隨著科技的進步，記憶體被要求到要有更高的容量，但近幾年來，小尺寸的元件已經快達到物理極限了，加上非揮發性記憶體在市面上占有 96%以上。其中電阻式非揮發性記憶體擁有結構簡單、高密度、操作電壓低、操作速度快、持久度高和儲存時間長等優點，使其成為次世代非揮發性記憶體最熱門的選擇之一。 本實驗中以多磁靶濺鍍系統在氧化鈦(TiN)下電極鍍上二氧化矽 (SiO 2 ) 摻雜微量鋯 (Zr) 金屬，再鍍上鉑 (Pt) 金屬作為上電極，形成金屬/絕緣層/金屬 (MIM) 結構的電阻式記憶體。以不同的介電常數材料堆疊造成不同的跨壓，接著進行基本電性量測實驗與材料分析。 電性量測中，首先進行 forming 的動作，接著再以正負電壓的來回操作觀察其 I-V 曲線特性；隨後作線性迴歸 （Fitting），探討不同限流下元件的傳導機制。 首先以高介電係數 HfO 2 與低介電係數 BN 的材料來製作 RRAM，因為電場在低介電材料係數下的電場比較大，因此能夠使電子在縱向電場移動，因而 set電壓會比較集中。後續以 Zr:SiO 2 /C:SiO 2 RRAM 來做為高低介電係數 RRAM，發現不管是在高電阻狀態 (HRS)或是低電阻狀態 (LRS)電流的傳導機制都是以Hopping 為主，從 Raman 與 FTIR 分析出來的結果發現，C 在 SiO 2 中所扮演的腳色有部分是以 graphene oxide 的形式存在，當金屬絲形成時，因為尖端電場效應所以金屬絲會連接到石墨稀，所以 RRAM 在石墨烯上的操作有更穩定的 set 電壓和使得操作電流降低。 緊接著，我們以 ICP 對 C 進行處理，目的是為了得到更低的介電係數和考慮碳的影響，從 FTIR 圖中可以很明顯看到 C 訊息的變化，在基本電性的分析上，我們發現在高電壓部分的傳導機制都是以空間電荷限制電流為主，電場模擬圖也顯示出當更低介電係數的材料存在時，電場最強的部分會存在於低介電係數材料，
導致電流傳導路徑會被侷限在小空間內，而形成空間電荷限制電流。

With the progress of technology, large capacity and scalable are required for the future. Recent years, the physical limit is approached and a next-generation memory
is needed in the future. In addition, non- volatile memory occupies more than 96% in the memory market, and RRAM has great advantages such as simple structure,
high scalable, low operation voltage, high operation speed, high endurance and retention. That is the reason RRAM is the candidate in the next generation.
In this experiment, multi-sputtering was used to deposit Zr:SiO 2 and Pt on TiN bottom electrode. The sandwich structure was metal/insulator/metal (MIM). With the different dielectric constant material, a different electrical field will be produced. And then I-V measurement and materials analysis were used to investigate the
characteristic of the RRAM. At first, a forming process is required to the RRAM. The device was swept from negative to positive voltage and obtained the conduction mechanism from curve fitting. The different dielectric constant materials were used to fabricate the RRAM. High and low dielectric materials were HfO 2 and BN, respectively. The electric field distribution is centralized in low dielectric material so the electrons will drift to the direction of electric field. Hence, the Vset will be centralized and more stable. We also fabricated a Zr:SiO 2 /C:SiO 2 RRAM as an high K and low K material. The current fitting results that a hopping conduction occurs in low resistive state (LRS)
and high resistive state (HRS). Both from Raman spectrum and FT-IR spectrum, a graphene oxide was existed in the C:SiO 2 thin film. While the filament was form, the tip of the filament will approach the graphene oxide because of the point effect. Hence, the resistance switching will happen in the grapheme oxide and set voltage will be more stable and lower the operated current. Next, an ICP treatment was used in order to "burn" the carbon in SiO 2 . The purpose is to make an extremely low K material and ignore the effect of the existence of carbon. From the FT-IR spectrum, the carbon signals were disappeared after the ICP oxygen plasma treatment. In the I-V fitting diagram, space char limit results in the high voltage region. The electrical field simulation was an auxiliary tool which shows a strong electrical field occurs in the extremely low K area. While the electrons flow through the conduction path, they will be confined in the porous area. The operation current will decrease because of the limited conduction area.

Acknowledgement ...................................................................... ii
中文摘要 ............................................................................... iii
Abstract ................................................................................ v
Contents .............................................................................. vii
Figure Captions .......................................................................... x
Table Captions ......................................................................... xiv
Chapter 1 Introduction ........................................................... 1
1.1 The development of Memories .......................................................... 1
1.2 Classification of memory................................................................... 2
1.2.1 Volatile Memories .............................................................................. 3
1.2.2 Nonvolatile Memories (NVM) .......................................................... 4
1.3 Motivation ......................................................................................... 4
Chapter 2 Literature Review ................................................. 6
2.1 Next-generation Nonvolatile Memories ............................................ 6
2.1.1 MRAM (Magnetic RAM) .................................................................. 6
2.1.2 FeRAM (Ferroelectric RAM) ............................................................ 8
2.1.3 PCRAM (Phase Change RAM) ......................................................... 9
2.1.4 RRAM (Resistive RAM) ................................................................. 10
2.2 Introduction to Resistance Random Access Memory ...................... 11
2.2.1 The switching mechanism of Resistance RAM ............................... 11
2.2.2 The mechanism of current conduction ............................................ 15
Chapter 3 Experimental instrument and principle ........... 24
3.1 Multi-target sputter .......................................................................... 24
3.2 N&K analyzer .................................................................................. 26
3.3 Fourier transform infrared spectroscopy ......................................... 27
3.4 X-ray photoelectron spectroscopy ................................................... 29
3.5 Multi-function semiconductor parameter analyzer .......................... 30
viii
Chapter 4 Resistance RAM characteristic of SiO 2 , HfO 2 ,
and HfO 2 /BN ....................................................... 32
4.1 The fabrication of the device and process flow ............................... 32
4.1.1 The preparation of the substrate ...................................................... 33
4.1.2 Deposition of SiO 2 thin film ............................................................ 33
4.1.3 Deposition of HfO 2 thin film ........................................................... 36
4.1.4 Deposition of HfO 2 /BN thin film .................................................... 36
4.2 The material analyses ...................................................................... 37
4.2.1 Fourier Transform Infrared Spectroscopy (FTIR) ........................... 38
4.2.2 FT-IR analyses of HfO 2 film. ........................................................... 38
4.2.3 FT-IR analyses of BN film. ............................................................. 39
4.3 The electrical measurement and analyses ........................................ 40
4.3.1 Basic I-V characteristic of Pt/SiO 2 /TiN device ............................... 42
4.3.2 Basic I-V characteristic of HfO 2 RRAM ......................................... 43
4.3.3 Basic I-V characteristic of HfO 2 /BN/ RRAM ................................. 47
Chapter 5 Resistance RAM characteristic of Zr:SiO 2 and
Zr:SiO 2 /C:SiO 2 double layer films.................... 50
5.1 The fabrication of the device and process flow ............................... 50
5.1.1 Deposition of Zr:SiO 2 thin film ....................................................... 50
5.1.2 Deposition of C:SiO 2 and Zr:SiO 2 thin films .................................. 51
5.2 The electrical measurement analysis ............................................... 53
5.2.1 Basic I-V characteristic of Pt/Zr:SiO 2 /TiN RRAM ......................... 53
5.2.2 Curve fitting of Pt/Zr:SiO 2 /TiN ....................................................... 57
5.2.3 Retention and Endurance ................................................................. 59
5.2.4 Basic I-V characteristic of Zr:SiO 2 /C:SiO 2 RRAM......................... 62
5.2.5 Endurance and retention .................................................................. 64
5.3 Material Analysis ............................................................................. 67
5.3.1 Fourier Transform Infrared Spectroscopy (FTIR) ........................... 67
5.3.2 Raman spectrum .............................................................................. 68
5.3.3 X-ray Photoelectron Spectroscopy (XPS) ....................................... 71
5.4 The comparison of Zr:SiO 2 and Zr:SiO 2 /C:SiO 2 RRAM ................ 74
5.5 The electrical model ........................................................................ 80
Chapter 6 Resistance RAM characteristic of Zr:SiO 2 and
ix
ZrSiO 2 /porous SiO 2 double layer films ............ 83
6.1 The fabrication of the device and process flow ............................... 83
6.1.1 Deposition of C:SiO 2 thin film and ICP treatment .......................... 83
6.2 Material analyses ............................................................................. 85
6.3 The electrical measurement analysis ............................................... 88
6.3.1 Basic I-V characteristic of Zr:SiO 2 /porous SiO 2 RRAM ................ 88
6.3.2 The comparison of Zr:SiO 2 and Zr:SiO 2 /porous SiO 2 RRAM ........ 90
6.3.3 Electrical mechanism fitting ............................................................ 93
6.3.4 Simulation of electrical field ........................................................... 95
Chapter 7 Conclusion ........................................................... 97
References .............................................................................. 99

99
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