Liang Rongqing

Improving the uniformity of RF-plasma density by a humped variable-gap spiral antenna

This paper develops a humped spiral antenna of top inductively coupled plasma with variable gap. Comparing with planar spiral antennae, it investigates the performance of humped spiral antennae in the calculated electromagnetic configurations and experimental results. It finds that the humped antenna has the improved uniformity of plasma density in the radial direction and the decreased electron temperature in the top inductively coupled plasma. By experimental and theoretical analyses, the plasma performance in the case of humped antennae is considered to be the combined results of the uniform electromagnetic configurations and the depressed capacitively coupling effect.

Large Volume and High Density Surface Wave Plasmas Sustained by Two Microwave Launchers

Surface wave plasma (SWP) is an electromagnetic excitation along the planar interface between a dielectric and plasma medium when plasma density is so large that its permittivity becomes negative. An experiment SWP system consisting of two microwave launchers (upper and side microwave launcher) has been developed for producing large volume surface wave plasmas in our laboratory. The experimental investigation shows that comparable uniformity plasma with not only large volume but also high density properties has been obtained by the two launchers.

Preliminary Investigation of a Dielectric Barrier Discharge Lamp in Open Air at Atmospheric Pressure

A dielectric barrier discharge (DBD) lamp is investigated by using sinusoidal power with a 10 kHz frequency in open air at atmospheric pressure. With increasing applied voltages, the different discharge phenomena appear. At relatively low voltages, the discharge states are general stochastic filamentary discharges with weak light. However, at relatively high voltages, the walls of quartz tubes are heated sharply by plasma, and then the dazzling light is emitted very quickly to form the DBD Lamp, corresponding to the low maintaining voltage that is lower than the ignited voltage. The discharge state or mode of the DBD lamp that corresponds to the glow discharge is deduced according to the wave form of the circuit current, which is evidently different from the filamentary discharges. Under these conditions, the spectrum of the DBD lamp is continuous in the range 400–932 nm, which is scanned in the range 300–932 nm. It is also shown that there is another discharge state or mode that is different from the traditional filamentary discharges. Therefore, it is concluded that the discharge state or mode of the DBD lamp is a glow discharge.

Theoretical Computation for Non-Equilibrium Air Plasma Electrical Conductivity at Atmospheric Pressure

Based on the Chapman–Enskog theory, we calculate the electrical conductivity of non-equilibrium air plasma in the two-temperature model. We consider different degrees of non-equilibrium, which is defined by the ratio of electronic temperature to heavy particles temperature. The method of computing the composition of air plasma is demonstrated. After calculating the electrical conductivity from electron temperature 1000 K to 15000 K, the present result is compared with Murphys study [Plasma Chem. Plasma Process 15 (1994) 279] for equilibrium case. All the calculation is completed at atmospheric pressure. The present results may have potential applications in numerical calculation of non-equilibrium air plasma.

Improvement of electrical properties of Cu/SiCOH low-k film integrated system by O2 plasma treatment

This paper investigates the effect of O2 plasma treatment on the electric property of Cu/SiCOH low dielectric constant (low-k) film integrated structure. The results show that the leakage current of Cu/SiCOH low-k integrated structure can be reduced obviously at the expense of a slight increase in dielectric constant k of SiCOH films. By the Fourier transform infrared (FTIR) analysis on the bonding configurations of SiCOH films treated by O2 plasma, it is found that the decrease of leakage current is related to the increase of Si-O cages originating from the linkage of Si dangling bonds through O, which makes the open pores sealed and reduces the diffusion of Cu to pores.

The Characteristics of Columniform Surface Wave Plasma Excited Around a Quartz Rod by 2.45 GHz Microwaves

A novel surface wave plasma (SWP) source excited with cylindrical Teflon waveguide has been developed in our previous work. The plasma characteristics have been simply studied. In this work, our experimental device has been significantly improved by replacing the Teflon waveguide with a quartz rod, and then better microwave coupling and higher gas purity can be obtained during plasma discharge. The plasma spatial distributions, both in radial and axial directions, have been measured and the effect of gas pressure has been investigated. Plasma density profiles indicate that this plasma source can produce uniform plasma in an axial direction at low pressure, which shows its potential in plasma processing on a curved surface such as an inner tube wall. A simplified circular waveguide model has been used to explain the principle of plasma excitation. The distinguishing features and potential application of this kind of plasma source with a hardware improvement have been shown.

Experimental Investigation of Surface Wave Plasma Excited by a Cylindrical Dielectric Rod

An improved surface wave plasma source equipped with a cylindrical quartz rod has been developed, which has great potential in processing inner wall of cylindrical workpieces. A cylindrical quartz rod not only excites the plasma around the rod, but also guides surface wave plasma along the rod. The distributions of plasma density and plasma temperature under different incident microwave powers and pressures are diagnosed by a Langmuir probe. The electron density near the rod is around the order of 1011cm−3. When the incident power is 450 W, the length of surface wave plasma column can reach up to 420 mm at 20 Pa.

X-ray Photoemission Spectroscopy Studies of Indium-tin-oxide Films Treated by Oxygen Plasma Immersion Ion Implantation

Oxygen plasma immersion ion implantation (PIII) was introduced to modify indium-tin-oxide (ITO) films. X-ray photoemission spectroscopy (XPS) was employed to characterize the elements ratio and core level spectra of O1s at the surface of ITO.

Enhancement of Emission Intensity of Y3Al5O12:Ce3+ Phosphor by Surface Modification of Wet Etching

The modified phosphor presents higher emission intensity (increased by 8.5%) and lower backscattering light. These are contributed by surface passivation and removal of surface defects after etched by the NH4F and HNO3 mixture solution.

Improvement of Uniformity of Inductively Coupled Plasma with a Cone Spiral Antenna

Uniformity of inductively coupled plasma (ICP) is improved with a cone spiral antenna in our experiment. Performance of the ICP with a new type of antenna is experimentally investigated. The results indicate that the uniformity of plasma density in the radial direction is obviously improved as compared to the ICP with a planar spiral antenna. Performance of ICP is analysed with the experimental results.