Transport in low pressure plasma reactors for materials processing.

摘要

Plasmas are used extensively in semiconductor manufacturing for etching features and vias, for depositing metals to make interconnects, and for cleaning reactors between wafers. The development of plasma equipment models (PEMs) for investigating chemical, physical, and engineering scaling issues for plasma processing has significantly advanced in recent years. The continuous shrinking of the minimum feature size in microelectronics fabrication has necessitated the use of high-density low-pressure plasma sources. At these pressures, conventional fluid or hybrid simulations are of questionable validity as transport is highly nonequilibrium and a kinetic approach may be warranted.; In this study, a Monte Carlo simulation for ion and neutral transport (IMCS) has been developed and integrated with a plasma equipment model to improve the capabilities to address lower pressures. The ion/neutral energy distribution functions obtained from the IMCS are used to obtain transport coefficients for use in heavy particle momentum conservation equations. The heavy particle temperatures are found to significantly influence densities, electron temperatures, and sputter rates. The consequences of varying power, pressure, and gas chemistries have been investigated for several low-pressure tools.; Ionized metal physical vapor deposition (IMPVD) at pressures of a few mTorr is being increasingly used to deposit diffusion barriers and Cu seed layers into high aspect ratio trenches. Understanding plasma-substrate interactions will be critical to designing the next generation processes as the industry transitions to the 45-nm node. In this work, IMPVD using a hollow cathode magnetron source has been modeled at the reactor and feature scale. The consequences of varying process parameters such as power, pressure and magnetic fields have been investigated for a hollow cathode magnetron source and comparison has been made with experiments. The fluxes incident on the wafer are strongly influenced by the magnetic field configuration and strength. A Monte Carlo Feature Profile Model has been used to investigate the Cu seed layer deposition process. The lateral overburden at the mouth of features, or "overhang," is strongly correlated to the ion and neutral energy and angular distributions and the ion flux incident on the substrate.