Development of surface-wave ion source using coaxial-type cavity

Abstract

A compact 2.45 GHz surface-wave ion source has been developed for the production of stable beams from gaseous feed materials. The source has been operated with two different geometries of surface wave generation, that is, a dielectric disk on ground plane structure and a dielectric disk between the parallel plate structure with a holey top plate. The designer can control the intensity of the emitted microwave simply by varying the thickness of the dielectric plate. The sources have been operated with three different thicknesses of the dielectric plate: td=10, 15, and 20 mm. td=10 mm is the optimum coupling condition. Moreover, the ion beam current of the holey-plate structure is 1.5 times as high as that of the dielectric disk structure.

High-density flat plasma production based on surface waves

“…Recently a similar configuration has been reported by Odrobina et al [27]. Another (however not largearea) plasma source based also on a coaxial cavity [25] demonstrates the applicability of a large aperture coupling for top-wall excitation. The plasma is created in a chamber with an upper dielectric wall placed directly facing the open end of a coaxial-line short-circuited at the other end to form a (5/4)λ resonator.…”

“…However, almost all studies are concerned with long (sometimes extremely long [9]) plasma columns, such that the plasma diameter D is much less than the column length L. Such high-density plasma columns are clean, quiescent and reproducible, but not suitable for the recent trend of large-diameter plasma processing. Therefore some new antenna structures have been developed to obtain a large-aperture surface-wave plasma of D>L [10][11][12][13][14][15][16][17][18][19][20][21][22][23][24][25][26][27]. In the present paper we give a short review of surface-wave excited flat plasma production in the absence of magnetic field, with emphasis on the slot-antenna excitation configuration we proposed recently [22][23][24].…”

Microwave plasma generation by the fast rotation and slow pulsation of resonant fields in a cylindrical cavity

“…Large-scale high-density microwave plasmas have been generated by injecting microwaves from a magnetron into rectangular or radial waveguides. [4][5][6][7][8][9][10][11][12][13] In the last decade, circular radial waveguides, called radial line slot antenna (RLSA), [14][15][16] were used to make uniform plasmas to process circular wafers in many applications of microwave plasma processing. However, the generated plasmas often had inhomogeneous ion density distributions in the radial and=or azimuthal directions, owing to a non-uniform field distribution of the microwave applicator, and partly owing to surface wave excitation.…”

Generation of slowly rotating microwave plasma by amplitude-modulated resonant cavity

“…Plasma generated by a microwave discharge is known to have the advantages of a low electron temperature (low sheath voltage) [1][2][3] and a high dissociation of reactive gasses when compared to radiofrequency (RF) plasmas such as capacitively coupled plasma and inductively coupled plasma. To date, magnetron microwave generators at ω=2π = 2.45 GHz have been widely used for the production of large-diameter, high-density microwave plasmas [4][5][6][7][8][9][10][11][12][13] owing to their low cost and high power outputs. Recently, a digitally controlled solidstate microwave generator (ω=2π = 2.4-2.5 GHz) has been adopted for microwave discharge 14) considering its variable frequency operation and capability to precisely control the phase and amplitude.…”