Production of Large-Diameter-Low Electron Temperature ECR Plasma

工业上需要300 mm直径的等离子体源作为下一代半导体加工等离子体源，其在几毫托下操作。电子回旋共振等离子体由于能在低气压下产生高密度等离子体而受到广泛关注。然而，通常情况下，ECR等离子体很难产生大直径的等离子体，即ECR等离子体的均匀性强烈地依赖于磁场梯度、气压、微波功率等，目前主要采用直径为200 mm的ECR等离子体。此外，充电效应也成为一个需要解决的重要问题。因此，等离子体处理需要大直径低电子温度等离子体。为了实现直径300 mm的ECR等离子体，我们利用900 MHz的TM模和2.45 GHz的TE模，进行了大直径低电子温度ECR等离子体的产生实验<01><10>。主要结果如下：（1）上杂波共振对ECR等离子体的均匀性起着重要的作用。通过控制微波功率，实现了直径为300 mm的均匀等离子体，其中电子密度高于10 μ <11>cm-3<-3>。(2)我们成功地利用磁镜产生了低电子温度等离子体。利用磁镜在狭缝处实现了Te&lt;2 eV的N_2等离子体。利用功率平衡和粒子平衡方程讨论了低电子温度产生的物理机制。(3)提出了一种利用该探针测量负离子浓度的有效方法。(4)我们成功地测量了ECR等离子体中的离子温度与光学发射光谱，提供Ti&lt;0.2 eV。这些结果有助于产生下一代等离子体加工，如半导体加工设备。

A 300 mm diameter plasma source is required from industry as a next generation semiconductor processing plasma source which operates at few mTorr. An electron cyclotron resonance plasma has paid much attention because it provides a high density plasma at low pressure. However, usually it is hard to produce a large diameter plasma with ECR, that is, the uniformity of ECR plasma strongly depends on magnetic field gradient, pressure, microwave powers and so on. Now a 200 mm diameter ECR plasma is mainly used. Furthermore, charging effect also becomes an important problem to solve. Thus, a large diameter-low electron temperature plasma is needed for plasma processing. Here, in order to realize a 300 mm diameter ECR plasma, we carried out the experiments on a large diameter-low electron temperature ECR plasma production using TM_<01> mode of 900 MHz as well as TE_<10> mode of 2.45 GHz,. The main results are as follows :(1) The upper hybrid wave resonance played an important role in ECR plasma uniformity. A uniform plasma of 300 mm in diameter was realized by controlling the microwave power, where the electron density was higher than 10^<11>cm^<-3>.(2) We succeeded in producing a low electron temperature plasma using the magnetic mirror. N_2 plasma with Te<2 eV was realized at the sloat using the magnetic mirror. Furthermore, the physical mechanism for low electron temperature production was discussed using the power and particle balance equations.(3) A powerful method to measure the negative ion density was proposed using the probe.(4) We succeeded in measuring the ion temperature in the ECR plasma with the optical emission spectroscopy, providing Ti<0.2 eV.These results contribute to producing a next generation plasma for plasma processing such as semiconductor processing devices.