橋切法於矽覆絕緣金氧半場效電晶體之模擬與矽覆絕緣功率元件之背部閘極偏壓效應特性分析; Branch-cut Method for the SOI MOSFETs Simulation and the Characteristics Analysis of Back Gate Bias Effect for the SOI Power Devices

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題名:	橋切法於矽覆絕緣金氧半場效電晶體之模擬與矽覆絕緣功率元件之背部閘極偏壓效應特性分析;Branch-cut Method for the SOI MOSFETs Simulation and the Characteristics Analysis of Back Gate Bias Effect for the SOI Power Devices
作者:	何志宏;Chi-hon Ho
貢獻者:	電機工程研究所
關鍵詞:	減少表面電場;矽覆絕緣;側向式雙擴散金氧半場效電晶體;橋切法;RESURF;LDMOSFET;SOI;Branch-cut method
日期:	2009-04-27
上傳時間:	2009-09-22 12:05:29 (UTC+8)
出版者:	國立中央大學圖書館
摘要:	近年來，半導體製程技術快速的發展。在半導體產業裡，元件特性的模擬經常被使用來降低製造的成本與時間。因此開發半導體元件 (如：金氧半場效電晶體、絕緣基板金氧半場效電晶體以及功率元件) 模擬的方法以及利用模擬方法來事先針對所設計的元件做模擬就變成相當重要的任務。首先我們對開發全模擬以及半模擬技術於設計功率元件進行研究，並針對矽覆絕緣側向式功率金氧半場效電晶體中基底偏壓對臨限電壓之影響作探討。進而我們提出了Branch-cut 方法，說明Branch-cut是如何定義Kink 效應在SOI元件發生的機制。利用Branch-cut技術把元件電流操作分為兩區：(1)寄生雙載子電晶體電流區；(2)通道電流區。並且找到三種不同的案例來分析Kink 效應：(1)Body效應；(2)寄生雙載子電晶體效應；(3)合併效應。而我們更近一步用遮蔽氧化層SOI結構來抑制部分空乏型矽覆絕緣元件的寄生雙載子電晶體效應。隨著半導體產業的發展，高功率元件經常被應用在許多電力電子方面。其形式基本上可分為垂直通道(vertical-channel)及橫向通道(lateral- channel)的結構。本論文我們主要探討橫向通道的功率元件，此結構以側向雙擴散金氧半電晶體(LDMOS)為代表。首先我們針對SOI PN二極體的崩潰電壓作一討論，利用SOI晶片提供較好的絕緣性及合併一半絕緣覆晶矽層(SIPOS, Semi-Insulating POly-crystalline Silicon)，其電性近似於低摻雜埋藏層(low-doped buried layer)，目的是增加元件的崩潰電壓，並使用元件模擬軟體ISE-TCAD驗證之。另外我們也將半絕緣覆晶矽層應用於SOI LDMOS元件上，並模擬此結構的電特性，發現仍具有正常金氧半場效電晶體的導通特性及耐壓特性，這說明此結構是可行的。本論文也對元件製程參數對崩潰電壓的影響做一探討，並建立有SIPOS結構側向功率元件的分析模型，此分析模型主要是計算元件表面電位及表面電場。此分析模型與數值模擬相吻合，並可利用該模型來幫助設計其他側向功率元件如SOI LDMOS及SOI LIGBT等元件。此外，在論文中我們提出了一種新穎的矽覆絕緣結構，結構中有別於傳統的矽覆絕緣結構多了一層低摻雜埋藏層(Low Doping Buried Layer, LDBL)，該結構可解決電路設計者在使用矽覆絕緣元件時，基底偏壓對元件崩潰特性所造成的負面影響。並完整的分析了基底偏壓所產生的背部金氧半效應(Back Gate Metal-Oxide-Semiconductor effect)，進而對該層的厚度以及濃度做進一步探討，其中發現LDBL濃度並非主要影響基底偏壓效應的主要因素；而當LDBL厚度等於2.65 ?m時，元件對基底偏壓效應有最佳的抑制效果。 In the recent years, the semiconductor manufacturing technology proceeded at a very rapid pace. The simulation of device’s characteristics is always used to reduce the manufacturing cost and time in the semiconductor industry. Therefore, it is a very important task to investigate the simulation method and use the simulation tools to develop the design structure of devices. At first, we use the simulation tools to develop the “fully simulation method” and “half simulation method”, and to study the power devices. The threshold voltage influenced by the substrate bias on SOI LDMOSFET was discussed. Furthermore, in the partially depleted (PD) SOI NMOSFET device, the floating body effect emerges due to the accumulation of excess holes in the neutral substrate region. The floating body effect will cause the current curve of kink effect in the saturation region. In this paper, we have discussed about the kink effect in different situations and the branch-cut method was used to separate the current component into two parts: (1) the parasitic BJT current, (2) the channel current, respectively. Then we find three different cases to analyze: (1) the body effect, (2) the parasitic BJT effect, (3) the combination effect. Furthermore, the partially covered oxide structure is used to suppress the parasitic BJT current without influencing the body effect. It can be proved that the kink effect has two different stages, the first kink effect and the second kink effect, respectively. An analytical model is presented to determine the potential and electric field distribution along the semiconductor surface of new silicon-on-insulator (SOI) reduced surface field (RESURF) device. The SOI structure is characterized by a semi-insulating polycrystalline silicon (SIPOS) layer inserted between a silicon layer and a buried oxide. An improvement in the breakdown voltage due to the presence of the SIPOS shielding layer is demonstrated. Numerical simulations using ISETCAD are shown to support the analytical model. Besides, an optimal design of a silicon-on-insulator (SOI) device structure to eliminate the back gate bias effect of the lateral double diffused metal-oxide-semiconductor field effect transistor (LDMOSFET) is presented and to improve breakdown voltage. The SOI structure was characterized by inserting an low doping silicon buried layer (LDBL) between the silicon layer and the buried oxide layer. The LDBL thickness is a key parameter that affects the strong inversion condition of the back MOS capacitor of the new SOI diode. The optimal LDBL thickness in the SOI diode was 2.65 ?m.
顯示於類別:	[電機工程研究所] 博碩士論文

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