柔性非晶InGaZnO薄膜晶体管栅绝缘层的研究

Fabrication of Flexible Amorphous InGaZnO Thin Film Transistors with SiO_x/TaO_x Gate Insulators

采用磁控溅射方法,在聚酰亚胺薄膜上室温制备了非晶铟镓锌氧(a-IGZO)柔性薄膜晶体管(TFT)。其中,栅绝缘层选择了不同厚度比例的氧化硅(SiO_x)与氧化坦(TaO_x)薄膜的搭配,对比研究了不同栅绝缘层结构的薄膜特性以及所对应的柔性TFT器件的操作特性和偏压稳定性。实验结果表明,TaO_x的成膜速率明显高于SiO_x;随着TaO_x所占比例的增加,栅绝缘层表面粗糙度降低,介电常数显著提高。以300nm厚TaO_x搭配300nm厚SiO_x为例,栅绝缘层相对介电常数可以达到10,对应的a-IGZOTFT表现出了更高的的开态电流和更低的阈值电压,但是器件漏电流略有增加,正偏压稳定性也会有所下降。

We experimentally addressed the influence of the thickness-ratio of SiOx/TaOxin the gate insulators（ GI） on the properties of the flexible amorphous InGaZnO thin film transistors（ a-IGZO TFTs）,fabricated at room temperature by magnetron sputtering on polyimide（ PI） substrate. The preliminary results show that when it comes to the performance and bias-stress stability of TFTs,the SiOx/TaOxlayers outperformed the conventional SiOxlayer. To be specific,the TaOxlayer grew much faster than the SiOxlayer; as the TaOxthickness increased,the GI dielectric constant increased,accompanied by the decrease of GI surface roughness. For instance,the 300 nm SiOxand 300 nm TaOxlayers increased the relative GI dielectric constant up to 10,resulting in a larger on-current,a lower threshold voltage,a little smaller off-current but a bit worse bias-stress stability of the corresponding a-IGZO TFTs.