Experimental Study on Favorable Properties of Compound RF Discharge Plasmas with a Tapered Shape Hollow Cathode Compared with a Plane Cathode

Abstract

An experimental investigation on the characteristics of compound RF discharge plasmas with a tapered shape hollow-cathode (HC) compared with a plane cathode is presented for the development of processing plasma. Dense plasmas are shown to be generated in the wide range of working pressures, 3< p<90 Pa. It is clarified that the higher RF power yields the greater HC effect to increase the ratio of electron density with the HC to that without it. The HC effect is shown to work well for decreasing the self-bias potential compared with the plane cathode. It is clarified that the dense plasma with relatively low electron temperature produced by the compound RF discharge results from the synergetic effect of the lowered input RF power density and the effective increased discharge area due to the HC effect.

Plasma parameters of RF capacitively coupled discharge: comparative study between a plane cathode and a large hole dimensions multi-hollow cathode

“…This trend is probably due to the slowdown of electrons by collisions that becomes more frequent since the free path length is reduced as the gas pressure is increased. A similar behavior was observed by Yambe et al in a comparative study between tapered shape hole and plane cathode [13].…”

“…In such situation, the cathode geometry configuration is one of the possibilities that can improve the plasma parameters in terms of self-bias voltage (V dc ), electron density (n e ) and electron temperature (T e ), etc. [12][13][14]. In this sense, hollow and multi-hollow (H and MH) cathodes were proposed to be utilized as a light source [15], active media for gas lasers [16], sources of electrons [17], or for thin films deposition and large area surface treatment [18][19][20], and recently for the treatment of nanoparticles, plasma polymerization and nanocomposite fabrication [21].…”

Generation of Highly Uniform Plasma on the Grounded Electrode Surface by Radio Frequency Discharge with the Use of Modified Multi Hollow Cathodes

“…The effect of low T e may be brought with the secondary electrons in the grooves, which are generated by accelerated electron in the sheath region on the HC. 7) On the other hand, the decrease in the effect of high n e becomes large. The n e of the MHC is about 0.55 times that of the HC at the center.…”

“…4) The RF discharge with the use of the tapered shape HC has been studied in our laboratory, and the realization of uniform plasma has been experimentally demonstrated. [4][5][6][7] Also, we successfully produced dense plasma (10 17 m À3 ) and low temperature (1.7 eV) by RF (13.56 MHz) discharge with the use of HC. 7) In the case of the HC electrode, it is confirmed that the effect of HC discharge was maximum around the gas pressure p ¼ 8:35 Pa.…”

“…[4][5][6][7] Also, we successfully produced dense plasma (10 17 m À3 ) and low temperature (1.7 eV) by RF (13.56 MHz) discharge with the use of HC. 7) In the case of the HC electrode, it is confirmed that the effect of HC discharge was maximum around the gas pressure p ¼ 8:35 Pa. The density of the plasma generated is modified by changing the effective width of grooves on the HC.…”