以薄膜形貌工程製作非晶態銦鎵鋅氧化物單極性反向器之改善與分析

Abstract

在本篇論文中，我們以本實驗室開發的薄膜形貌工程製作出以空乏式電晶體作為負載的反向器，其中薄膜形貌工程可藉由改變不同的橋梁長度來調整元件之臨界電壓，達到調變反向器之電壓轉換曲線的效果。整個電路製程中最主要的問題為，如何消除位於元件汲極與源極兩旁的懸浮物體。為解決此問題，我們減小元件下閘極的高度，藉由元件TEM圖形證實了以上方法確實有助於消除此懸浮物體，且經量測後結果的比較也證實了元件特性的變異大幅縮小。 針對遲滯現象，我們分別探討三種不同的閘極氧化層對其之影響，並提出適當的模型來解釋。在反向器電路運作方面，無論在轉換特性或輸出擺幅上皆有良好的結果，其中當操作電壓於九伏特之情形下，電壓增益值將近111。同時我們還探討單顆薄膜電晶體之特性對於反向器增益大小之影響，並分析元件尺寸與反向器之電壓轉換曲線的關聯性。最後，除了靜態性能之外，我們還針對反向器的動態性能做進一步的分析與討論。

In this thesis, we use the FPE structure developed by our group recently to fabricate the depletion-mode load inverters. The Vth of the FPE TFTs can be adjusted by varying the suspended bridge length. The major problem of the process is the undesirable suspended objects hang above the two sides of the bottom gate. One simple way to eliminate this issue is to reduce the height of the bottom gate. Effectiveness of this way is confirmed with the cross-sectional TEM images, and through the measured results, variation in device characteristics can also be greatly improved. The effect of different oxide materials on the hysteresis phenomenon of the TFTs is also investigated and a model is adopted to explain the occurrence of the hysteresis. For the fabricated inverters, they have excellent switching performances and large swing ranges. Moreover, the voltage gain is about 111 at operation voltage of 9V. We also discuss the impact of characteristics of TFTs on the performances of inverters, and analyze the correlation between the VTC trends and device’s dimensions. Besides the static performances, dynamic properties of the inverters are also discussed, too.