Specific Process Knowledge/Lithography/MiR: Difference between revisions

During exposure, interaction between the incoming light and the light reflected by the substrate can cause a standing wave to form in the resist (especially true for single line/wavelength exposure). This leads to a wavy sidewall after development. The standing wave pattern can be reduced by introducing a post-exposure bake before development, which allows the activated PAC to diffuse into un-activated regions, thus smoothing the sidewall. The recommended PEB for MiR is 60 s at 110°C (for a 1 - 2 µm film). Thicker coatings may require longer bake, and substrate thickness and material may also affect the required baking time.

Since the post-exposure bake is at an elevated temperature compared to the soft bake, it will cause the resist film to become 5-10% thinner (probably due to continued evaporation of solvent). A 1.5 µm thick MiR resist film will be approximately 1.4 µm after PEB.