Investigation on the mechanism of the 193nm resist linewidth reduction during the SEM measurement

Linewidth reduction (or line slimming) of resist features has been previously observed during routine scanning electron microscopy (SEM)((1)). The impact of the linewidth reduction may result in measurement precision and accuracy errors and potential device reliability issues due to permanent feature deformation. The magnitude and the origin of these effects for various resist platforms are not well understood. In this study the measurement of the extent of slimming is performed on two 193nm single layer resist (SLR) platforms, including an acrylate based SLR and a polynorborene (poly-CO) based SLR. The maximum shrinkage is found to be approximately 15% and varies as a function of resist composition and electron beam landing energy and flux. Mechanisms for the resist shrinkage that impact both the physical (e.g., annealing or solvent loss) and chemical (e.g., bond scission, cross-linking, fragmentation, or deprotection) properties are evaluated. Potential methods for reducing the slimming effect are proposed in this paper.