栅极绝缘层工艺优化对氢化非晶硅TFT特性的改善

Growth and Optimization of Hydrogenated Amorphous Si Films for Thin Film Transistor Fabrication

在TFT小型化趋势下,需要进一步提高氢化非晶硅薄膜晶体管的TFT特性,尤其是开态电流特性。本文结合生产实际,阐述了工艺上改善氢化非晶硅开态电流特性的方法,包括提高单位面积栅绝缘层电容和改善载流子迁移率。实验结果表明,降低高速沉积栅绝缘层的气压和厚度,能有效提高单位面积栅极绝缘层电容。增加低速沉积栅绝缘层的Si/N比及优化氢等离子体处理工艺,可以有效改善载流子迁移率。

The hydrogenated amorphous Si（a-Si：H） films were grown by plasma enhanced chemical vapor deposition（PECVD） on NSi substrate,to be used in fabricating thin film transistor（TFT）.The impacts of deposition conditions,such as deposition rate,film thickness and substrate temperature,on interfacial microstructures and properties of a-Si：H films as gate insulator material were evaluated.The results show that a thinner gate insulator layer,grown at a high deposition rate and a lower pressure,displays an improved gate capacitance per unit area.We found that for the gate insulator,grown at a low deposition rate,an increase of Si/N ratio and the optimization of hydrogen plasma resulted in a higher carrier mobility.