Effect of nonsinusoidal bias waveforms on ion energy distributions and fluorocarbon plasma etch selectivity
- University of Illinois, Department of Chemical and Biomolecular Engineering, Urbana, Illinois 61801 (United States)
The distributions of ion energies incident on the wafer significantly influence feature profiles and selectivity during plasma etching. Control of ion energies is typically obtained by varying the amplitude or frequency of a radio frequency sinusoidal bias voltage applied to the substrate. The resulting ion energy distribution (IED), though, is generally broad. Controlling the width and shape of the IED can potentially improve etch selectivity by distinguishing between threshold energies of surface processes. In this article, control of the IED was computationally investigated by applying a tailored, nonsinusoidal bias waveform to the substrate of an inductively coupled plasma. The waveform we investigated, a quasi-dc negative bias having a short positive pulse each cycle, produced a narrow IED whose width was controllable based on the length of the positive spike and frequency. We found that the selectivity between etching Si and SiO{sub 2} in fluorocarbon plasmas could be controlled by adjusting the width and energy of the IED. Control of the energy of a narrow IED enables etching recipes that transition between speed and selectivity without change of gas mixture.
- OSTI ID:
- 20723057
- Journal Information:
- Journal of Vacuum Science and Technology. A, Vacuum, Surfaces and Films, Vol. 23, Issue 5; Other Information: DOI: 10.1116/1.2013318; (c) 2005 American Vacuum Society; Country of input: International Atomic Energy Agency (IAEA); ISSN 0734-2101
- Country of Publication:
- United States
- Language:
- English
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