薄(厚)膜材料熱傳導係數量測與探討

當物體的尺寸縮小至微奈米等級的時候，許多的材料性質均會有所改變。同時薄膜厚度小至微奈米尺度時，熱載子(carrier)-聲子(phonon)與自由電子(free electron)的散射效應(scattering)增強，使的薄膜之有效熱傳導係數降低。而薄膜之熱邊界效應(thermal boundary effect)也因薄膜厚度減少而增加。因此本研究首先利用3ω method量測相變化記憶體材料以及光碟片中不同材料所沉積的介電層熱傳導係數，並進一步探討材料與量測而得的熱傳導係數值其相關性以及應用。接著針對3ω method的缺點，利用二維熱傳模型推導出一組數學的解析解應用於量測薄膜厚度50nm~2μm，熱傳導係數範圍約0~10W/mK之間的平行線法(Parallel-Strips Method)。利用易取得的簡單量測儀器，建構一套量測薄膜的系統。而平行線法最大的優點為試片製做簡單，量測時間快速，系統成本低廉，儀器易取得以及量測樣品廣泛。實驗方面利用PECVD、Thermal、E-beam三種不同方式沉積的二氧化矽當作量測材料，成功的將E-beam evaporation、PECVD、Thermal量測出本質熱傳導係數分別為0.96 W/mK、1.05 W/mK、1.504 W/mK以及邊界熱阻分別為2.58×10-8m2K/W、2.84×10-8 m2K/W、3.57×10-8m2K/W。最後根據平行線法的理論基礎，進一步建立厚膜的理論以及量測系統。膜厚範圍適用於10μm~1mm，熱傳導係數值適用於0.01W/mK~10 W/mK的膜厚差異法(Thickness Difference Method)。並以負光阻SU8-3050為量測材料，成功的量測出SU-8的本質熱傳導係數為0.2W/mK，也印證Thickness Difference Method的正確性。總體而言本文利用3ω method、Parallel-Strips Method、Thickness Difference Method三種不同的方法成功的建立膜厚範圍介於200nm~1mm之內以及熱傳導係數介於0.01~10W/mK範圍之內的熱傳導係數量測方法。並運用這些方法探討不同的功能性材料熱傳導係數以及驗證其量測方法的正確性。

關鍵字

熱傳導係數；薄膜；厚膜；界面熱阻；量測

並列摘要

It is well known that material prosperities will be different as the material in micro and nano scale. For instance, the effect of interface boundary and the carriers such as phonon and free-electron scattering have become the primary issue in thin film material. In this study, measurements of thermal conductivities of phase change memory material and several dielectric films by 3ω method is investigated. However, the limitation of 3ω method restricts the film thickness under 1 μm. For film thickness of 1um to 1 mm, further studies of pertinent measuring methods such as parallel-strip method and thickness difference method are constructed. Parallel-strip method is suitable for film thickness of 50 nm to 2 μm. The intrinsic thermal conductivities and boundary thermal resistances of three kinds of SiO2 films are measured, in which these specific SiO2 films are fabricated by PECVD deposition, thermal furnace growing and E-bean deposition respectively. In addition, thickness difference method is suitable for thick films where film thickness is in a range of 10 μm to 1 mm. The intrinsic thermal conductivities of three kinds of SU8-3050 thick films are also measured, in which the thickness of these specific SU8-3050 films are 42, 70 and 95 μm respectively. In short, the objective of this work provides three methods which thermal conductivities and boundary thermal resistance of dielectric films are characterized and are verified with the theory and literatures.

並列關鍵字

thermal conductivity ； thin film ； thick film ； interfacial thermal resistance ； measurement

參考文獻

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[2] T. Paskova, D. A. Hanser, and K. R. Evans, "GaN Substrates for III-Nitride Devices," Proceedings of the IEEE, vol. 98, pp. 1324-1338, 2010.

[3] T. Beechem, A. Christensen, S. Graham, and D. Green, "Micro-Raman thermometry in the presence of complex stresses in GaN devices," Journal of Applied Physics, vol. 103, pp. 124501-8, 2008.

[4] J. Bodzenta, B. Burak, A. Jagoda, and B. Stanczyk, "Thermal conductivity of AlN and AlN-GaN thin films deposited on Si and GaAs substrates," Diamond and Related Materials, vol. 14, pp. 1169-1174, 2005.

[5] T. Borca-Tasciuc and G. Chen, "Experimental Techniques for Thin-Film Thermal Conductivity Characterization," in Thermal Conductivity, pp. 205-237, 2004.

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薄(厚)膜材料熱傳導係數量測與探討

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