Superconformal Filling of Through Vias in Glass Interposers

Abstract

The additive tetranitroblue tetrazolium chloride (TNBT) has been applied successfully in this work to superconformal filling (SCF) of through-vias with an aspect ratio (AR) of 6 in glass interposers (TGVs). The TGVs were initially coated with thin conformal Cu using an earlier developed hybrid method. Optimization of plating parameters and bath composition led to SCF of these TGVs in only 3 h at a current density of 2.5 mA/cm2 in a stagnant bath containing 0.88M CuSO4, 40 ppm TNBT, 40 ppm Cl−, 0.1M CH3COOH, and 0.6M Na2SO4. This is the shortest reported filling time for this AR using DC plating and a single-additive system. © 2014 The Electrochemical Society. [DOI: 10.1149/2.0081408eel] All rights reserved.