Modeling of charging damage during interlevel oxide deposition in high-density plasmas

Monte Carlo simulations of pattern-dependent charging during interlevel dielectric (ILD) deposition in high-density plasmas reveal that the initial conformity of the ILD film plays a crucial role in metal line charging up and the subsequent degradation to the buried gate oxide to which the metal line is connected. Line charging occurs when the top dielectric is thick enough to prevent tunneling currents while the sidewall dielectric thickness still allows tunneling currents to flow to the metal line; the differential charging of the sidewalls, which induces the latter currents, is caused by electron shading. The results suggest that charging can be reduced by depositing a more conformal ILD film around the metal line and/or by increasing the ability of the film surface to dissipate charge.