chapter 12-Principles of Plasma Discharges and Materials Processing Second Edition精品.pdfVIP

CHAPTER 12 INDUCTIVE DISCHARGES The limitations of capacitive rf discharges and their magnetically enhanced variants have led to the development of various low-pressure, high-density plasma discharges. The distinction between low- and high-density discharges is described in Sections 10.1 and 10.2. A few examples are shown schematically in Figure 1.14, and typical parameters are given in Table 1.1. In addition to high density and low pressure, a common feature is that the rf or microwave power is coupled to the plasma across a dielectric window or wall, rather than by direct connection to an electrode in the plasma, as for a capacitive discharge. This noncapacitive power transfer is the key to achieving low voltages across all plasma sheaths at electrode and wall surfaces. The dc plasma potential, and hence the ion acceleration energy, is then typically 20–40 V at all surfaces. To control the ion energy, the electrode on which the sub- strate is placed can be independently driven by a capacitively coupled rf source. Hence independent control of the ion/radical fluxes (through the source power) and the ion-bombarding energy (through the substrate electrode power) is possible. The relation between substrate electrode power and ion-bombarding energy at the sub- strate is described in Chapter 11. High-density inductive rf discharges are described in this chapter, and high-density wave heated discharges are described in Chapter 13. Nonresonant inductive discharges operated at high densities and low pressures, which are driven at frequencies below the self-resonant frequency of the exciting coil, are described in Section 12.1. Other operating regimes and power transfer con- siderations are described in Section 12.2. The planar coil configuration, which is com- monly used for materials processing, is described in Section 12.3, with emphasis on Principles of Plasma Discharges and Ma