atom probe tomography

• Main Authors: Yorinobu Kunimune, Yasuhiro Shimada, Yusuke Sakurai, Masao Inoue, Akio Nishida, Bin Han, Yuan Tu, Hisashi Takamizawa, Yasuo Shimizu, Koji Inoue, Fumiko Yano, Yasuyoshi Nagai, Toshiharu Katayama, Takashi Ide
• Format: Article
• Language: English
• Published: AIP Publishing LLC 2016-04-01
• Series: AIP Advances
• Online Access: http://dx.doi.org/10.1063/1.4948558

We have demonstrated that it is possible to reproducibly quantify hydrogen concentration in the SiN layer of a SiO2/SiN/SiO2 (ONO) stack structure using ultraviolet laser-assisted atom probe tomography (APT). The concentration of hydrogen atoms detected using APT increased gradually during the analysis, which could be explained by the effect of hydrogen adsorption from residual gas in the vacuum chamber onto the specimen surface. The amount of adsorbed hydrogen in the SiN layer was estimated by analyzing another SiN layer with an extremely low hydrogen concentration (<0.2 at. %). Thus, by subtracting the concentration of adsorbed hydrogen, the actual hydrogen concentration in the SiN layer was quantified as approximately 1.0 at. %. This result was consistent with that obtained by elastic recoil detection analysis (ERDA), which confirmed the accuracy of the APT quantification. The present results indicate that APT enables the imaging of the three-dimensional distribution of hydrogen atoms in actual devices at a sub-nanometer scale.