The Formation of Ultra Fine Cu Metal Line with Sub 5 Micron Using Photolithography and Semi Additive Process

• Published in: ECS transactions Vol. 52; no. 1; pp. 337 - 341
• Main Authors: Lee, Youngjae, Harr, Kyoungmoo, Lee, Chang-Bae, Kim, Jin-Gu, Kim, Dahee, Kweon, Youngdo
• Format: Journal Article
• Language: English
• Published: 01.01.2013
• DOI: 10.1149/05201.0337ecst
• ISSN: 1938-5862

Recently changes in the semiconductor industry continue toward higher functionality that leads to higher input/output (I/O) counts, pushing packaging towards higher density architectures. With increasing these market demands of electric products, printed circuit board (PCB) are pushed to accommodate these requirements also. In other words, PCB industry is experiencing tremendous pressure to enhance the wiring density and reduce that feature size of PCBs, while retaining low cost. To keep up these trends, we developed substrate technology with ultra fine line/space and high aspect ratio using sputter, photolithography and semi additive process (SAP). Photolithography is the technology of reproducing images or patterns by using UV light. The designed patterns for constructing circuits are transferred onto a photosensitive thin or thick film by photolithographic method. This technology dominates the process capability of producing fine line structure. Wet etch is currently the most popular subtractive method used in PCB industry. It is known as low resolution technology due to the nature of isotropic etches or undercut. To minimize undercut, we introduced sputtering system to SAP method for seed layer deposition. SAP method is used for build up substrate manufacturing and uses electrolytic copper plating to fill in the patterned photo resist. In this study, we have successfully formed copper lines of sub 5um which have bellow 0.5um undercut by using SAP method and photolithography.