Development of wafer level hybrid bonding process using photosensitive adhesive and Cu pillar bump

Abstract

Development of low temperature wafer level hybrid bonding process using Cu/SnAg bump and photosensitive adhesive was reported. Two kinds of photosensitive adhesives, i.e., polyimide and dry film, were selected for adhesive bonding. The proposed hybrid bonding method has been successfully applied to 8 inch wafer to wafer bonding. Hybrid bonding using both polyimide and dry film achieved seam-free bonding interface. However, the wafer bonding quality using polyimide is poor and dies were separated during dicing process. As comparison, dry film is more suitable to integrate with Cu/SnAg bump for hybrid bonding and the bonded chip has robust bonding strength.