Critical adhesion energy determination of low K dielectrics using four point bending

Abstract

The critical adhesion energies of BCB/PECVD SiO2, BCB (with AP)/Si, porous MSQ/Ta and PaN pore sealed MSQ/Ta were determined using four point bending. The interfacial adhesion energy of BCB/PECVD SiO2 is estimated to be 5 ± 1.7 Jm-2, BCB (with adhesion promoter)/Si was 21 ± 5 Jm-2. The adhesion appeared to strongly depend on sample width for small widths (2.5-5 mm). Wider samples were prepared (5-11 mm) and there was less sample width dependence for this set. The adhesion energy of wider samples was found to be equal to that of the thin samples but the standard deviation is lower (1 Jm-2). The Gc of pooous MSQ/Ta is estimated to be 1.3 Jm-2 ± 0.2 Jm-2 and the Gc of Parylene-N pore sealed MSQ/Ta is estimated to be 2.2 Jm-2 ± 0.6 Jm-2. The pore sealant increases the adhesion of MSQ to Ta, but not high as reported in literature (Gc = 10 Jm-2). there is a Gc dependence on displacement rate for pore sealed MSQ/Ta. This could be due to higher plastic dissipation energy at higher displacement rates.