基于双重栅极绝缘层的双栅MOSFET研究

发布时间：2018-01-28 12:58

  本文关键词： DI结构 介电常数 电流模型 阈值电压 SCE　出处：《安徽大学》2015年硕士论文　论文类型：学位论文

【摘要】：随着信息技术发展,MOSFET尺寸进一步减小,使得对集成电路的密集度进一步提升。器件尺寸减小能有效地提高集成度、大信息量存储等要求,但是伴随而出的各种不良性能却越来越多。通过各种新型结构设计和新的工艺技术能有效降低上述不良性能,目前解决的办法主要有三种途径：一是在多研究一些新的理论模型；二是优化设计,寻找有效设计办法来提升MOSFET性能；三是在工艺上寻找新半导体材料、新型器件结构等。本文从上述第三点出发,构造了一个新的器件模型,对其相关特性进行了模型建立与仿真,并对四种DI层结构随两种介电材料介电常数(ε)差值变化的相关特性进行了分析与讨论。本文在双栅DG (Double Gate)勺框架上,将栅绝缘层(Gate Insulator, GI)材料用两个ε值不同材料替换构成一个双重栅极绝缘层结构(Dual Insulator, DI),构造了一个新的DIDG MOSFET,并以DI层两种介质材料ε差值的不同,建立了四种DIDG器件。研究发现,DIDG器件在沟道区域内有两个电场最大值而普通DG器件在沟道区域内只有一个电场最大值；这个增加的电场会使得DI器件电场平均值大于普通DG器件电场平均值；DI结构沟道内电子平均速度大于普通DG结构电子平均速度,然而DI器件漏端电场却比DG器件漏端电场要小,因此在热载流子效应(HCE)抑制方面DI器件更有优势。同时仿真ID-VDS特性和ID-VGS特性发现,DI器件比普通DG器件,具有更高的漏电流及较好负载力、电流在饱和区的饱和度更好,在HCE抑制方面更有优势。伴随着DI层两种材料ε差值的增大,器件沟道电场越高且分布更均一、ID-vDS特性和ID-VGS特性更加优越、漏电流越高及负载力越好、对SCE抑制作用更强、器件的阈值电压(Vth)越大、亚阈值斜率(S)越小、器件开关性能越好、电子平均速度更高、电流密度更大。依据DI层两种材料ε差值的仿真分析,对DI层材料长度进行不同配比率优化设计,设计发现,随着配比率降低(3：2→1：1→2：3),沟道电场越大且更均-漏电流更高且负载力越强、漏电流饱和度越好且对SCE抑制更好好、电子平均速度更大、电流密度更大。同时通过不同的配比率仿真发现,随着配比率降低(3：2→1：1→2：3),器件的Vth值越大,因此可以通过不同配比率进行Vth值调控。本文对四种DI结构硅体中最低电势点电势进行修正,建立了最小电势点电势模型,同时在电势模型前提下,构造了阈值电压(VT)模型和亚阈值电流(ID)模型。通过MEDICI对模型进行了仿真验证,结果趋势一致,吻合度良好。
[Abstract]:With the development of information technology, the size of MOSFET is further reduced, which makes the density of integrated circuits increase further. The reduction of device size can effectively improve the integration, large amount of information storage and other requirements. However, there are more and more bad properties, which can be effectively reduced by a variety of new structural design and new technology. At present, there are three main ways to solve the problem: first, we are studying more new theoretical models; The second is to optimize the design to find effective design methods to improve the performance of MOSFET; The third is to find new semiconductor materials and new device structures in the process. In this paper, a new device model is constructed from the third point above, and its related characteristics are modeled and simulated. The correlation characteristics of four kinds of DI layer structures with the difference of dielectric constant (蔚) of two kinds of dielectric materials are analyzed and discussed. The gate insulator (GI) material is replaced by two different 蔚 values to form a dual gate insulator (dual Insulator) structure. A new DIDG MOSFET is constructed, and four kinds of DIDG devices are built according to the difference of 蔚 between two kinds of dielectric materials in DI layer. The DIDG device has two maximum electric fields in the channel region, while the ordinary DG device has only one maximum electric field in the channel region. The increasing electric field will make the average electric field of DI device larger than the average electric field of ordinary DG device. The average electron velocity in the channel of DI structure is higher than that in ordinary DG structure, but the leakage electric field of DI device is smaller than that of DG device. Therefore, DI devices have more advantages in the suppression of hot carrier effect (HCE). At the same time, the simulation of ID-VDS and ID-VGS characteristics shows that DI devices are better than ordinary DG devices. With higher leakage current and better load force, the saturation of the current in the saturation region is better, and the HCE suppression is more advantageous, with the increase of 蔚 difference between the two kinds of materials in DI layer. The higher the channel electric field and the more uniform distribution of ID-vDS and ID-VGS characteristics, the better the leakage current and load force, the stronger the inhibition to SCE. The larger the threshold voltage is, the smaller the sub-threshold slope is, the better the switch performance, the higher the average electron speed and the greater the current density. The simulation analysis is based on the 蔚 difference between two kinds of materials in DI layer. The optimum design of different ratio of DI layer material length was carried out. It was found that with the ratio ratio decreasing, the ratio decreased by 3: 2. 鈫，

本文编号：1470829