雙重中性粒子束氧化處理於高介電係數二氧化鋯及銦鎵鋅氧通道電晶體之研究

Abstract

因為非晶的氧化銦鎵鋅薄膜電晶體，具備較好的場效遷移率，較小的次臨界擺幅和較穩定的電性，目前已被廣泛研究，並且應用在下世代的主動式陣列顯示器，例如: 液晶顯示器和平板顯示器。

在這篇論文中，我們使用大氣壓電漿輔助化學氣相沉積系統之氫電漿來沉積我們氧化銦鎵鋅通道，這系統不用在真空系統下運作，因此可以降低我們的成本，並且可以大範圍面積的製作。

隨著莫爾定律的演進，氧化層的厚度也越來越薄，當傳統二氧化矽厚氧化層度薄到1.4奈米時會導致不可避免得漏電流飆高，造成電性上的影響。因此我們採用高介電係數材料二氧化鋯來當我們的氧化層，藉此我們可以獲得較薄的等效氧化層厚度(4.05奈米)，以及較高的驅動電流，卻又不會造成漏電的上升。氮電漿處理可以調變二氧化鋯薄膜的物理及電特性。較好的二氧化鋯薄膜應用在我們的非晶銦鎵鋅氧薄膜電晶體上可以得到更好的電性。

中性粒子束是一種對於未來奈米元件很有前途的一項技術，因為其無損傷及有機和無機材料表面修補，我們利用中性粒子束在我們的鎵鋅氧薄膜和二氧化鋯薄膜，讓我們的電晶體可以得到更好的電性。

我們成功的藉由大氣壓電漿輔助化學氣相沉積製作出以二氧化鋯當氧化層的非晶銦鎵鋅氧薄膜電晶體，它的電子遷移率有12.26 cm2/(V•S)，臨界電壓 1.77 伏特，次臨界擺幅 124 mV/decade，開關電流比 4.2×10^5。而經中性電子束氧電漿處理過的二氧化鋯當氧化層的非晶銦鎵鋅氧薄膜電晶體表現出更佳的電性，它擁有更高的電子遷移率52.22 cm2/V•S，臨界電壓 2.86伏特，更小的次臨界擺幅 74 mV/decade，更高的開關電流比 8.2×10^5。

Amorphous InGaZnO (a-IGZO) Thin Film Transistor (TFTs) has been studied extensively for their perspective applications in next generation active-matrix displays such as liquid crystal displays and flat-panel displays, due to its better field-effect mobility, smaller subthreshold swing (SS) and better electrical characteristics.

In this investigation, we used atmospheric-pressure PECVD (AP-PECVD) to deposit our IGZO active layer. With AP-PECVD, we could deposit IGZO thin film without vacuum system, thus, it could lower our cost, improved the throughput, and applied to large area manufacturing.

As the scaling to Moore’s law, it is terrible that gate oxide is too thin (1.4nm) which caused an intolerable gate leakage due to direct tunneling current. We use the high- material ZrO2 as our oxide to achieve the thinner EOT (4.05nm) and high on current but not degrade the leakage current. Furthermore, the post N2 plasma treatment on ZrO2 oxide can modify the physical and electrical properties, such as RMS, leakage current, the formation of interfacial layer, et al. We could use the modified ZrO2 thin film which shows better electrical properties as the a-IGZO TFT oxide. Thus, the a-IGZO TFT will exhibits better electrical characteristics.

Neutral beam is a promising candidate for the practical fabrication technology for future nano-devices because of damage-free and surface modification of inorganic/organic materials. We use neutral beams in our IGZO and ZrO2 thin films. Thus, our transistors will exhibits better electrical characteristics.

Successfully, we fabricated a-IGZO TFT with AP-PECVD using ZrO2 high-k dielectric. It exhibits comparable mobility of 12.26 cm2/V•S, VT of 1.77 V, subthreshold swing of 124 mV/decade, Ion/Ioff is 4.2×10^5. With the post O2 plasma treatment on ZrO2 oxide by neutral beams, the a-IGZO TFT exhibits higher mobility of 52.22 cm2/V•S, VT of 2.86 V, lower subthreshold swing of 74 mV/decade, higher Ion/Ioff of 8.2×10^5.