複合式薄膜電晶體之可靠度分析

我們提出複合式薄膜電晶體（compound TFT）元件結構，來改善主動式陣列有機發光二極體顯示器（AMOLED）。在過去，我們已經證實此元件結構不僅可以展現出高的開啟狀態電流，並且具有與非晶矽薄膜電晶體相同的關閉狀態的表現。在本論文中，我們針對此複合式薄膜電晶體進行可靠度研究。在高電場電氣應變測試中，我們施加不同偏壓於複合式薄膜電晶體之閘極。其結果顯示，不管閘極偏壓的極性為何，複合式薄膜電晶體相較於非晶矽薄膜電晶體，其展現出較高的穩定性。此外，在複合式薄膜電晶體承受負閘極偏壓應變時，因為在非晶矽補償層中微弱的矽-氫鍵容易被打斷，其所產生的氫原子受到閘極負偏壓的吸引至通道層中，補償了閘極絕緣層與通道界面的懸浮鍵以及因偏壓應變所產生的缺陷狀態，使得元件的操作得到改善。我們稱這種機制為「氫原子補償效應」。在元件老化的測試中，複合式薄膜電晶體在測試條件為VGS=20V且VDS=80V之下，其壽命終止於4,450秒。此外，由於閘極內部缺陷狀態隨著測試而漸漸被填補，剩下較少的空間讓載子進行跳躍傳輸，因此漏電流隨著測試時間而降低。在本論文內所有的實驗結果均顯示複合式薄膜電晶體具有比非晶矽薄膜電晶體較高的可靠度。其可能是因為複合式薄膜電晶體其通道的結晶性遠遠優於非晶矽薄膜電晶體其通道的結晶性。因此，對於主動式陣列有機發光二極體顯示器的應用，複合式薄膜電晶體可能可以成為較佳的選擇。

關鍵字

薄膜電晶體；可靠度

並列摘要

We had proposed previously a μc-Si:H TFTs with vertical a-Si:H offset structure (compound TFT) to improve the performance of active-matrix organic light emitting diode (AMOLED). It was proved previously that this proposed compound TFTs structure presenting not only high ON-state current but also low OFF-state current, which was similar to that of a-Si:H TFTs. In this thesis, the reliability of compound TFT was studied. In high-field stress test, various bias stresses on gate electrode were performed on the compound TFTs, and the results showed that the instability in compound TFTs was less than that in a-Si:H TFT without regarding the polarity of the VGS. A new mechanism named “H atom compensation effect” was proposed resulting in an improvement in the sub-threshold swing of the compound TFT when compound TFT was tested in the negative gate bias stress. This mechanism resulted from the released H atoms, which caused by the breaking of weak Si-H bonds in the a-Si:H offset layer, and they could be injected into the channel resulting in the reduction of the states located in the gate insulator/channel interface under negative gate bias stress. It improved the operation of compound TFT. In the aging test, the lifetime of the compound TFT was stopped after about 4,450sec in the condition VGS=20V while VDS=80V. Additionally, the leakage current decreased gradually with the time due to there was gradually not enough space in the insulator for carriers to hop. All the experimental results in this thesis implied that the compound TFTs showed good reliability as compared with conventional a-Si:H TFTs. It was possible that the crystallinity of the channel layer in compound TFT was much better than that in a-Si:H TFT. Therefore, the compound TFTs may be a good candidate for the practical AMOLED operation.

並列關鍵字

Thin Film Transistors ； Instability

參考文獻

[1-7] C. Y. Chang and C. W. Lin, IEEE Trans. Electron Device Lett. 17, No.12, 1996, pp.572

[2-8] M. J. Powell, C. van Berkel, I. D. French, and D. H. Nicholls, Appl. Phys. Lett. 51, 1987, pp.1242

[1-8] C. Y. Chang and C. W. Lin, Japanese Journal of Applied Physics, 1997

[1-5] Y. Uchida and M. Matsumura, IEEE Trans. Electron Devices, 36, 1989, pp.2940

[1-6] Y. Uchida, Y. Nara and M. Matsumura, IEEE Trans. Electron Device Lett. 5, 1984, pp.105

國際替代計量

複合式薄膜電晶體之可靠度分析

未授權

主題瀏覽