Advanced Interconnection Technology Overview

Mass reflow (MR), thermocompression bonding (TCB) and laser assisted bonding (LAB) are major bonding technologies in flip chip bump interconnections on substrates. Each method has its pros and cons. MR is a mature process, but it has limitations on fine pitch devices and large/thin substrate packages. TCB can prevent or minimize high warpage die but its productivity is very low. LAB provides a solution for advanced devices with its localized heating and short bonding time. Recently, demand for fine-pitch flip chip bumps and large/thin substrate packages has increased, resulting in industry interest in LAB due to its good quality and high productivity.However, as the industry continues to require high bonding performance for various new devices, existing LAB technology may not support all these applications. These devices have led to the development of next-generation LAB technology with a new bonding concept. Amkor Technology invented reverse laser-assisted bond (R-LAB) and reverse laser thermocompression bond (R-LTC) technologies to overcome the limitations of existing LAB with target applications for backside metallization (BSM) die, and chip let module (molded silicon (Si) die) bonding on substrates.R-LTC is a combination of R-LAB and TCB and targets high and large warpage module devices. The majority of bump interconnections rely on laser power, but there is a bond head on top of the module to hold the and flatten the die during bump wetting by heating. One advantage of R-LTC is it helps to minimize thermal stress to the die compared to TCB because bump wetting is mainly done by the reverse laser heating. Additionally, it enables bonding micro lead-frame chip carrier (MLCC) packages or integrated passive devices (IPDs) with the module simultaneously by a single (one shot) laser emission. As a result, R-LTC might be a possible solution for large or high warpage module bonding.This paper overviews each bonding technology and provides guidelines for the best bonding method for various devices in the future.