Integrating system and feature scale models to study copper reflow

Abstract
The reflow of sputtered copper is a microelectronics metallization procedure compatible with damascene processing [Murarka et al., MRS Bull. 18, 46 (1993)]. During the reflow process, copper films are deposited via traditional sputter technologies and subsequently made to fill submicron trenches and vias through surface diffusion enhanced by annealing [Gardner and Fraser, in 1995 Proceedings of the VLSI Multilevel Interconnection Conference, edited by T. E. Wade (VMIC, Tampa, FL, 1995), p. 287]. This article studies the copper reflow processing parameters through simulation using the process simulators SIMSPUD and GROFILMS. Simulation results are presented as depictions of the film on the feature scale and as an analysis of the process parameter space. In particular, factors such as initial film profiles and anneal temperatures are shown to be important considerations in developing a successful Cu reflow process. The effects of the deposition procedure on the reflow process are presented regarding system configuration, copper film thickness, and trench aspect ratios. The deposition system parameters are shown to be important when multiple feature sizes are to be filled concurrently.

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