Flash Lamp Annealing Method for Improving Adhesion Strength on the Dielectric Material and Reducing Substrate Warpage

Abstract

Today's electronic devices have required higher performance properties for 5G and artificial intelligence (AI). High-performance system on chip (SOC), graphic processing unit (GPU), and central processing unit (CPU) requires advanced packages to meet demands for performance, size, and high-speed transmission. To respond to these demands, integration approaches such as 3D IC chip stacking, package on package (PoP), 2.5D interposer integration, system-in-package (SiP), and fan-out packaging technologies have emerged [6, 8, 11, 12]. Therefore, the package substrate for high-performance device will require low transmission loss and the small package warpage. Low loss materials have limitation of seed layer formation with electroless Cu plating. Also, heat treatment has major impact on substrate warpage in order for growth of plated Cu metal and curing for epoxy mold compound (EMC) process. In this paper, we believe it is possible to create a seed layer on the low-loss material by combining electroless Cu plating and flash lamp annealing (FLA) method instead of sputtering process. In terms of warpage control and metal growth, the flash lamp treatment, not the conventional convection or hot plate type heat treatment, could improve electro-migration between metal line and line through improving large number of (111) slip directions. In addition, flash lamp not only provides alternative to conventional heat treatment process but also significantly reduces substrate warpage. Through result of this study, by using FLA method for advanced package, it is possible to provide solutions in improving adhesion strength between dielectric materials and deposited metal film, and to reduce the warpage of the substrate.