臺灣博碩士論文加值系統

複晶矽長久以來已被當作為懸浮閘極快閃式記憶體儲存電荷的薄膜層來使用。複晶矽亦是個相當可靠的材料，而且可以完全的和CMOS 的製程流程相容。然而，複晶矽有著些許先天上的缺點，因此隨著快閃式記憶體元件的微縮下，複晶矽已經到達做為儲存電荷薄膜層的極限。
在這篇論文中，我們因應CMOS 製程的需要，分別提出二種富含鉿金屬和釓金屬的奈米點記憶體。同樣在6.5 MV/cm的電場下，鉿金屬奈米點記憶體的memory window 較釓金屬奈米點記憶體來的大。經過快速退火處理後，釓金屬奈米點記憶體的memory window並不會隨著快速退火的溫度高低而變化。但是鉿金屬奈米點記憶體的memory window卻會隨快速退火溫度上升而變小。可見釓金屬奈米點記憶體擁有極佳的熱穩定性。此兩種記憶體的寫入速度可達1 ms，抹除速度大概在5 s。釓金屬奈米點記憶體的抹除速度又較快些。記憶保留能力上，釓金屬奈米點記憶體的表現也比鉿金屬奈米點記憶體來的好。在85oC下以及相同電場的條件下，鉿金屬奈米點記憶體的電荷流失率比釓金屬奈米點記憶體要來的快。最後，不論是鉿金屬或釓金屬奈米點記憶體，都有著極佳的忍耐度特性。

Poly-silicon has been used as the charge trap/storage layer in floating gate flash memory for a long time. Poly-silicon is a very reliable material and is fully compatible with the current CMOS process flow. However, poly-silicon shows some intrinsic disadvantages and thus may not be the ultimate charge trap/storage material for scaled flash memory technology.
In this work, we propose metal-rich Hafnium (Hf) and Gadolinium (Gd) NC memory that are fully compatible with the current CMOS technologies. The memory window of Hf nanocrystal is larger than the one of Gd nanocrystal as both they are under 6.5 MV/cm. After RTA treatment, the window of Gd nanocrystal is almost the same when RTA temperature increases. The window of Hf nanocrystal will narrow after RTA temperature rise. It means Gd nanocrytal has highly robust thermal stability. The speed of program can be at 1 ms and erase at 5s. Gd nanocrystal can be erased faster. The retention characteristic of Gd nanocrystal is better than Hf nanocrystal. At 85oC, the charge loss rate of Hf nanocrystal is faster than Gd nanocrystal at the same electric field. Final, superior endurance characteristics can be found in both Hf and Gd nanocrystal.

Content
Chapter 1 Introduction
1-1 Background ………..…...……………………………………………1
1-2 Advantages of using high-k materials …...…………...……………...3
1-3 The motivation in this study...……..………………..….…………….5
1-4 Thesis Organization …………………………………….……...........5

Chapter 2 The Characterization of Hf Nanocrystal Thin Film
2-1 Introduction ………………………………………..………………...9
2-2 Experiment ……………...…………………………………………...9
2-3 Results and Discussion...…………………….………..…………….10
2.3.1 Blocking oxide 20 nm...………………………..………..…….10
2.3.2 Blocking oxide 10 nm...………………………..………..…….12
2-4 Summaries ……………………………………….….………...........13



Chapter 3 The Characterization of Gd Nanocrystal Thin Film
3-1 Introduction ……………………………….…………….………….45
3-2 Experiment ………………………………….…………….………..45
3-3 Results and Discussion……………………………………………...46
3-4 Summaries ……………………………………….…….……...........48

Chapter 4 Conclusions and Future Works
4-1 Conclusion …………….....…….…………………….….………….68
4.1.1 Hf nanocrystal ………………....……………….….………….68
4.1.2 Gd nanocrystal ………...……....……………….….………….68
4.1.3 Compare Gd nanocrystal to Hf nanocrystal ....……………….69
4-2 Future work…………………………………………………………69

Reference ……………………………………………..………….……..73

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