優化物理氣相沉積薄膜介面於半導體、仿生材料及生醫領域

Optimizing interfaces upon semi-conductor, bio-mimetic, and bio-medical materials through controlling parameters of PVD and composition of thin films

郭倍宏(Pei-Hung Kuo)

指導教授 ： 杜正恭

國立清華大學/工學院/材料科學工程學系/博士(2021年)

摘要

論文包含三個主題，分別為半導體、仿生以及生醫部分。
半導體的領域，主要為內部連結的擴散阻障層研究；使用非晶金屬薄膜作為主要材料並探討其耐受溫度及最薄厚度，是否可用於現今半導體製程需求。
仿生材料以大自然蚌殼為發想，透過物理氣相沉積方法鍍製有週期性的薄膜。並嘗試解決兩種不親合的材料間，如何以獨創的中介層作為兩者材料間的結合來提升整體的機械性能。
生醫的領域以去除非晶金屬薄膜中幫助成非晶相的穩定元素，以物理氣相沉積的快速冷卻優勢，進行成分調變，找出一個完全無毒的非晶薄膜。並以兩種生物相容性測試驗證其無毒性。

關鍵字

非晶薄膜 ； 半導體 ； 擴散阻障層 ； 仿生 ； 多層膜 ； 生醫材料

並列摘要

Three essential studies in this thesis are distinguished into semi-conductor, bio-mimetic, and bio-medical fields. In the field of semi-conductor, the thinnest diffusion barrier was demonstrated by thin film metallic glass (TFMG) of Zr-Cu-Ni-Al-N at 2.5 nm to suppress atomic migration that would help to minimize the package size and improve its reliability. In the bio-mimetic field, through observing growth behavior of nacre, meso-layer was introduced into interface of TiO2/PI (polyimide) to reinforce the adhesion that successfully solve the problem of delamination between TiO2 and PI to achieve a true mimic layer-by-layer (LBL) film learned from mother nature. In the bio-medical field, Zr-Ti-Si-N TFMG was synthesized and coated on the surface of medical graded Ti-6Al-4V. Both of E-coli survival test and muscle growth test were passed for proving its novel biocompatibility.
TFMG of Zr-Cu-Ni-Al-N around 10nm thick has been shown that it could be used as a diffusion barrier due to material’s thermal properties, e.g., glass transition temperature, and super-cooled region. A tri-layered structure was demonstrated to simulate the interconnects with TFMG inserted between Cu and Si, yet the thickness can be reduced from 10nm to approximate 2.5nm to test the limitation of Zr-Cu-Ni-Al-N TFMG, suppressing the atomic migration of Cu diffused into Si. This can be achieved by rapid temperature annealing under the fully recrystallized temperature for 30 min, with a protective atmosphere to avoid unfavorable chemical reactions. Using XRD, ESCA and HR-TEM, the strong stability of Zr-Cu-Ni-Al-N TFMG can be revealed as a robust diffusion barrier.
The adhesion between TiO2/PI interface of layer-by-layer artificial nacre-like hybrid coating study did not fulfill the results expected in the initial stage. The hardness and toughness could not be enhanced by a hard/soft interlaced structure due to its poor
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adhesive strength, as the composite should not be put with two different materials without gradient media in between. In this study a meso-layer have been introduced by mixing TiO2/PI with a suitable ratio and inserted into the interface of these two different materials. The architectural design was applied for lower TiO2/PI thickness to increase the repetition of total numbers of lamellar multilayers to accumulate stored energy and to dissipate the propagation of cracks perpendicular to the film. Both H/E value and fracture toughness exhibited much higher performance than the original materials did. One kind of bio-inspired thin film can be achieved like the natural growth of creatures inspired by mother nature.
Finally, a brand-new compositional combination of Zr-Ti-Si-N thin film metallic glasses (TFMGs) was successfully demonstrated that, showing novel properties, such as no grain boundaries that help to decrease the coefficient of friction, to enhance hardness and modulus; especially its non-toxic, and biocompatible behaviors. zirconium, titanium, and silicon as non-toxic agents were chosen to form TFMGs according to its atomic radius and electro-negativity. Micro-alloying technique was applied to well blend elements through multi-target sputtering with superior cooling rate to enhance thin films remaining in amorphous state. This provides the ability to create TFMGs with good mechanical properties and biocompatibility. Furthermore, nitrogen was introduced as the fourth dopant to increase the glass forming ability and to improve the stability to enhance its mechanical performance as good as traditional Zr-Cu-Ni-Al TFMGs. The evaluation of cytotoxicity test was cultured with Escherichia coli (E-Coli) by observing the shapes and survival numbers to detect if the metallic ions contained toxicity released. The in-vitro biocompatibility test was applied by co-culturing with human skeletal muscles. Through observing the adhesion and complete coverage of human skeletal muscles, the potential feasibility of Zr-Ti-Si-N TFMG used in medical implanting application are affirmative.

並列關鍵字

amorphous thin film ； semi-conductor ； diffusion barrier ； bio-mimetic ； multi-coatings ； bio-medical

參考文獻

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