An experimental fracture mechanics study of a strong interface: The silicon/glass anodic bond

Abstract

The fracture behavior of the silicon/Pyrex glass anodic bond was investigated using the methods of linear elastic bimaterial fracture mechanics. Due to the high bond strength, interfacial cracks were invariably observed to kink away from the interface into the more compliant glass under approximately mode I remote tensile loading. Kink angles measured by profilometry increased from 14 to 28°as bonding temperature increased from 300 to 450 °C. A regime of stable cracking accompanied penetration of cracks into the glass, with maximum load and corresponding fracture toughness measurement occurring at a location significantly removed from the interface. Approximately mode I, near-interface, plane-strain fracture toughness values (KIC) measured by rising load testing of chevron-notched and straight-thru-cracked compact-tension specimens increased from 0.63 to 0.68 MPa-m1/2 and 0.66 to 0.75 MPa-m1/2, respectively, as bonding temperature increased from 300 to 450 °C. In addition, XPS measurements revealed a sodium depletion zone of decreasing size and depletion magnitude with increasing bonding temperature over the same range. The near-interface region of the glass also experiences compressive residual stresses which decrease linearly with distance from the interface according to linear elastic computations. These stresses increase in magnitude with increasing bonding temperature due to enhanced differential thermal contraction upon cooling to room temperature. It is proposed that the trends in toughness and in kink angle with bonding temperature can be at least partially accounted for by variation of crack-tip shielding with compressive residual stress magnitude, the effects of interfacial. crack-tip shear stresses induced by the thermal mismatch, and by an increase in Young's modulus of the near-interface glass accompanying sodium depletion.

Si-to-Si wafer bonding using evaporated glass

“…We did not observe a relation between bond strength and bonding temperature as reported in [6,7] for bonding of Si to bulk Pyrex. As reported in [7], by raising the bonding temperature from 300°C to 450"C, the bond strength increases and reaches the strength of the Pyrex glass substrate. Failure of the bond then occurs when the bulk glass fractures [7,8].…”

“…As reported in [7], by raising the bonding temperature from 300°C to 450"C, the bond strength increases and reaches the strength of the Pyrex glass substrate. Failure of the bond then occurs when the bulk glass fractures [7,8]. In general, the strength of the anodic bond using evaporated glass (> 30 N/mm2) is greater than a bond where sputtered glass [2] or bulk glass [6,8] Line Width (pm) Figure 4: Bond strength versus line width for various bonding temperatures (same data as in Fig.…”

Factors influencing stresses and movements in continuously reinforced concrete pavements – A review

“…In other words, this movement can be analyzed using an interfacial fracture model. The process of crack initiation and propagation at the interface of two dissimilar materials (He & Hutchinson, 1989;Hurd et al, 1995;Martin et al, 2001;Evans et al, 1990;Ayatollahi et al, 2010a;Mirsayar, 2014a;Campilho et al, 2011;Álvarez et al, 2014; and in different engineering materials (Arabi et al,74 2013; Ayatollahi et al, 2010bAyatollahi et al, , 2013Mirsayar, 2013Mirsayar, , 2014bMirsayar, ,c, 2015aMirsayar, ,b, 2017Mousavi & Aliha 2016;Mohammad Aliha et al 2017;Mirsayar et al, , 2017aMirsayar & Park, 2015Mirsayar & Takabi, 2016;Razmi & Mirsayar, 2017) has widely been studied in the past. Depending on the bond strength, the mechanism of interfacial crack propagation can be classified into two types: strong interfaces, and weak interfaces.…”

“…He and Hutchinson (1989), presented an energy based framework for crack propagation at the interface of two dissimilar elastic solids. Hurd et al (1995) studied the mechanism of fracture at the strong interface of silicon and glass. They measured the mode I fracture toughness and kinking angles using a compact tension test specimen.…”

Mixed-mode interface toughness of wafer-level Cu–Cu bonds using asymmetric chevron test

“…The interface toughness, which is measured using fracture mechanics specimens, provides a direct measure of interfacial adhesion and is less sensitive to details of the specimen and, therefore, is a key quantity of interest. Common mechanical testing methods for quantitative interface toughness characterization include double-cantilever beam (DCB) (Maszara et al, 1988), four-point bend (Charalambides et al, 1989), and Mode I chevron tests (Hurd et al, 1995;Bagdahn et al, 2001).…”