The performance of ferroelectric random access memory devices (FeRAM) relies on the remnant polarisation. For high performance, the remnant polarisation of a ferroelectric thin film memory capacitor is desired to be as great as possible. However, the remnant polarisation in thin film form is typically only a third to a half of its bulk value. The coercive field is also several times greater in a thin film than in its bulk counterpart. A theoretical work is carried out in this study to explore the roles played by substrate and ferroelectric properties in altering the remnant polarisation. A constitutive law based on the crystal plasticity theory and the finite element method are used to model the ferroelectric switching behavior of a memory capacitor. In particular, it is found that factors such as crystallographic orientation and the initial volume fractions of ferroelectric variants, that are dependent on the type of substrate and film deposition method, can significantly alter the achievable remnant polarisation. An explanation of these dependencies is given, suggesting approaches to the problem of increasing the remnant polarisation of a thin film memory capacitor.© (2008) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.