不同電極對下電極結構之非晶系銦鎵鋅氧薄膜電晶體之影響

Abstract

藉由探討氧通量，退火，半導體與介電層介面性質，與不同電極材料的變化，研究了不同製程因素對於銦鎵鋅氧薄膜的特性影響，以提升非晶系銦鎵鋅氧薄膜電晶體的效能。一開始，先藉由氧通量的變化，來探討氧通量對薄膜特性的影響，而優化薄膜的半導體特性。另一方面，藉由退火改善了半導體與介電層的介面特性，結果隨著退火時間增長，臨界電壓會減小。進一步的，藉由引入介面修飾層，來探討半導體與介電層介面特性，找出適合銦鎵鋅氧的接觸面性質，而發現疏水性的HMDS改善了載子遷移率。接下來，藉由探討不同電極材料之功函數與接觸阻抗的關係，對下電極結構之非晶系銦鎵鋅氧薄膜電晶體效能的影響，進而找出適合匹配銦鎵鋅氧的電極材料，用來改善非晶系銦鎵鋅氧薄膜電晶體的效能，結果鈦電極展現了最佳的特性。最後，因為不具通道保護層的裝置會與環境中的水氧反應，而進一步討論了臨界電壓隨時間減小的不穩定性。

Via investigating the oxygen and annealing effects, interface property, and source/drain materials, high performance a-IGZO TFT was fabricated. First, the oxygen flow rate was varied to examine oxygen absorption effect. Post-annealing improves the bonding in a-IGZO because of the semiconductor/insulator interface modification. The device mobility can be up to 11.42 cm2(Vs)-1. Second, the dual stack a-IGZO TFT structure is introduced to examine the properties of the a-IGZO/gate insulator interface. HMDS-buffered a-IGZO TFT has larger mobility, implying improved channel/dielectric interfacial condition when it is stacked with the hydrophobic material HMDS. Following, the effects of source/drain electrode types on a-IGZO TFT were investigated. The performance of the a-IGZO TFT with Ti source/drain electrodes is appropriate for the display applications. Finally, the ambient effect was discussed. The water molecule absorption dominates the a-IGZO ambient interaction in ambience and the threshold voltage shifts negatively.