Step coverage and continuity of an I-PVD Ta(N) barrier layer: limitations

The step coverage and continuity of a Ta(N) I-PVD barrier layer is investigated combining an HF-dip technique, X-SEM and TEM. The HF dip technique appears to be the most sensitive in revealing imperfections on the sidewall of recesses. The aspect ratio (AR) dependence of the I-PVD deposited barrier is apparent. The studies were complemented with with Single Wavelength Ellipsometry. It is pointed out that the IMP deposition technique can successfully be applied for AR<4. Above an aspect ratio of four the deposited barrier can become discontinuous on recess sidewalls. It is also illustrated how process parameters can influence step coverage.