臺灣博碩士論文加值系統

摘要
本論文主要是要探討如何有效的去節省在模擬半導體時所需的記憶體空間，我們開發了四種不同的方法去模擬半導體元件。第一種方法是聯合法，，此種方法所需的記憶體空間在所有的方法裡面是最大的。第二種方法是部分分離法，此種方法所需的記憶體空間會比聯合法小。最後我們開發了元件分割法，此種方法可區分為二個不同的模式，分別為部分重疊和非部分重疊，元件分割法的優點是我們執行程式時將不會再受限於記憶體的空間。我們將會用上述的這幾種方法去模擬n型通道的金氧半場效電晶體，並比較它們模擬的結果，最後我們將使用這些方法去模擬互補式金氧半導體並且比較它們模擬的結果。

Abstract
In this thesis, we focus on how to effectively save required memory space when simulate a semiconductor device. We develop four different methods to simulate semiconductor devices. First method is coupled method(CM). It requires biggest memory space in all of the methods. Second method is partial decoupled method(PDM). The memory space with PDM is less than CM. Last, we develop device-partition method. It can be divided into two different modes. One is overlapped mode, the other is unoverlapped mode. The advantage of device-partition method is that our program can be compiled without limitation by memory space. We will use these methods to simulate an n-channel MOSFET and compare simulation result. Finally, we will use these methods to simulate a CMOS circuit and compare simulation result also.

Contents
1.Introduction………………………………..…………………..……………….1
2.Memory Reduction in Device Simulation………………………………….3
2.1 Introduction………………………………………………….………………3
2.2 Coupled Method……………………………………………….…………….5
2.3 2-D Equivalent Circuit………………………………………….……………7
2.4 Partial Decoupled Method…………………………………………………..10
2.5 Band Solver…………………………………………………………………12
2.6 MOSFET Simulation Result with CM and PDM Method………………..14
3.Device-partition method…………………………………………………….17
3.1 Device-partition Method with Overlapped Mode……………….………….17
3.2 Device-partition Method with Unoverlapped Mode………….…………….19
3.3 Unoverlapped Mode with three-part Partition…...…………………...……..23
3.4 MOSFET Simulation Result with Device-partition Method………………26
4.2-D CMOS Device simulation……………………………………………...30
4.1 Introduction to CMOS Characteristic and Structure……..………………30
4.2 CMOS Transfer-characteristic simulation……………….………………..34
4.3 Simulation in CMOS Propagation Delay Time….…………………...……37
5.Conclusion……………………………………………………………………...41
List of figures
2.1 Device grid diagram.……………………...…...…………………………………..4
2.2 Sketchy diagram of memory space.……………...………………………………..5
2.3 Flowchart of coupled method…………………………………………………….6
2.4 A rectangular mesh in two-dimensional simulation.………………………………7
2.5 The equivalent circuit of Poisson’s equation.………………..………………….8
2.6 The equivalent circuit for electron continuity equation.……………………….….9
2.7. The equivalent circuit for hole continuity equation.……………………………10
2.8 Flowchart of partial coupled method.…………………………………..………11
2.9. The diagram of band matrix.………………………………………………..…12
2.10 Bandwidth of interleaving method.………………….……………………..…13
2.11 Comparison of matrix size in CM and PDM.…………………………………...14
2.12 MOSFET structure diagram.……………………………………………………14
2.13 VDS-ID curve with 10 channel length.……………….…………………..15
2.14 VDS-ID curve with 1 channel length.…………………………………….16
2.15 Transfer characteristic of MOSFET with 1 channel length.……………….16
3.1 Dividing device into two parts with overlapped mode.…………………………..18
3.2 The flowchart of device-partition method.…………………………………….18
3.3. Dividing device into two parts with unoverlapped mode.……………………….20
3.4. The equivalent circuit of Poisson’s equation in 1st part.……………………….21
3.5. The equivalent circuit of electron continuity equation in 1st part.……………...21
3.6. The equivalent circuit of hole continuity equation in 1st part.………………….21
3.7. The equivalent circuit of Poisson’s equation in 2nd part.……………….………22
3.8. The equivalent circuit of electron continuity equation in 2nd part.…….……….22
3.9. The equivalent circuit of hole continuity equation in 2nd part.……….……...22
3.10 Dividing device into three parts with unoverlapped mode.……………………24
3.11. The flowchart of dividing device into three parts.……………………………25
3.12 ID-VDS curves for the MOSFET with overlapped mode.…………..……….27
3.13 ID-VDS curves for the MOSFET with unoverlapped mode and two-part partition………………………………………………………………………...27
3.14 ID-VDS curves for the MOSFET with unoverlapped mode and three-part partition.………….…………………………………………………………….28
3.15 Comparison of the CPU time for all of the methods…………………………...29
4.1 CMOS inverter…………………………………………………………………...31
4.2 CMOS DC transfer characteristic and operating regions.………………………..31
4.3 CMOS n-well process……………………………………………………………33
4.4 CMOS p-well process……………………………………………………………33
4.5 CMOS twin-tub process……………………………………………………….…33
4.6. CMOS structure.…………………………………………………………….…34
4.7 DC transfer characteristics for CM and PDM.………………………...…………35
4.8 DC transfer characteristics for CM and Unoverlapped_3parts…………………..35
4.9 Transfer-characteristic dependence on the ratio .………………….36
4.10 The delay-time definition of a typical inverter.……………….………………...37
4.11 The waveforms for output voltage and input voltage.……………………..…..38
4.12 The waveform dependence of output voltage on …..………………………39
List of tables
3.1 Memory space required by different methods.………………………………….26
4.1 Each region of CMOS.…………………………………………………………...32
4.2 Comparison of CMOS propagation delay time......………………………………40

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