Estimation and Closed-Loop Control for Rapid Thermal Processing Systems

9312451弗里德兰最近开发了一种快速热处理技术，有望打破半导体制造的瓶颈。这项新技术涉及到使用大功率卤钨灯将半导体晶片的温度迅速提高到所需的固化温度。通过使用多变量反馈控制，可以将晶片温度保持在可接受的容差范围内。直到最近，执行所需温度测量的唯一准确方法是在晶片中嵌入热电偶。然而，这种技术在生产中并不实用。在执行所需测量方面的潜在突破是基于NJIT电子成像实验室与David Sarnoff研究中心最近开发的多波长红外成像高温计的使用。这种传感器原则上能够通过蓝宝石窗口以所需的精度测量晶片的温度。温度数据的提取将需要复杂的数据处理，因为需要估计不同波长的发射率和温度。扩展卡尔曼滤波(EKF)是首选算法。然而，EKF算法的使用会影响控制问题的表达方式。特别是，有必要使用过程的非线性动力学模型，以捕捉估计发射率的正确的温度依赖关系。因此，设计一个闭环系统控制器需要处理一个非线性控制和估计问题。拟议的调查将解决这一问题及其引发的理论问题。***

9312451 Friedland A technique of rapid thermal processing (RTP) has recently been developed which promises to break a bottleneck in semiconductor manafacturing. This new technique involves the use of high power tungsten-halogen lamps to raise the temperature of a semiconductor wafer rapidly to the desired curing temperature. By use of multivariable feedback control it is possible to maintain the wafer temperature within an acceptable tolerance band. Until recently, the only accurate method of performing the required temperature mearsurments was to imbed thermocouples in the wafer. This technique, however, is not practical for use in production. A potential breakthrough in performing the required measurement is based on the use of a multi-wavelength infrared imaging pyrometer recently developed by NJIT's Electronic Imaging Laboratory in conjunction with the David Sarnoff Research Center. This sensor, in principle, is capable of measuring the temperature of the wafer through a sapphire window with the required accuracy. Extraction of temperature data will entail sophisticated data processing, owing to the requirement of estimating both emissivity and temperature at the different wavelengths. Extended Kalman filtering (EKF) is the preferred algorithm. Use of the EKF algorithm, however, impacts on how the control problem is formulated. In particular, it is necessary to use a nonlinear dynamic model of the process in order to capture the correct temperature dependence for estimation of emissivity. Hence, designing a closed loop controller necessitates dealing with a nonlinear control and estimation problem. The proposed investigation will address this problem and the theoretical issues it raises. ***