近年來，快閃記憶體的需求量大幅上升。然而，在元件日漸微縮的趨勢下，平面式元件微縮空間有限，造成元件密度難增且製程難度跟著大幅的提升，因此如何提高電性又要能降低製程難度為目前最重要的課題之一。有些解決方法已漸漸被提出，如多晶矽的使用、矽化鍺材料的應用、奈米線通道的結構、無接面快閃記憶體元件的應用等等。本篇論文以多晶鍺無接面奈米式通道快閃記憶體元件為主體，加以研究並探討電性的表現。
在本論文中，第一個實驗是將多晶鍺通道運用至平面式電容快閃記憶體元件，並與多晶矽的電容元件做比較。多晶矽電容元件在寫入速度以及抹除速度上都比多晶鍺有著較優秀的表現，在電荷保持力部分，在室溫下，多晶鍺電容元件與多晶矽電容元件具有相同的堆疊結構，所以常溫下兩者表現相當；而高溫之下多晶矽的元件電荷保持力，相對較多晶鍺來的好。而在耐久力方面，Poly-Ge電容元件整體元件的可靠度欠佳，可能是在於元件的穿隧介電層品質不佳所至。而Poly-Si電容元件的表現相對則較為穩定。
在第二個實驗中，我們將多晶鍺材料應用在無接面奈米通道式快閃記憶體元件上，試圖觀察是否可以提升多晶鍺這種通道在無接面式奈米通道式元件的表現。在寫入速度上，Poly-SiNW有著較快的寫入速度，在抹除速度上依然為Poly-SiNW較快。另外，在電荷保持力的比較中，常溫之下兩者差異不大，而在高溫(850C)之下Poly-SiNW表現較佳。而在耐久力部分，Poly-SiNW元件只需花相對較少的時間即可以完成寫抹循環，所以對於穿隧氧化層的傷害也會較少，所以有較好的耐久力表現。
在第三個實驗裡，我們想探討無接面元件的通道濃度是否也會對多晶鍺後對元件的表現造成影響，寫入速度的表現中，PolyGe-3元件的寫入速度是最快的，而在抹除上PolyGe-3元件的抹除速度比PolyGe-2元件以及PolyGe-1元件都還要慢。而在電荷保持力上的表現，PolyGe-3元件有著通道有著較少空的能態，所以表現較為其他兩者佳。此外三種元件的耐久力的表現也會因為快速寫抹的能力而有所提升，是相當有潛力應用在未來3D立體堆疊的記憶體元件上的。
從上面三個實驗中我們知道，多晶鍺的確在於元件的寫抹速度，電荷保持力以及電荷耐久力的各項表現上還不足以與多晶矽匹敵，但藉由無接面奈米通道式的這種結構改善了其電性，大大提升了多晶鍺在快閃記憶體這方面的潛力。若能再把多晶鍺的品質提升，與多晶矽在相同的起跑點上再來做比較，相信多晶鍺是會有很大的發展空間。況且在元件不斷微縮的趨勢之下，多晶鍺無接面奈米通式元件可能會是未來的發展趨勢，以上研究結果對未來快閃記憶體元件的發展是很有幫助的。

The flash memory devices with some advantages like low power consumption, higher device density and portable devices are more needed recently. However, as the devices scale down to few nanometers, there is limited space for planar devices to microminiaturize, which makes the process flow more difficult. Therefore, improvement of the device characteristic and how to make the process easier at the same time becomes two of the most important issues today. Some solutions have been reported like the implement of SiGe, nanowire channel structure and junctionless channel flash memory devices etc. In this thesis, we implemented the polycrystalline Ge on the nanowire channel flash memory devices, and the device electrical characteristics are investigated.
In the first experiment, the poly-Ge planar flash memory device is compare with Si planar capacitor one. The poly-Si planar devices show higher P/E speeds, better endurance and similar retention compared to poly-Ge one.
In the second experiment, the poly-Ge and poly-Si nanowire channel are implemented on the junctionless flash memory devices. Effects of poly-Ge channel on junctionless nanowire flash devices are studied. The results show that the junctionless nanowire devices perform well on the programming speed and reliability characteristics. Moreover, the erasing speeds of poly-Ge junctionless nanowire flash devices are faster compare to those of the poly-Ge planar capacitor ones.
In the third experiment, effects of channel concentration on the characteristics of junctionless poly-Ge nanowire channel flash memory devices are investigated. It is that the heavily doped junctionless poly-Ge nanowire devices show better P/E speeds and reliable characteristics, indicating that the channel concentration is still on important parameter in the Ge nanowire channel flash memory devices.
From above, the characteristics of poly-Ge flash memory device including P/E speed, endurance and retention are not good enough compare to those of the poly-Si ones. However, the electrical performance of poly-Ge flash device improved by junctionless nanowire structure shows great potential for nonvolatile memory industry in the future. It is believed that the results of poly-Ge flash memory device above are helpful to the future development memory technology.

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