| AVS 60th International Symposium and Exhibition | |
| Plasma Science and Technology | Thursday Sessions |
| Session PS-ThM |
| Session: | Plasma Modeling |
| Presenter: | S.-H. Song, University of Michigan |
| Authors: | S.-H. Song, University of Michigan M.J. Kushner, University of Michigan |
| Correspondent: | Click to Email |
In the fabrication of microelectronics devices, the performance and quality of the devices are ultimately determined by the energy distribution of charged particles and radicals in the plasma. High aspect ratio dielectric etching in microelectronics fabrication using dual frequency capacitively coupled plasmas (DF-CCPs) continues to be challenged to optimize the fluxes and energy distributions of radicals and ions to the wafer. Pulsed power is one technique being investigated to achieve these goals. In one configuration of DF-CCP, the high frequency (HF) power is applied to the upper electrode and low frequency (LF) power is applied to the lower electrode serving as the substrate which is serially connected through a blocking capacitor generating self dc bias. In this presentation, ion energy distributions, fluxes to the wafer, and SiO2 etch properties in a pulsed DF-CCP sustained in Ar/CF4/O2 are discussed with results from 2-dimensional plasma hydrodynamics and feature profile models. The ion energy distribution (IED) can be uniquely manipulated by either pulsing the LF or HF power for a given size of the blocking capacitor (BC). During the pulse, the dc-bias can have a time variation – small BC produces more time variation than large BC. This time variation in the dc bias provides an additional control mechanism for the IED. In this paper we report on a computational study of IEDs and SiO2 etch profiles in DF-CCPs. To investigate this coupling we applied a pulsed format for HF and LF power with different duty cycles and blocking capacitances. We found that high energy ions are dominant when pulsing HF power and low energy ions are dominant when pulsing LF power. Smaller BC generally broadens the IED. We also found that the ratio of F/CFx (x = 1 – 3) fluxes increases by pulsing either the HF or LF however the effect is more sensitive to pulsing HF power. Control of etch profiles will be demonstrated by combinations of pulsing HF and LF power, and BC. For example, bowing and undercut may occur when pulsing HF while these effects are suppressed by pulsing LF. The propensity for twisting is less when pulsing LF.
* Work supported by the Department of Energy Office of Fusion Energy Sciences, the Semiconductor Research Corp. and National Science Foundation.