金氧半結構中含金奈米粒子應用於電荷儲存

Metal-Oxide-Semiconductor Structure with Au Nanocrystals for Charge Storage

沈冠源(Kuan-Yuan Shen)

指導教授 ： 管傑雄

國立臺灣大學/電機資訊學院/電子工程學研究所/碩士(2006年)

https://doi.org/10.6342/NTU.2006.01874

摘要

本研究中，吾人製作金氧半結構含有化學還原法製成之金奈米粒子的元件，應用於儲存電荷。對於製作完成的元件吾人利用穿透式電子顯微鏡及掃描式電子顯微鏡驗證結構。對於元件儲存電荷的特性，吾人利用高頻電容電壓量測元件的記憶窗口來比較電荷儲存量以及充電效率；另一方面，也藉由量測定電壓下元件電容對時間的變化，計算出等效的電荷流失率，用以比較元件對於儲存電荷的保持能力。對元件的研究中，首先比較不同結構參數對元件的影響，包含了金奈米粒子層密度、氧化層沈積後熱退火溫度及穿遂氧化層的厚度。從比較中討論了不同結構對元件特性的影響，並且找出了較佳的元件參數。接著，對於氧化層沈積後熱退火製程做了更進一步的研究。首先製作經熱退火處理及未經熱退火處理的不同元件，並對元件進行變溫電流電壓量測，再將實驗所得的結果以適當的傳導機制加以擬合，求出不同傳導機制所佔的成分並加以比較。由比較中發現熱退火處理減少氧化層中的陷阱及缺陷，進而抑制缺陷所主到的漏電流，使漏電流所佔的比例於不同溫度下趨於收斂。另外也對擬合所得的傳導機制參數進行比較，發現經由熱退火處理，缺陷密度被降低，使得元件對儲存電荷有較佳的侷限能力，也抑制了經由缺陷及陷阱跳躍傳導的漏電流。

關鍵字

金奈米粒子 ； 非揮發性記憶體

並列摘要

In this work, Metal-Oxide-Semiconductor structure with Au nanocrystals formed by chemical redundant method for charge storage is fabricated. Scanning Electron Microscopy and Transmission Electron Microscope are utilized to characterize the structure of fabricated devices. In the characterization of memory performance, we use high frequency capacitance-voltage (C-V) measurement to measure the memory window for comparing the storage capacity and charging efficiency. On the other hand, through the time dependent variation of device capacitance measured under fixed voltage, the effective charge loss rate can be calculated to compare the retention regarding the stored charge of devices. In the first part of study on our devices, the devices with different structure parameters including the density of Au nanocrystals, the temperatures of post-deposition-anneal (PDA) process, and the thickness of tunnel oxide are measured to compare the effects of different structures. From the results of measurements, the effects of different structures are discussed and the optimized parameters of our devices are found. In the second part of our study, the effect of PDA process is further studied. Different devices with/without PDA process are fabricated and their current-voltage (I-V) characteristics at various temperatures are measured. The measured I-V curves are then fitted with appropriate conduction mechanisms to calculate the ratio of currents caused by different mechanisms. By comparing the ratios of different conduction currents, we found that PDA process can reduce defects and traps in oxide and suppress the leakage current, at the same time, make the leakage current converged and limited. The fitting parameters in different conduction mechanisms are also compared. We found that through PDA process the trap density is decreased to enhance the confinement of stored charge in Au nanocrystal. Besides, the results indicate that the PDA process can also suppress the leakage current attributed to the hopping of electrons from one traps to another.

並列關鍵字

Au nanocrystal ； non ； Non-volatile memory

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