Monte Carlo simulation for temperature dependence of Ga diffusion length on GaAs(0 0 1)

Diffusion length of Ga on the GaAs(0 0 1)-(2×4)β2 is investigated by a newly developed Monte Carlo-based computational method. The new computational method incorporates chemical potential of Ga in the vapor phase and Ga migration potential on the reconstructed surface obtained by ab initio calculations; therefore we can investigate the adsorption, diffusion and desorption kinetics of adsorbate atoms on the surface. The calculated results imply that Ga diffusion length before desorption decreases exponentially with temperature because Ga surface lifetime decreases exponentially. Furthermore, Ga diffusion length L along and [1 1 0] on the GaAs(0 0 1)-(2×4)β2 are estimated to be and L_[110]200 nm, respectively, at the incorporation–desorption transition temperature (T860 K).     

亚0.1μm栅长CMOS器件和电路的研制

利用侧墙图形转移实现亚 0 .1μm栅线条 ,重掺杂多晶硅做固相扩散源实现 CMOS晶体管超浅源漏扩展区 ,并且将二者有机结合起来 ,成功实现了栅长约为 84 .6 nm的 CMOS器件和电路 .报道了利用重掺杂多晶硅固相扩散同时实现 CMOS源漏扩展区的方法 .     

二维变系数对流扩散问题的特征配置法

1引言 在多种问题的数值模拟中均涉及抛物型对流扩散方程的数值求解问题.由于配置法 无需计算数值积分，计算简便，收敛阶高等优点，使之在工程技术和计算数学的许多领域 得到广泛的应用，但范围一般局限在一维常系数{1，21和二维常系数问题降，4]，90年代[s] 提出了二维变系数     

非局部反应扩散方程组的爆破性质

本文讨论带Dirichlet边界条件的反应扩散方程组ut(x,t)=△u(x,t)+uα(x,t)．up(0,t),vt(x,t)=△v(x,t)+uβ(x,t)vq(0,t),研究了该问题正解的爆破性质并给出爆破集及其爆破速率．     

Unified Solution of the Expected Maximum of a Discrete Time Random Walk and the Discrete Flux to a Spherical Trap

Two random-walk related problems which have been studied independently in the past, the expected maximum of a random walker in one dimension and the flux to a spherical trap of particles undergoing discrete jumps in three dimensions, are shown to be closely related to each other and are studied using a unified approach as a solution to a Wiener-Hopf problem. For the flux problem, this work shows that a constant c = 0.29795219 which appeared in the context of the boundary extrapolation length, and was previously found only numerically, can be derived analytically. The same constant enters in higher-order corrections to the expected-maximum asymptotics. As a byproduct, we also prove a new universal result in the context of the flux problem which is an analogue of the Sparre Andersen theorem proved in the context of the random walker's maximum.     

SiO2/Ta界面反应及其对铜扩散的影响

利用磁控溅射方法在表面有SiO2层的Si基片上溅射Ta/NiFe薄膜,采用X射线光电子能谱(XPS)研究了SiO2/Ta界面以及Ta5Si3标准样品,并进行计算机谱图拟合分析.实验结果表明在制备态下在SiO2/Ta界面处发生了热力学上有利的化学反应:37Ta+15SiO2=5Ta5Si3+6Ta2O5,界面处形成更稳定的化合物新相Ta5Si3、Ta2O5.在采用Ta作阻挡层的ULSI铜互连结构中这些反应产物可能有利于对Cu扩散的阻挡.     

Sodium transport in polyimide-SiO2 systems

The use of polyimide (PI) in integrated circuits either as a passivant or as an interlevel dielectric requires an understanding of the potential for transfer of contaminant ions, always present to some degree in device-grade PI, from the PI to other device constituents. Sodium, in particular, if transferred from PI to SiO₂ where it is relatively mobile at typical device operating temperatures, could affect device thresholds and create a reliability problem. In this paper, the quasistatic Q-V technique of Brown using metal-PI-SiO₂-Si structures has been applied to the quantitative study of the transfer of Na between PI and SiO₂. Removal of the PI after cure or after application of bias-temperature stress has been used to demonstrate that (1) quantitative, reversible ion transfer between PI and SiO₂ does occur at temperatures above 200°C in the presence of an applied bias, but (2) in the absence of an applied bias, Na ions are not transferred from PI to SiO₂ during PI cure at 350°C. It is also shown that the kinetics of Na transfer from PI to SiO₂ in the presence of a bias are dominated by an activated diffusion process, with an activation energy on the order of 2.0eV and a prefactor on the order of 2x10⁹ cm²/s.     

具有电阻场板的薄膜SOI-LDMOS的精确解析

介绍了一种对具有电阻场板的薄膜SOI LDMOS的精确解析设计方法.在对电场分析的基础上,提出了新的电离率模型,并求出了电离率积分的准确路径,进而得到击穿电压、漂移区掺杂、漂移区长度与SOI硅层厚度、埋氧层厚度的关系.模拟结果表明,解析与模拟结果具有很好的一致性,而且设计的器件具有击穿电压大、比导通电阻极小的优点.该解析理论为在薄膜SOI材料上制作性能优良的高压功率器件提供了一个很好的参考     

A Diffusion Approximation for a Markovian Queue with Reneging

Consider a single-server queue with a Poisson arrival process and exponential processing times in which each customer independently reneges after an exponentially distributed amount of time. We establish that this system can be approximated by either a reflected Ornstein–Uhlenbeck process or a reflected affine diffusion when the arrival rate exceeds or is close to the processing rate and the reneging rate is close to 0. We further compare the quality of the steady-state distribution approximations suggested by each diffusion.