Abstract
高頻高功率元件在近幾年來由於通訊及電力方面的需求日益增加而愈受重視, 就材料及結構考慮主要是三五族材料 (如砷化鎵) 及金屬半場效電晶體. 然而互補式金氧半電晶體製程具有技術成熟, 成本低廉的優點,而且隨著積體電路製程技術的進步, 通道長度已進入次微米的範圍, 這使得互補式金氧半電晶體元件的截止頻率與三五族材料相差無幾. 因此一個適合金氧半電晶體的高頻小訊號模型是必需的. 本論文在提出適用於金氧半電晶體的高頻模型, 並建立一套參數分析萃取的方法, 經由不同佈局結構的功率元件加以驗證, 可作為日後研究高功率金氧半元件的準則.在第二章中, 我們介紹各種不同頻率範圍的高頻金氧半元件小訊號模型, 發現非近似穩態模型比較適合高頻操作範圍. 此外我們也提出一個適用於三端元件的高頻模型, 比起前述所提之模型, 簡化模型的等效線路較為簡單, 方便參數的萃取. 接下來的章節中, 我們將討論幾種不同佈局結構的功率電晶體, 網狀結構電晶體具有密度較高且雜散電容小的優點, 適合高頻高功率元件的需求. 另外我們也提出一套參數萃取及分析的方法,不用另行設計假想元件即可得到本質及外部的參數. 我們測量所設計的元件, 其直流及高頻特性將於第四章中討論, 其餘有關參數萃取的方法也將略作修正以達到更佳的準確度. 經由參數的比較, 我們證明簡化模型較其它近似穩態模型更準確. 最後則是總結及未來發展部分.High-frequency high-power devices have been valued recently asthe demand of communication and power electronics increased.The main streams of material and structure are III-V family (egGaAs) and MESFET. Many small-signal models and analysis methodshave been presented and well-developed. However, as the greatprocess in IC technology, the channel length of a device hasbeen scaled down to submicron range. The frequency of operationof silicon MOSFET is competitive with that of GaAs MESFET.Moreover, the MOS technology has the advantages of low-cost andeasy-fabri- cation. In this paper we present a high-frequencymodel suited for MOSFET and establish procedures for extractingand analyzing parameters which is useful as guidelines ofresearch and for de- signing power MOS devices in the future.In Chapter two, we compare various small-signal models forMOSFET devices which are valid up to different upper frequencylimits. We concluded that the Non-Quasi-Static (NQS) modelwhich considers "transmission-line effects" is appropriate forhigh frequency operations. A simplified high-frequency modelbased on NQS analysis is presented, which is valid for three-terminal de- vices. In the next chapter, the design ofdifferent layouts of power devices is discussed. A mesh-structured transistor with benefits of high-packing density andminimum parasitic capaci- tance is preferable. Besides, we willintroduce a method of ex- tracting parameters includingintrinsic and extrinsic parts of a transistor without designingdummy devices. The d.c. character- istics and high frequencyperformances of designed MOSFET samples will be characterizedin Chapter four. The method of extracting parameters would bemodified to get high degree of precision. Concluding remarksand recommendations are given in the last chapter.