Study on Narrow Tube Inner Coating Method by Harmonic ECR Plasma

针对窄管内表面涂层，研究了微等离子体在磁场作用下的脉冲同轴溅射工艺，特别是二次谐波电子回旋共振（ECR）等离子体。电子在二次谐波ECR下的共振约束导致了有趣的微等离子体特性：与ECR条件相比，电子密度更高，等离子体电位更低，电子温度更低，有效功率吸收更低。通过对目标离子电流和电压随时间变化的详细研究，我们发现了脉冲偏置电压和间隙长度的选择规律。测量的目标离子电流为均匀型，离子电流随目标偏置电压的增大而减小。护套宽度的扩大可以认为是这一原因。当对均匀型和镜面型进行比较时，可以了解到离子电流密度的趋势是相同的。但离子电流密度高于均匀型离子电流密度。认为镜面型离子电流密度的增加是由于镜面效应减少了轴向电子损失引起的。由此可知，等离子体密度高于均匀型等离子体密度。结果，我们成功地利用Xe气体在内径为1mm的绝缘窄管的内表面溅射镀上了Au膜。利用扫描镜式磁场对40mm长的窄管进行了内涂覆。

For the inner surface coating of narrow tubes, we have investigated pulsed coaxial sputtering process with the micro plasmas in a magnetic field, especially, the 2nd harmonic electron cyclotron resonance (ECR) plasmas. Resonant confinement of electrons at the 2nd harmonic ECR leads to interesting micro plasma characteristics: the higher electron density, the lower plasma potential, the lower electron temperature and the effective power absorption compared with ECR condition.As a result of detailed investigation of temporal evolutions of the target ion current and voltage, we found that the selection rule of pulse bias voltage and gap length. The target ion current was measured at uniform type, and the ion current is decreased with increasing the target bias voltage. Expansion of a sheath width can be considered as this reason. When the uniform type and the mirror type are compared, it is understood that the tendency to the ion current density was the same. However, the ion current density was higher than that of uniform type one. It is considered that the increase of ion current density in mirror-type is caused by decreased axial electron loss by mirror effect. From this result, it is understood that plasma density was higher than that of uniform type one.As a result, we have succeeded in sputter coating of Au films onto the inner surface of insulated narrow tube with 1mm inner diameter by using Xe gas. And it was performed that inner coating of narrow tube with 40mm length by using scanning-mirror-type magnetic field.