Development of Laser and Photodefinable Toughened Benzocyclobutene Dielectric Materials for 3D-TSV Integration

Abstract

3D IC integration based on TSV technology has been recognized as a key enabler for next generation of electronic devices with reduced size factor and improved performances. The adoption of 3D-TSV technology also requires the development of innovative interconnect solutions that reduces the size of signal routing and therefore imposes new demands on dielectric materials used to isolate the copper interconnects. Benzocyclobutene polymers (Dow's CYCLOTENE™ Advanced Electronic Resins) have been used to isolate copper interconnects in packaging applications for more than 20 years, due to a number of good attributes of the BCB polymer including low copper drift rate, low dielectric constant and low loss, low moisture absorption and proven reliability. However, the low fracture toughness and low elongation of BCB polymer has limited its use in stress buffer applications due to solder bump failure. Here we report the development of new laser and photodefinable toughened benzocyclobutene (BCB) dielectric materials that have following improved properties and benefits over commercial materials including: 1) Higher elongation to break at 25%, 2) Higher fracture toughness, 3) Improved lithographic performance, < 8μm minimal size feature, 4) Better stability, no change in Eo after 30 days at room temperature. The patterning and integration of these toughened benzocyclobutene materials and the processing conditions are also discussed. We believe this toughened BCB material will find wide applications as a stress buffer layer in 3-D IC.