塑膠基板上半導體元件之試作

Abstract

近年來，現代化家電用品的需求日增，使得大、小尺寸的液晶顯示器應用範圍越來越為廣泛。以大面積以及高畫素密度的主動式矩陣液晶顯示器而言，低於400℃的鋁閘極複晶矽薄膜電晶體乃是最佳的選擇；主要是因為使用了低阻值的鋁。除此之外，塑膠基板液晶顯示器也適於此產品演進的發展趨勢。塑膠基板有量輕、形薄、以及不易摔壞的優點。然而，於塑膠基板上製作半導體元件的技術發展尚未成熟。在本研究裡，我們探討了幾項關於在塑膠基板上製作半導體元件的關鍵技術：包括塑膠基材的選取、陽極氧化系統的建立以及金屬薄膜於基板上的沈積。 眾多基板經由物化性的充分檢驗，選擇出由日本JSR公司所出產之ARTON基板來進行實驗。另外，由於低溫製程的訴求及較佳的絕緣層特性，在塑膠基板製作金屬-絕緣層-金屬（MIM）二極體的最佳選擇是採用以陽極氧化法所形成的五氧化二鉭（Ta2O5）薄膜。鉭（Ta）金屬薄膜在基板上龜裂的現象為實驗初期最大挑戰。利用鈦（Ti）薄金屬層介於鉭金屬層及氧化層之間來增進薄膜的附著力，終於我們在塑膠基板上製作出以陽極氧化五氧化二鉭（Ta2O5）薄膜為絕緣層之金屬-絕緣層-金屬二極體（MIM diodes）。製程中所產生的應力對元件製作有相當大的影響。因此在塑膠基板的處理和製程條件都要非常小心仔細，才能製造高良率的塑膠基板顯示器。最後，我們設計一系列的信賴性測試來評估元件的穩定性，包括：溫度測試，濕度測試，曝曬測試及震動測試。並針對量測到的結果加以討論。

In recent years, increasing requirement of modern household appliances promote the application range of small or large size Liquid Crystal Displays (LCDs) extensively. Low temperature (< 400oC) Al-gate poly-Si TFTs is the most promising candidate for large-size and high pixel-density AMLCDs because of low resistivity. Besides, polymer-film LCDs (PFLCDs) are also adequate for the tendency of product improvement. Plastic substrates have the advantages of light-weighted, thin-shaped and not-so-easily-broken characteristics. But the technologies of producing semiconductor devices on plastics are not mature yet. In this research, several key technologies about fabricating semiconductor devices on plastics including selection of plastic substrates, setup of anodic oxidation system and metal thin film deposition on plastics are investigated. We selected the ARTON plastic film produced by JSR Corporation to carry out the following experiments after testing out the physical and chemical properties of various plastics. Further, the best candidate for active matrix addressing on plastics is Metal-Insulator-Metal (MIM) diodes with anodic Ta2O5 as insulator because of low temperature and good dielectric properties. In the beginning of the experiments, It's the biggest challenge that peeling effect upon Ta film deposited on plastics. Depositing a thin Ti film between Ta and oxide layer to improve adhesion. Hence, the MIM devices with anodic tantalum oxide on plastics are finally fabricated. Due to process induced stresses that have large influences on devices fabrication, special care should be taken to substrate handling practices and to process conditions in order to produce robust plastic displays at high yield. Eventually, we design a series of reliability tests for evaluation of device stability which include temperature tests, humidity test, exposure tests and shoch tests. Then we discuss the results measured form the experiments.