Method for improved adhesion between a metal layer and a BCB layer in wirebond RDL applications

Method for improved adhesion between a metal layer and a BCB layer in wirebond RDL applications

Disclosed is a method for improved adhesion between a metal layer and a benzocyclobutene (BCB) layer in wirebond redistribution layer (RDL) applications. Benefits include improved functionality and improved performance.

Background

� � � � � The concept of anchors is conventionally used in wafer technology to promote the adhesion of various layers with different material properties.

        � � � � � The metal stacks used in forming redistribution traces can adhere poorly to the underlying BCB layer during RDL wirebond application (see Figure 1).

        � � � � � Conventionally, no solution exists to solve the poor adhesion between the metal and the BCB layer.

Description

� � � � � The disclosed method is improved adhesion between a metal layer and a BCB layer in RDL applications. The contact surface of the metal and BCB layers is increased. Anchors are created (using the via lithography process) selectively under the traces in the BCB layer prior to the deposition of the metal stack (see Figure 2).

        � � � � � The key element of the method includes the use of the anchor concept to create an increased surface area for traces that are created on top of the BCB layer.

Advantages

        � � � � � The disclosed method provides advantages, including:

•        � � � � Improved functionality due to enabling RDL applications for wirebond

•        � � � � Improved functionality due to creating an increased surface area for...