Effects of plasma treatment on the high frequency characteristics of Cu/Ta/hydrogen silsesquioxane (HSQ) system and electrical behaviors of Cu/Ta/HSQ/Pt MIM capacitors

With the increasing of the operating frequencies, insertion loss, signal propagation delay, and parasitic coupling capacitance become the significant problems. Small capacitance (C) between interconnects is required to reduce the crosstalk, insertion loss, and RC delay associated with the metal interconnect system. Therefore, the interconnect with low dielectric constant (k) material is required. Implementation of Cu/low-k dielectric is used for reducing insertion loss, RC delay, crosstalk noises, etc. In this work, Cu-hydrogen silsesquioxane (HSQ) systems are studied. Ammonia (NH₃) plasma is employed for the nitridation of HSQ. The effects of NH₃ plasma treatments on the high frequency characteristics (100 MHz to 20 GHz) of the interconnect structure Cu/Ta/HSQ and electrical behaviors of Cu/Ta/HSQ/Pt MIM capacitors are evaluated.Auger electron spectroscopy (AES) results suggest the diffusion of oxygen and copper atoms during copper annealing. This raises resistance of Cu interconnect and increases the conductance of the HSQ films. Hence, 400 °C-annealed Cu/Ta/HSQ interconnect systems become lossy at high frequencies (>2 GHz). Ammonia (NH₃) plasma bombardments break some of the Si-H bonds and the resulting dangling Si bonds increase the moisture absorption. Meanwhile, NH₃ plasma treatments reduce the leakage current by passivating the Si dangling bond and forming silicon nitride. The absorption of moisture and/or the formation of SiN_x result in high dielectric constant of HSQ after prolonged NH₃ plasma bombardment. The dielectric constant of HSQ decreases and then increases with the increase of NH₃ plasma treatment time and a minimum dielectric constant of 2.2 is obtained after 50 s NH₃ plasma treatment at 200 W. Among various specimens in this study, the smallest insertion loss is 1.97 dB/mm at 20 GHz for the 400°C-annealed Cu/Ta/HSQ (NH₃-plasma-treated for 50 s). Appropriate NH₃-plasma bombardment helps to form a thin SiN_x barrier layer which prevents the diffusion of oxygen without increasing the dielectric constant of the Cu-HSQ interconnect system. The leakage currents versus electric field characteristics suggest that a Schottky emission dominate conduction mechanism.     

基于Weibull分布高斯谱的脉冲压缩雷达海杂波信号的仿真与合成

运用无记忆非线性变换法及海杂波后向散射系数模型产生了基于Weibull分布、高斯谱的相干海杂波信号,仿真结果符合理论分析,并可以直接应用于脉冲压缩雷达模拟器的仿真中。     

硅片键合界面缺陷分布与Weibull模数的关系

从理论推导分析了键合片的缺陷分布与Weibull模数m之间的关系。此关系与实验相符,并利用此关系很好地解释了硅片键合强度随退火温度变化的关系。     

Effect of PECVD of SiO2 passivation layers on GaN and InGaP

Thin (200 ) layers of SiO₂ were deposited by plasma enhanced chemical vapor deposition onto GaN and InGaP patterned with transmission line measurement contact pads. The sheet resistance of n-GaN and n- and p-InGaP was measured as a function of N₂O/SiH₄ ratio, rf chuck power, pressure and substrate temperature during the SiO₂ deposition. The sheet resistance ratio before and after the deposition varied from 0.7 to 1.2, reflecting a competition between mechanisms that decrease doping (hydrogen passivation, ion-induced deep traps) and those that increase it (creation of shallow donor states in n-type material through preferential ion of the group V elements, gettering of hydrogen in p-type material). Under most conditions, SiO₂ deposition creates minimal changes to the electrical properties of GaN and InGaP.     

The separation of generation lifetimes of Si and SiGe using capacitance-transient measurements on MOS capacitors formed by plasma anodisation of Si:Si0.9Ge0.1:Si substrates

A simple technique leading to the measurement of minority carrier lifetimes of UHV compatible LPCVD Si and SiGe by C–t depth profiling of Metal:Oxide:Si:SiGe:Si structures is reported. A high quality gate oxide is realised by low temperature (<100°C) plasma anodisation thereby reducing any oxidation effects on the underlying epitaxial layer quality. Capacitance response times were observed for an impurity concentration of 2.5×10¹⁷ cm⁻³, giving rise to generation lifetimes of the Si and Si_0.9Ge_0.1 of >0.55 and 2.6 μs respectively, reflective of very high quality epitaxial semiconductor material.     

Influence of the additives argon, O2, C4F8, H2, N2 and CO on plasma conditions and process results during the etch of SiCOH in CF4 plasma

Reactive ion etch processes for modern interlevel dielectrics become more and more complex, especially for further scaling of interconnect dimensions. The materials will be damaged within such processes with the result of an increase in their dielectric constants. The capability of selected additives to minimize the low-k sidewall damage during reactive ion etching (RIE) of SiCOH materials in fluorocarbon plasmas was shown in different works in the past. Most of the investigated additive gases alter the fluorine to carbon ratio as well as the dissociation of the parent gas inside the etch plasma. The result is a changed etch rate, a modified polymerization behavior and other characteristics of the process induced SiCOH damage. Heavy inert ions like argon will be accelerated to the sample surface in the cathode dark space and enhance therewith the sputter yield on the SiCOH network [1]. In this paper the additives Ar, O₂, C₄F₈, H₂, N₂ and CO were added to a conventional CF₄ etch plasma. We try to provoke different changes in the plasma conditions and therewith in the process results. Contact angle measurements, spectroscopic ellipsometry, Hg-probe analysis, FTIR measurements and SEM cross-sections were used to overview the additive induced modifications. To understand the influences of the additives gases more exactly, changes in the physical and chemical plasma behavior must be analyzed. Therefore quadrupole mass spectrometry (QMS) and quantum cascade laser absorption spectroscopy (QCLAS) were used.     

硼预淀积对自组织生长Ge量子点尺寸分布的影响

研究了以不同B2H6流量预淀积硼对UHV/CVD自组织生长Ge量子点尺寸分布的影响。在适当的生长条件下,得到了尺寸分布很窄的均匀Ge量子点,用AFM对量子点的形貌进行观察,Ge量子点尺寸的涨落小于±3%,量子点的水平尺寸和高度分别为60nm和10nm,密度为8×109cm-2。实验结果表明,通过预淀积硼表面处理,可以得到尺寸分布很窄的量子点,以满足量子点光电器件方面应用的要求。     

Effect of raindrop size distribution and rain rate inhomogeneity on the relationship between attenuation and depolarization

In addition to attenuation, depolarization due to rain is another factor that degrades satellite propagation signals, especially in the higher frequency bands and in places that have high rates of rainfall. A formula to predict cross‐polarization as a function of attenuation has been proposed, and it is derived by a theoretical calculation using frequency, the forward scattering amplitude of raindrops, rainfall rates, the raindrop size distribution (DSD), and various other propagation parameters. In this paper, a formula for predicting cross‐polarization is derived on the basis of the assumption of a gamma‐type DSD up to 100 GHz. These results are compared with conventional exponential‐type DSDs, such as the Marshall‐and‐Palmer DSD. Moreover, for a more realistic propagation situation, we consider the effect on the aforementioned relationship of rainfall rate inhomogeneity along the propagation path. It is shown that, for practical purposes, this inhomogeneity does not have a significant effect on satellite propagation. Copyright © 2017 John Wiley & Sons, Ltd.     

浅谈10千伏配网线路故障处理方法

在整个电力系统中,10千伏配网扮演着非常重要的角色,其直接面对终端客户,关系着配网运行的安全性和稳定性,同时影响着人们的正常生活以及企业的效益.但由于10千伏供电线路的范围最广,且多位于架空线露天工作,在运行过程中也存在着诸多的问题,本文结合实际工作经验,对10千伏配网线路常见故障的原因,并线路的检修措施和运行维护进行了讨论,以期能对相关人士有所裨益.     

Influence of NH3 plasma treatment on chemical bonding and water adsorption of low-k SiCOH film

Carbon-doped silicon oxide (SiCOH) dielectrics are one of the most suitable candidates for advanced low-dielectric-constant (low-k) interlayer material. To improve water adsorption resistance, the plasma-enhanced chemical vapor deposited SiCOH films have been post-treated by the NH₃ plasma for various times, and the resulting SiCOH films are thus examined by water adsorption experiments. The results indicate that the SiCOH films treated by the NH₃ plasma exhibit enhanced resistance against water adsorption. Further, Fourier-transform infrared spectroscopy and X-ray photoelectron spectroscopy are used to characterize the chemical composition and bonding states of the pristine and NH₃ plasma treated SiCOH films. It is revealed that the plasma surface treatment leads to the formation of Si-N, C(sp³)-N, C(sp²)N, (N-)_nSi-C (n = 1-3) configurations, and loss of carbon atoms.     

浅谈10kV配网不停电作业技术发展与应用

随着社会经济的飞速发展,科学技术手段不断更新,人民的物质生活不断的得到提升,各行各业的生产加工作业日益的在加班加点,城市的夜生活越来越色彩斑斓,每家每户的家用电器也越来越多种多样,因此对供电设施的配电要求也越来越升级.随着中国城镇化的发展趋势不断前进,房屋,道路的建造与维护,供电设施的迁动,需要改造道路,迁移线路等需要更高标准的的输电设备比如说箱式变压器、环网柜、电缆配电用具和材料.原来常规的10kV架空线路的带电作业法无法满足城市需要,所以要开展10kV电缆不停点作业技术.     

不同状态下激光器电场强度分布的电光检测与初步分析

连续波电光检测技术是近几年发展起来的测量光电材料及光电材料制备的器件的电特性的一种新型测量技术。它基于线性电光效应。采用连续波激光作为测量手段。 CW EOP技术已在GaAs,LiNbO_3等光电材料及器件的电场分布检测中得到实质性应用。采用CWEOP技术对半导体激光器内场分布电光检测的初步结果在文献[4]中已有报道,本文是对激光器在不同状态下进行场分布电光检测的更进一步探讨。     

Effects of the fluorine plasma treatment on low-density drain AlGaN/GaN HEMT

Low-density drain high-electron mobility transistors (LDD-HEMTs) with different F^- plasma treatment were investigated by simulations and experiments. The LDD region was performed by introducing negatively charged fluorine ions, which modified the surface field distribution on the drain side of the HEMT, and the enhancement of breakdown voltage were achieved. With the increased fluorine plasma treatment power and LDD region length, the breakdown voltage can be maximumly improved by 70%, and no severe reductions on output current and transconductance were observed. To confirm the temperature stability of the devices, annealing experiments were carried out at 400℃ for 2 min in ambient N₂. Moreover, the gate leakage current and breakdown voltage before and after annealing were compared and analyzed, respectively.     

Effect of the discharging and recharging of the stress generated oxide charge in metal–oxide–semiconductor capacitors on the low field leakage current

Low field leakage currents, through thin gate oxides of metal-oxide-semiconductor capacitors, increase after negative high field stress. We have observed that this increase could be reduced and even suppressed if the trapped holes created by the stress were neutralized by application of low voltage pulses. We have also observed that these pulses had the effect of making the recharge of the stress created slow states more and more difficult.     

Effect of the spatial distribution of SiO2 thickness on the switching behavior of bistable MOS tunnel structures

Simulations of the reverse current-voltage characteristics of an Al/l-3 nm SiO₂/n-Si tunnel structure are carried out, considering the spatial non-uniformity of oxide thickness. In a certain range of average thickness, these characteristics are S-shaped, exhibiting thereby a bistability. The shift of the turn-on and holding voltages related to the thickness deviation is predicted. The electric overload leads to the displacement of switching voltages as if the deviation of oxide thickness had became larger. Supporting experimental data are also provided.     

Detailed study about influence of oxygen on trap properties in SiOxNy by the thermally stimulated current and maximum entropy method

The trap amount depending on trap energy levels [N_t(E_t)] in various silicon oxynitride films were investigated. Using the thermally stimulated current and the maximum entropy method, we determined N_t(E_t) with very high energy resolution. In N_t(E_t), many E_t were observed between 1.2 and 1.6 eV. Interestingly, their amounts significantly depended on the film compositions. The influence of oxygen on N_t(E_t) is also discussed.     

沟道电场分布对AlN/GaN HFETs极化库仑场散射的影响

Based on the measured capacitance–voltage(C–V) curves and current–voltage(I–V) curves for the prepared differently-sized Al N/Ga N heterostructure field-effect transistors(HFETs), the I–V characteristics of the Al N/Ga N HFETs were simulated using the quasi-two-dimensional(quasi-2D) model. By analyzing the variation in the electron mobility for the two-dimensional electron gas(2DEG) with the channel electric field, it is found that the different polarization charge distribution generated by the different channel electric field distribution can result in different polarization Coulomb field(PCF) scattering. The 2DEG electron mobility difference is mostly caused by the PCF scattering which can reach up to 899.6 cm2/(V s)(sample a), 1307.4 cm2/(V s)(sample b),1561.7 cm2/(V s)(sample c) and 678.1 cm2/(V s)(sample d), respectively. When the 2DEG sheet density is modulated by the drain–source bias, the electron mobility for samples a, b and c appear to peak with the variation of the 2DEG sheet density, but for sample d, no peak appears and the electron mobility rises with the increase in the2 DEG sheet density.     

Frequency and gate voltage effects on the dielectric properties of Au/SiO2/n-Si structures

To determine the dielectric constant (ε′), dielectric loss (ε″), loss tangent (tan δ), the ac electrical conductivity (σ_ac) and the electric modulus of Au/SiO₂/n-Si structure, the measurement admittance technique was used. Experimental results show that the values of ε′, ε″, tan δ, σ_ac and the electric modulus show fairly large frequency and gate bias dispersion especially at low frequencies due to the interface charges and polarization. An increase in the values of the ε′ and ε″ were observed with both a decrease in frequency and an increase in frequency. The σ_ac is found to increase with both increasing frequency and voltage. In addition, the experimental dielectrical data have been analyzed considering electric modulus formalism. It can be concluded that the interface charges and interfacial polarization have strong influence on the dielectric properties of metal-insulator-semiconductor (MIS) structures especially at low frequencies and both in depletion and accumulation regions.     

Impact of time dependent dielectric breakdown and stress-inducedleakage current on the reliability of high dielectric constant(Ba,Sr)TiO3 thin-film capacitors for Gbit-scale DRAMs

Time dependent dielectric breakdown (TDDB) and stress-induced leakage current (SILC) are investigated for the reliability of (Ba,Sr)TiO₃ (BST) thin films. Both time to breakdown (T_BD) versus electric field (E) and T_BD versus 1/E plots show universal straight lines, independent of the film thickness, and predict lifetimes longer than 10 y at +1 V for 50 nm BST films with an SiO₂ equivalent thickness of 0.70 nm. SILC is observed at +1 V after electrical stress of BST films; nevertheless, 10 y reliable operation for Gbit-scale DRAMs is predicted in spite of charge loss by SILC. Lower (Ba+Sr)/Ti ratio is found to be strongly beneficial for low leakage, low SILC, long TBD, and therefore greater long-term reliability. This suggests a worthwhile tradeoff against the dielectric constant, which peaks at a (Ba+Sr)/Ti ratio of 1.05     

快速退火对Pt/BST/Pt电容器结构和性能的影响

采用脉冲激光沉积(PLD)法在Pt/Ti/SiO2/Si(001)基片上制备了Ba0.6Sr0.4TiO3(BST)薄膜,对Pt/BST/Pt电容器在空气中进行400℃快速退火(RTA)处理,研究了快速退火对Pt/BST/Pt电容器的结构和性能的影响。结果表明:快速退火虽然对BST薄膜的结晶质量影响较小,但却极大改善了Pt/BST/Pt电容器的电学性能。当测试频率为100kHz、直流偏压为0V时,介电损耗从快速退火前的0.07减小到0.03,介电常数和调谐率略有增加。快速退火后负向漏电流过大现象得到了明显抑制,正负向漏电流趋于对称,在300×103V/cm电场强度下,漏电流密度为4.83×10–5A/cm2。