微波退火對大氣電漿沉積氧化銦鎵鋅層於電阻式記憶體元件之影響

Abstract

非揮發性記憶體在現代科技有著非常重要的角色，其在任何消費性電子產品中皆為不可或缺的。目前最普遍的非揮發性記憶體為快閃記憶體，然而隨著半導體元件的微縮，快閃記憶體內穿隧介電層的厚度將隨之下降，導致嚴重的漏電現象而無法滿足記憶功能。電阻式記憶體由於其結構簡單，存取速度快，以及省電等特性，近年來被視作最有可能成為下一個世代的非揮發性記憶體元件之一。 本論文採用的電阻式記憶體結構為－金屬／氧化層／金屬，其金屬部分用常見之鋁作為電極，而氧化層部分則用具有高載子遷移率、可低溫沉積、均勻度佳的非晶態氧化半導體－氧化銦鎵鋅，也探討其記憶之功能、特性。在本實驗中，氧化銦鎵鋅層利用大氣電漿技術來沉積，如此可降低製程成本。此外，由於非晶態氧化銦鎵鋅存在一些本質上之缺點，因而期待利用微波退火，可改善元件之特性、可靠度。 從實驗結果我們發現本元件可展現出無極性的模式，而在雙極性操作下具有較好之特性，且選用適當的微波退火能量與時間條件時，可以提升元件可靠度。

Non-volatile memory (NVM) plays a important role in modern science, and it is essential in almost every consumer electronic products. The most prevalent NVM used nowadays is flash memory. However, with the scaling down of semiconductor device, tunneling oxide thickness is also reduced, which leads to a severe leakage of storage charge and unable to satisfy the memory requirement. Recently, Resistive random access memory (RRAM) is considered to be the most promising one to become the next-generation NVM device since its simple structure, fast program/erase speed, and low power consumption. Owing to its metal/oxide/metal structure in this thesis, our RRAM was fabricated by common metal - Aluminum, as its top and bottom electrode. And we used amorphous oxide semiconductor - indium gallium zinc oxide (IGZO) to be the oxide layer due to its high mobility, low temperature deposition, and uniformity. And the memory capability and characteristics are also investigated here. In this experiment, the IGZO layer was deposited by using APPECVD technique which can reduce the cost of the process. However, there are some inherent defect in amorphous IGZO film thereby affect the device, we expect that the performance and reliability can be improved by using microwave annealing (MWA) treatment. From the experiment results, we find that our device exhibits the nonpolar mode and has better performance under bipolar operation. Besides, the reliability is therefore enhanced in suitable microwave power and annealing time conditions.