Open Access

ARTICLE

Modelling and Validation of Contribions to Stress in the Shallow Trench Isolation Process Sequence

by K. Garikipati¹, V.S. Rao², M.Y. Hao³, E. Ibok⁴, I. de Wolf⁵, R. W. Dutton⁶

1 Stanford University, Stanford, California
2 Schlumberger Cambridge Research Centre, Cambridge, UK
3 Advanced Micro Devices Inc., Santa Clara, California
4 Advanced Micro Devices Inc., Santa Clara, California
5 Interuniversity Micro-electronics Center, Leuven, Belgium
6 Stanford University, Stanford, California

Computer Modeling in Engineering & Sciences 2000, 1(1), 65-84. https://doi.org/10.3970/cmes.2000.001.065

Abstract

This work is based upon a careful rendering of mechanics and mathematics to describe the phenomena that influence the stress engendered by the Shallow Trench Isolation process. The diffusion-reaction problem is posed in terms of fundamental mass balance laws. Finite strain kinematics is invoked to model the large expansion of SiO₂, dielectrics are modelled as viscoelastic solids and annealing-induced density relaxation of SiO₂ is incorporated as a history-dependent process. A levelset framework is used to describe the moving Si/SiO₂ interface. Sophisticated finite element methods are employed to solve the mathematical equations posed for each phenomenon. These include the incorporation of discontinuity-resolving shape functions to describe jumps in concentration of O₂, methods to prevent oscillations of numerical solutions and techniques that allow highly inhomogeneous deformation of a single element. The use of experimental data to rigorously obtain material properties is emphasized. Mechanical properties of viscoelastic solids are extracted directly from stress-strain data, following which, parameters for the diffusion-reaction problem are obtained. Qualitative and quantitative validation of the models is presented; the latter by comparison with micro-Raman spectroscopy measurements.

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