APC技术在刻蚀工艺过程控制中的研究进展

APC是一个多层次的控制系统,其包含了实时的设备及工艺控制和非实时的RtR控制。APC引入等离子体刻蚀过程控制可极大提高等离子刻蚀机的使用效率和产品成品率,适应当前深亚微米半导体工艺技术发展的需求。针对等离子体刻蚀机及其刻蚀工艺过程控制的需求,本文分别从实时控制和RtR控制两个不同层次展开了论述,讨论了APC技术的发展趋势。     

光刻过程RtR控制方法研究进展分析

首先对光刻过程和RtR(Run-to-Run)控制技术的产生背景进行了介绍,对统计过程控制的不足进行了分析并给出了RtR控制器的一般结构。然后从过程建模和控制算法两个角度对三种主要的光刻过程RtR控制器EWMA,MPC和ANN进行了综述和评价,对这三种控制器在非线性控制、单变量控制、多变量控制的适用性和优化控制效果进行了比较分析。最后指出基于MPC的非线性多变量控制器将成为光刻过程RtR控制器的主要研究方向。     

基于OES的等离子体刻蚀过程

光学发射光谱(OES)诊断技术是高密度等离子体刻蚀工艺过程的关键技术,OES信号作为一种实时信号可以用来预测刻蚀过程的进展程度和判断刻蚀性能的好坏.在自行研发的等离子体刻蚀机平台上,采用美国海洋公司的OES传感器系统,采集多晶硅刻蚀工艺中所产生的OES信号,利用主元素分析法(PCA)对OES数据进行压缩处理,提高了实时信号的快速处理能力.对实验数据的分析表明:波长为405 mn的OES谱线可以明确显示出等离子体刻蚀进程,是一条表征等离子体刻蚀过程的状态检测及终点检测控制的特征谱线.在此基础之上,提出了基于PCA法的终点检测算法,用以判断刻蚀终点.     

等离子体刻蚀工艺中的OES监控技术

采用光学发射光谱(OES)原位检测技术,对等离子体刻蚀机中的等离子体状态进行实时监控,讨论了其在故障诊断、分类、刻蚀终点的判断及控制方面的应用。实验平台为在新研发的高密度等离子体刻蚀机,采用化学气体HBr/Cl₂为刻蚀气体进行多晶硅刻蚀工艺实验,实验过程中所采集的OES数据通过PCA法进行分析,得到与刻蚀过程相关的特征谱线。实验结果表明：OES技术适合于深亚微米等离子体刻蚀工艺过程的终点检测及故障诊断。最后就OES技术未来发展面临的挑战进行了讨论。     

等离子体刻蚀工艺控制模型分析

讨论了主因素分析法以及神经网络法在等离子体刻蚀工艺中的应用.结果表明主元素分析法可以实现对数据的压缩,而神经网络算法则显示出比传统的统计过程控制算法更好的准确性.     

新型氨气等离子体有机材料刻蚀工艺研究

本文系统研究了氨气等离子体进行有机材料(BARC)的刻蚀,研究了工艺参数:压力,静电吸盘温度对刻蚀的影响。使用氨气可以得到高的刻蚀速率,通过刻蚀参数的控制,可以在保持光刻胶顶部形貌的条件下得到直的侧壁形貌。发射光谱的研究显示,NH3等离子体中的活性组分为H*和NH*.H*是刻蚀的主要活性物种,NH自由基会产生CN聚合物保护刻蚀目标的侧壁。     

高密度等离子体刻蚀机中的终点检测技术

高密度等离子体刻蚀是当今超大规模集成电路制造过程中的关键步骤.目前已经开发出许多终点检测技术.文章讨论了终点检测技术的原理,综述了目前主流刻蚀机使用的两种终点检测技术-OES和IEP-的最新进展,讨论了终点检测技术在深亚微米等离子体刻蚀工艺中的应用,以及所面临的挑战.     

基于APC技术的“过程控制”课程改革

"过程控制"课程是自动化专业主干课程之一,其对于自动控制类专业人才培养具有极其重要的意义。先进控制(APC)技术已经成为过程控制发展的必然趋势,本文通过优化教学内容,探讨基于APC技术的"过程控制"课程教学改革,旨在培养学生运用先进控制方法分析和解决过程控制中相关工程应用问题的能力。     

α—Si TFT矩阵等离子体刻蚀技术的研究

本文介绍了α-Si TFT有源矩阵的CF_4等离子体刻蚀技术。分析了CF_4等离子体刻蚀α-Si:H和α-SiN_x的机理,对α-Si TFT的有源层与绝缘层之间刻蚀选择性和均匀性进行了研究,讨论了等离子体刻蚀速率与射频功率、反应室压力及衬底温度的依赖关系。根据实验结果总结了CF_4等离子体刻蚀速率随射频功率、反应室压力和衬底温度的增加而增大的规律,通过控制合适的工艺条件,成功地实现了选择性刻蚀并改善了刻蚀的均匀性。     

微波等离子体刻蚀技术研究

以Corial 200M型干法刻蚀机的三种刻蚀模式为基础,分析了微波等离子体刻蚀技术的优缺点．并讨论了下电极结构对干法刻蚀形貌、一致性和重复性的影响。利用微波等离子体刻蚀技术与反应离子刻蚀技术相结合,实现了SiO2各向同性刻蚀,成功应用于质量控制和失效分析等环节。     

Extensions and performance/robustness tradeoffs of the EWMArun-to-run controller by using the internal model control structure

We consider the run-to-run (RtR) correction of input recipes for semiconductor manufacturing processes using measurement information from previous runs. A RtR control algorithm that has been experimentally tested by industry and academia is the EWMA (exponentially weighted moving average) RtR controller. In this paper we provide extensions to this algorithm to address some of its drawbacks and also provide a rigorous theoretical analysis of its properties based on discrete control theory. By formulating the RtR control problem in the internal model control (IMC) structure used in feedback process control, we are able to extend the algorithm to completely eliminate offsets due to unmodeled process drifts, which is a common problem in semiconductor manufacturing. We also develop conditions for robustness with respect to modeling error and measurement delays. Tradeoffs between robustness guarantees and fast RtR response as well as handling of measurement noise are developed and presented in the form of plots that can be used for tuning the parameters of the RtR-IMC controller to accomplish the objectives set by the process engineer. The results are illustrated through several simulations including control of film deposition uniformity in an epitaxial reactor and tungsten deposition rate in a tungsten CVD reactor     

Recursive least squares estimation for run-to-run control with metrology delay and its application to STI etch process

Run-to-run (RtR) control technology has received tremendous interest in semiconductor manufacturing. Exponentially weighted moving average (EWMA), double-EWMA, and internal model control (IMC) filters are recognized methods for online RtR estimation. In this paper, we consider recursive least squares (RLS) as an alternative for online estimation and RtR control. The relationship between EWMA-type and RLS-type estimates is analyzed and verified with simulations. Because measurement delay is almost inevitable in semiconductor manufacturing, we discuss and compare the performance of EWMA, RtR-IMC, and RLS controllers in handling measurement delay and measurement noise for processes with a deterministic drift. An ad hoc solution is proposed to handle measurement delay for processes with time-varying drifts. The results are illustrated through several simulations and a shallow trench isolation (STI) etch process as an industrial example.     

基于dSPACE设计平台的过程控制系统

本文介绍了基于dSPACE设计平台的过程控制系统,阐述了dSPACE系统的框架、软硬件组成,并以水箱液位系统为研究对象,采用内模控制器为主调节器的双闭环串级控制,同时利用dsPACE的实时监测软件对实验过程进行了在线监测.结果表明,在该实时控制平台上,满足对液位的控制要求.     

Threaded EWMA Controller Tuning and Performance Evaluation in a High-Mixed System

The exponentially weighted moving average (EWMA) controller is a very popular run-to-run (RtR) control scheme in the semiconductor industry. However, in any typical step of semiconductor process, many different products are produced on parallel tools. RtR control is usually implemented with a “threaded” control framework, i.e., different controllers are used for different combinations of tools and products. In this paper, the problem of EWMA controller tuning and performance evaluation in a mixed product system are investigated by simulation and time-series analysis. It was found that as the product frequency changed, the tuning guidelines of a threaded EWMA controller were different for different types of tool disturbances. For a stationary ARMA(1,1) noise, the tuning parameter $lambda$ should be decreased as product frequency decreases. If the tool exhibits nonstationary tool dynamics, e.g., ARIMA(1,1,1) noise, the tuning parameter should increase as the product frequency decreases.      

开关磁阻电机全数字控制系统中FPGA的应用

提出了基于数字信号处理器（DSP）和现场可编程门阵列（FPGA）的开关磁阻电动机全数字控制系统,对DSP和FPGA的功能进行了分配。根据开关磁阻电动机的驱动要求,分析控制逻辑,由FPGA实现了电流斩波、角度位置和PWM电压斩波相结合的控制方案。仿真结果表明,设计的开关磁阻电动机调速系统具有高效、实时、动态性能好等优点。     

激光快速成形过程的实时监测与闭环控制

激光快速成形是一个受多因素影响的过程,在开环控制条件下,工艺条件改变时,成形系统不能做出适当地调整,因而无法获得期望的成形效果。为了解决这个问题,国内外研究机构发展了基于实时监测原理的闭环控制系统,通过不断地调整加工工艺,最终获得了几何性能(尺寸精度、表面粗糙度)和力学性能达到设计要求的三维实体零件。本文简要论述了激光快速成形过程的影响因素,并介绍了目前激光快速成形实时监测与闭环控制技术的发展现状,列举了部分监控系统,并对激光快速成形过程的监测与闭环控制系统的进一步发展提出了自己的见解。     

Improvement of Photolithography Process by Second Generation Data Mining

The advanced process control (APC) system has been developed. The APC system has already been introduced regarding critical dimension (CD) and overlay controls in a photolithography process. It has improved the productivity and device performance. However, the current APC is based on the inspection data where process deviation is mingled with machine fluctuation and which has a very small quantity to be analyzed, then it has the limit in the effect. We have collected and stored the CD and overlay inspection data as well as the log data of the exposure tool in a relational database. So, we have investigated the method to compensate and solve the above-mentioned problem. First, we have extracted relationships between inspection data and many equipment parameters, especially correlation coefficients, in huge tool log data. Next, we have investigated the issues with significant relationships and have consequently extracted useful information not extracted by the conventional method. The purpose of this paper is to show that we have developed a second generation data mining system in cooperation with APC to prove the effect of stabilizing machine fluctuation.     

增强90nm以下节点应用的工艺控制适应性(英文)

器件尺寸正在对半导体加工工艺从多方面提出新的挑战。对于在90nm节点之后的应用,需要更大改进,且用适应性强的先进工艺来克服更大节点工艺中已得到验证的固有技术的限制。不仅基于先进工艺控制(APC)的下一代工艺设备能够得到来自一个以上信息来源的测量数据,而且将这些测量数据转换成为工艺控制参数以减少性能变化,下一代工艺设备必须提供生产线许多表明圆片经过工艺设备的整个控制程序特性。这种先进工艺控制系统将给予生产线高度理想的、适合先进工艺控制的适应能力需求,实现对其独特的生产线提供最大的优势。     

Accuracy and Real-Time Considerations for Implementing Various Virtual Metrology Algorithms

In the semiconductor industry, run-to-run (R2R) control is an important technique to improve process capability and further enhance the production yield. As the dimension of electronic devices shrink increasingly, wafer-to-wafer (W2W) advanced process control (APC) becomes essential for the critical stages of production processes. W2W APC requires the metrology values of each wafer; however, it will be highly time and cost consuming to obtain actual metrology values from each wafer by physical measurement. Recently, an efficient and cost-effective approach denoted “virtual metrology (VM)” was proposed to substitute the actual metrology. To implement VM in W2W APC, both conjecture-accuracy and real-time requirements need to be considered. In this paper, various VM algorithms, including back-propagation neural networks (BPNN), simple recurrent neural networks (SRNN), and multiple regression (MR), are evaluated to see whether they can meet the accuracy and real-time requirements of W2W APC or not. The fifth generation TFT-LCD chemical–vapor deposition process is used to test and verify the requirements. Test results show that both one-hidden-layered BPNN and SRNN VM algorithms achieve acceptable conjecture accuracy and meet the real-time requirements of semiconductor and TFT-LCD W2W APC applications.