Metal-oxide semiconductor TFTs are widely investigated for their remarkable performance in high-end applications, e.g. high resolution and AMOLED. However, reliability issues such as degradation under gate bias temperature stress have not been solved sufficiently. From an industrial point of view, device reliability is one of the most important factors. For this challenge, a suitable passivation has a big influence.
The passivation material for the metal-oxide semiconductor (e.g. IGZO, IZO, IGO, etc.) usually cited in literature is silicon-oxide (SiOx) or silicon-nitride (SiNx). The growth of SiOx- and SiNx-films applied via chemical vapor deposition (CVD) is generally known to incorporate significant concentrations of hydrogen into the underlying metal-oxide semiconductor layer. This affects the electrical properties and device reliability to a significant extent.
Evonik is developing, under the brand iXsenic PV, unique electronic-grade hybrid polymers with photosensitive characteristics and a hydrogen-free passivation layer for sputtered and solution-processed metal-oxide semiconductor. Our photosensitive hybrid polymers have significant advantages compared to other photoresists:
High transparency in visible range
Low k-dielectric material with low leakage current and high breakdown voltage
Low process temperature
High thermal stability
High chemical resistance (especially oxalic acid and aluminum acid)
Low water-vapor transmission rate
Our electronic-grade hybrid polymers are produced under strictly controlled conditions and are systematically tested to ensure highest performance in critical applications and batch-to-batch consistency. They offer a big advantage since they can be tuned to both, their intrinsic material properties and their capability to be processed by numerous process and patterning techniques. Our hybrid polymers are already widely used in applications as functional films for interlayer dielectrics, etch-stop layer and barrier layer for plastic substrates. Furthermore, Evonik is capable of synthesizing a specific functional product based on customer requirements, too.