改良式元件轉移技術製程之研發與應用

Abstract

在可彎曲塑膠基板上製作薄膜電晶體的技術近年來已受到很大的矚目，這是因為塑膠基板具有重量輕、厚度薄、可彎曲、堅固耐用、以及成本低的優勢，因此適合作為大面積電子產品（如顯示器）的應用然而，要在可彎曲塑膠基板上製作高性能的薄膜電晶體仍有許多問題待克服，因為塑膠的熱膨脹係數比玻璃要大很多，製程上的難度相對較高。在本論文中，我們提出一種改良式元件轉移製程技術（DTBE）並搭配「旋塗-蝕刻（spin-etch）」的方法，可以成功地將矽基板上的薄膜元件轉移到可撓曲的塑膠上。 我們將完整介紹利用DTBE技術將元件轉移到可撓曲塑膠基板的方法。另外，塑膠基板和接合劑的選擇、複晶矽元件的製作方法，以及如何量測元件特性在承受機械應力情況下的變化，也會逐一提出。透過轉移前和轉移後的元件特性比較可以證明，使用DTBE技術轉移元件到可撓曲塑膠基板上是一個可行的方法。 除此之外，我們也探討了利用DTBE技術轉移單晶矽電晶體到玻璃基板上做為顯示器應用的可行性。就我們所知這是第一個提出用單晶矽電晶體取代傳統複晶矽電晶體作為顯示器開關元件的研究。本論文中，我們設計了一種測試結構來驗證我們的構想，此種測試結構有全暗以及全透明兩種型態。利用DTBE技術我們成功地轉移了這種測試結構，因而證明了要轉移單晶矽電晶體到玻璃基板上做為顯示器的應用並非不可能。

Thin film transistors (TFTs) on flexible plastic substrates were of considerable interest due to their light weight, thinness, flexibility, shock resistance, and low cost for large area electronics. However, the fabrication of high performance TFTs on flexible plastics is extremely challenging because of the inherently poor thermal properties of plastics. A modified device transfer process (DTBE) with the aid of “spin-etch,” was investigated for overcoming the previous obstacles. In addition, the DTBE approach for transferring poly-Si devices from the silicon wafer onto the flexible plastic substrate was introduced. The choices of substrate and adhesive, the methods for manufacturing poly-Si devices, and the concept for measuring the electric characteristics of these devices under mechanical stress were also explained. From the comparisons of device performance before and after transfer, DTBE was proved to be a practicable approach for transferring devices from silicon wafer onto the flexible plastic substrate. Besides, the study of transferring single crystalline silicon (sc-Si) transistors from a silicon wafer to the glass substrate by applying DTBE technology was demonstrated in this thesis. It is the first investigation of using sc-Si transistors to replace poly-Si transistors for display application, so far as we know. One test structure was designed for verifying whether this approach is workable. Transfer of normally opaque and transparent structures was successfully achieved. Thus this kind of approach can be applied towards transferring sc-Si transistors from silicon substrate onto the glass substrate.