A new model for the thermal oxidation kinetics of silicon

A model is presented which reasons that the thermal oxidation of silicon is surface reaction limited, and that the reaction rate is controlled by the viscous flow of newly forming oxide to accommodate the volume expansion that occurs when silicon oxidizes. The SiO₂ must form at silicon lattice sites and therefore epitaxially. This thermody-namically unstable epitaxial structure reconfigures and this reconfiguration results in an increase of the average viscosity of the oxide. The continual increase of average oxide viscosity accounts for the continual decrease in oxidation rate with time. A mathemat-ical analysis based on this model is used to derive the simple power law x = at^b relating oxide thickness, x, to oxidation time, t which has been shown previously to model phe-nomenologically all of the extant dry oxidation data.¹ The physical significances of the coefficient a and exponent b are obtained by the interpretation of the x vs t data in the literature in terms of this mathematical analysis.     

The modelling of silicon oxidation from 1 × 10−5 to 20 atmospheres

Studies of (100) silicon oxidation in dry oxygen at 800° C and 20 atmospheres showed the data to be modelled accurately over a wide thickness range by the simple equationx =a(t _g +t _o ) ^b , wherex is the final measured thickness,a andb are constants,t _g is the time for growth measured in an oxidation experiment, andt _o is the time to grow an oxide of thickness,x _o , already present on the silicon surface, and/or formed as a consequence of furnace ramp-up and ramp-down sequences. The values fort _o , andx _o are determined readily fromx-t data. Employing this power law model, there is no evidence of an “anomalous” oxidation region at small thicknesses, or of a linear oxidation region in the earlier stages of oxidation. These surprising results led to an analysis of most of the published silicon “dry” oxidation data from 1965 to the present time to determine whether this power law model was general, or representative only of the data obtained in the present study. It was found that all of the published data, including that published by Deal and Grove in 1965, could be mathematically modelled precisely and simply in all of the thickness ranges reported, and at partial pressures of oxygen from less than 1 × 10⁻⁵ up to 20 atm. The critical parameterb was found to range from less than 0.25 to about 0.8, the value decreasing with decreasing partial or total pressure of oxygen. The constanta represents the value of oxide thickness at unit time, and for constant values ofb andt _o , causes a shift of thex-t curves along the thickness axis. The physical origin(s) for the model is not known. However, as the data appear to suggest a diffusion limited oxidation is in play over the entire thickness regime, it is likely that the diffusion coefficient for the process varies with oxidation time, therefore oxide thickness.     

Hydrogen implanted silicon oxidation

The oxidation rate and the oxide thickness of the hydrogen ion implanted silicon wafers were examined. It was observed that the native oxide thickness is higher for the H⁺ implanted Si(100) compared to the Si(111). Also the native oxide thickness depended on the implanted hydrogen distribution. The thickness increased with the hydrogen con-centration. The oxide thickness after wet oxidization of the H⁺ implanted Si(111) was higher than that of the unimplanted wafers. The oxide thickness also depended on the resistivity of the H⁺ implanted Si wafers. The suggested explanation is that in high energy H⁺ implanted Si the oxidation rate is higher as a result of the higher diffusion and reaction kinetics. All these measurements were done with the assumption that the implanted and the unimplanted samples have the same indices of refraction for the oxide as well as for the substrate.     

干法腐蚀在硅微波功率晶体管研制中的应用

干法腐蚀与传统的湿法腐蚀相比,具有明显的各向异性,并且具有较好的可重复性、可控性及在硅片加工中易实现连续生产等优点,已成为目前硅微波功率晶体管研制和生产的关键技术.本文对目前干法腐蚀在硅微波大功率晶体管中的应用进行了分析,指出随着硅微波功率晶体管工作频率的不断提高,对高性能各向异性的干法腐蚀技术要求也更加迫切.     

Electrical characterization of ultrathin oxides of silicon grown by N2O plasma assisted oxidation

The ultrathin (2.0–3.5 nm) oxides of silicon have gained renewed importance in view of ultra large scale integration (ULSI) of the silicon devices. In the present investigation, the ultrathin oxides are grown on (100) oriented p-type single side polished silicon using N₂0 plasma assisted oxidation in a PECVD reactor at 200°C. The oxide growth as a function of oxidation time is studied. The oxidation growth conforms to the reaction limited regime. In order to understand the electrical quality of Si/ultrathin SiO₂ interface, Al-thin SiO₂-Si tunnel capacitors are fabricated and their capacitance-voltage (C-V) and current-voltage (I–V) characteristics are studied. The effect of annealing on these oxides (termed as “post oxidation annealing”) has also been studied. The C-V characteristics of tunnel capacitors with “as grown” oxide showed a frequency dependence, possibly due to the presence of large fast interface state density. These fast interface states are observed to decrease with increasing oxidation time. The tunnel capacitors that the oxides undergone “post oxidation annealing” (POA) at 350°C in N₂ ambient for 20 minutes have shown practically no frequency dependence of the C-V characteristics; this observation along with the data on I-V characteristics confirms that POA reduces the interface state density considerably. The forward and reverse currents of POA capacitors are observed to decrease considerably indicating the reduction in the trap assisted tunneling transport process across the tunnel insulator.     

3.5GHz 65W硅脉冲大功率晶体管研制

介绍了采用梳状发射极自对准工艺研制的硅微波脉冲大功率晶体管的实验结果。在3．5GHz频率下,该晶体管脉冲输出功率65W,功率增益7dB,集电极效率35％（脉冲宽度100微秒,占空比5％）。     

A silicon carbide LOCOS process using enhanced thermal oxidation by argon implantation

A process is described for creating local oxidation of silicon structure (LOCOS) structures in silicon carbide using enhanced thermal oxidation by argon implantation. Thicker oxides were created in selective regions by using multiple energy argon implants at a dose of 1 × 10¹⁵ cm⁻² prior to thermal oxidation. Atomic force microscopy was used to analyze the fabricated LOCOS structure.     

An accurate and computationally efficient semi-empirical model for arsenic implants into single-crystal (100) silicon

In this paper is reported an accurate and computationally efficient semiempirical model based on an extensive set of experimental data for arsenic implants into (100) single-crystal silicon. Experimental and model development details are given, and issues of the measurements are discussed. The newly developed model has explicit dependence on tilt angle, rotation angle, and dose, in addition to energy. Comparisons between the model predictions and experimental data are made in order to demonstrate the accuracy of this model.     

探究新形势下电力企业依法治企的管理问题

电力企业是我国市场经济的主体之一,随着市场经济体系的确立和完善,电力企业在发展中面临着日趋激烈的市场竞争。新形势下,电力企业要保持健康稳定的发展,就必须依法治国,建立完善的法律风险防范体系。基于此,本文分析并论述了电力企业依法治企的管理问题,探讨了其重要性,并对电力企业依法治企提出了切实可行的有效措施。     

碳化硅电力电子器件在电力系统的应用展望

就目前来看,我国的科学技术得到快速发展。在这一背景下,半导体的器件在制作以及生产的工艺上都得到一定的发展。而碳化硅属于宽带材料的一种,其主要的特点是高热导率、高饱和电子漂移速率以及高击穿场强等。通过这种新型的半导体,可以实现大功率、高压以及高温应用。另外,由于碳化硅成本的大幅度降低,且其性能得到提升,使得碳化硅在电力系统中得到普遍使用。本文将对电子系统中碳化硅电力电子器件的应用进行了深入的分析以及探讨。     

功耗分析攻击中的功耗与数据相关性模型

在对密码设备进行功耗分析攻击时,攻击者需要建立密钥或者与密钥关联的数据值与被攻击设备的功耗相关性模型,藉此通过对功耗的分析破解出敏感信息。从攻击者的角度对器件功耗物理特性分析的基础上,重构了汉明距离模型和汉明重量模型,并从理论上证明了汉明重量模型的正确性,并建立起MCU功耗采集平台,验证了汉明重量模型的有效性和实用性。     

功率器件寿命预测模型

分析了功率器件寿命预测研究现状,并通过恒定应力加速寿命试验来提取器件失效参数,利用正态分布统计方法提取Coffin-Manson寿命预测模型参数建立功率器件寿命预测模型并进行分析。结果表明,模型参数拟合值和实测值的相关系数均在96.8%以上,试验结果满足正态分布统计,说明得到的模型参数是有效的。模型在ΔTj为70.5℃下仿真值与试验值的相对误差为2.768%,证明了该模型的可行性和准确性。     

A new cleaning process combining non-ionic surfactant with diamond film electrochemical oxidation for polished silicon wafers

This paper presents a new cleaning process for particle and organic contaminants on polished silicon wafer surfaces.It combines a non-ionic surfactant with boron-doped diamond(BDD) film anode electrochemical oxidation. The non-ionic surfactant is used to remove particles on the polished wafer's surface,because it can form a protective film on the surface,which makes particles easy to remove.The effects of particle removal comparative experiments were observed by metallographic microscopy,which showed tha...     

非离子型表面活性剂结合金刚石膜电化学氧化的新型抛光后晶片清洗工艺

本文针对抛光后晶片的颗粒和有机污染物提出了一种新型清洗方法,它结合了非离子表面活性剂和掺硼金刚石膜（BDD）阳极电化学氧化的优势。非离子表面活性剂可以在抛光后晶片上形成一层保护膜,使晶片表面颗粒易于去除。颗粒去除对比实验结果通过金相显微镜观察得知,体积比为1%的非离子表面活性剂的颗粒去除效果最佳。然而表面活性剂保护膜本身属于有机物,它最终也需要被去除。金刚石膜阳极电化学氧化（BDD-EO）可以用来去除有机物,因为它可以有效降解有机物。三个有机污染物去除对比实验分别为：一是先用非离子表面活性剂再用BDD-EO,二是单纯用BDD-EO去除有机物,第三种是用传统RCA清洗技术。通过XPS检测结果表明,用BDD-EO清洗的晶片表面的有机残留明显少于传统RCA技术,并且晶片表面的非离子表面活性剂也可以有效去除。     

导弹仿真模型验证系统的研究与实现

为评估数字仿真系统的仿真模型与实际物理模型之间的接近程度,确保仿真结果的可信性,在对现有模型验证方法的优缺点及适用性分析的基础上,研究开发一套仿真模型验证系统。该系统采用自顶向下的模块化结构设计,实现了仿真模型验证方法在系统中的高度集成,为仿真系统的整体性能评估奠定了坚实的基础。     

情景模式背景下电力应急演练仿真平台研究

合理的电网结构、坚强的一次设备以及可靠的二次设备是保证电力系统安全稳定运行的基础和前提,考虑到电力系统事故影响的严重性,应该尽可能做好事故预防工作,建立相应的电力系统应急体系,通过电力应急演练的方式,及时发现应急体系中存在的问题并对其进行解决.本文提出了一种基于情境模式的电力应急演练仿真平台方案,对于应急演练的展开和应急模式的制定具有一定的指导意义.     

并联混合型有源电力滤波器的建模仿真

为了达到抑制谐波污染的目的,采用了并联混合型有源滤波器的方法,并在Matlab／Simulink平台针对并联混合型有源滤波器的各个组成部分建立了仿真模型,并对该APF进行了详尽的动态仿真。通过频谱图分析数据结果,说明了谐波得到有效的补偿,获得了比较满意的仿真效果,为并联混合型有源滤波器应用于实际提供了设计依据。     

TCR无功补偿系统仿真分析

电力电子器件的广泛应用会引起电网和用电单位的无功功率下降。基于瞬时无功功率理论,以济宁2号井的电力系统为背景,设计了TCR单闭环控制策略,以此提高功率因数并补偿无功功率的下降。并对设计的无功功率系统进行仿真,仿真结果验证了设计的有效性。     

高功率CO2激光作用下硅镜热畸变的动态过程研究

以光学干涉方法,实验研究了在CO2激光束入射在硅镜上,硅镜热畸变的动态过程。在变形之初,硅镜镜面的位移量变化迅速。对于一面70mm,厚8mm的硅镜,吸收激光功率140W,作用时间4s时最大挠变形0.76μm.这对于高功率短波长激光器而言是不可忽略的。     

硅纳米线的固-液-固热生长及升温特性研究

该文报道一种直接在硅片上热生长硅纳米线的新方法。与传统的VLS生长机制不同,该方法在生长硅纳米线的过程中没有引入任何气态或液态硅源.是一种全新的固液固(SLS)生长机制。实验中使用了Ni,Au等金属作为催化剂,由Ar,H2等作为载流气体.系统压强为2.5104Pa,生长温度为950-1000℃.生长出的硅纳米线表面光滑,呈纯非晶态,直径为10-40 nm,长度可达数十微米,升温特性对硅纳米线SLS热生长起重要作用。研究了各项实验参数(包括气氛压强,加热温度及加热时间等)对硅纳米线生长的影响。