Dielectric cap layers of sophisticated high-k metal gate electrode structures may be efficiently removed on the basis of a sacrificial fill material, thereby reliably preserving integrity of a protective sidewall spacer structure, which in turn may result in superior uniformity of the threshold voltage of the transistors. The sacrificial fill material may be provided in the form of an organic material that may be reduced in thickness on the basis of a wet developing process, thereby enabling a high degree of process controllability.