Optimization of Material Microstructure Study for Thin-Film Inductors

• Main Authors: Kuang-Yuan Hsu, 許廣元
• Other Authors: Chuan-Pu Liu
• Format: Others
• Language: zh-TW
• Published: 2004
• Online Access: http://ndltd.ncl.edu.tw/handle/77626492914502483210

碩士 === 國立成功大學 === 材料科學及工程學系碩博士班 === 92 === Abstract 　　In this study, we first discuss the evolution of Cu and Co thin film microstructure as function of sputter parameters, including substrate-to-target (DT-Sub) distance, working pressure and negative substrate bias. Subsequently, the Cu and Co thin films with best quality and low resistivity are applied as the spiral conductor in spiral thin film inductor.The inductance and quality factor of inductor properties are discussed in terms of Cu and Co resistivity. Furthermore, we discuss the effect on inductor quality factor from different dielectric materials, including organosilicate glass, florinated silicon glass, silicon dioxide and polyimide. 　　Experimental results reveal that recrystallization and grain growth proceed with high energetic Cu adatom bombardment on substrates through strain energy relaxation by reducing DT-Sub, low working pressure and high negative substrate bias. The crystal structure of the Cu thin film will change from (111) preferred orientation with low surface energy to (200) preferred orientation with low strain energy. The preferred (200) orientation via recrystallization results in large grains, low defect density and low resistivity. On the other hand, Co thin film with low-temperature stable ε phase can be obtained by sputtering at working pressure of 3 mTorr and DT-Sub of 7cm. The crystal orientation of the Co thin film will change from (002) to (100) with increasing negative substrate bias and hence better resistivity. 　　The use of the lower resistive Cu thin film as the metal line in the spiral thin film inductors can reduce series resistance, which induces small eddy current from skin- effect and proximity-effect, and hence increases quality factor significantly and slightly improves inductance for thin film inductors. Furthermore, quality factor of thin film inductor can be largely enhanced by using low-dielectric-constant dielectrics due to the reduction of dielectric polarization losses. Although, the inductor consisting of Co thin film with large permeability but high resistivity, which revelers the inductor only applicable for very small frequency range with poor quality factor.