(Invited) Capillary Pattern Collapse: Prediction and Prevention from Past to Future

Abstract

Pattern collapse due to capillary forces continues to be a difficult issue in semiconductor cleaning and processing. This paper gives an overview of the history of research into this phenomenon, first looking at the basic 2D model for collapsing lines, then models for pillars, other shapes, and direct numerical simulations. It then discusses experimental methods to investigate pattern collapse, including structures of photoresist, high aspect ratio lines and pillars, MEMS, and the use of AFM to measure material properties. The paper then reviews methods used to prevent pattern collapse, from changing surface tension and contact angle to the elimination of surface tension entirely. Finally the paper discusses the future of pattern collapse, and what methods and techniques are likely to be used in the future to model, predict, and prevent the collapse of structures due to capillary forces.