Suzuki Atsushi, Nonaka Hidehiko
National Institute of Advanced Industrial Science and Technology, AIST, Tsukuba Central-2, 1-1-1 Umezono, Tsukuba, Ibaraki 305-8568, Japan.
Rev Sci Instrum. 2009 Sep;80(9):095109. doi: 10.1063/1.3223345.
A simple method using a quartz sensor (Q-sensor) was developed to observe gas composition changes in radio frequency (rf) plasmas. The output depends on the gases' absolute pressure, molecular weight, and viscosity. The pressure-normalized quartz sensor output depends only on the molecular weight and viscosity of the gas. Consequently, gas composition changes can be detected in the plasmas if a sensor can be used in the plasmas. Influences imparted by the plasmas on the sensor, such as those by reactive particles (e.g., radicals and ions), excited species, electrons, temperature, and electric potentials during measurements were investigated to test the applicability of this quartz sensor measurement to plasma. The Q-sensor measurement results for rf plasmas with argon, hydrogen, and their mixtures are reproducible, demonstrating that the Q-sensor measurement is applicable for plasmas. In this work, pressure- and temperature-normalized Q-sensor output (NQO) were used to obtain the gas composition information of plasma. Temperature-normalization of the Q-sensor output enabled quartz sensor measurements near plasma electrodes, where the quartz sensor temperature increases. The changes in NQO agreed with results obtained by gas analysis using a quadrupole mass spectrometer. Results confirmed that the change in NQO is mainly attributable to changes in the densities and kinds of gas molecules in the plasma gas phase, not by other extrinsic influences of plasma. For argon, hydrogen, and argon-hydrogen plasmas, these changes correspond to reduction in nitrogen, production of carbon monoxide, and dissociation of hydrogen molecules, respectively. These changes in NQO qualitatively and somewhat quantitatively agreed with results obtained using gas analysis, indicting that the measurement has a potential application to obtain the gas composition in plasmas without disturbing industrial plasma processes.
开发了一种使用石英传感器（Q传感器）的简单方法来观察射频（rf）等离子体中的气体成分变化。其输出取决于气体的绝对压力、分子量和粘度。经压力归一化的石英传感器输出仅取决于气体的分子量和粘度。因此，如果能将传感器用于等离子体中，就可以检测到等离子体中的气体成分变化。研究了等离子体在测量过程中对传感器施加的影响，例如反应性粒子（如自由基和离子）、激发态物种、电子、温度和电势等的影响，以测试这种石英传感器测量方法对等离子体的适用性。对含有氩气、氢气及其混合物的射频等离子体的Q传感器测量结果具有可重复性，表明Q传感器测量适用于等离子体。在这项工作中，使用经压力和温度归一化的Q传感器输出（NQO）来获取等离子体的气体成分信息。对Q传感器输出进行温度归一化，使得能够在石英传感器温度升高的等离子体电极附近进行石英传感器测量。NQO的变化与使用四极质谱仪进行气体分析得到的结果一致。结果证实，NQO的变化主要归因于等离子体气相中气体分子密度和种类的变化，而非等离子体的其他外在影响。对于氩气、氢气和氩 - 氢等离子体，这些变化分别对应于氮气的减少、一氧化碳的产生和氢分子的解离。NQO的这些变化在定性和一定程度上的定量方面与使用气体分析得到的结果一致，表明该测量方法在不干扰工业等离子体过程的情况下，具有获取等离子体中气体成分的潜在应用价值。
