Patent ID: 7410833
Filing Date: 2008-08-12
Classification: H01L

Abstract:
1. A method for forming an interconnection structure suitable for flip-chip attachment of microelectronic device chips to chip carriers, comprising: depositing an adhesion layer on a wafer or substrate serving as said chip carrier; depositing a solder reaction barrier layer on said adhesion layer; depositing a solder wettable layer on said reaction barrier layer, said solder wettable layer containing Cu; depositing a lead free solder on said solder wettable layer, said lead free solder being substantially binary Sn—Ag; and reflowing said solder so that said solder wettable layer diffuses into said lead free solder; wherein said Cu of said solder wettable layer diffuses into said solder, and a ternary Sn—Ag—Cu lead-free solder is formed during reflowing.