Removal mechanism of nano-bubble with AFM for immersion lithography

We discuss adhesion and removal mechanisms of nano-bubble adhered on a resist surface for immersion lithography. We employed the AFM (atomic force microscope) for the observation of nano-bubbles on a resist surface. In addition, by the thermodynamic analysis, it can be considered that the nano-bubble adhered on the resist surface tends to be a flat shape and spread on the resist surface. It is difficult to adhere the bubbles on the resist surface. We also observed the nano-bubble adhered on both ArF and F2 excimer resist surfaces with the AFM.