Abstract: This paper attempts to analyze and characterize the dielectric properties of the grid insulation layer of TFT devices, and establish the relationship between the dielectric loss of the dielectric layer and the compressive strength and electrical properties of TFT. Firstly, the MIS capacitor composed of gate, gate insulator and Si was prepared, and the optimum test parameter combination was optimized. Then the dielectric loss and breakdown voltage of the capacitor are tested to analyze the relationship between dielectric loss and compressive strength. Then, based on the preparation process of MIS capacitor, the TFT device was prepared and the post-TFT transfer curve was tested, and the relationship between dielectric loss and Ion of TFT open-state current was analyzed. The results show that the dielectric loss is negatively correlated with the compressive strength. The dielectric loss increases from 0.03% to 0.40%, and the breakdown voltage decreases from 334V to 300V, and the Ion decreases by 3.99uA→3.48uA. Temperature, frequency and humidity will all affect the dielectric loss measurement. This paper defines the optimal combination of measurement parameters and develops a set of methods to characterize the dielectric loss of TFT grid insulation layer. The dielectric loss of the gate insulation layer is related to the compressive strength and electrical properties of the TFT. The dielectric loss of the dielectric layer can be used to characterize the TFT properties in multiple dimensions. This study provides reference for performance analysis, characterization and optimization of TFT.

Key words: Dielectric loss, Breakdown voltage, TFT characteristics, Gate insulation layer, TFT compressive strength, MIM device