Contact printing for improved bond-strength of patterned adhesive full-wafer bonded 0-level packages

This paper reports on a novel technology using Benzocyclobutene (BCB) contact printing to significantly improve the bond strength of a full-wafer adhesive bond with patterned BCB structures. The BCB pattern on the first wafer acts as a stamp which is ´inked´ by an auxiliary wafer containing a thin layer of uncured BCB. The wafer with the ´inked´ stamp is then bonded to the second wafer. Tensile strength test are carried out on patterned adhesive bonded samples with and without the contact printing method. The tests show that the contact printing technique makes the bond strength of patterned BCB stronger by a factor of at least 2.3, and the bond strength even exceeds the adhesion forces of the BCB spun onto the substrate. Furthermore, this paper presents a way of how this technique is used for 0-level glass-lid packaging by full-wafer adhesive bonding. Here, the encapsulating lids are separated after the bonding by dicing the top wafer independently of the bottom wafer.