The conventional double-probe technique was improved with a combination of selfpowering and radio-frequency（RF） choking.RF perturbations in dual-frequency capacitively coupled discharge were effectively eliminated,a...The conventional double-probe technique was improved with a combination of selfpowering and radio-frequency（RF） choking.RF perturbations in dual-frequency capacitively coupled discharge were effectively eliminated,as judged by the disappearance of self-bias on the probes.The improved technique was tested by spatially resolved measurements of the electron temperature and ion density in both the axial and radial directions of a dual-frequency capacitive plasma.The measured data in the axial direction were compared with simulation results,and they were excellently consistent with each other.The measured radial distributions of the ion density and electron temperature were influenced significantly by the lower frequency（LF） power.It was shown that superposition of the lower frequency to the higher frequency（HF） power shifted the maximum ion density from the radial center to the edge region,while the trend for the electron temperature profile was the opposite.The changing feature of the ion density distribution is qualitatively consistent with that of the optical emission intensity reported.展开更多
Low pressure argon dual-frequency （DF） capacitively coupled plasma （CCP） is generated by using different frequency configurations, such as 13.56/2, 27/2, 41/2, and 60/2 MHz. Characteristics of the plasma are inves...Low pressure argon dual-frequency （DF） capacitively coupled plasma （CCP） is generated by using different frequency configurations, such as 13.56/2, 27/2, 41/2, and 60/2 MHz. Characteristics of the plasma are investigated by using a floating double electrical probe and optical emission spectroscopy （OES）. It is shown that in the DF-CCPs, the electron temperature Te decreases with the increase in exciting frequency, while the onset of 2 MHz induces a sudden increase in Te and the electron density increases basically with the increase in low frequency （LF） power. The intensity of 750.4 nm emission line increases with the LF power in the case of 13.56/2 MHz, while different tendencies of line intensity with the LF power appear for other configurations. The reason for this is also discussed.展开更多
Nitrogen dual-frequency capacitively coupled plasmas （DF-CCPs） with different fre- quency configurations, i.e., 60/2 MHz and 60/13.56 MHz, are investigated by means of opticM emission spectroscopy （OES） and a floa...Nitrogen dual-frequency capacitively coupled plasmas （DF-CCPs） with different fre- quency configurations, i.e., 60/2 MHz and 60/13.56 MHz, are investigated by means of opticM emission spectroscopy （OES） and a floating double probe. The excited nitrogen molecule ion N＋（B） is monitored by measuring the emission intensity of the （0,0） bandhead of the first neg- ative system （FNS） at 391.44 nm. It is shown that in the discharge with 60/13.56 MHz, the N＋ emission intensity decreases with the increase in pressure. In the discharge with 60/2 MHz, however, an abnormal enhancement of N＋ emission at higher pressure is observed when a higher power of 2 MHz is added. Variation in the ion density shows a similar dependence on the gas pressure. This indicates that in the discharge with 60/2 MHz there is a mode transition from the alpha to gamma type when a higher power of 2 MHz is added at high pressures. Combining the measurements using OES and double probe, the influence of low frequency on the discharge is investigated and the excitation route of the N＋（B） state in the discharge of 60/2 MHz is also discussed.展开更多
基金supported by National Natural Science Foundation of China(No.10635010)the Specialized Research Fund for the Doctoral Program of Higher Education of China(No.20090041110026)
文摘The conventional double-probe technique was improved with a combination of selfpowering and radio-frequency（RF） choking.RF perturbations in dual-frequency capacitively coupled discharge were effectively eliminated,as judged by the disappearance of self-bias on the probes.The improved technique was tested by spatially resolved measurements of the electron temperature and ion density in both the axial and radial directions of a dual-frequency capacitive plasma.The measured data in the axial direction were compared with simulation results,and they were excellently consistent with each other.The measured radial distributions of the ion density and electron temperature were influenced significantly by the lower frequency（LF） power.It was shown that superposition of the lower frequency to the higher frequency（HF） power shifted the maximum ion density from the radial center to the edge region,while the trend for the electron temperature profile was the opposite.The changing feature of the ion density distribution is qualitatively consistent with that of the optical emission intensity reported.
基金supported by National Natural Science Foundation of China (Nos. 10635010, 10775103)
文摘Low pressure argon dual-frequency （DF） capacitively coupled plasma （CCP） is generated by using different frequency configurations, such as 13.56/2, 27/2, 41/2, and 60/2 MHz. Characteristics of the plasma are investigated by using a floating double electrical probe and optical emission spectroscopy （OES）. It is shown that in the DF-CCPs, the electron temperature Te decreases with the increase in exciting frequency, while the onset of 2 MHz induces a sudden increase in Te and the electron density increases basically with the increase in low frequency （LF） power. The intensity of 750.4 nm emission line increases with the LF power in the case of 13.56/2 MHz, while different tendencies of line intensity with the LF power appear for other configurations. The reason for this is also discussed.
基金supported by National Natural Science Foundation of China (Nos.10635010, 10775103)
文摘Nitrogen dual-frequency capacitively coupled plasmas （DF-CCPs） with different fre- quency configurations, i.e., 60/2 MHz and 60/13.56 MHz, are investigated by means of opticM emission spectroscopy （OES） and a floating double probe. The excited nitrogen molecule ion N＋（B） is monitored by measuring the emission intensity of the （0,0） bandhead of the first neg- ative system （FNS） at 391.44 nm. It is shown that in the discharge with 60/13.56 MHz, the N＋ emission intensity decreases with the increase in pressure. In the discharge with 60/2 MHz, however, an abnormal enhancement of N＋ emission at higher pressure is observed when a higher power of 2 MHz is added. Variation in the ion density shows a similar dependence on the gas pressure. This indicates that in the discharge with 60/2 MHz there is a mode transition from the alpha to gamma type when a higher power of 2 MHz is added at high pressures. Combining the measurements using OES and double probe, the influence of low frequency on the discharge is investigated and the excitation route of the N＋（B） state in the discharge of 60/2 MHz is also discussed.
