Effects of amplitude modulated discharge on growth of nanoparticles in TEOS/O2/Ar capacitively coupled plasma

Abstract

We investigate the effects of the amplitude modulation (AM) discharge method on the growth of nanoparticles and the relation between growth of nanoparticles and plasma generation in tetraethylorthosilicate (TEOS)/O2/Ar plasma. The laser-light scattering (LLS) intensity, which is proportional to the density and the sixth power of the size of nanoparticles in the Rayleigh scattering regime, decreases by 18% at an AM level of 10% and by 60% at an AM level of 50%. On the other hand, the ArI emission intensity, which is roughly proportional to plasma density, is higher than that for the continuous wave discharge. Thus, AM discharges suppress growth of nanoparticles in TEOS plasma. We have shown oscillations of the axial electric field Ez with the AM frequency for AM discharge by electric field measurement using an electro-optic probe. We have discussed that these fluctuations of Ez mainly lead to the vertical oscillation of the levitation position of nanoparticles trapped in the plasma sheath boundary region by taking into account the force balance equation in the axial direction on these negatively charged nanoparticles.