A Novel Alignment Technique in Wafer-Level Packaging of MEMS Components

Abstract

In recent years, assembling and packaging methods of Micro Electro Mechanical System (MEMS) components have been profoundly studied. The focus of this paper is presenting a novel alignment technique in wafer-level packaging. In conventional wafer-level strategies, either an Alignment Template (AT) must have special receptor sites according to the microchip geometry and its material, or the microcomponents should be additionally featured by circular and cross pegs for shape recognition stage. In this article, we have developed electrothermal microclamps (ETMCs) to hold and locate six microchips of 360×360×20 micrometers in a microfixturing cell. This is to provide accurate preliminary positioning for final flip-chip bonding process of wafer-level packaging on a main assembly board (MAB). The new approach enjoys the advantages of omitting special AT with receptor sites and using identical ETMCs for diverse assembly configurations. Being applicable for different types of microcomponent materials, it does necessitate no surface treatment on microcomponents such as Semidry uniquely orienting self-organizing parallel assembly (Semi-DUO-SPASS) technique. Comparing nickel and polysilicon as fabrication materials, corresponding values of input voltage to reach 3 micrometers displacement of the ETMC arm are estimated via finite element analysis to ascertain positioning and holding of microchips. Nickel showed to be a better choice for fabrication due to requiring lower input voltage and lower maximum resulting temperature. The simulation results are verified with published experimental measurements.