In TFTs the gate dielectric or gate insulator is the layer that separates the gate electrode and the semiconductor. To allow high-performance switching of the device, it is necessary to have a gate dielectric that fulfills a whole set of specifications including good coating quality and excellent insulating behavior.

In common displays PECVD silicon nitride (or silicon oxide) is used as gate dielectric. This material achieves the necessary specifications but is deposited in a complex and expensive vacuum process.

Evonik is developing, under our brand iXsenic D, a series of solution-based gate dielectrics that can be deposited without vacuum by using simple techniques like spin coating or slot-die coating. These processes simplify the process flow and help to save time and costs.

Our dielectric linecard is characterized by good processability, especially for large area coating by means of slot-die coating, and it realizes films with thicknesses of 50 – 500 nm, high homogeneity and low surface roughness (Rq < 2 nm). The layers are well known for their low leakage currents, high breakdown fields and good stability under electrical stress.