結合X光繞射與光學曲率技術量測薄膜材料之彈性係數

Measuring Elastic Constants of Thin Films by Combining X-ray Diffraction and Laser Curvature Techniques

張捷茵(Jeh-Yin Chang)

指導教授 ： 黃嘉宏 ； 喻冀平

國立清華大學/原子科學院/工程與系統科學系/碩士(2008年)

摘要

In this study, we have proposed a non-destructive method to simultaneously determine the Young’s modulus (E) and Poisson’s ratio (ν) of polycrystalline thin film materials. The method involved independent stress measurement by laser curvature technique and strain components determination by sin2□ X-ray diffraction (XRD) method, and afterward, elasticity theory was employed to calculate E and ν. The proposed method has several advantages including (1) Both XRD and optical curvature techniques are non-destructive; (2) Both measurements are well-developed techniques supported by established theoretical bases and therefore good reliability can be expected in the measurement. The accuracy of the obtained values of E and ν were further verified. The cos2αsin2□ method, associated with asymmetrical grazing incident X-ray geometry, was performed on the same film and the previously determined E and ν were used to calculate the stress which was compared with that from optical curvature method. Sine sin2y method and cos2αsin2y method explore distinct groups of crystals lying in different depth of the film, the diffraction information of these two methods does not extract from identical diffraction planes. Provided the two stress values are close enough to be within the measurement error, the accuracy of the measured E and ν can be confirmed. Furthermore, if the elastic constants of the film can be precisely determined, the depth profile of residual stress can be assessed using cos2αsin2y method by appropriately adjusting the incident angle. The experimental results also demonstrated that the elastic constants in two TiN films may have significant difference. This may be due to the variation in compositions and film structure, which results in different interatomic force and thus divergent E values. In addition, one should be cautious when employing the NIP-determined E in sin2y or cos2αsin2y method to calculate the residual stress because the modulus may not give correct stress value all the time. However, the trend of the residual stress may not be significantly affected due to the uncertainty in E value.

關鍵字

彈性係數 ； 楊氏系數 ； 浦松比

並列摘要

HASH(0x1bb189a0)

並列關鍵字

elastic constant ； Young's modulus ； Poisson's ratio

參考文獻

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