Specific Process Knowledge/Lithography/MiR: Difference between revisions
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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 | 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. | 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. | ||
<gallery style="text-align: center;" widths=450 heights=350> | |||
MIR_noPEB.jpg|1.5 µm AZ MIR 701 without PEB | |||
MIR_withPEB.jpg|1.5 µm AZ MIR 701 with PEB | |||
</gallery> | |||
==Development== | ==Development== | ||
'''Development speed:''' | '''Development speed:''' | ||
*Puddle development in 2.38% TMAH (AZ 726 MIF): ~2 µm/min | *Puddle development in 2.38% TMAH (AZ 726 MIF): ~2 µm/min | ||