Ultra-Fine Pitch RDL (UFPRDL) using Polymer Dual Damascene processing

In this work, we demonstrate a completely functional
$\mathbf{2}\ \boldsymbol{\mu} \mathbf{m}$
pitch RDL with two interconnecting metal layers and discuss results targeting a
$\mathbf{1}\ \boldsymbol{\mu} \mathbf{m}$
pitch. Polymer-based RDL interconnects are a key enabler for advanced packaging utilized for the integration of heterogeneous systems. A growing number of components and increasing bandwidth needs have driven the number of layers and RDL critical dimensions (CD) ever lower [1]–[4]. In addition, areal densities for the vertical via interconnects are demonstrated down to 4 by
$\mathbf{4}\ \boldsymbol{\mu} \mathbf{m}$
, twice the line pitch. Further scaling enables higher IO capabilities overlapping Back End of Line (BEOL) metallization capabilities.