MOSFET抗辐照能力预测方法

基于金属-氧化物-半导体场效应晶体管(MOSFET)噪声的载流子数涨落和迁移率涨落理论,建立起MOSFET抗辐照能力预测模型.利用该模型,可较好地通过辐照前的1/f噪声参量,预测辐照后分别由氧化层陷阱和界面陷阱诱使阈值电压漂移的情况.模型模拟结果与实际测量结果符合良好,验证了预测模型的正确性,并为工程应用提供MOSFET抗辐照能力预测方法.     

光电耦合器总剂量辐照的噪声表征

 本文在研究光电耦合器工作原理、辐照理论及1/f噪声理论的基础上,分析了光电耦合器辐照噪声产生机理及特性,建立了光电耦合器总剂量辐照损伤噪声模型.研究结果表明,随着辐照总剂量增强, LED及光敏管氧化层中引入的氧化层陷阱密度增多,载流子数涨落增强,从而使电压噪声功率谱密度增加.实验结果验证理论分析的正确性,电压噪声功率谱密度可作为光电耦合器辐照损伤表征参量.     

MOSFET 1/f噪声的相关积分分析方法

文章将相关积分方法用于MOSFET 1/f噪声分析,发现器件的1/f噪声与RTS叠加模型产生的1/f噪声相关积分极其相似.通过对MOSFET噪声物理模型的分析和讨论,证明n-MOSFET的1/f噪声以载流子数涨落模型为主,p-MOSFET的1/f噪声以迁移率涨落模型为主结论的正确性.研究表明,相关积分方法可用于鉴别电子器件测量噪声所属的模型类型.     

国产中高压抗辐照功率MOSFET单粒子效应

功率金属-氧化物半导体场效应晶体管(MOSFET)空间使用时易遭受重离子轰击产生单粒子效应(单粒子烧毁和单粒子栅穿)。本文对国产新型中、高压(额定电压250 V,500 V)抗辐照功率MOSFET的单粒子辐射效应进行了研究,并采取了有针对性的加固措施,使器件的抗单粒子能力显著提升。结果表明：对250 V KW2型功率MOSFET器件进行Bi粒子辐照,在栅压等于0 V时,安全工作的漏极电压达到250 V;对500 V KW5型功率MOSFET器件进行Xe粒子辐照,在栅压等于0 V时,安全工作的漏极电压达到400 V,并且当栅压为-15 V时,安全工作的漏极电压也达到400 V,说明国产中、高压功率MOSFET器件有较好的抗单粒子能力。     

源区浅结SOI MOSFET的辐照效应模拟

研究了源区浅结的不对称SOI MOSFET对浮体效应的改善,模拟了总剂量、抗单粒子事件(SEU)、瞬时辐照效应以及源区深度对抗辐照性能的影响.这种结构器件的背沟道抗总剂量能力比传统器件有显著提高,并且随着源区深度的减小,抗总剂量辐照的能力不断加强.体接触不对称结构的抗SEU和瞬时辐照能力优于无体接触结构和传统结构器件,这与体接触对浮体效应的抑制和寄生npn双极晶体管电流增益的下降有关.     

GaAlAs红外发光二极管功率老化对其1/f噪声特性的影响

在可靠性筛选中检测具有潜在损伤的器件一直是个难题.对GaA lAs红外发光二极管(IRLED)功率老化前后低频噪声的测量发现,1/f噪声幅值与偏置电流的γ次方成正比(小电流区γ=1,在大电流区γ≈2),且老化后1/f噪声幅值比老化前增大2个数量级.基于载流子数涨落和迁移率涨落机制建立了一个GaA lAs IR LED的1/f噪声模型,分析结果表明GaA lAs IR LED的1/f噪声在小电流时反映体陷阱特征,大电流时反映激活区陷阱特征,1/f噪声的增加归因于功率老化诱生的界面陷阱和表面陷阱,1/f噪声可以用来检测GaA lAs IR LED s的潜在缺陷.     

线性余因子差分亚阈电压峰技术测量电应力诱生MOSFET界面陷阱的研究

本文提出了用线性余因子差分亚阈电压峰测量电应力诱生MOSFET界面陷阱的新技术并进行了实验验证 .详细介绍了该方法的基本原理和实验实现 ,得到了电应力诱生MOSFET界面陷阱和累积应力时间的关系 .该方法具有普适性 ,可用于MOSFET的一般可靠性研究和寿命预测 .     

MOSFET中大幅度随机电报信号噪声的动力学特性

对 MOSFET器件的随机电报信号噪声 ( RTS)的特征进行了研究。室温下在极细沟道样品中观测到了大幅度 (大于 60 % )的 RTS,通过测量 RTS的俘获时间和发射时间与栅压和温度的依赖关系 ,获得了氧化层陷阱的位置与能级 ,证实了氧化层陷阱的热激活模型在细沟道 n MOSFET中仍然成立。同时发现当器件工作在弱反型区时 ,RTS幅度基本与栅压无关。对 RTS的动力学机制的分析及数值模拟表明 ,当沟道宽度减小至 4 0 nm以下时 ,由荷电陷阱对沟道载流子散射而产生的迁移率涨落对 RTS的幅度的影响起主导作用。     

全耗尽SOIMOSFET辐照导致的阈值电压漂移模型

报道了全耗尽SOI MOSFET器件阈值电压漂移与辐照剂量和辐照剂量率之间的解析关系.模型计算结果与实验吻合较好.该模型物理意义明确,参数提取方便,适合于低辐照总剂量条件下的加固SOI器件与电路的模拟.讨论了抑制阈值电压漂移的方法.结果表明,对于全耗尽SOI加固工艺,辐照导致的埋氧层(BOX)氧化物电荷对前栅的耦合是影响前栅阈值电压漂移的主要因素,但减薄埋氧层厚度并不能明显提高SOI MOSFET的抗辐照性能.     

MOSFET表面1/f噪声的研究

本文从表面载流子数涨落机构出发,对MOSFET的1/f噪声性质作了较全面的理论和实验研究。将MOSFET的表面1/f噪声理论推广到了所有的偏置区,包括沟道均匀区,线性区和饱和区。对MOSFET的等效输入噪声电压的频率特性、偏置特性和几何特性等进行了实验测试,结果表明与理论规律符合良好。     

Oxide thickness dependent compact model of channel noise for E-mode AlGaN/GaN MOS-HEMT

In this paper, a compact channel noise model for gate recessed enhancement mode GaN based MOS-HEMT which is valid for all regions of operation is proposed. The compact noise model consists of high frequency thermal noise and low frequency flicker noise. The drain current, which is one of the most important parameters for compact noise model is developed by incorporating interface and oxide traps, mobility degradation due to vertical electric field, velocity saturation effect and self-heating effect. The flicker noise model is derived by considering mobility and carrier fluctuation due to traps present in both oxide and interface layer. The thermal noise and flicker noise models are validated by comparing the results with TCAD simulation and experimental results from literature respectively. Effect of thermal and flicker noise power spectral density (PSD) variation with different oxide thickness has also been analyzed.     

Impact of post-oxidation annealing on low-frequency noise, threshold voltage, and subthreshold swing of p-channel MOSFETs

The impact of post-oxidation annealing on the low-frequency noise, threshold voltage, and subthreshold swing of p-channel MOSFET is reported. The low-frequency noise is improved significantly with post-oxidation annealing and a modest V/sub T/ and S reduction is observed. Oxide traps are primarily extracted from measured noise. They are also extracted from threshold voltage and subthreshold slope shift. The contribution of oxide traps to threshold voltage shift and 1/f noise is analyzed through quantitative approach in the light of correlated fluctuation theory. Analysis on experimental results shed light on the well-known controversy about the origin of low-frequency noise, suggesting that experimental results are in agreement with mobility fluctuation theory whereas correlated number fluctuation theory explains the result assuming only a fraction of total oxide charge at a given energy level participates in the generation of low-frequency noise.     

Noise model of gate-leakage current in ultrathin oxide MOSFETs

A physics-based analytical model of the gate-leakage current noise in ultrathin gate oxide MOSFETs is presented. The noise model is based on an inelastic trap-assisted tunneling transport. We employ the barrier height fluctuation model and the Lorentzian-modulated shot noise of the gate-leakage current stemming from the two-dimensional electron gas channel to explain the excess noise behavior. The excess noise can be interpreted as the sum of 1/f/sup /spl gamma// noise and the Lorentzian-modulated shot noise. Trap-related processes are the most likely cause of excess current noise because slow traps in the oxide can result in low-frequency dissipation in the conductance of oxides and fast traps can produce the Lorentzian-modulated shot noise associated with generation-recombination process at higher frequencies. In order to verify the proposed noise model, the simulation results are compared with experimental data, and excellent agreement is observed.     

Low-frequency noise spectroscopy of polycrystalline siliconthin-film transistors

Polycrystalline silicon thin-film transistor (polysilicon TFT's) characteristics are evaluated by using a low-frequency noise technique. The drain current fluctuation caused by trapping and detrapping processes at the grain boundary traps is measured as the current spectral density. Therefore, the properties of the grain boundary traps can be directly evaluated by this technique. The experimental data show a transition from 1/f behavior to a Lorentzian noise. The 1/f noise is explained with an existing model developed for monocrystalline silicon based on fluctuations of the inversion charge near the silicon-oxide interface. The Lorentzian spectrum is explained by fluctuations of the grain boundary interface charge with a model based on a Gaussian distribution of the potential barriers over the grain boundary plane. Quantitative analysis of the 1/f noise and the Lorentzian noise yield the oxide trap density and the energy distribution of the grain boundary traps within the forbidden gap     

Low-frequency noise characteristics in p-channel FinFETs

We report on the characterization of low-frequency noise in fully depleted (FD) double-gate p-channel FinFETs. While the average noise follows a 1/f dependence, considerable device-to-device variations in noise level are observed due to the statistical fluctuation of the number of oxide traps involved. We found that the low-frequency noise in poly-Si-gated p-FinFETs is mainly governed by the carrier number fluctuation with correlated mobility fluctuation. The low-frequency noise characteristics indicate that the FinFET device can be a promising candidate for analog and RF applications.     

电应力对GaAlAs红外发光二极管低频噪声的影响

在宽范围偏置条件下,测量了电应力前后GaAlAs红外发光二极管（IRED）的低频噪声,发现应力前后1／f噪声随偏置电流变化的规律没有改变,但应力后1／f噪声幅值比应力前增加大约i00倍。基于载流子数和迁移率涨落的理论分析表明,GaAlAs IRED的1／f噪声在小电流时反映体陷阱特征,大电流时反映激活区陷阱特征,1／f噪声的增加归因于电应力在器件有源区诱生的界面陷阱和表面陷阱,因而,1／f噪声可以用来探测电应力对该类器件有源区的潜在损伤。     

A nonfundamental theory of low-frequency noise in semiconductordevices

A general low-frequency noise theory based on the fluctuation in the number of carriers is presented. In this theory, the low-frequency noise is attributed to the traps within the bandgap of a semiconductor, which are the sources of the generation-recombination noise. The cumulative effect of the generation-recombination noise from each trap center generates a 1/f type noise. It is shown that in fact, 1/f noise may have any frequency dependence between 1/f⁰-1/f². If not masked by thermal noise, the low-frequency noise generated from these traps becomes 1/f² at very high frequencies. Also, if the lifetime of the carriers in the semiconductor under nonequilibrium condition is finite, at very low frequencies, the noise spectral density reaches a plateau. While this theory can be applied to any semiconductor device, only heterojunction bipolar transistors (HBTs) were considered in detail. Based on this theory, a model for low-frequency noise in the base of HBTs is derived. Frequency and current dependence of low-frequency noise are modeled. Results of the base noise measurements in AlGaAs/GaAs HBTs were found to agree with the noise theory presented here. This significant theory, for the first time, proves the possibility of the number fluctuation model as a general 1/f noise cause without a need for specific and nonrealistic carrier lifetime probability functions     

Theory and experiments on surface 1/f noise

A theoretical low-frequency noise model for the epitaxial-channel surface field-effect structure is presented where random modulation of the channel conductance arises from fluctuation of charges trapped at the oxide trap states near the Si-SiO2interface. In this model, charge fluctuation in the oxide traps arises from carrier tunneling between the fast interface surface states and the oxide trap states. A second fluctuation, at higher frequencies, arises from the random thermal emission and capture of electrons and holes at the fast interface states through the thermal or Shockley-Read-Hall process. Different oxide trap densities were introduced into the interface region of the metal-oxide-silicon field-effect structures using a carefully controlled and reproducible oxygen heat treatment technique. Energy distributions of the oxide trap densities are obtained from capacitance measurements. Humps are observed between the flat band and the onset of strong surface inversion (lower half of the bandgap) in both the noise power and the oxide trap density versus gate voltage (or surface band bending) plots. Theoretical noise power calculations using the experimental oxide trap density profile from the capacitance-voltage data agree very well with the experimental noise humps in both magnitudes and fine structures. It is shown that the frequency spectra of noise depend strongly on the oxide trap density profile in the oxide. It is suggested that the oxide traps are due to the excess oxygen at the SiO2-Si interface.     

Flicker noise in gate overlapped polycrystalline silicon thin-filmtransistors

A study of the noise performance of gate overlapped polycrystalline silicon thin-film transistors (TFTs) is presented. Low-frequency noise measurements were carried out on n- and p-type samples fabricated by excimer laser crystallization. It is shown that the carrier number fluctuation model applies not only to n-type but also to p-type devices. The density of oxide traps was extracted from the noise measurements and was of the order of 10¹⁸-10¹⁹ eV^-1 cm^-3     

Intrinsic noise equivalent-circuit parameters for AlGaN/GaN HEMTs

Intrinsic noise sources and their correlation in gallium-nitride high electron-mobility transistors (HEMTs) are extracted and studied. Microwave noise measurements have been performed over the frequency range of 0.8-5.8 GHz. Using measured noise and scattering parameter data, the gate and drain noise sources and their correlation are determined using an equivalent-circuit representation. This model correctly predicts the frequency-dependent noise for two devices having different gate length. Three noise mechanisms are identified in these devices, namely, those due to velocity fluctuation, gate leakage, and traps.