Benzocyclobutene (BCB) is a dielectric, polymer resin used in microelectronics for its physical properties and its chemical resistance. UV/ozone photochemical treatment modifies the chemical properties of BCB: It creates a near SiO2 composition oxidized surface layer and degrades the polymer structure of BCB. The oxidized surface layer can be etched with fluoride acid and the degraded layer underneath is soluble with acetone. These BCB chemical modifications may be. useful for BCB reworking after polymerization. UV/ozone treatment also has an effect on surface characteristics improving the surface tension and decreasing surface roughness of. BCB. (C) 2003 American Vacuum Society.