Dissertation Defense

Controlling Photon and Ion Fluxes in Low Pressure Low Temperature Plasmas

Peng Tian


Low temperature plasmas are widely used in both industry and everyday life, from fluorescent lighting, water purification to important processes in semiconductor industry fabricating electronic devices. In most of these applications, the flux of various energetic species generated by low temperature plasmas are the main promoter of necessary reactions facilitating the applications, efficiently delivering energy for chemical reactions at molecular level.

In semiconductor industry, control of ion fluxes and ion energy distribution is critical to optimizing fabrication process and pushing the limit of Moore's law. In this thesis, an unconventional tri-frequency capacitively coupled plasma (TF-CCP) was investigated numerically for scaling of ion fluxes and energy over power of individual frequencies. It was discovered that additional control of ion energy distribution can be achieved by the power of two lower frequencies. Ion fluxes scale positively with increasing power at all frequencies, and are more sensitive to low frequency power.

VUV photon fluxes have also been discovered to have important effect during plasma etching. This work studied the dynamics of a low pressure inductively coupled plasma (ICP), and developed approaches of controlling VUV and ion fluxes by pressure, pulsed power, gas mixture and surface conditions of the reactor wall.

Sponsored by

Professor Mark J. Kushner