Virtual metrology for prediction of etch depth in a trench etch process

Abstract

In semiconductor manufacturing, advanced process control systems have become essential for cost effective manufacturing at high quality. Algorithms for new control methods such as virtual metrology where post process quality parameters are predicted from process and wafer state information need to be developed and implemented for critical process steps. The objectives of virtual metrology application are to support or replace stand-alone and in-line metrology operations, to support fault detection and classification, run-to-run control, and other new control entities such as predictive maintenance. As virtual metrology is typically based on statistical learning methods, a large variety of potential algorithms are available. The challenge of virtual metrology application is the capability to obtain precise predictions even in complex semiconductor manufacturing processes. In this paper, the approach and results towards the development of a virtual metrology algorithm for the prediction of trench depth after a complex dry-etch process are presented

A Realizable Overlay Virtual Metrology System in Semiconductor Manufacturing: Proposal, Challenges and Future Perspective

“…In [20], the authors presented a feasibility evaluation of the VM developed to predict the etch depth of two different recipes of the plasma etch process in a high product-mixed scenario. According to the authors, although various VM algorithms have been proposed as a result of active research in this area, applying VM for accurate prediction in a real complex production environment remains the key challenge.…”

“…• A VM approach that enables early stage metrology outcome prediction and a process control through the generated feedforward control signal [20] Etching Etch depth…”