Improving Releasability of Mold Materials for IC Encapsulation Using Epoxy Compounds

The effect of dopants such as zirconium and nitrogen on the releasability of Y2O3-based ceramics from molds was investigated for integrated circuit packaging using epoxy molding compounds (EMCs). Co-doping of these elements was carried out by annealing the surfaces of 5mol% ZrO2-Y2O3 samples under a N2 flow at 1100-1300 °C, resulting in concentration of nitrogen near the surfaces of the samples. The adhesion strength was minimized by exposure at about 1200-1250 °C, which was less than half the value for the undoped Y2O3. The co-doping remarkably decreased the polar part of the surface energy and consequently hydrophobicity of the ceramic surfaces increased. The excellent releasability characteristics were likely related to the depression of dissociative adsorption of water molecules, which are considered to act as active sites for the adhesion of EMCs.