Development of plasma synthesis technology for advanced complex compound materials based on mass-selective momentum control

我们已经开发了新的等离子体加工的实验装置，面向先进的功能氧化物，如ZnO薄膜，应用质量选择性动量控制的基础上的有质动力磁化离子。由频率为ω的局域射频电场产生的有质动力势叠加在样品基片的无碰撞鞘层上。在回旋频率Ω_o（或Ω_<zn>）和Ω_o（或Ω_<zn>）-ω附近分别改变ω，可以控制ZnO的成分和晶体取向。虽然氧化物对载流子浓度起主导作用，而且对工艺压力和温度非常敏感，但这种新方法比传统的溅射方法更能得到氧化物的理论性质，并证明了氧离子对基片的通量抑制和对磁化活性分子离子的有质动力效应。 ...更多信息 这种与质量选择性动量控制有关的现象被应用于合成具有比铟基薄膜更低电阻率的ZnO透明导电薄膜。有质动力的增强，是必要的回旋离子的物种的高选择性，预计将出现通过减速离子的初始速度成正比的等离子体中的电子温度的平方根。为了在等离子体中证实这一点，我们制备了压力为10^ Pa左右的ECR氧等离子体低温等离子体<-2>，并研究了有质动力对电子温度的增强效应。当烘箱温度超过400℃时，在10^ Pa的低压下，O^+、O_2^+和Zn^+离子存在于等离子体中<-2>。蒸汽源可以三维移动，通过原位质谱和/或膜厚度测量来搜索更合适的沉积几何形状。对ZnO透明导电薄膜的电阻率进行了测量，发现当ω接近单电荷氧分子的回旋频率时，厚度为100 nm的ZnO透明导电薄膜的电阻率下降到100 ^<-4>Ωcm。这种现象被认为是由于有质动力引起的氧分子离子的反射。少

We have developed the experimental apparatus of new plasma processing oriented to the advanced functional oxide compounds such as ZnO film, applying the mass-selective momentum control based on the ponderomotive force on the magnetized ions. The ponderomotive potential generated by the localized rf electric field with the frequency ω is superimposed on the collision-less sheath of the sample substrate. Then the composition and crystal orientation of ZnO are expected to be controlled just before the substrate by varying ω near the cyclotron frequency Ω_o (or Ω_<zn>) and Ω_o (orΩ_<zn>)-ω, respectively. Although the oxide dominates the carrier concentration and is very sensitive for process pressure and temperature, this new way could draw more the theoretical properties of the oxide compounds than the conventional sputtering type.The flux depression of oxygen ion upon the substrate has been demonstrated accompanying with the ponderomotive effect on the magnetized reactive molecular ion. … More This phenomenon connecting to mass-selective momentum control is applied to synthesis the ZnO transparent conductive film with lower resistivity comparable to the Indium based film. The enhancement of ponderomotive force, being necessary for high selectivity of cyclotron ion's species, is expected to appear by decelerating ion's initial velocity proportional to the square root of electron temperature in a plasma. To confirm this expectation even in a plasma, we have prepared the low-temperature plasma extracted from ECR oxygen plasma around a pressure of 10^<-2> Pa and investigated the enhancement effect of the ponderomotive force against electron temperature.The mixture plasma source is developed by evaporating zinc into ECR oxygen plasma confined by the axial magnetic field. The O^+, O_2^+, and Zn^+ exist in our plasma at a low pressure of 10^<-2> Pa when oven temperature exceeds around 400℃. The vapor source can move 3-dimensionally, searching the more proper deposition geometry with in-situ mass-spectroscopy and/or film thickness measurement. The resistivity measurement of ZnO transparent conductive film has been performed during the deposition.It is found that the resistivity of film with 〜 100 nm thickness decreases until 〜 10^<-4>Ωcm when ω approaches to the cyclotron frequency for the singly charged oxygen molecular. This phenomenon is considered to be attributed to the reflection of the oxygen molecular ion due to the ponderomotive force. Less