應用紫外光遮罩於銦鎵鋅氧薄膜電晶體之光穩定研究

Abstract

非晶態銦鎵鋅氧化物的高載子移動率、可低溫製成、以及在可見光下具有高透明度等特性，使其成為當今熱門的薄膜電晶體主動層材料並逐漸取代傳統非晶矽半導體材料。然而，非晶態銦鎵鋅薄膜電晶體的電性容易受到外界環境的影響，例如水氣、氧氣以及紫外光波段的光，阻礙了其實用化的發展。因此，在主動層上加上一層保護層是最有效降低水氧吸附問題的方法之一，例如:二氧化矽或氮化矽保護層。然而，光敏感性的問題依然存在。 鑑於此，本論文研究一種可吸收紫外光波段的透明半導體材料:鋅氧化鉬作為非晶態銦鎵鋅氧化物電晶體的保護層改善其嚴重的光敏感性問題，並同時檢驗其隔絕水氧吸附的能力，以得到高穩定及高可靠度的非晶態銦鎵鋅氧化物薄膜電晶體。此外，亦與具有二氧化矽保護層的非晶態銦鎵鋅氧化物薄膜電晶體進行比較。 實驗結果顯示，具鋅氧化鉬保護層的非晶態銦鎵鋅氧化物薄膜電晶體在負偏壓照光應力測試下保持穩定的特性曲線，而無保護層與具二氧化矽保護層的元件特性曲線呈現明顯的負偏移現象；同時在正偏壓與負偏壓應力測試下，具鋅氧化鉬與二氧化矽保護層的非晶態銦鎵鋅氧化物薄膜電晶體都得到穩定的結果。因此，鋅氧化鉬不僅能夠降低非晶態銦鎵鋅氧化物的光敏感性問題，在水氧的阻隔上也表現出與傳統二氧化矽保護層相似的結果。

The electrical characteristics of a-IGZO TFTs affected by ambient environment, including oxygen, moisture, and light illumination, are still among the issues for a-IGZO TFTs to be the commercialization of for flat panels. Passivation layers, e.g. SiO2 or SiNX, on an active layer are an effective method to improve the oxygen or moisture effects. However, the photosensitivity issue still occurs in a-IGZO TFTs by introducing above mentioned passivation layers. A transparent metal oxide semiconductor: Mo-doped ZnO (MZO) with UV shielding ability as the passivation layer to improve the photosensitivity issue of a-IGZO TFTs is proposed. Results reveal that MZO-passivated a-IGZO TFTs remain the stable properties during NBIS tests, while the transfer curves of unpassivated and SiO2-passivated a-IGZO TFTs have apparent negative shifts during NBIS tests. Moreover, during PBS and NBS tests, MZO passivation layer presents the similar protective ability under ambient environment to SiO2 passivation layer. Hence, MZO passivation layer shows high potential to be used in next generation displays.