Mechanical Properties Characterization of Bulk and Thin Film Materials Using Nanoindentation Technique

• Main Authors: Hong-Yi Yan, 顏宏益
• Other Authors: Kuo-Shen Chen
• Format: Others
• Language: zh-TW
• Published: 2007
• Online Access: http://ndltd.ncl.edu.tw/handle/07261881797181653054

碩士 === 國立成功大學 === 機械工程學系碩博士班 === 95 === Nanoindentation technique has been widely used in characterization of mechanical properties of materials at small scales. However, due to some real consideration faced, such as pile-up and substrate effect, during indentation testing, the primary conversion formula proposed by Oliver and Pharr would result in significant errors and it must be modified to compensate these effects. The motivation and goal of this research is therefore in two aspects. First, by characterizing polymers and thin film materials, it is possible to evaluate and quantify the influence of these imperfections during a typical nanoindentation test as the basis toward a more sophisticated conversion model. Second, by characterizing the mechanical properties of novel materials using nanoindentation associated with different processing parameters, it is possible to yield important information for semiconductor and MEMS process optimizations. In order to achieve both goals, a novel polymer photoresist, KMPR, a semiconductor-grade o-ring, and PECVD nitride films, were chosen for this study. For the study on bulk polymeric materials, it was found that the mechanical properties of KMPR and o-ring rubber varied significantly with respect to thermal treatment temperature and the service period, respectively. Furthermore, it could be observed that KMPR specimens have strongly piled-up after nanoindentation. In order to evaluate the pile-up effect, both uniaxial tensile and vibration tests were used for the purposes of comparison and validation. The strong discrepancy between various test results suggested that KMPR is an anisotropic material. On the other hand, the test data obtained from indentation and uniaxial compression for o-ring rubber was highly correlated. By checking the difference in the pile-up extent, it is concluded that the pile-up phenomenon would cause mis-interpretation on the nanoindentation test data. Finally, for the study of thin film materials, it was found that the rapid thermal anealing (RTA) processes could effectively modify the elastic modulus, hardness, and residual stress of PECVD nitride. Fracture and interfacial toughness were also changed after RTA by inspecting the cracks generated during indentation. Moreover, it could also be found that the apparent elastic modulus and hardness were also varied as the penetration depth increased because of the substrate effect. Modified King model and FEM simulation were subsequently performed to compensate the substrate effect. In summary, this study integrated specific testing and simulation methods with nanoindentation for understanding and correcting these non-ideal effects indicated above for different categories of materials. The proposed approach and analyses could also be adopted for testing other similar materials faced in real applications. Finally, by realizing those testing results, structural properties of KMPR after thermal treatment, sealing performance of the o-ring rubber during different service periods, and the structural integrity of PECVD nitride used in semiconductor fabrication, could be obtained. These are important information for structural design optimization to enhance the device longevity and process yield.