MODELING, IDENTIFICATION, AND CONTROL OF RAPID THERMAL-PROCESSING SYSTEMS

A wafer temperature control system is developed for rapid thermal proc essing (RTP) semiconductor manufacturing equipment. The control algori thm is based on a physical model describing the heat transfer effects in advanced RTP equipment. A model identification procedure is propose d to estimate the uncertain parameters of the model from a set of expe riments. Through singular value analysis, the impact of equipment desi gn on feedback controller development is studied. An internal model co ntrol (IMC) design methodology is used to develop a low-order multivar iable feedback control algorithm. The feedback controller is coordinat ed with additional modules including feedforward control and gain sche duling to achieve improved performance and flexibility. The algorithms are applied to three different multizone RTP systems. Temperature con trolled ramps are demonstrated from 20 to 900-degrees-C at 45-degrees- C/s with less than +/-5-degrees-C during the ramp at high temperatures and less than +/-1-degrees-C average nonuniformity during steady stat e as measured by three radially distributed temperature sensors.