Modelling Calibration and Validation of Contributions to Stress in the STI Process Sequence

Abstract

The mathematics and mechanics of the Shallow Trench Isolation process are described. The di#usionreaction problem is posed in terms of fundamental mass balance laws. Finite strain kinematics is invoked to model the large expansion of SiO 2 , dielectrics are modelled as viscoelastic solids and annealing-induced density relaxation of SiO 2 is incorporated as a historydependent process. A levelset framework is used to describe the moving Si/SiO 2 interface. Sophisticated finite element methods are employed to solve the mathematical equations posed for each phenomenon. Mechanical properties of viscoelastic solids are extracted directly from stress-strain data, following which, parameters for the di#usion-reaction problem are obtained. Comparison with micro-Raman spectroscopy provides validation of the model. Keywords: mathematical modelling, continuum mechanics, viscoelasticity, semiconductor processing, finite element methods. 1. INTRODUCTION Isolation structures are employed in IC tec..