The Effect of SF$_{6}$ dilution in an Argon plasma

Plasma etching is widely used in semiconductor industries. There have been extensive studies in the dilution of rare gases; however, limited studies are found in the dilution of electronegative gases. In this work, SF$_{6}$ content is varied from 5{\%} to 60{\%} in an Ar plasma in a deep reactive ion etching system. A Langmuir probe is used to measure electron temperature (T$_{e})$, electron density (n$_{e})$, and electron energy distribution function (eedf). T$_{e}$ decreases monotonically with increasing SF$_{6}$ at first, and then increases for SF$_{6}$ content greater than 20{\%}. This increase is attributed to the loss of low energy electrons in attachment and high energy electrons in excitation and ionization. As the content of SF$_{6 }$is increased above 20{\%}, the dissociation of SF$_{6}$ increases and most of the low energy electrons are lost in attachment and hence the average electron temperature increases. n$_{e}$ decreases by an order of magnitude as the SF$_{6}$ dilution is increased from 5{\%} to 60{\%}. eedf shows that the distribution shifts towards high energy with the increase of SF$_{6}$ content, which is because of the depletion of low energy electrons.