Method and system for detecting and correcting problematic advanced process control parameters

Abstract

The invention may be embodied in a system and method for monitoring and controlling feedback control in a manufacturing process, such as an integrated circuit fabrication process. The process control parameters may include translation, rotation, magnification, dose and focus applied by a photolithographic scanner or stepper operating on silicon wafers. Overlay errors are used to compute measured parameters used in the feedback control process. Statistical parameters are computed, normalized and graphed on a common set of axes for at-a-glance comparison of measured parameters and process control parameters to facilitate the detection of problematic parameters. Parameter trends and context relaxation scenarios are also compared graphically. Feedback control parameters, such as EWMA lambdas, may be determined and used as feedback parameters for refining the APC model that computes adjustments to the process control parameters based on the measured parameters.

Description

technical field [0001] The present invention relates to integrated circuit fabrication, and more particularly to a method for monitoring and controlling feedback parameters in the integrated circuit fabrication process. Background technique [0002] Advanced process control (APC) systems are currently used to implement feedback control in integrated circuit (IC) manufacturing processes. An IC fabrication process typically includes wafer handling tools (eg, scanners or steppers) suitable for forming a series of desired patterned layers in a wafer (eg, a silicon wafer) to produce IC devices. The manufacturing process can be controlled by several process control parameters applied by the process tools at each step of the manufacturing process. These process control parameters may include, but are not limited to, the rate at which the wafer is translated across the process tool (scanner or stepper), the angle of rotation of the wafer relative to the process tool, the radiation ...

AI Technical Summary

Problems solved by technology

[0005] Although this is a very successful IC manufacturing technique, the calculation of such control parameters has traditionally been a "black box" for technicians, where the inner workings of the APC system (such as underlying overlay errors and measurement parameters) are not available for observe or analyze

This makes it difficult for technicians to understand how IC manufacturing systems function to help identify difficult process control parameters and develop model changes to counteract problems and develop improvements to feedback control systems

Therefore, it can be difficult to diagnose and correct errors within the APC system

Images