Cure Technology for Controlled Stress in Thin Benzocyclobutene Coatings

The stress at room temperature in many typical polymer coatings used for microelectronic dielectrics is near 40 MPa. Polymer coatings derived from divinylsiloxane bisbenzocyclobutene (BCB), (CAS 117732-87-3), have a stress level of ca. 38 MPa after a conventional thermal oven cure. In this work, a novel approach based on curing the BCB polymeric network in the vitrified state has been used to achieve far field stresses of 24 MPa in the final coatings. This represents a 36% reduction in the far field stress of BCB coatings cured at 250 °C. The cure methodology and compatibility with device process design are discussed.