Capacitively coupled plasma

MHz was capacitively coupled to the substrate susceptor to control the ions energy in the plasma. 

FIG. 4. Schematic representation (a) of a parallel-plate, capacitively coupled RF-discharge reactor, with unequal-size electrodes. The potential distribution (b) shows the positive plasma potential Vp and the negative dc self-bias voltage... 

The plasma potential is about 25 V (Figure 63a). This value of the plasma potential is typical for the silane plasmas in the asymmetric capacitively coupled RF reactors as used in the ASTER deposition system, and is also commonly found in argon or hydrogen plasmas [170, 280, 327]. From the considerable decrease of the dc self-bias with increasing frequency (Figure 63a) it is inferred that the... 

In contrast, Heintze and Zedlitz [236] also presented data on the plasma potential as function of frequency in silane plasmas the plasma potential varies from about 27 V at 35 MHz to about 20 V at 180 MHz. Moreover, Dutta et al. [284] used a symmetric capacitively coupled RF reactor and estimated the plasma potential in their system from the applied voltage at the powered electrode. A decrease of the plasma potential from 45 V at 13.56 MHz to only 15 V at 70 MHz is observed. This difference in behavior is thought to be solely due to the different reactor geometries. 

Exposure of bulk GaAs Si wafers to a capacitively coupled rf deuterium plasma at different temperatures generates deuterium diffusion profiles as shown in Fig. 1. These profiles are close to a complementary error function (erfc) profile. At 240°C, the effective diffusion coefficient is 3 x 10 12 cm2/s. The temperature dependence of the hydrogen diffusion coefficient is given by (Jalil et al., 1990) ... 

Atsuya and Akatsuka [140] have described a method for determining trace amounts of arsenic. The technique, which uses capacitively coupled microwave plasma with an arsine generation system, has been used to determine arsenic in sewage sludge. 

Most of plasma polymerizations have been carried out in the frequency range from 50 Hz to 13.56 MHz with using the capacitively coupled discharge system (.4,16). For the inductively coupled discharge system, a frequency of 13.56 MHz was mostly used as a discharge frequency (17,18). In this paper, the discussion will be concentrated on the discharge in the capacitively coupled discharge system. 

The capacitatively coupled microwave plasma is formed by coupling a 2450 MHz magnetron, via a coaxial waveguide, to metal plates or a torch where the plasma is formed. Considerable problems have been encountered with this low-cost plasma, particularly from easily ionizable elements which cause dramatic changes in the excitation temperature in the plasma. 

Further designs of ion sources applied in plasma spectroscopy such as electrodeless microwave induced plasmas (MIPs) operating in a noble gas atmosphere at low power (mostly below 200 W) or capacitively coupled microwave plasma using Ar, He or N2 the as plasma gas (at 400-800 W) were described in detail by Broekaert.33 Microwave plasmas produced by a magnetron are operated at 1-5 GHz. Their special application fields for selected elements and/or element species are based (due to the low power applied) in atomic emission spectrometry.33... 

Furnace atomisation plasma emission spectrometry (FAPES) this consists of an atmospheric pressure source combining a capacitively coupled radiofrequency helium plasma formed inside a graphite tube which contains an axial powered electrode. This miniplasma has rarely been used in analytical atomic spectrometry, probably because of the small number of users and a lack of information about its applications and capabilities [7]. 

Physical and Electrical Characteristics. The electrical potentials established in the reaction chamber determine the energy of ions and electrons striking the surfaces immersed in a discharge. Etching and deposition of thin films are usually performed in a capacitively coupled parallel-plate rf reactor (see Plasma Reactors). Therefore, the following discussion will be directed toward this configuration. 

Cordos, E.A., Frentiu, T., Rusu, A.-M. and Vatca, G. (1995) Elemental speciation of lead, zinc and copper in sedimented dust and soil using a capacitively coupled plasma atomic emission spectrometer as detector. Analyst, 120, 725-731. 

One particular example of what may be called a gas-liquid discharge microreactor is the work of Baba et al. (2006, 2007), who have demonstrated the generation of an atmospheric pressure glow-discharge plasma in contact with liquid paraffin, using a capacitively coupled plasma method. The choice for paraffin has two reasons no hydroxyl group present (which is thought to capture electrons, as is the case in water)... 

Figure 11 Geometries of plasma-assisted CVD reactors (A) parallel-plate discharge, (B) tube with capacitive coupling, (C) tube with inductive coupling.13...

A grounded, electrical shield can be placed between the load coil and torch to reduce the capacitive coupling between the load coil and the plasma in order to reduce the plasma potential [10]. A thin metal cylinder, split along its length (to... 

The Au-PPFC films were deposited in a triode system shown schematically in Fig. 1. The powered main electrode (7 cm in diameter) was capacitively coupled to an RF (13.56 MHz) power supply, the opposing electrode (15 cm in diameter) was grounded, and the third electrode (3.6 cm in diameter) was located perpendicularly in the gap between the larger ones at the edge of the plasma zone. On it were placed the substrates for coating experiments. 

All plasma exposures were carried out in an IPC (International Plasma Corporation) 2005 capacitance-coupled barrel reactor at 13.56MHz. The reactor was equipped with an aluminum etch tunnel and a temperature controlled sample stage. Pressure was monitored with an MKS capacitance manometer RF power was monitored with a Bird R.F. power meter and substrate temperature was measured with a Fluoroptic thermometer utilizing a fiber optic probe which was immune to R.F. noise. 

---