WLP用喷镀装置中的匀流板优化设计

喷镀式电镀已广泛应用于圆片级封装(WLP)中,电镀杯是喷镀装置中最关键的部件,杯中的匀流板又是影响电镀质量关键。对匀流板的形状和位置进行了计算机模拟和优化,并实际应用于喷镀装置中,取得了很好结果。     

喷镀系统在凸点制备中的应用

介绍了利用电镀法制造晶圆凸点的典型工艺和喷镀设备.喷镀系统是凸点电镀设备中最关健的部件.通过计算机软件模拟试验,对喷镀系统中的喷杯体和匀流板等各种参数和位置进行了优化设计,并在设备上应用验证.该系统在凸点电镀设备上应用后,在晶圆片上成功做出了高质量的均匀凸点,取得了良好效果.     

Single wafer processing in stagnation point flow CVD reactor: Prospects,constraints and reactor design

A stagnation point chemical vapor deposition (CVD) reactor that obviates substrate rotation can deposit a uniform, thin layer by developing a uniform boundary layer adjacent to the surface of deposition in an axially uniform flow. Such a geometry is highly desirable for high throughput, reproducible single wafer processing in electronic industry. It can also operate effectively at atmospheric pressure if its geometrical and operational parameters are optimized. It is shown here that the nature of the gas distributor, optimized diffuser shape inlet with respect to its angle of divergence, diffuser height and its inverted geometry are the key design parameters. The pressure drop across the gas distributor, inlet gas velocity, gas viscosity, width of hydrodynamic boundary layer on the inner walls of the diffuser that limits the available area for uniform deposition and thermal convection are its important operational parameters. The inverted reactor geometry minimizes the convection related instabilities and helps stabilize the gas flow in the reactor. Analytical expressions are developed to correlate these functional parameters of a stagnation point CVD reactor to its performance in order to develop the reactor design. Finally, the practical aspects including the experimental results of operation of such a CVD reactor design are discussed.     

芯片冷却用分形微管道散热器内的压降与传热

受到哺乳动物消化系统和血液循环系统中物质运输与分配网络所具有的分形特征启发,文中设计、加工出了一种电子芯片冷却用的硅制分形微管道网络散热器.在给出分形微管道网络构造过程的基础上,探讨了分形微管道网络内部微流体的换热与压力降特性.针对利用多路感应耦合等离子蚀刻工艺制造出的硅制分形微管道网络散热器,理论计算所得结论与流动与传热实验数据均证明:当热传递面积、温差、努谢尔特数均相同的情况下,分形微管道网络散热器比传统的平行微管道阵列散热器具有更高的热传递效率;而在具有相同流速、热传递率的要求下,分形微管道网络散热器所需的泵送功率远低于平行微管道阵列散热器所需的泵送功率;分形维数越高,分形微管道网络散热器的热传递效率将越高,且所需的泵送功率将越低.     

Investigation on the critical velocity for liquid loss in immersion lithography

Immersion lithography seeks to extend the resolution of optical lithography by filling the gap between the final optical element and the wafer with a liquid characterized by a high index of refraction. The semiconductor industry demands high throughput, leading to relatively large wafer scanning velocities and accelerations. For higher scanning velocities, an issue that has been identified is the deposition of the immersion liquid while confining a relatively small amount of liquid to the under-lens region. Liquid loss occurs at the receding contact line that forms when a substrate is withdrawn from a liquid, which potentially leads to defects on printed patterns. There has been substantial prior work relative to understanding and building semi-empirical correlations and numerical models to investigate this behavior of the receding three-phase contact line. In the current work, a new liquid injection and collection model with analytic solutions is presented and compared with experimental results, in which the critical velocity for liquid loss is mainly a function of the vacuum degree, the injection flow rate, the properties of the immersion liquid. This correlation allows the critical velocity to be predicted with a given gap height between wafer and lens using only a measurement of the injection speed and knowledge of the fluid properties. Experimentally, glycerin–water mixtures of varying viscosities and different injection flow rates were tested, with variable outlet vacuum degree and inlet speed, showing a mean average error within 12%. This correlation represents a useful tool that can serve to approximately guide the development of fluid control for immersion systems as well as to evaluate alternative immersion fluid candidates to minimize liquid deposition while maximizing throughput.     

抛光片IPA干燥技术研究

以Marangoni效应为基础的IPA干燥技术在衬底抛光片的干燥中遇到了瓶颈,即干燥后出现水痕缺陷。Marangoni干燥过程中,抛光片表面的水符合重力场下的杨方程模型,其脱离效果与晶片提拉速率和IPA流量密切相关。研究中发现,IPA流量在20L／min、提拉速率在lmm／s时干燥效果最佳;另外,Marangoni干燥过程不能完全去除晶片底部的残水．需要营造合适的蒸发环境,减压排风下供给适量的IPA蒸汽有助于底部残水的去除。晶片与花篮在干燥过程中有相互影响,完全分离的模式可以消除这种影响,但同时会使干燥时间增长。     

变结构反应离子刻蚀腔室流场热场的数值仿真

为了提高刻蚀的均匀性, 对400mm反应离子刻蚀(RIE)腔室建立了气体流动的连续流体模型和热传递模型, 研究了反应腔室内压强、流速和温度分布。冷却板恒温285K时, 依次改变入口流量和出口压强, 分别分析了腔室内部基片晶圆附近的流速、压强、温度的分布; 依次改变极板间距离(30mm~60mm)、进气口直径(300mm~620mm)、抽气口直径(50mm~250mm), 分析了反应腔室内气流和温度分布。结果表明, 压强分布呈现出边缘低中心高的特征, 流速呈现边缘高且中心低的特征, 且在小流量时压强的均匀性较好; 压强分布的均匀性随腔室极板间距离增加而有所提高, 且随腔室气体出口面积减小与进口面积增加也有所提高; 基片晶圆上方附近处温度场大面均匀、稳定, 几乎不受入口流量波动变化的影响, 热稳定性良好。该研究对大口径RIE腔室结构设计改进及对大口径反应离子刻蚀工艺控制具有重要意义。     

硅晶片表面污染物去除的关键工艺

硅晶片的清洗通常是在一个“过流(overflow)”清洗槽中进行,其中流过晶片的水流平均速度为1cm蛐s,而在晶片表面的速度则为零。清洗效率受到污染物从硅片表面扩散出并进入到水流速率的限制。报告了清洗效率的提高熏通过对初次将污染物扩散进停滞层的1min循环进行重复,然后“倾倒”清洗槽,从而去除大部分污染的停滞层。通过旋转晶片,并利用离心力去除更大部分的停滞层,每个清洗循环可将清洗效率再提高10倍眼1演。与目前的浸泡式清洗技术相比,本方法可以完全去除可溶性污染物,而使用的水量降低20倍。     

Visualized characterization of slurry film between wafer and padduring chemical mechanical planarization

Chemical mechanical planarization (CMP) has emerged recently as an indispensable processing technique for planarization in submicrometer multilevel very large scale integration (VLSI). The demand from industry for fast material removal and a high degree of uniformity has been a serious challenge for the advancement of this key technology. Among various process aspects, the slurry flow between wafer and pad plays an important role in the pursuit of these goals. This study provides a visualized characterization of the amount and distribution of the fluid film between the wafer and pad. The fluid film is analyzed by the digital picture obtained through the transparent carrier and dyed fluid. The effects of process parameters are extensively investigated, including platen and carrier speed, pad design, rinsing location, and flow rate of slurry and wafer size. Suggestions for process recipes aiming at fast and uniform CMP are drawn based on the current results     

硅片传输单元洁净系统的研制

在集成电路制造的硅片传输过程中,硅片传输机器人等机械设备的运动会产生尘埃粒子污染硅片.为解决这一问题,设计并研制了硅片传输单元的洁净系统,分析了该洁净系统的设计方案和结构设计,计算了它的送回风管直径,并用计算流体力学的方法,对洁净系统内部的硅片传输机器人区域进行了流场的模拟分析.该洁净系统已达到设计要求.     

PCB高稳定性中速化学镀铜工艺研究

主要研究微量添加剂对化学镀铜镀液沉积速率及镀液稳定性的影响,通过试验筛选合适的微量添加剂,在不改变化学镀铜镀液主反应物质含量的情况下实现镀速提高和镀液稳定性增加。开发出的高稳定性中速化学镀铜工艺,其性能满足PCB工业化生产。     

压电锥形流管无阀泵的研究——气穴现象

分析了压电锥形流管无阀泵的气穴现象,首先发生在高速吸入过程的振动子中心区域;同时利用气穴现象阐述了流体温度变化对泵流量影响的原因;最后通过实例说明了增加流量减少气穴现象发生的具体方法,为 泵的应用设计提供了依据。     

Vapor levitation epitaxy reactor hydrodynamics

Vapor Levitation Epitaxy (VLE) is a new epitaxial growth technique for III-V compound semiconductor crystals, characterized by upward stagnation flow of a reactant gas stream against a floating, circular semiconductor substrate wafer. In this work, the hydrodynamics of the process have been mathematically modeled by a complete solution of the governing Navier-Stokes equation to obtain radial and axial velocity profiles, pressure distribution under the wafer, and levitation height as a function of operating parameters. In addition, experimental measurements of levitation height as a function of gas flow rate for different wafers and gases have been performed. By the addition of experimental constants to the analytical solution of levitation height to account for system non-idealities, the functional dependences predicted by theory have been verified. In comparison to the complex flow occurring in other vapor phase epitaxy techniques, the hydrodynamics in the VLE reactor are simple, well behaved, and can be fully described by a few algebraic equations.     

基于MEMS技术的仿生纤毛风速传感器的设计和仿真

设计了一种可以实现二维风速测量的电容式纤毛传感器,其特点为通过差分电容检测流速,传感器运动结构所对应的背硅被完全刻蚀。采用有限元分析软件,通过流体-固体-静电场的多物理场仿真,分析得到了传感器的差分电容与风速的变化关系。结合电容传感器AD7746的理论精度,计算得出传感器的风速灵敏度为0.25mm/s。此外,设计了基于SOI硅片的传感器微加工制备的工艺流程。     

New plating bath for electroless copper deposition on sputtered barrier layers

A new copper plating bath for electroless deposition directly on conductive copper-diffusion barrier layers has been developed. This plating bath can be operated at temperatures between 20 and 50°C and has good stability. High temperature processing allows for increased deposition rates and decreased specific resistivity values for the deposited copper films. Electroless Cu films deposited from this bath showed a conformal step coverage in high aspect ratio trenches and, therefore, are promising as seed layers for copper electroplating. The effect of the bath composition, activation procedure and processing temperature on the plating rate and morphology of the deposited copper has been studied and is presented here.     

电镀Au-Sn合金的研究

Au-Sn(质量分数为20%)共晶焊料有着优良的导热和导电特性,已被广泛应用在光电子和微电子的器件封装工业中.对微氰和无氰电镀Au-Sn合金的两种电镀方法进行了研究,概述了镀液组分和电镀工艺条件,用扫描电镜的方法测试不同电流密度下Au-Sn合金组分,用测厚仪测试镀层厚度,计算出镀速,最终确定电镀Au-Sn(质量分数为20%)合金的电镀条件,并对微氰和无氰电镀液优缺点进行了对比分析.     

以酒石酸钠钾为络合剂的常温化学镀铜液研制

常温化学镀铜溶液具有反应温度低、甲醛自我分解少、维护费用低等优点。为了寻找合适添加剂并确定各组份最佳含量,获得一种反应活性好,维护简单的沉铜液,文中通过设计七因素三水平正交实验的方法,综合研究了沉铜液中各组份对沉积速率、溶液稳定性、镀层外观的影响,确定了一种以酒石酸钠钾为络合剂,甲醛为还原剂,稳定性较好、沉积速率较高、镀层外观较好的常温化学镀铜配方。     

Inverse analysis of material removal data using a multiscale CMP model

This paper describes a mechanical model for a representative dual axis rotational chemical mechanical planarization (CMP) tool. The model is three-dimensional, multiscale and includes sub-models for bulk pad deformation, asperity deformation, lubrication based slurry flow, carrier film deformation, wafer compliance and material removal by abrasive particles in the slurry. With the model, material removal rate (MRR) can be determined as a function of stress applied to the wafer, relative sliding speed, and material and geometric parameters of the pad and slurry. Experimental material removal rate profiles obtained from Cu polishing experiments performed on a wafer without rotation are analyzed as an inverse problem. We use MRR data to predict local CMP conditions such as fluid film thickness, fluid pressure and contact pressure. The results are consistent with available experimental and analytical information. This inverse technique offers promise as an improved method of CMP model verification.     

Electroless Cu deposition process on TiN for ULSI interconnect fabrication via Pd/Sn colloid activation

In this study, (100)-orientation silicon wafer coated with TiN barrier is catalyzed by a Pd/Sn colloid, which serves as an activator for electroless copper deposition. After activation, electroless deposition of Cu occurs on the catalytic surface. The coverage of the Cu deposit reaches 100% and the adsorptive amount of Pd is greatly increased by the conditioning process. The correlation between deposition rate, resistivity, morphology, crystal structure, and composition of the deposit when varying the temperature of the plating bath is discussed. The deposition rate of Cu is monitored by both the electrochemical method and the profilometer (α-step), while the other properties of the deposit are measured by four-point probe, scanning electron microscopy (SEM), x-ray diffraction (XRD), and Auger electron microscopy (AES). Deposition at 70°C is favorable due to the higher deposition rate, lower resistivity, less impurities, and more preferred orientation in the crystal structure than that at lower temperature. Problems regarding adhesion and high resistivity can be greatly mitigated via 400°C thermal annealing. The resistivity of Cu can be reduced to 2.2 μΩcm. Moreover, trenches of 1 μm and 0.25 μm on patterned wafer have been successfully filled by electroless deposition of Cu with the aid of surfactant C12.     

玻璃基板上的微细图形形成技术

概述了平滑玻璃基板上的微细图形形成技术以及纳米多孔ZnO膜,弱酸性铅催化液和弱酸性乙酸铜镀铜液的开发,可以在玻璃/ZnO中间层化学镀铜层/乙酸铜镀铜层/硫酸铜镀铜层上采用减成法形成L/S=100μm/100μm的微细铜电路图形。