Table 2.

A summary of salient characteristics of polymer, inorganic, multilayer, and composite barrier materials evaluated for flexible electronic applications.

Material	Thickness [μm]	Fabrication Method	WVTRa) [g m−2 day−1]		Accelerated Lifetime Test		Failure Mechanism	Refs
Polymer Films
Parylene C	3–4.5	CVDb)		>4 year at 37°C		Defects (Cracks, pinholes), Delamination		[454,455]
Polyimide PI2611	9	Spin-coat	6	-		Defects (cracks, pinholes)		[456]
Silicone MED6–6606	12	Spin-coat	7	-		High Moisture Diffusivity		[456]
Liquid Crystal Polymer	25	Thermo-press	-	>300 days at 75°C		Diffusivity, Delamination		[454]
Inorganic Thin Films
t-SiO2	0.1	Thermal growth	2E-8	22 days at 70°C		Hydrolytic Degradation (15 nm/year @ 37°C), ionic diffusion		[436,457]
SiO2	0.1	PECVDc)	0.1 (double-side)	-		Hydrolytic Degradation, Defects		[458]
SiNx (Si3N4)	0.43	High Freq. PECVD	4.39E-04	-		Hydrolytic Degradation (18.3 nm/day @ 87°C)		[459,460]
	0.01–0.04	PEALDd)	Order of 1e-6	-				[461]
	0.2	LPCVD	-	2 days at 96°C		Hydrolytic Degradation (0.3 nm day−1), defects (pinholes)		[447]
Al2O3	0.025	PEALD	1.7E-05	-		Hydrolytic Degradation		[462]
Inorganic Multilayers
SiO2/SiNx	0.1/0.2	Thermal growth/LPCVDe)	-	16 years at 37°C				[447]
t-SiO2/HfO2	0.1/0.1	Thermal growth/ALD		>40 years at 37°C		HfO2: Pinhole Defects		[463]
Al2O3/TiO2 Nanolaminate	0.003, 12 alternating layers 1.8/0.75Å	PEALD	1.81E-04	-				[464]
Al2O3/ZrO2	0.03	ALD	2.00E-04	-				[465]
Composite Multilayers
SiNx-PMMA-SiNx	0.05/0.3/0.05	PECVD/Spin-coat/PECVD	8.00E-04	-				[466]
SiNx-Parylene C	0.1	PECVD/Vacuum Deposition	1.00E-02	-				[467]
Parylene C/HfO2/t-SiO2	0.05/0.05/0.1	CVD/ALD/thermal		13 days at 95°C				[450]
Al2O3/Parylene C	0.05/6	PEALD/CVD		>3 years at 37°C				[468]

^a)WVTR- water vapor transmission rate;

^b)CVD- chemical vapor deposition;

^c)PECVD- plasma-enhanced CVD;

^d)PEALD- plasma enhanced atomic layer deposition;

^e)LPCVD- low-pressure CVD