Practical issues in the deployment of a run-to-run control system in a semiconductor manufacturing facility

Run-to-run feedback process control for semiconductor manufacturing uses process models to relate the equipment settings to the wafer-state responses of interest. Engineers specify processes in terms of their desired wafer-state effects (the targets), and process models transform these targets into machine settings. To account for drifts and shifts in process behavior, the models are updated to match the current state of the equipment. These tuned, or adapted, models are used to calculate process adjustments to keep the wafer-state responses for subsequent wafers on target. Automatic recipe adjustments reduce wafer processing complexity, increase processing efficiency, and improve processing quality. Configuring an optimal control strategy for a particular process on a specific tool is fundamental to implementing run-to-run control in a semiconductor manufacturing environment. However, there is a significant effort involved to move from a standalone controller for a single process on a single tool to the deployment of a run-to-run control system across an entire area of the fab or across an entire fab. Some of the key issues include 1) communication between the run-to-run controller and existing factory systems and tool automation, 2) controlling multiple processes per tool and multiple chambers/tools per process, 3) handling non-production runs, and 4) non-constant data sampling due to metrology delays. ProcessWORKS, a factory-level run-to-run control architecture, originally developed at Texas Instruments and now a product of Adventa Control Technologies, can treat complex control problems in an automated, predictable, and repeatable fashion. ProcessWORKS is compatible with different techniques for data acquisition and analysis, model adjustment and feedback, and model optimization. ProcessWORKS is also designed to deal with practical implementation issues in the fab. In this talk we will review the benefits of ProcessWORKS run-to-run control. We will discuss some practical problems in the deployment of run-to-run control in the fab, and we will show how ProcessWORKS deals with these issues. Examples from the deployment of ProcessWORKS at Texas Instruments on state of the art semiconductor technologies will be given.