磁控溅射CuO-TFT的制备工艺及性能研究

发布时间：2018-02-22 01:38

  本文关键词： p型半导体氧化物 磁控溅射 Cu_xO薄膜 薄膜晶体管(TFT)　出处：《郑州大学》2017年硕士论文　论文类型：学位论文

【摘要】：21世纪以来,氧化物薄膜晶体管的研究和应用取得了很大的进展。其中n-TFT由于迁移率较高,在可见光区光透过率较高和可低温制备等优点已经广泛应用于液晶显示器件的制备,而p型氧化物材料较少且光电性能较差,严重阻碍了互补型金属氧化物的研究进展,因此非常有必要对p型半导体氧化物进行研究。为了制备出性能较好的p型薄膜晶体管,本文着重对CuO-TFT的磁控溅射制备工艺和器件的性能进行研究,文章的主要内容包括以下几个部分:本文采用射频磁控溅射法,以金属Cu为靶材,普通玻璃为衬底,在不同的氧分压条件下镀膜,经过不同温度的退火处理后分别进行一系列的表征分析。XRD和XPS结果表明随着氧分压的增大,薄膜中的Cu逐渐被氧化,氧分压为3%时薄膜为纯相Cu_2O,3%以下的薄膜中含有Cu,3%以上则被氧化为CuO;随着退火温度的升高,薄膜中晶体的结晶质量变好,晶粒尺寸增大;100 nm以下的Cu_xO薄膜在可见光波段的透过率均超过70%;不同工艺制备的薄膜的光学带系宽度都在1.9 V~2.6 V之间;室温下制得薄膜的载流子迁移率随氧分压的增大而增大,退火后载流子迁移率最大提升到8.433 cm2/Vs,载流子浓度最低可以降低到2.873×1013 cm-3。通过比较不同工艺条件下制备的薄膜的性能,确定两种CuO薄膜的最佳制备工艺分别为:(1)本底真空度5×10~(-7) mbar,工作压力3×10~(-3) mbar,射频功率60 W,氧分压3%,沉积时间1 min,600℃空气中退火处理10 h。(2)本底真空度5×10~(-7) mbar,工作压力3×10~(-3) mbar,射频功率60 W,氧分压7%,沉积时间3min,600℃空气中退火处理10 h。用以上两种工艺途径制得的CuO作为有源层制备CuO-TFT器件,分析有源层制备工艺对TFT性能的影响。进一步地,为了分析不同工艺条件对TFT性能的影响,本文采用错排型底栅极(S-BG)结构制备出“Si-SiO_2-CuO-Al”薄膜晶体管器件,其中CuO薄膜分别采用上述两种工艺制得。两个CuO-TFT器件都是典型的p型沟道增强型TFT器件,都具有良好的栅压调控性能,器件都有较为明显的饱和性。其中用上文(1)条件制备的CuO作为有源层的TFT器件电学性能较好,其场效应迁移率为0.32 cm2/Vs、开关电流比为3.0×102、阈值电压为-9 V、亚阈值摆幅约为5.4 V/dec、界面态密度为1.4×1012 cm-2。总体来看,两个TFT器件的电学性能并不理想,这可能是因为在TFT器件有源层和绝缘层界面处存在较高密度的空穴陷阱态。最后,对CuO-TFT转移特性曲线进行了正反向扫描测试和受环境影响的测试,CuO-TFT经过正反向扫描后其转移特性曲线产生了1 V左右的滞回电压。在大气中放置一段时间后,TFT转移特性曲线整体向上漂移,关态电流明显增大,同时阈值电压发生负向偏移。而且放置时间越长,漏电流增大越明显。
[Abstract]:Since 21th century, great progress has been made in the research and application of oxide thin film transistors, in which n-TFT has been widely used in the fabrication of liquid crystal display devices due to its high mobility, high optical transmittance and low temperature fabrication in the visible region. However, there are few p-type oxide materials and poor optoelectronic properties, which seriously hinder the research progress of complementary metal oxides, so it is necessary to study p-type semiconductor oxides. In order to prepare p-type thin film transistors with better performance, In this paper, the preparation technology of CuO-TFT magnetron sputtering and the properties of the devices are studied. The main contents of this paper are as follows: in this paper, the RF magnetron sputtering method is used, the metal Cu is used as the target material, the common glass is used as the substrate, After annealing at different temperatures under different oxygen partial pressure conditions, a series of characterization analysis and XPS results showed that Cu in the film was oxidized gradually with the increase of oxygen partial pressure. When the oxygen partial pressure is 3, the films with pure phase Cu _ 2O _ 3% or less are oxidized to CuO by more than 3% Cu _ 2O _ 3. With the increase of annealing temperature, the crystal quality of the films becomes better. The transmittance of Cu_xO films below 100nm is higher than 70nm, the width of optical band system is between 1.9V and 2.6V. the carrier mobility of the films increases with the increase of oxygen partial pressure at room temperature, and the optical band width of the films is between 1.9V and 2.6V. at room temperature, the carrier mobility of the films increases with the increase of the oxygen partial pressure, and the optical band width of the films is between 1.9V and 2.6V. After annealing, the maximum carrier mobility is increased to 8.433 cm ~ 2 / V _ s, and the lowest carrier concentration can be reduced to 2.873 脳 10 ~ (13) cm ~ (-3). The optimum preparation conditions of the two CuO films were determined as follows: 1) background vacuum 5 脳 10 ~ (-1) m ~ (-1), working pressure 3 脳 10 ~ (-1) m ~ (-1), RF power 60 W, oxygen partial pressure 3 W, deposition time 1 min ~ 600 鈩，

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