Plasma polymerization of methyl methacrylate: a photoresist for 3D applications

The use of plasma polymerized methyl methacrylate (PPMMA) as a deep UV photoresist is described. By depositing a light sensitive polymer film from a plasma, very irregular surfaces can be coated and patterned. Other key parameters for a photoresist are photosensitivity, stability, selectivity, and resolution. These parameters are used here as a means of optimizing the plasma process, exposure, and development cycle. The optimum process sequence results in stable films which withstand subsequent exposure to acetone and isopropyl alcohol, have a line width resolution of at least 1.5 mu m, and have a selectivity of at least 70%.<
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