本文選題：半解析法　切入點：電勢　出處：《安徽大學(xué)》2017年碩士論文

【摘要】：隨著集成電路的發(fā)展,MOS器件已進入深亞微米的時代,傳統(tǒng)的MOS器件在結(jié)構(gòu)和尺寸上將會達到物理極限,這時基于物理的問題會對MOS器件產(chǎn)生很大的影響,如短溝道效應(yīng)(SCE)、漏致勢壘降低效應(yīng)(DIBL)等。為了克服這些影響,研究者努力尋找新的材料,開發(fā)新的器件結(jié)構(gòu),試圖制作出理想的半導(dǎo)體器件。SOI器件與傳統(tǒng)的體硅器件相比不僅能有效地抑制短溝道效應(yīng),還擁有更多的優(yōu)點:如低功耗、無閂鎖效應(yīng)、寄生電容小、集成度高、抗輻射能力強、速度快、制作工藝簡單等。為了對SOI MOSFET器件進行更加深入的研究,我們需要建立一個精確而又簡單的電勢模型,本文具體開展的工作如下。第1章介紹了傳統(tǒng)MOS器件的發(fā)展及存在的問題,針對這些問題引入SOI MOSFET器件,并分析了 SOI MOSFET器件的研究意義,研究現(xiàn)狀和應(yīng)用。第2章綜述了 SOI MOSFET模型的研究方法,討論了已有的拋物線近似模型和準(zhǔn)二維模型的解法和優(yōu)缺點,并在此基礎(chǔ)上著重分析了基于半解析法的SOI MOSFET亞閾值表面勢模型。該模型先通過矩形等效源的方法將器件結(jié)構(gòu)劃分三個區(qū)域,確立各個區(qū)域的電勢方程,邊界條件。然后根據(jù)各個區(qū)域的電勢相等和電位移相等確立銜接條件。第3章介紹了半解析法SOI MOSFET器件亞閾值表面勢模型的解法。該解法的主要過程如下:首先根據(jù)分離變量法和特征函數(shù)展開法對各個區(qū)域進行求解,得到含有待定系數(shù)的電勢表達式。其次根據(jù)交界面處的電勢相等,設(shè)氧化層和硅膜交界面處的上表面勢為φ1(x),硅膜和埋氧化層交界面處的下表面勢為φ2(x),將電勢方程中的待定系數(shù)用上下表面勢代替,避免了由于方程中sinh和cosh的存在導(dǎo)致方程不收斂。然后根據(jù)交界面處的電位移相等,得到兩個含有上下表面勢的方程。根據(jù)相關(guān)區(qū)域的邊界條件和三角函數(shù)的特性,將上下表面勢設(shè)成廣義傅里葉級數(shù)形式進行計算,避免由于傅里葉級數(shù)同時存在正弦和余弦函數(shù)所帶來的大量計算。最后對方程進行正交函數(shù)化簡,得到含有待定系數(shù)的矩陣方程。通過數(shù)學(xué)計算工具MATLAB進行求解,得到要求的系數(shù),再將系數(shù)帶入上下表面勢和電勢方程中,可以得到很直觀的電勢和表面勢的解析式。半解析模型不同于數(shù)值模型和解析模型,它是在兩者的基礎(chǔ)上提出的,不僅具有很好的精確度,還具有明確的解析表達式,具有很強的實用性和價值性。第4章對全耗盡SOIMOSFET模型的驗證分析。首先,利用PDE工具對模型進行數(shù)值驗證,對比了各個區(qū)域的等值線圖。其次,在相同尺寸下將模型計算得到的表面勢和SILVACO仿真得到的表面勢進行了比較,驗證了模型的精確性。從比較結(jié)果可知,在不同的溝道長度、氧化層厚度、摻雜濃度、硅膜厚度下模型的計算結(jié)果和SILVACO仿真結(jié)果都能夠較好的吻合,因此建立的模型能夠很好的反映表面勢隨著器件參數(shù)的變化。
[Abstract]:With the development of integrated circuits, MOS devices have entered the age of deep submicron, and the traditional MOS devices will reach the physical limit in structure and size. At this time, the physical-based problems will have a great impact on the MOS devices.For example, short channel effect (SCE), leakage barrier reduction effect (DIBL) and so on.In order to overcome these effects, researchers try to find new materials, develop new device structures and make ideal semiconductor devices. Compared with traditional bulk silicon devices, SOI devices can not only effectively suppress the short channel effect.It also has many advantages, such as low power consumption, no latch effect, small parasitic capacitance, high integration, strong radiation resistance, high speed, simple fabrication process and so on.In order to study the SOI MOSFET devices more deeply, we need to establish an accurate and simple EMF model. The work of this paper is as follows.Chapter 1 introduces the development and existing problems of traditional MOS devices, introduces SOI MOSFET devices to these problems, and analyzes the research significance, research status and application of SOI MOSFET devices.In chapter 2, the research methods of SOI MOSFET model are summarized, and the methods of solving parabola approximate model and quasi two-dimensional model are discussed. Based on this, the sub-threshold surface potential model of SOI MOSFET based on semi-analytical method is emphatically analyzed.In this model, the structure of the device is divided into three regions by the method of rectangular equivalent source, and the potential equations and boundary conditions of each region are established.Then the connection condition is established according to the equal potential and the equal electric displacement of each region.In chapter 3, the semi-analytical method for solving the subthreshold surface potential model of SOI MOSFET devices is introduced.The main process of the solution is as follows: firstly, the potential expressions with undetermined coefficients are obtained by solving each region according to the method of separating variables and the expansion method of characteristic function.Secondly, according to the equal electric potential at the interface, let the upper surface potential of the interface between the oxide layer and the silicon film be 蠁 1kW, and the lower surface potential at the interface between the silicon film and the buried oxide layer be 蠁 2 x, so the undetermined coefficient in the potential equation is replaced by the upper and lower surface potential.It is avoided that the equation does not converge due to the existence of sinh and cosh in the equation.Then, according to the equal electric displacement at the interface, two equations with upper and lower surface potentials are obtained.According to the boundary conditions of the related regions and the characteristics of trigonometric functions, the upper and lower surface potentials are calculated in the form of generalized Fourier series, which avoids the large amount of calculation caused by the existence of both sine and cosine functions in Fourier series.Finally, the equation is simplified by orthogonal function, and the matrix equation with undetermined coefficients is obtained.The required coefficients are obtained by means of the mathematical calculation tool MATLAB, and then the coefficients are brought into the upper and lower surface potential and potential equations. The analytical expressions of the surface potential and the surface potential can be obtained directly.The semi-analytical model is different from the numerical model and the analytical model. It is based on the two models. It not only has good accuracy, but also has a clear analytical expression, which has strong practicability and value.Chapter 4 verifies the fully depleted SOIMOSFET model.First, the PDE tool is used to verify the model, and the isoline maps of each region are compared.Secondly, the accuracy of the model is verified by comparing the surface potential calculated by the model with that obtained by SILVACO simulation at the same size.From the comparison results, it can be seen that the calculation results of the model under different channel length, oxide layer thickness, doping concentration and silicon film thickness are in good agreement with the SILVACO simulation results.Therefore, the model can well reflect the change of surface potential with the device parameters.
【學(xué)位授予單位】：安徽大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2017
【分類號】：TN386

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本文編號：1703683