Plasmas: sheaths

Figure C2.18.3. Relationship between ion-assisted etching and directionality in plasma etching, (a) Demonstration of the synergy between ion bombardment and reactive species during ion-assisted etching, (b) Ions incident on an etched feature. This situation prevails in glow discharges when the feature dimensions are much less than the plasma sheath thickness. Reproduced from [35]...

Butler, H.S. and Kino, G.S., Plasma sheath formation by radio-frequency... 

The consequence of the plasma sheaths is two fold first, significant voltages have to be applied to plasma electrochemical cells in order to draw sufficiently... 

Figure 10.20. Field strength distribution in the cathode plasma sheath above a bare and a diamond-coated Si substrates for Kh = —200 V. The field strength was evaluated from the Stark splitting (broadening) of the Hoi and Hp lines [234].

Application to capacitively-coupled reactors Figure 24a shows the electron temperature distribution in an argon discharge sustained in a one-dimensional parallel plate reactor of the kind shown in Fig. 7. The temperature peaks near the plasma-sheath interface, where the product of the current and electric field (Eq. 31) is highest, and steep gradients develop in that region. Electrons which diffuse towards the electrode during the sheath potential minimum (around r = 0.25 at left electrode, see also Fig. 

Set plasma sheath parameters Assume Sheath Model (Lleberman)... 

Ions in a bulk plasma can be accelerated with the electric potential of a plasma sheath near a solid surface so that they reach the siuface, quickly neutralize, and finally attach to the surface. It is experimentally difficult to discriminate this mechanism from free radical mechanism 5, the deposit of reactive species near the surface. 

Particles are trapped, nucleate, and grow at the plasma sheath boundary near the powered electrode. 

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