高性能输运非晶半导体氧化物沟道及TFTs性能研究

In comparison with the contemporary competing techniques such as amorphous silicon thin-film transistors (TFTs) or low-temperature polycrystalline silicon (LTPS) TFTs, IGZO-TFTs, as one of the typical amorphous oxide semiconductor-based TFTs, possess good processing compatibility and balanced cost-performance ratio. However, the exploration of new n-type amorphous oxide channel-based TFTs, not limited by IGZO-TFTs but comparable to the performance of LTPS-TFTs, is still a challenging academic issue. To this end, this project will focus on developing Zinc-free InGaZnO-like InGaCdO-based TFTs with high field-effect mobility and robust drive current by means of material innovation. The successful implementation of this project is definitely based on obtaining InGaCdO material with competitive transport property, finding out the variations of the band gap, uncovering the electron effective mass and its relation to the sound transport property, revealing the carrier conduction mechanism, and finally constructing InGaCdO-TFTs with high field-effect mobility approaching that of LTPS-TFTs. This project is innovative, represented by the exploration of novel n-type channel material and the integrated solutions to understand the origin of the material properties. It is expected that the successful implementation of the project would provide technological support and theoretical basis whether for the display-related industry upgrading or for the research community, and then pave the way for amorphous oxide semiconductor-based driving circuit used in the next-generation displays.

跟非晶硅或低温多晶硅(LTPS) TFTs相比较，IGZO-TFTs制程跟现有主流工艺兼容，性能价格均衡。然而，开发不拘泥于IGZO、性能上接近LTPS 的新型n型氧化物及薄膜晶体管是非常具有挑战性的学术课题。基于此，本项目将通过有源层的材料创新手段，研发不含Zn元素的类IGZO新型非晶氧化物沟道材料InGaCdO，研制高场效应迁移率、高驱动电流特性的n型薄膜晶体管原型器件。明晰InGaCdO带隙变化趋势，阐明其电子有效质量跟高输运特性之间的关联关系，澄清载流子的输运机理，构筑类LTPS高性能输运特性的薄膜晶体管。本项目在新材料前瞻性研究和表征、分析方法的集成等方面体现了创新性。通过本项目的实施，有望为基础研究提供实验数据和理论依据，为我国显示行业的产业技术升级提供技术支撑，从而有助于推动氧化物半导体驱动电路的研发应用进程。

超高分辨率显示、3D显示、虚拟现实技术发展非常迅猛，它们对显示相关的技术，尤其对核心驱动器件薄膜晶体管的迁移率提出了更高要求。本项目设计了高迁移率InGaCdO沟道材料，采用溶液旋涂法和磁控溅射法分别制备了InGaCdO薄膜及薄膜晶体管，研究了材料组分和关键工艺参数对其性能的影响规律与机理。.首先，利用溶液法易于调控多元材料组分的特点，制备了系列不同Cd比率的InGaCdxO薄膜，系统了研究了Cd比率对薄膜结构、形貌、光学和电学性能以及对应晶体管器件性能的影响规律与机理。当Cd比率x从0增加到8时，薄膜均表现为直接带隙半导体特征，带隙从3.4 eV持续降低至2.4 eV；当Cd比率x在0.75-1.5之间时，薄膜具有非晶/纳米晶结构、光滑的表面形貌、较宽的直接光学带隙（>3.1 eV），最优晶体管器件的饱和区场效应迁移率>10 cm2/Vs，优于同条件下溶液法InGaZnO薄膜晶体管的报道值。.其次，在溶液法研究结果的基础上，选用了优化比率的InCaCdO靶材，利用射频磁控溅射技术，制备了系列薄膜晶体管，分别研究了沟道膜厚、Ar/O2比、源漏电极材料等工艺参数对器件性能的影响规律；初步掌握了器件优化制备的工艺。优化后晶体管的饱和场效应迁移率~30 cm2/Vs，亚阈值摆幅~0.23 V/decade，开关比~1.1×10^10。.最后，深入研究了优化器件的偏压稳定性，正、负偏压下阈值电压漂移量均小于1.5 V，表现出了较好的偏压稳定性。