Opportunities for developing new and enabling packaging schemes are being pursued as part of device improvement strategies for electronic products. Processes such as embedded technologies in wafer level packaging and 3-D chip architecture schemes open up opportunities for realization of a variety of package configurations. As a result, there are many opportunities to impact both device performance and the processes used to create them. In the area of electroplated solder application, one area of growing interest is cleaning technology. There is a need for an integrated process to fabricate defect-free copper pillars with lead-free caps and lead-free solder plated bumps compatible with advanced packaging schemes and with improved yields and reliability. Photoresist removal and surface preparation have been identified as critical to the success. In familiar and widespread technology using 150 micropitch solder bumping, the introduction of RoHS rules for lead-free solder bump compositions, (SnAg, SnAgCu), proceeded in the absence of an integrated and tailored process capable of defect-free surface preparation. It was relatively simple for solder bump compositions in many devices to be converted to lead-free alloys. However, new challenges continue to arise in higher volume fabrication of SnAg micro-pillars (micro-pillars) or copper micro-pillars with lead-free solder caps as the bump pitch approaches 25 microm with aspect ratios of 1:1 or 1.5:1. Individual processes that are involved in the total integration, including (1) dielectric cleaning steps, (2) PVD seed Ti and Cu deposition, (3) electroplating, (4) thick photoresist application and patterning, (5) photoresist removal, (6) associated descum processes, and (7) copper seed metal etch steps, have been challenged to meet the demands. New geometries, higher aspect ratios and very dense solder bump arrays have created further challenges for these processes, stretching the older 150 microm technology beyond its capability. The focus of this paper is to identify a reliable route to defect-free copper micro-pillars with lead-free caps and lead-free solder plated micro-bumps after photoresist removal in applications compatible with advanced packaging schemes and with improved yields and reliability.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
customersupport@researchsolutions.com
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
This site is protected by reCAPTCHA and the Google Privacy Policy and Terms of Service apply.
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.