Ultra large scale integration (ULSI) technologies require uniform metallization layers over extreme topographies of submicron dimensions. On this scale, the fundamental properties of thin films and the processes during growth are increasingly important considerations. This paper introduces a new thin film growth model called GROFILMS (grain orientated film microstructure simulator). By using a line segment algorithm and by the incorporation of interfacial and surface energy calculations, GROFILMs can depict both the surface and microstructure of a film deposited over ULSI topography. GROFILMs is capable of simulating many of the fundamental processes involved with thin film growth, such as nucleation, substrate wetting, grain boundary grooving, columnar growth and crystal facetting. This paper will describe the model and demonstrate the ability of GROFILMs to simulate film growth and produce microstructural and surface information about the film.