The effect of F₂attachment by low-energy electrons on the electron behaviour in an Ar/CF₄inductively coupled plasma

Abstract

The electron behaviour in an Ar/CF 4 inductively coupled plasma is investigated by a Langmuir probe and a hybrid model. The simulated and measured results include electron density, temperature and electron energy distribution function for different values of Ar/CF 4 ratio, coil power and gas pressure. The hybrid plasma equipment model simulations show qualitative agreement with experiment. The effect of F 2 electron attachment on the electron behaviour is explored by comparing two sets of data based on different F atom boundary conditions. It is demonstrated that electron attachment at F 2 molecules is responsible for the depletion of low-energy electrons, causing a density decrease as well as a temperature increase when CF 4 is added to an Ar plasma.

Bulk plasma fragmentation in a C4F8 inductively coupled plasma: A hybrid modeling study

“…These species, including radicals, molecules, and positive and negative ions, can be divided into six types, i.e., belonging to C, F, CF a , C 2 F b , C 3 F c , and C 4 F d , with different possibilities for the subscripts a, b, c, and d. The reactions of C, F, CF a , and C 2 F b species with electrons, as well as the chemical reactions between these species, were already presented in our previous papers. 45,46 Therefore, in the present paper, only the reactions involving the C 3 F c and C 4 F d species are listed in Table II. In the surface reaction set, all ions and excited neutrals are recycled back into the plasma as neutrals, after neutralization and de-excitation, respectively.…”

Effects of feedstock availability on the negative ion behavior in a C4F8 inductively coupled plasma

“…The reactions of the light CF a (a ¼ 1-4) and C 2 F b (b ¼ 3-6) species, including both neutrals and ions, as well as the electron reactions, were presented in our two previous papers. 30,31 The reactions of the heavy fc species, like C 3 F c and C 4 F d , are listed in Ref. 32, where the fragmentation behavior of a C 4 F 8 ICP is studied.…”

“…The references where these reaction data are adopted from can be found in our previously published papers. [30][31][32] Moreover, in this work, we focus on the various negative ion production processes, i.e., the parent and dissociative electron attachments with fc species, as well as their loss mechanisms, like autodetachment, collisional stabilization and dissociation of excited parent anions, and neutralization and collisional detachment of F À . Therefore, these processes are summarized in Table IV for better reference.…”

“…The F atoms and light fc neutrals are assumed to stick to the surface with specific probabilities, as explained in detail in Ref. 30. The heavy fc neutrals are all reflected from the surface into the plasma.…”

“…Chemical reaction set for the CF a (a ¼ 1-4) species. The rate coefficients or cross sections are all adopted from Ref 30…”