奈米壓痕技術由於負載與位移之解析度高，以及量測方法之均一性與簡易性等優點，故近年來廣泛被應用於各種類型之材料測試。然而，此方法的原始實驗資料僅提供壓痕器之負載及位移，尚須輔以合適的力學模型方得以運作。目前常用於楊氏模數及硬度值檢測之力學模型為Oliver與Pharr所發展的塊材力學模型，若應用於薄膜材料之機械性質檢測會受到基材的影響，使得量測的結果為深度的函數，大大減低試驗數據的可靠度。因此，許多研究皆致力於探討基材對奈米壓痕試驗的影響，希望能提出改善的方法。鑒於雙層材料的接觸行為較單一均值材料複雜，解析解並不容易求取，故本研究使用有限元素分析模擬雙層材料的接觸行為，以半解析的方式說明其接觸特性。首先，本研究探討基材效應對試驗結果的影響，以能量分佈定量地分析基材之貢獻度。此外，深度感測技術於雙層材料之可靠度亦是本研究所探討的主題之一，善用有限元素分析的優勢，比較深度感測技術之結果與理想值的差異。接著，本研究善用上述於雙層材料之接觸特性研究，輔以King model於雙層材料接觸響應分配之概念，發展一適合用於奈米壓痕試驗之雙層材料力學模型。最後，將此修正模型應用於熱處理之氮化矽薄膜機械性質檢測。由塊材力學模型所得到的結果可以發現：氮化矽薄膜之楊氏模數為深度的函數，其數值之可靠度大打折扣。藉由本研究所發展的雙層材料力學模型，有效地說明基材對試驗結果的影響，減少試驗結果的不確定性，有助於合理地探討熱處理對薄膜機械性質的影響。

Depth-sensing instrumental indentations provide an approach for studying elastic and inelastic properties of thin films. However, the obtained experimental data can only provide the relationship between the applied load and the penetration depth and adequate mechanical models are therefore required for converting the test data into final mechanical properties such as Young’s modulus and hardness. However, the traditional Oliver and Pharr conversion model does not consider the substrate effect and can only work for the situation where the indentation depth significantly less than the film thickness. Several models have been proposed for extracting Young’s modulus based on Oliver and Pharr's model with King’s analysis. However, the original King's model is for flat punch and the accuracy of those models should be justified. In this work, a novel model for extracting the Young’s modulus of thin films is proposed. Dimensional analyses are firstly used to find the governing parameters and to obtain scaling relationships for subsequent finite element analysis. Based on the initial suggestion of King model, a more rational relationship between the reduced modulus and the Young’s modulus of both film and substrate are assumed and the associated model parameters are determined by fitting the results obtained using finite element analysis. In comparison with the previous models, the computer experimental results indicated that the proposed model can provide better accuracy in extracting thin film’s Young’s modulus. Finally, in conjunction with existed nanoindentation experimental data, we utilize this new conversion model to calculate the Young’s modulus of plasma enhanced chemical vapor deposited (PECVD) silicon nitride after various rapid thermal annealing processes. The answers show that the structure exhibited strong substrate effect and the traditional Oliver and Pharr model could significantly over- or under-estimate the Young's modulus of PECVD nitrides. And this could be critical for microsystem longevity evaluations. In summary, in comparison with other models, the proposed model is more accurate in extracting the Young’s modulus of thin film with presence of substrate effect for related applications in material characterization or structural integrity design.

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