Spatiotemporal optical emission spectroscopy of atmospheric VHF plasma process

研究了电容耦合大气甚高频氦等离子体。等离子体腔室由腔腔谐振腔和真空腔组成。VIIF电能被放大，并通过谐振器传导到真空室。在150 MHz的功率下，在平行板电极之间的1尼米间隙内产生等离子体。利用条纹相机发射光谱对等离子体的时空特征进行了诊断。所得等离子体的时空图像与出现在电极上的VHF电压波形进行了比较。该电压波形作为安装在间隙之间的激光二极管的时间发射曲线被间接观察到。通过对波形的比较，发现等离子体发射发生在负极表面附近。所以大气甚高频等离子体基本上是负辉光。等离子体的颞叶图像估计鞘宽约为30微米。鞘层的等离子体光谱包含了氦亚稳态的强谱线发射。采用388.8Cnm （3^3P*2^3P）线，用空心阴极灯吸收光谱法测定了亚稳数密度。鞘区密度约为1.1 * 10^<14> cm^3。这意味着等离子体的激活区可以在电极，即半导体晶片的表面附近形成。大气VHF等离子体的配置有利于等离子体CVM和大气等离子体CVD工艺。

Capacitively coupled atmospheric VIF(Very High Frequency) helium plasma was investigated. The plasma chamber was consisted of a cavity resonator and vacuum chamber. VIIF electric power was amplified and is conducted to the vacuum chamber via the resonator.The plasma was generated in 1 nun gap between the parallel plate electrodes with 150 MHz electric power. The spatiotemporal characteristics of the plasma was diagnosed by optical emission spectroscopy with streak camera.The resultant spatiotemporal image of the plasma was compared with the exact VHF voltage waveform which appeared on the electrodes. The voltage waveform was indirectry observed as the temporal emission profile of the laser diode which was installed between the gap. As a result of comparison between the waveforms, the plasma emission was occured near the surface of the negative electrode. So the atmospheric VHF plasma was basically negative glow. The sheath width estimated with the spat iotemporal image of the plasma was about 30 micron.The plasma spectrum of the sheath contained the strong line emission from the helium metastables. Use 388.8Cnm (3^3P*2^3P) line, the metastable number density was measured by absorption spectroscopy with hollow cathode lamp. In the sheath region, the density was about 1.1 * 10^<14> cm^3. This means that the activated region of the plasma could be formed near the surface of the electrode, i.e., semiconductor wafer. The disposition of the atmospheric VHF plasma is advantagious in plasma CVM and atmospheric plasma CVD processes.