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Title

氧在介面的加入對鋁/鉻薄膜與氧化銦錫玻璃結合強度的影響

Effect of Interfacial Oxygen on Adhesion Strength Between Al/Cr and Indium-Tin-Oxide(ITO) Thin Film Coated Glass

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[[abstract]]在電子及光電元件的製造及構裝上,經常遭遇氧化膜(物)表面的金屬化問題。一般而言,此金屬化均以金屬薄膜行之。因此,在薄膜化的過程當中,金屬膜與氧化物間的結合力,被視為金屬化之成功與否的重要指數。此種較高的結合力之介面能承受較高的機械應力,在可信度的測試方面,通常代表較高的可信度。 在液晶顯示器中,氧化銦錫(ITO)玻璃是主要之組件之一,雖然它的主要功用是導電與透視,但在先進的晶粒-玻璃(Chip -on-glass)構裝上卻是重要的模組基板。由於IC晶片無法直接接合於玻璃基板上,氧化銦錫玻璃的薄膜金屬化成為構裝製程上之一重要步驟。一般製程上,鋁薄膜常被用於提供電子導電性及鍵結性,而鉻薄膜則鍍在鋁與玻璃間以增加金屬膜之結合力。根據先前的研究,此種複合鍍層仍會有結合力不足的問題,因而產生構裝後可信度之疑慮,因此,我們在介面滲氧以提高金屬/氧化膜(物)之介面黏著,所以元件的可靠性可依賴著氧化物與氧化物間之鍵結強度得到改善。 本實驗藉由不同的鍍膜參數(基板偏壓、氧流量)探討其對Cr/ITO及所形成氧化物介面之影響;經實驗證實在施以一基板偏壓,使靶材原子有較高的移動力,讓成長的結晶膜受到帶有數百eV的能量粒子的轟擊,而使得薄膜因原子槌擊效應(atomic peening)而產生壓應力,且隨著偏壓的上升至-80V,薄膜的壓應力越大、晶粒尺寸越小、薄膜內的缺陷越多;而後由於基板偏壓的增加,使得轟擊基板的帶電粒子能量也隨偏壓大小升高,使得基板溫度在一連串高能量轟擊下升高,殘餘應力也因到達某一程度後便會因原子擴散而下降。我們發現基板偏壓-110V時有最小的內應力。 當此薄膜實際應用時,其機械性質亦格外重要。我們藉由在鉻與氧化銦錫之間注入不同含量的氧以增強金屬膜之結合力,實驗中利用拉力試驗來研究結合力與介面氧含量的關係,我們發現氧流量6sccm時,氧化物厚度達最大值375Å,且為最佳之附著力,這是因為槌擊效應使得氧化物表面粗糙度變大,且因氧流量增加,氧空位減少,避免晶格失序(disorder)或扭曲的現象,減少薄膜內殘留之張應力,故有較佳之附著性。同時藉由表面分析的儀器(AES,XPS)我們可發現介面氧化物是Cr2O3,而由AES縱深輪廓圖可清楚的看出介面中間層的變化,使我們清楚地觀察氧流量與中間氧化層的關係。接著我們在鉻薄膜上沉積不同厚度的鋁薄膜,並經拉力試驗及硬度測試後,發現厚度1.0μm的鋁薄膜有最佳的硬度及抗拉強度。

[[abstract]]Metallization of oxide surfaces using aluminum(Al)or gold(Au)is a key process in the fabrication or packaging of electronic and optoelectronic devices. Since these metal thin films provide the electrical and mechanical connection, the adhesion between metal thin films and oxide layer is one of the main concerns in the processing. Higher adhesion strength of metal thin film to oxide surface normally leads to high mechanical reliability of devices. Al thin film with Cr interlayer has been used as a composite layer to metallize ITO-coated glass. The top Al layer provides bondability and electrical conductivity, while the Cr layer is inserted to provide adhesion strength . From a previous study, it is well known that the adhesion between Al/Cr and ITO glass needs to be increased in order to sustain some thermal and mechanical tests. In order to enhance the adhesion between the Al/Cr and ITO glass, oxygen interface doping at the Cr - ITO interface has been proposed in this study. Various deposition parameters(bias, oxygen flow rate)have been used to determine the optimal condition for thin film deposition. From the results of compressive stress and crystalline size, they indicate the optimal bias voltages are in the range of —40 to —80V. The maximum improvement in adhesion strength can be obtained as the oxygen flow rate at 6 sccm. The structure and morphology of this change can be studied by X-ray photoelectron spectroscopy (XPS) and Auger electron spectroscopy (AES).

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