Table 2.

Summary of interfacial fracture energy from literature and this study.

Interface type	Fracture energy (J/m2)	Measuring technique	Sample description and literature source
Al/PI	(2.40 ± 0.36) × 103	ADCB	E-VUV-assisted bonding at 150 °C for 10 min; no post-annealing; this study.
Al/Al	2.40	Theoretical calculation	Thermodynamic work of cohesion; DFT calculation; (111) plane59.
	11.92 ± 1.86	DCB	Direct bonding at 200 °C for 10 min after Ar-FAB treatment; no post-annealing; this study.
Al2O3/Al2O3	7.42–7.96	Theoretical calculation	Thermodynamic work of cohesion; ab initio calculation; unrelaxed α-Al2O3 basal plane60.
	4.14 ± 0.24	DCB	ALD growth on Si wafer; room-temperature direct bonding after plasma activation, and subsequently annealed at 200 °C for 2 h44,61.
PI/PI	7.44 × 10−2	Theoretical calculation	Thermodynamic work of cohesion; Dupont Kapton (PMDA-ODA)62.
	(3.31 ± 0.64) × 10−3	DCB	Direct bonding at 150 °C for 10 min after water-vapor-assisted VUV treatment; no post-annealing; this study.
Silicon wafer bonding	4.26	Theoretical calculation	Thermodynamic work of cohesion; (100) plane63.
	~4.50	DCB	Direct bonding via sequential plasma activation; room-temperature storage for 24 h44,64.
	2.20–2.60	DCB	Room-temperature direct bonding after standard RCA cleaning; hydrophilic surface; post-annealing at 150 °C for 20 h44,65.
	3.80–4.20	DCB	Room-temperature direct bonding after TMOS modification; post-annealing at 150 °C for 20 h44,65.
	4.00–4.60	DCB	Direct bonding at 1400 °C for 10 min after sprayed with deionized water44,58.
	2.50–3.00	DCB	Direct bonding at 1200 °C for 10 min after soaked in NH4OH44,58.

Thermodynamic work of cohesion⁶⁶ (W_c) was calculated based on W_c = 2γ, where γ is the surface energy of solids.