Effective Inspection Methods for Advanced Packaging Technologies

Abstract

Abstract Advanced packaging technologies have ramped up to provide solutions for new high density devices that are based on the integration of several components with different functions. The need for thin packages with memory, APU, modem and analog all packed in one requires each individual layer thickness to have exacting specifications. In this work we concentrate on the challenging task of measuring epoxy mold compound (EMC) thickness distribution across the wafer. We will present how an optical sensor based on spectral coherence interferometry (SCI) can be utilized to collect critical measurements related to mold thickness, uniformity and height information between bumps and the mold surface. SCI provides an optical, non-destructive, high-throughput solution to measure mold thickness and surface warpage simultaneously. This is done by utilizing a sensor with high numerical aperture (NA) which enables one to measure layers and surfaces of mold materials despite the usual measurement constraints introduced from high roughness values, high internal scattering, and severe wafer warpage. By adding a bottom sensor in a so called twin-configuration, further simultaneous data collection is possible.