*********************************
There is now a CONTENT FREEZE for Mercury while we switch to a new platform. It began on Friday, March 10 at 6pm and will end on Wednesday, March 15 at noon. No new content can be created during this time, but all material in the system as of the beginning of the freeze will be migrated to the new platform, including users and groups. Functionally the new site is identical to the old one. webteam@gatech.edu
*********************************
Title: Modeling, Fabrication and Characterization of Impedance Controlled 2 Micron Multilayer RDL for 20 Micron Bump Pitch Glass Interposers
Committee:
Dr. Tummala, Advisor
Dr. Peterson, Chair
Dr. Brand
Dr. Sundaram
Dr. Sitaraman
Abstract:
The objective of this proposed research is to explore a cost effective and large panel scalable RDL formation method for 2.5D glass interposers by design, modeling, fabrication, and characterization, leading to 20 µm bump pitch compatible, impedance controlled RDL design guideline. The impedance controlled multi-layer RDL design for low cost glass interposer based on the existing materials has been proposed. A thin, low loss polymer has been applied on thin glass substrate with double side process to improve the thin glass handling and enhance the build-up copper RDL adhesion. The lithography process for RDL patterning with advanced dry film resist (DFR) has been optimized to achieve 2 µm resolution across the 6-inch panel, and scalable to 12 by 12 inch. An improved low cost novel differential seed layer etching was employed to reduce the copper trace side wall etch, undercut issue, and improve the overall SAP yield. A cost effective surface planarization process was applied and optimized to thin down dielectric polymer, control copper layer thickness uniformity, and improve overall co-planarity of the whole package. A novel atmospheric ozone treatment was proposed as a higher throughput alternative to traditional plasma treatment for electrolytic copper plating yield improvement and surface cleaning. Combining all the process advancement discussed above, the semi-additive process (SAP) was advanced to achieve ultra-fine pitch RDL routing ready for 20 µm bump pitch applications. Different transmission lines have been fabricated on glass interposers by proposed advanced SAP method. The measurement results correlated well with 3D model simulations. New TOK’s photosensitive dielectric materials was employed for high throughput small via formation by photolithographic process. A special ring-resonator with enhanced coupling feed line was designed for the photosensitive dielectric material characterization.
