Epoxy resins for deep UV lithography

Abstract

A difficulty often encountered with crosslinking negative resists is swelling of the crosslinked matrix during development with organic solvents. This swelling manifests itself in distorted images and/or complete adhesion loss, especially when submicron features are involved. The authors' goal has been to address these problems and develop an organic developable deep UV resist capable of providing submicron images. Optically transparent commercial resins, styrene-allyl alcohol copolymers, have been converted to glycidyl ethers, thereby providing cationically polymerizable functionalities. The synthetic procedure and characterization of the epoxy resin is presented. The effect of the molecular weight distribution upon swelling during development and general solubility properties is discussed. Resist formulations exhibited sensitivities of 19-30 mJ/cm2 on a Perkin Elmer 500 in the deep UV (UV2) mode. The electron beam sensitivity is 3-5 μC/cm2 at 20KeV.