氧分压对射频溅射制备Zn-Sn-O沟道层的薄膜晶体管器件性能的影响

Effect of oxygen partial pressure on the performance of thin-film transistors devices with Zn-Sn-O channel layer prepared by RF sputtering

摘要:

以锌锡氧化物(ZTO)薄膜作为沟道层,聚甲基丙烯酸甲酯(PMMA)薄膜作为介质层低温(100℃)制备了顶栅共面结构的薄膜晶体管(TFT),并研究了ZTO沟道层成膜过程中氧分压对器件性能的影响。结果表明,ZTO沟道层具有稳定的非晶结构、较高的可见光透明性(在400nm~700nm范围内平均透过率≥89.61%),且增大氧分压有促于其可见光透明性的提升；霍尔测试结果表明增大氧分压(由3.5×10-2^Pa 增大到7.5×10-2^Pa)会降低ZTO电子载流子浓度(由4.73×1015^cm-3^降低到6.11×1012^cm-3⁾,致使基于ZTO沟道层TFT器件的能耗降低(表现为关态电流的降低和耗尽型器件阈值电压的正向移动),此外,增大氧分压还有益于沟道层/介质层界面状态的优化(即亚阈值摆幅减小)。

Abstract:

Thin-film transistors (TFTs) with top-gate and top-contact structure were prepared using zinc-tin-oxide (ZTO) film as the channel layer and polymethyl methacrylate (PMMA) film as the dielectric layer at low temperature (100 ℃), and the effect of oxygen partial pressure on the device performance was investigated during the ZTO channel layer formation process. The results show that ZTO channel layer has stable amorphous structure and high visible light transparency (average transmittance ≥ 89.61% in the range of 400nm~700nm), and increasing the oxygen partial pressure is beneficial to the improvement of visible light transparency; Hall test results show that the oxygen partial pressure is increased (from 3.5× 10-2^Pa to 7.5 × 10-2^{Pa) will re}duce the ZTO electron carrier concentration(from 4.73×1015^cm-3 to 6.11×1012^cm-3⁾, resulting in a reduction in the energy consumption of TFT devices based on ZTO channel layer (shown by the reduction of the off state current and the forward shift of the depletion device threshold voltage). In addition, increasing the oxygen partial pressure is also conducive to the optimization of the channel/dielectric layer interface state (that is, the subthreshold swing is reduced).