氨浴法阴离子掺杂有源层的氧化物TFT缺陷态与稳定性研究

Zinc oxide (ZnO)-based oxide thin-film transistor (TFT) is one of the key technologies in microelectronics, especially in the field of display engineering. The stability of oxide TFT is an important research topic. As the radius and electronegativity of N ion is close to that of O, doping with N ions can effectively inhibit the oxygen vacancy in the ZnO film. By replacing the inactive oxygen, the defects can thus be suppressed. The anion doping will cause the change of valence band rather than conduction band, so it will improve the stability of devices without decreasing the mobility. In this project, an efficient doping technology of N anion into ZnO will be proposed and applied to the active layer of TFTs. In the micro environment of ammonia bath, doping N anions into ZnO can be realized by molecular diffusion mechanism. The effect of N anion introduction on film defects will be investigated through XPS and CV detection. In addition, the mechanism of defect inhibiting through N doping will be analyzed from the atomic level using the bond valence theory. The influences of the intensity and duration of the stress field on the uniformity of the films will be investigated for realizing uniformly N doping into the films by adjusting the electric field and temperature field. The intrinsic mechanism of N doping on device stability will be further elucidated. The density of states of ZnO TFT will be determined by online temperature stress detection, and the correlation model between the state density and the stability will be established.

氧化锌基氧化物薄膜晶体管是微电子特别是显示工程领域的核心技术之一，其稳定性是一个重要研究课题。利用N离子半径及电负性接近O，能够对ZnO薄膜中的氧空位有效抑制及对不活跃氧的取代实现对缺陷的抑制。阴离子掺杂会引起价带而不是导带的变化，在不损失器件迁移率的情况下提高器件稳定性。本项目提出一种实现高效N离子阴性掺杂ZnO的途径，并应用于薄膜晶体管有源层的研究。在氨浴微环境下，利用分子扩散机制实现N离子对ZnO的掺杂，通过XPS、CV检测，研究N的引入对于薄膜缺陷的影响，利用键价理论，从原子层面研究N掺杂对于薄膜缺陷抑制的原理，探索缺陷抑制的方法。通过电场、温度场作用实现N元素在薄膜中的均一化掺杂，研究应力场强度、时间等对于薄膜均一化的影响规律。深入探讨N掺杂对于器件稳定性的内在机制，通过在线温度应力检测确定器件态密度，探明缺陷密度-态密度-稳定性的内在联系机制，建立态密度与稳定性之间的关联模型。

项目针对科学研究和量产过程中的晶体管的制造和稳定性问题进行了系统的研究，在研究过程中和液化空气集团合作开发的高质量介电层有很强的实用价值，对于量产有重要的借鉴意义。开发了氨浴法实现阴离子N 掺杂ZnO TFT 的新技术，成功通过温度场诱致下N均一化掺杂氧化锌；实现了高迁移率的TFT器件，最高达36cmV-1S-1，开关比大于107，偏压应力作用下器件阈值电压飘移0.18 V。通过温度应力在线测试方法，建立了态密度定量计算的模型，揭示了器件缺陷态与稳定性的内在机制。发表SCI论文9篇，会议论文1篇。其中二区以上6篇，包含了微电子器件领域权威期刊IEEE EDL 1篇，IEEE TED 3篇，第一发明人授权发明专利2项。项目执行期为3年：整个研究过程中，按预期计划进行，并取得预期研究成果。