封闭形栅NMOS晶体管的设计与器件特性研究

发布时间：2018-04-13 05:16

本文选题：封闭形栅 + 抗辐射设计加固　；参考：《电子科技大学》2015年硕士论文

【摘要】：随着半导体技术的飞速发展和器件工艺尺寸的减小,互补型金属氧化物半导体(Complementary Metal Oxide Semiconductor,简写为CMOS)集成电路的可靠性问题越来越明显。尤其是在航天领域中,辐射所带来的可靠性问题尤为突出,抗辐射加固产品的需求越来越高,对使用芯片及系统抗辐射能力的要求也越来越高。在众多抗辐射加固方法中,采用封闭形栅晶体管的版图设计对于总剂量辐射效应是一种有效的抗辐射加固方法。于是,如何使用正确的宽长比提取方法对封闭形栅进行设计,并估算其带来的面积损耗以及封闭形栅NMOS晶体管的可靠性进行研究成为了现阶段半导体器件的研究热点。基于以上背景,本文围绕封闭形栅NMOS晶体管的设计与器件特性展开了研究。具体内容如下:基于商用CMOS工艺线,我们设计并制备了不同栅氧化层厚度和不同栅形状的封闭形栅NMOS晶体管,主要有环形栅、半环形栅和用于对比研究的条形栅。通过对完成制备的各种样片进行电特性测试,表明所设计的NMOS晶体管达到设计要求。并对条形栅、半环形栅和环形栅NMOS晶体管的最小宽长比和所占的版图面积进行了对比研究,并对比研究了三种提取封闭形栅NMOS晶体管的有效宽长比的方法,实验显示环形栅常使用的中线近似法和半环形栅使用的均值法提取有效W/L都存在误差,在可接受范围内,是最简单有效的方法。通过对不同栅氧厚度的封闭形栅NMOS晶体管进行辐射实验研究和计算机仿真研究,通过对工艺修正参数的调整,可以使实验数据和仿真数据达到很好的一致性,仿真结果和实验结果显示在栅氧化层更薄的工艺线中,封闭形栅NMOS的抗总剂量辐射加固效果更加显著,环形栅的加固效果优于半环形栅。对比研究了基于0.18μm CMOS工艺的环形栅、半环形栅和条形栅NMOS晶体管的热载流子效应,通过对其应力前后电特性的对比研究分析,结果显示,随着直流应力退化时间的累积,NMOS晶体管的漏电流会减小,阈值电压变大、跨导的峰值也会变小。并且,同一宽长比的NMOS,环形栅的退化最严重,半环形栅其次,与条形栅相差不大。所以,封闭形栅NMOS晶体管虽然能很好提高抗总剂量辐射能力,但对于抗HCI效应没有任何优势。
[Abstract]:With the rapid development of semiconductor technology and the decrease of device size, the reliability of complementary Metal Oxide Semiconductors is becoming more and more obvious.Especially in the field of spaceflight, the reliability problem caused by radiation is particularly prominent. The demand for radiation hardening products is more and more high, and the demand for radiation resistance ability of chips and systems is also higher and higher.The layout design of closed gate transistors is an effective method for the total dose radiation effect.Therefore, how to design the closed gate with the correct ratio of width to length and estimate the area loss and the reliability of the closed gate NMOS transistor has become the research focus of semiconductor devices at present.Based on the above background, the design and device characteristics of closed gate NMOS transistors are studied in this paper.The main contents are as follows: based on the commercial CMOS process line, we have designed and fabricated closed gate NMOS transistors with different gate oxide thickness and different gate shapes, including ring gate, semi-ring gate and strip gate for comparative study.The electrical properties of various samples are tested and the results show that the designed NMOS transistors meet the design requirements.The minimum aspect ratio and layout area of strip gate, half ring gate and ring gate NMOS transistor are compared, and three methods of extracting the effective aspect ratio of closed gate NMOS transistor are compared and studied.The experimental results show that there are errors in extracting effective W / L by the median approximation method and the mean value method used in the annular gate, which is the simplest and most effective method in the acceptable range.Through the radiation experiment and computer simulation of closed gate NMOS transistor with different gate oxygen thickness, the experimental data and the simulation data can be well consistent by adjusting the parameters of the process correction.The simulation and experimental results show that in the process line with thinner gate oxide the reinforcement effect of closed gate NMOS against total dose radiation is more remarkable and the reinforcement effect of annular gate is better than that of semi-annular gate.The hot carrier effect of ring gate, half ring gate and strip gate NMOS transistor based on 0. 18 渭 m CMOS process is studied.With the accumulation of DC stress degradation time, the leakage current of NMOS transistor decreases, the threshold voltage increases and the peak value of transconductance decreases.Moreover, for NMOS with the same aspect ratio, the degradation of annular gate is the most serious, and that of semi-annular gate is less than that of strip gate.Therefore, although the closed gate NMOS transistor can improve the total dose radiation resistance, it has no advantage in resisting the HCI effect.
【学位授予单位】：电子科技大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TN386

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