臺灣博碩士論文加值系統

近年來，電阻式記憶體成為非常受歡迎的非揮發性記憶體在下一世代。有高密度陣列下製程是最大的吸引力；然而，在陣列中因與其他記憶體形成串連路徑產生的漏電流將會影響讀取下的有效範圍。因此，有許多輔助的元件能夠與電阻式記憶體結合同時改善此問題。選擇器是一個可行的元件在此其中。
在本文中，我們利用多層氧化層夾層於氮化鉭形成三明治結構製程選擇器原件。藉由蕭基特電子發射和F-N電子穿隧，選擇器能擁有高度選擇比在不同電壓區間下。此高度電壓對電流選擇比現象也利用能代圖分析以圖型表示。電性上的討論，透過不同種量測方式例如變溫量測也考量不同材料間的相互影響。在電阻式記憶體的章節中，多加上鈦金屬在原結構的記憶體上電極，記憶體的表現能有明顯得提升，同時鈦金屬能吸取更多氧原素幫助了原結構記憶體做為記憶燈絲更加粗曠，藉此提升記憶體轉態的次數和穩定度。在選擇器與電阻式記憶體的結合下，透過模擬來計算出元件能夠製程的最大陣列。擁有高度選擇比的選擇器輔助下，電阻式記憶體能夠克服漏電流，同時還能保有原始的轉態特性。除此之外，我們還製程了兩種不同特性的電阻式記憶體和相同的選擇器做整合來進行探討。

Recently, resistive random access memory has become one of the most promising candidates for the next generation non-volatile. For ultra-high integration density, cross-point array is the most attractive architecture. However, it is essential to suppress the sneak path current from the neighboring cells that can reduce the readout sense margin. As a result, there are several devices which is used to support the RRAM device. Selector is the one of possible solutions among of them.
In this thesis, we proposed multilayer oxide based insulator with TaN electrode in Metal-Insulator-Metal (MIM) sandwiches structure which was investigated for selector application. The highly nonlinear current-voltage characteristics are occurred by the Schottky emission and Fowler-Nordheimen tunneling in different voltage regime. The band diagram of the best sample is also schematically illustrated in each bias condition. The electrical characteristics of the selector have been investigated by using various approaches such as activation energy method and by considering factors such as material dependence. In resistive RAM part, compare with ITO/HfO2/TiN single top electrode device, Titanium capping RRAM device Pt/Ti/ITO/HfO2/TiN exhibits higher endurance performance and higher resistive switching uniformity. These substantial improvements in resistive switching properties are attributed to the thicker conductive filament by Titanium assisted to getter more oxygen from HfO2 oxide layer. In one selector one RRAM part, we try to combine both selector and RRAM device and make simulation of the maximum array which can suppress the sneak path current. By high nonlinear of selector device to suppress sneak path current, the RRAM device can maintain good performance and be realized to fabricated in cross bar array. Also, there are two 1S1R device which are different RRAM combining with the same selector is be investigated in each characteristics.

摘要 I
Abstract III
Acknowledgement V
Contents VI
Table captions X
Figure captions XI
Chapter 1 Introduction 1
1.1 Introduction to Random Access Memory 1
1.2 Volatile memory 2
1.2.1 DRAM 2
1.2.2 SRAM 2
1.3 Non-volatile memory 3
1.3.1 Flash Memory 4
1.3.2 FeRAM 5
1.3.3 MRAM 6
1.3.4 PCRAM 6
1.3.5 RRAM 7
Chapter 2 Selector and RRAM 15
2.1 Sneak path current problem 15
2.2 Solutions for sneak path current 15
2.2.1 One MOSFET transistor-one resistor 16
2.2.2 One diode-one resistor 16
2.2.3 One selector-one resistor 17
2.2.4 Self-Rectifying cell 18
2.2.5 Complementary resistive switching 19
2.3 Current Conduction Mechanisms 19
2.3.1 Direct tunneling 19
2.3.2 Fowler-Norheim tunneling 20
2.3.3 Schottky Emission 21
2.3.4 Poole-Frenkle Emission 21
2.4 Overview of RRAM 22
2.4.1 Electrical Operation in RRAM 22
(a) Forming 23
(b) Switching operation mode 23
2.4.2 Memory Characteristics in RRAM 24
(a) Resistive Ratio 24
(b) Endurance 24
2.4.3 Mechanism of Electrical Conduction in RRAM 25
(a) Filament Model 25
(b) Oxygen Vacancy Migration 25
(c) Cation Migration 26
(d) Joule Heating 26
Chapter 3 Experiment Details 34
3.1 Sample Preparation 34
3.1.1 Fabrication of TaN/ (Al2O3, TaOx, TiOx)/TaN single layer Selector Device 34
3.1.2 Fabrication of TaN/Al2O3/ (TaOx, TiOx)/ (TiOx, TaOx)/TaN Triple-layer-oxide Tunneling Selector device 35
3.1.3 Fabrication of ITO/HfO2/ (TaN, TiN) and Pt/Ti/ITO/HfO2/ (AlN) / TiN RRAM Device 36
3.1.4 Fabrication of one Selector one RRAM Device 36
3.2 Electrical Measurement 37
3.2.1 DC current-voltage Measurement 37
3.2.2 Barrier height Measurement 37
3.2.3 Endurance Test 38
Chapter 4 Triple-layer tunneling oxide-based selector 44
4.1 Motivation 44
4.2 Electrical Property of Single layer Selector 44
4.3 Electrical Property of Triple layer Selector 46
4.4 Discussion on Mechanism of Triple-oxide Tunneling layer Selector Device 47
Chapter 5 Optimization of ITO-electrode RRAM and Application of one selector one RRAM 62
5.1 Motivation 62
5.2 Electrical Property of ITO/HfO2/BE structure RRAM with TaN and TiN different Bottom Electrode 63
5.3 Electrical Property of Pt/Ti/ITO/HfO2/TiN structure RRAM 64
5.4 Discussion on Mechanism of Resistive Switching of ITO/HfO2/TiN and Pt/Ti/ITO/HfO2/TiN 66
5.5 Electrical Property of Pt/Ti/ITO/HfO2/AlN/TiN structure RRAM 67
5.6 One Selector one RRAM device 69
5.6.1 Electrical Property of one Selector one RRAM ( Selector :TaN/TaOx/TiOx/Al2O3/TaN) ,( RRAM :Pt/Ti/ITO/ HfO2/TiN) 69
5.6.2 Electrical Property of one Selector one RRAM ( Selector :TaN/TaOx/TiOx/Al2O3/TaN) ,( RRAM :Pt/Ti/ITO/ HfO2/AlN/TiN) 70
5.6.3 Discussion on Performance of one Selector one RRAM in different RRAM device 71
Chapter 6 Conclusions and Future Works 89
References 91
Appendix 98

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