The interfacial reliability of through-glass vias for 2.5D integrated circuits

Abstract

Purpose Glass is a promising interposer substrate for 2.5 D integration; yet detailed analysis of the interfacial reliability of through-glass vias (TGVs) has been lacking. The purpose of this paper is to investigate the design and material factors responsible for the interfacial delamination in TGVs and identify methods to improve reliability. Design/methodology/approach The interfacial reliability of TGVs is studied both analytically and numerically. An analytical solution is presented to show the dependence of the energy release rate (ERR) for interfacial delamination on the via design and the thermal mismatch strain. Then, finite element analysis (FEA) is used to investigate the influence of detailed design and material factors, including the pitch distance, via aspect ratio, via geometry and the glass and via materials, on the susceptibility to interfacial delamination. Findings ERR for interfacial delamination is directly proportional to the via diameter and the thermal mismatch strain. Thinner wafers with smaller aspect ratios show larger ERRs. Changing the via geometry from a fully filled via to an annular via leads to lower ERR. FEA results also show that certain material combinations have lower thermal mismatch strains, thus less prone to delamination. Practical implications The results and approach presented in this paper can guide the design and development of more reliable 2.5 D glass interposers. Originality/value This paper represents the first attempt to comprehensively evaluate the impact of design and material selection on the interfacial reliability of TGVs.

Thermo-Mechanical Reliability Study of Through Glass Vias in 3D Interconnection

“…Cracks were generated by the existence of radial stress ( ) and shear stress ( ) at the TGV–Cu interface in the preliminary theoretical and FE model investigation [ 12 , 13 , 14 ]. The elastic-plastic yield criterion was used in the analysis.…”

Layout Dependence Stress Investigation in through Glass via Interposer Architecture Using a Submodeling Simulation Technique and a Factorial Design Approach

“…In addition, the failure mechanism and optimization rule of TGV interposer architecture were systemically investigated [ 11 , 12 , 13 , 14 , 15 , 16 , 17 , 18 , 19 ]. Tensile radial and circumferential stresses were attributed to the origin of the circumferential cracks and the formation of radial cracks, respectively [ 11 , 13 , 14 ].…”

“…Different layout designs, such as fully filled via and conformal via, were demonstrated and investigated in terms of their thermomechanical reliability [ 17 ]. Interfacial delamination between glass interposers and Cu-filled TGV was explored, and the corresponding energy release rate was proportional to the via diameter and the thermal mismatch strain, which was highly dependent on the layout design parameters [ 18 ]. A metallization process filled with Ag-paste composite solution was presented, and its effectiveness was compared with that of the general Cu electroplating process; the analytical results revealed that the aforementioned metallization process would introduce different cracking behaviors [ 19 ].…”

Reliability Assessment of Thermocompressed Epoxy Molding Compound through Glass via Interposer Architecture by the Submodeling Simulation Approach

“…To reduce Cu protrusion-induced stress, a conformal-type TGV has been demonstrated, and a fully-filled TGV with considerable copper protrusion during thermal cycling was revealed [ 16 ]. The interfacial energy release rate of the interface between Cu-filled TGV and different glass materials has been investigated through the finite element analysis (FEA) simulation and analytical model [ 17 ]. For different filling materials of TGV, the crack formation mechanism can differ considerably; moreover, radial-type and circumferential-type cracks were found in electroplated Cu-filled TGV and sliver-paste-filled TGV during the heating process in [ 18 ].…”