Low-temperature full wafer adhesive bonding

Frank Niklaus, Peter Enoksson, Edvard Kälvesten, Göran Stemme
2001 Journal of Micromechanics and Microengineering  
We have systematically investigated the influence of different bonding parameters on void formation in a low-temperature adhesive bonding process. As a result of these studies we present guidelines for void free adhesive bonding of 10 cm diameter wafers. We have focused on polymer coatings with layer thicknesses between 1 µm and 18 µm. The tested polymer materials were benzocyclobutene (BCB) from Dow Chemical, a negative photoresist (ULTRA-i 300) and a positive photoresist (S1818) from Shipley,
more » ... 1818) from Shipley, a polyimide (HTR3) from Arch Chemical and two different polyimides (PI2555 and PI2610) from DuPont. The polymer material, the bonding pressure and the pre-curing time and temperature for the polymer significantly influence void formation at the bond interface. High bonding pressure and optimum pre-curing times/temperatures counteract void formation. We present the process parameters to achieve void-free bonding with the BCB coating and with the ULTRA-i 300 photoresist coating as adhesive materials. Excellent void-free and strong bonds have been achieved by using BCB as the bonding material which requires a minimum bonding temperature of 180 • C. (Some figures in this article are in colour only in the electronic version; see www.iop.org)
doi:10.1088/0960-1317/11/2/303 fatcat:6sxasmitsfckdjbqhp5uvp2oo4