PROFILE SIMULATION OF CONFORMALITY OF CHEMICAL-VAPOR-DEPOSITED COPPERIN SUBQUARTER-MICRON TRENCH AND VIA STRUCTURES

Copper profile evolution in ultralarge scale integration via and trenc h structures was investigated for thermal low pressure, low temperatur e, chemical vapor deposition (LPCVD) from Cu-I(tmvs)(hfac). The invest igation examined copper profiles in specialized cantilever structures as a function of systematic changes in key processing conditions, name ly, substrate temperature, precursor flux, and hydrogen reactant flow. Resulting experimental observations from cross section scanning elect ron microscopy were incorporated in a fast analytical simulator, using a two-dimensional adsorption/re-emission model, to simulate copper pr ofile evolution. The deposition profiles were simulated using a single rate limiting precursor model. A comparison of simulation results and actual experimental profiles for thermal LPCVD copper showed that spe cies re-emission within the via and trench structures play a critical role in achieving conformal step coverage and complete filling. In add itional, precursor flux and substrate temperature were identified as t he dominant parameters in the species re-emission process, with the pr obability for re-emission being inversely proportional to substrate te mperature and directly proportional to precursor flux. The results of this study were employed in the development of an optimum LPCVD proces s window for complete copper filling of aggressive via and trench stru ctures at growth rates above 2000 Angstrom/min and as-deposited resist ivity below 2.0 mu Omega cm. (C) 1997 American Institute of Physics. [ S0021-8979(97)01221-8].