Investigation of optical properties of benzocyclobutene wafer bonding layer used for 3D interconnects via infrared spectroscopic ellipsometry

• Published in: Thin solid films Vol. 519; no. 9; pp. 2924 - 2928
• Main Authors: Kamineni, Vimal K., Singh, Pratibha, Kong, LayWai, Hudnall, John, Qureshi, Jamal, Taylor, Chris, Rudack, Andy, Arkalgud, Sitaram, Diebold, Alain C.
• Format: Journal Article Conference Proceeding
• Language: English
• Published: Amsterdam Elsevier B.V 28.02.2011; Elsevier
• Subjects: 3D interconnects; Applied sciences; Benzocyclobutene; Bonding; Condensed matter: electronic structure, electrical, magnetic, and optical properties; Condensed matter: structure, mechanical and thermal properties; Curing; Defects and impurities in crystals; microstructure; Dendritic structure; Design. Technologies. Operation analysis. Testing; Electronics; Ellipsometry; Exact sciences and technology; Infrared spectroscopic ellipsometry; Integrated circuits; Microelectronic fabrication (materials and surfaces technology); Microscopic defects (voids, inclusions, etc.); Optical properties and condensed-matter spectroscopy and other interactions of matter with particles and radiation; Optical properties of specific thin films; Physics; Scanning acoustic microscopy; Scanning electron microscopy; Semiconductor electronics. Microelectronics. Optoelectronics. Solid state devices; Structure of solids and liquids; crystallography; Three dimensional; Voids; Wafer bonding; Wafers; Wafer bonding; Benzocyclobutene; Curing; Scanning acoustic microscopy; 3D interconnects; Infrared spectroscopic ellipsometry; Scanning electron microscopy; Crystal defects; Spectroscopic ellipsometry; Dielectric properties; Infrared spectra; Voids; Microelectronic fabrication; Acoustic microscopy; Wafers; Optical properties; Dendrites; Silicon; Absorption spectra
• ISSN: 0040-6090; 1879-2731
• DOI: 10.1016/j.tsf.2010.11.084

Benzocyclobutene (BCB) used for bonding silicon wafers to enable 3D interconnect technology is characterized using spectroscopic ellipsometry (SE). SE is a non-destructive technique that has been used to characterize the thickness and dielectric properties of BCB. The infrared (IR) absorption spectrum was used to calculate the percentage of curing of BCB on 300mm bare and bonded wafers. The percentage of curing in BCB is a key parameter that impacts the bond strength and bond quality. This study presents the potential application of IRSE for measurements on bonded wafers to characterize the chemical information, curing percentage, bond quality and thickness of the BCB bonding layer. One of the key issues in the process development and characterization of BCB bonding for 3D interconnects of 300mm wafers is the presence of dendrites and voids between the bonded wafers. The presence of dendrites and voids was identified by using scanning acoustic microscopy (SAM) and imaged by scanning electron microscope (SEM).