Method for aligning semiconductor die to interconnect metal on flex substrate

摘要

A method and process sequence for accurately aligning (14) die (108) to interconnect metal (112) on flex substrate (100) such as polyimide flex is described. A mask (102) for via formation is first patterned (12) in a metal layer on the bottom surface of the flex substrate (100). Die attach means (104) such as die attach adhesive is then applied (13) to the top side of flex substrate (100). The bond pads (106) on die are locally, adaptively aligned (14) to the patterned metal via mask (102) on the flex (100) with high accuracy. Vias (110) down to the die bond pads (106) are then created (15) by either plasma etching or excimer laser ablation through the existing aligned metal mask (102) on the flex substrate (100), and interconnect metal (112) is then deposited (16), patterned and etched (17). As a result of this process, the flex metal interconnect artwork does not have to be customized for each die misplacement using "adaptive lithography". Lower cost commercially available lithography equipment can be used for processing, reducing capital equipment and processing cost. The method is compatible with the projected designs of the next generation die which will have bond pads on the order of 40 mu m in size.