Heuristic tabu search scheduling algorithm for wet-etching systems in semiconductor wafer fabrications

To improve overall equipment efficiency(OEE) of a semiconductor wafer wet-etching system,a heuristic tabu search scheduling algorithm is proposed for the wet-etching process in the paper,with material handling robot capacity and wafer processing time constraints of the process modules considered.Firstly,scheduling problem domains of the wet-etching system(WES) are assumed and defined,and a non-linear programming model is built to maximize the throughput with no defective wafers.On the basis of the model,a scheduling algorithm based on tabu search is presented in this paper.An improved Nawaz,Enscore,and Ham(NEH) heuristic algorithm is used as the initial feasible solution of the proposed heuristic algorithm.Finally,performances of the proposed algorithm are analyzed and evaluated by simulation experiments.The results indicate that the proposed algorithm is valid and practical to generate satisfied scheduling solutions.

Bottleneck Identification and Prediction of Wafer Fabrication Systems in Transient States

According to theory of constraints( TOCs), the performance of a complex manufacturing system,such as a wafer fabrication system,is mainly determined by its bottleneck machine.A method of the identification and prediction of the bottleneck machine was proposed in transient states of a system. Firstly,the bottleneck index was formulated based on the workloads and the variability in wafer fabrication systems. Secondly, main factors causing the variability and their influences on the bottleneck machine in transient states of the system were analyzed and discussed. An effective bottleneck identification and prediction model was presented,which incorporated the variability and queuing theory,and took machine breakdowns and setups into considerations.Finally,the proposed bottleneck prediction method was verified by simulation experiments. Results indicate that the proposed bottleneck prediction method is feasible and effective.

Modeling of photolithography process in semiconductor wafer fabrication systems using extended hybrid Petri nets

To describe a semiconductor wafer fabrication flow availably, a new modeling method of extended hybrid Petri nets （EHPNs） was proposed. To model the discrete part and continuous part of a complex photolithography process, hybrid Petri nets （HPNs） were introduced. To cope with the complexity of a photolithography process, object-oriented methods such as encapsulation and classifications were integrated with HPN models. EHPN definitions were presented on the basis of HPN models and object-oriented methods. Object-oriented hybrid Petri subnet models were developed for each typical physical object and an EHPN modeling procedure steps were structured. To demonstrate the feasibility and validity of the proposed modeling method, a real wafer photolithography case was used to illustrate the modeling procedure. dynamic modeling of a complex photolithography process effectively The modeling results indicate that the EHPNs can deal with the dynamic modeling of a complex photolithography process effectively.

Fabrication of 4-Inch Nano Patterned Wafer with High Uniformity by Laser Interference Lithography

We report the fabrication of 4-inch nano patterned wafer by two-beam laser interference lithography and analyze the uniformity in detail. The profile of the dots array with a period of 800 nm divided into five regions is characterized by a scanning electron microscope. The average size in each region ranges from 270 nm to 320 nm,and the deviation is almost 4%, which is approaching the applicable value of 3% in the industrial process. We simulate the two-beam laser interference lithography system with MATLAB software and then calculate the distribution of light intensity around the 4 inch area. The experimental data fit very well with the calculated results. Analysis of the experimental data and calculated data indicates that laser beam quality and space filter play important roles in achieving a periodical nanoscale pattern with high uniformity and large area. There is the potential to obtain more practical applications.

腔室清洗的单臂组合设备初始暂态调度

为了提升腔室洁净度,晶圆厂需对组合设备腔室进行清洗操作,从而提高晶圆的加工质量.考虑腔室清洗时间和晶圆驻留时间的约束条件下,本文研究了单臂组合设备的初始暂态调度问题.首先,提出了机械手的初始暂态活动规则,并对机械手活动序列进行描述,实现了系统的初始暂态可调度性;其次,对机械手在初始暂态和稳态的活动时间进行了建模;然后,根据系统的时间特性,建立了初始暂态调度的线性规划模型;最后,通过实例验证了该方法的有效性.与已有的虚拟晶圆方法相比,该调度方法能有效减少初始暂态的完工时间,提高了组合设备的晶圆生产效率.

基于门控循环单元强化学习的晶圆光刻区实时调度方法研究

为求解具有动态性、实时性、多约束、多目标特点的晶圆光刻区调度问题,提出一种基于门控循环单元强化学习的晶圆光刻区实时调度方法。设计引入门控循环单元学习光刻区历史调度决策与状态的时序信息,为双深度强化学习模型提供辅助决策信息;设计双深度强化学习模型的输入状态空间、输出动作集,并面向晶圆最小化最大完工时间和晶圆准时交货率指标设计多目标奖励函数,为智能体优化调度输出;设计设备专用性约束与掩模版约束的解约束规则与调度方法相结合,提高调度方案实施的实用性。通过某晶圆制造企业实际算例,将该方法与传统双深度强化学习和光刻区启发式规则方法比较,该方法均为最优,证明了其解决此问题的有效性。

考虑晶圆驻留时间约束的双臂组合设备群调度

组合设备群代表了当前晶圆制造装备发展的新趋势,其调度控制水平直接攸关半导体芯片制造企业的整体经济效益。针对半导体芯片制造中考虑晶圆驻留时间约束的双臂组合设备群,文章提出了一种基于特征转换的调度控制方法。首先,引入一种概念型晶圆制造系统,即特征双臂组合设备,并给出相应的稳态调度方法。其次,采用特征转换方法,将线性/树形结构的双臂组合设备群转换为特征双臂组合设备。随后,根据转换后的特征双臂组合设备重新调整双臂组合设备群的机械手作业序列,并求解可行的稳态调度方案。最后,通过实例验证了所提方法的有效性。

Scheduling Dual-Arm Cluster Tools With Multiple Wafer Types and Residency Time Constraints

Accompanying the unceasing progress of integrated circuit manufacturing technology, the mainstream production mode of current semiconductor wafer fabrication is featured with multi-variety, small batch, and individual customization, which poses a huge challenge to the scheduling of cluster tools with single-wafer-type fabrication. Concurrent processing multiple wafer types in cluster tools, as a novel production pattern, has drawn increasing attention from industry to academia, whereas the corresponding research remains insufficient. This paper investigates the scheduling problems of dual-arm cluster tools with multiple wafer types and residency time constraints. To pursue an easy-to-implement cyclic operation under diverse flow patterns,we develop a novel robot activity strategy called multiplex swap sequence. In the light of the virtual module technology, the workloads that stem from bottleneck process steps and asymmetrical process configuration are balanced satisfactorily. Moreover, several sufficient and necessary conditions with closed-form expressions are obtained for checking the system's schedulability. Finally, efficient algorithms with polynomial complexity are developed to find the periodic scheduling, and its practicability and availability are demonstrated by the offered illustrative examples.

A modeling method of semiconductor fabrication flows with extended knowledge hybrid Petri nets

A modeling method of extended knowledge hybrid Petri nets （EKHPNs）, incorporating object-oriented methods into hybrid Petri nets （HPNs）, was presented and used for the representation ~d modeling of semiconductor wafer fabrication flows. To model the discrete and continuous parts of a complex semiconductor wafer fabrication flow, the HPNs were introduced into the EKHPNs. Object-oriented methods were combined into the EKHPNs for coping with the complexity of the fabrication flow. Knowledge anno- tations were introduced to solve input and output conflicts of the EKHPNs. Finally, to demonstrate the validity of the EKHPN method, a real semiconductor wafer fabrication case was used to illustrate the model- ing procedure. The modeling results indicate that the proposed method can be used to model a complex semiconductor wafer fabrication flow expediently.

基于双层编码遗传算法的晶圆制造排产系统

为了解决晶圆制造排产系统的全局优化问题,首先考虑晶圆制造系统各设备之间的约束关系及晶圆卡等待时间成本、缓冲时间成本、搬运时间成本、设备状态转换时间成本,建立以晶圆制造整体加工时间成本最小为目标函数的数学模型;其次对遗传算法编码方式进行改进寻找较优排产顺序;最后利用MATLAB对某晶圆加工制造企业真实数据进行仿真、求解,并与经典遗传算法和蚁群算法对比。3种算法迭代过程表明,改进的双层编码遗传算法在解决晶圆制造系统的排产问题中有明显优势,求解速度更快,搜索到较优解的时间更短、更准确,验证了模型的有效性。

基于Petri网的组合设备建模与调度综述

组合设备是半导体晶圆制造的核心装备,其调度与控制优化是半导体制造领域极具挑战性的课题. Petri网因其强大的建模能力和简约的图形化表达优势,被广泛地应用于组合设备的建模与调度.对基于Petri网的组合设备建模与调度方法进行综述,归纳总结了组合设备的结构类型、晶圆流模式、调度策略及Petri网建模方法,并系统阐述组合设备的7类典型调度问题,包括驻留时间约束、作业时间波动、晶圆重入加工、多品种晶圆加工、加工模块(Process module, PM)故障、PM清洗和组合设备群.最后,讨论了当前组合设备调度存在的挑战及后续可能的研究方向.

融合双重注意力机制与并行门控循环单元的晶圆加工周期预测方法

晶圆制造过程中的生产特征数据大规模、特征间复杂关联和特征样本强相关特性导致晶圆加工周期预测效率低与预测精度不高,因此提出了一种融合双重注意力机制与并行门控循环单元的晶圆加工周期预测方法。首先,利用Relief-F算法对生产特征数据进行降维处理;然后,基于模糊C均值算法对数据样本进行工艺相似性聚类,并设计并行门控循环单元网络来挖掘晶圆lot特征样本间的强相关特性;最后,设计了双重注意力机制来学习关键特征内部及特征与加工周期的复杂关联信息。实验结果表明,所提出方法能有效缩短预测训练时间,提高预测精度。

基于SOI-SOG键合的圆片级真空封装MEMS电场传感器

圆片级真空封装是提高微电子机械系统(Micro-Electro-Mechanical Systems,MEMS)电场传感器品质因数及批量化制造效率的重要途径.本文提出了一种基于绝缘体上硅(Silicon On Insulator,SOI)-玻璃体上硅(Silicon On Glass,SOG)键合的圆片级真空封装MEMS电场传感器,设计并实现了从传感器敏感结构制备到真空封装的整套圆片级加工工艺.本文建立了传感器的结构电容模型,进行了有限元仿真,分析了传感器的特性,突破了传感器微结构制备与释放、SOI与SOG键合等工艺技术难点.该传感器具有工作电压低、品质因数高的突出优点.实验结果表明,工作电压仅为5 V直流与0.05 V交流电压.在60天测试过程中,传感器品质因数始终保持在5000以上.在0~50 kV/m范围内,传感器灵敏度为0.15 mV/(kV/m),线性度为2.21%,不确定度为4.74%.

Machine Allocation in Semiconductor Wafer Fabrication Systems:A Simulation-Based Approach

The problem of maximizing the throughput of Semiconductor Wafer Fabrication Systems is addressed.We model the fabrication systems as a Stochastic Timed Automata and design a discrete-event simulation scheme.The simulation scheme is explicit,fast and achieves high fidelity which captures the feature of reentrant process flow and is flexible to accommodate diversified wafer lot scheduling policies.A series of Marginal Machine Allocation Algorithms are proposed to sequentially allocate machines.Numerical experiments suggest the designed methods are efficient to find good allocation solutions.

基于遗传算法的半导体生产线调度研究进展

半导体生产线调度是制造系统实际生产中的重要问题,也是理论研究的难点之一.遗传算法是计算智能的主要研究对象,因此基于遗传算法的半导体生产线调度研究,具有非常重要的研究价值和实践意义,已经引起了国内外研究者的广泛关注.文中评述近几年来在半导体生产线调度优化中遗传算法的应用,详细介绍了算法编码、操作、参数的选择、算法的改进及具体应用,并指出这一领域中值得进一步研究的一些问题和可能的发展方向.

基于规则的批处理设备调度方法在半导体晶圆制造系统中应用

针对半导体炉管区瓶颈设备的批处理调度问题,提出满足工艺约束和设备限制的组批调度算法.在考虑产品动态到达的基础上,根据半导体制造系统大规模、多重入、混合型生产等特征,针对晶圆平均等待时间进行优化,实现多产品、多机台的实时组合派工.仿真实验在一个虚拟的晶圆制造系统上进行.结果表明,该算法在实时派工中对瓶颈设备填充率和利用率显著提升,有效地缩短了产品加工周期.

半导体生产线动态调度方法研究

为了满足半导体生产线多目标优化要求,提出了多目标优化动态调度规则。它由正常状态调度规则、瓶颈设备较低在制品水平的调度规则、非瓶颈设备较高在制品水平的调度规则、多批加工设备调度规则以及紧急工件调度规则五种类型的调度规则组成。使用具有半导体生产线本质特征的简化模型,将多目标优化动态调度规则与先入先出法、最早交货期法、临界值法进行了比较,结果表明,多目标优化动态调度规则能够改善半导体生产线的整体性能,更好地优化模型的生产率、加工周期与在制品水平,最终提高准时交货率。

半导体硅片加工过程复合控制策略研究及仿真

复合优先级控制策略CPC是一种兼顾投料与调度策略的生产过程综合控制策略。通过比较加工任务的复合优先级系数,CPC策略能够确定下一个加工任务,以及决定何时投放新工件。CPC策略甚至能够暂停非瓶颈设备以避免瓶颈设备前的在制品堆积。仿真结果表明,这种复合控制策略是一种能够同时优化多种性能指标的生产过程控制策略,可降低加工周期及其方差,减少生产过程中的在制品数,提高设备利用率及生产率等。

基于数据挖掘的晶圆制造交货期预测方法

晶圆订单的交货期预测对于保证订单交付的准时性和平顺性,具有重要的意义。然而,晶圆制造中的在制品数量多、生产周期长的特点加剧了交货期预测的复杂性。基于海量晶圆制造数据,设计回归模型来对1669个晶圆加工过程参数与订单交货期指标之间的关联关系进行分析,并采用费舍尔Z变换筛选得到强相关变量,对所得到的强相关变量采用案例推理方法实现了晶圆制造订单交货期的精准预测。

基于Petri网与遗传算法的半导体生产线建模与优化调度

针对半导体生产线调度复杂、难以优化的问题,本文提出一种基于层次有色赋时Petri网技术和遗传算法相结合的优化调度方法.该方法利用层次化的思想结合自顶向下建模方法对半导体生产线进行模块化建模,模型不仅能够反映生产线待加工产品的多条加工路径及其资源约束,还可以对系统的设备维护、各种优先级等特性进行描述,得到对生产系统更完善更精确的刻画.通过在遗传算法编码中考虑投料策略、工件选设备规则、批加工调度规则和单件加工设备规则等因素得到更加有效的调度方案,提高了模型的优化程度.在此基础上,对实际半导体生产线的不同调度方案分别进行仿真,并对仿真结果进行比较,从而验证了建模方法的正确性及调度策略的有效性.