Vacuum ultraviolet photon formation from oxygen atoms in pulsed inductively coupled plasmas*

Photons in the vacuum ultraviolet (VUV) range formed in low pressure plasma sources can induce defects in plasma-processed materials. Given the atomic scale precision require to manufacture current generation semiconductor devices, such defects can ultimately lead to decreased device performance. Because of this, a detailed understanding of VUV photon formation processes, and the development of strategies to control them, is important. Oxygen-containing plasmas are widely used in the semiconductor industry and can exhibit strong VUV formation from oxygen atom resonance emission at 130 and 135 nm. In this work, a 0-D plasma-chemical model [1], including a collisional radiative scheme for excited oxygen atom formation, is used to study photon formation in pulsed inductively coupled plasmas formed in oxygen.  The maximum and time-integrated photon fluxes to surfaces are studied as a function of plasma power, duty cycle and pulse repetition frequency. The ratio of these fluxes to those of oxygen atoms and positive ions reaching the surface are discussed, to understand the extent to which these can be controlled by pulsed power deposition. Since both resonance emission lines show different degrees of radiation trapping, they exhibit different temporal profiles in the pulse afterglow. The relative importance of this for the time-integrated and time-varying photon fluxes and photon-to-ion flux ratio will be discussed.

 

[1] M. Osca Engelbrecht et al arXiv:2402.08092 [physics.plasm-ph]