Underlying Thinning Mechanisms of Cu/Amorphous SiO₂ Heterostructure in Through Glass Via Wafer from an Atomic Perspective

Through glass via (TGV) interconnect structure serves an essential part in 3D advanced packaging technology. The Cu/amorphous SiO2 (a-SiO2) heterostructure is an important component in the TGV wafer. Atomistic simulations are conducted to explore the thinning mechanisms of the Cu/a-SiO2 heterostructure at various thinning depths. The results show the deformation mechanisms of Cu and a-SiO2 layers in thinning are plastic flow and densification, respectively, and the atomic densification phenomenon in a-SiO2 is strongly associated with the formation of the 5-coordination structure. There is an obvious von Mises stress concentration in the transition region composed of diffused atoms of Cu and a-SiO2. Atoms near the contact area between the abrasive and workpiece are subjected to higher stresses, and the high-stress areas become larger with increasing thinning depth. Atomic strain maps suggest that large thinning depths are more likely to induce severe plastic deformation of the workpiece. The appearance and annihilation of BCC structures in the Cu layer correspond to the increase and decrease of the normal force. The Cu/a-SiO2 heterointerface does not exhibit desirable thermal resistance properties in heat transfer due to atomic diffusion. These results may offer crucial theoretical guidelines for the manufacturing of the TGV wafer.