Non-Invasive Plasma Characterization Through the Ion Velocity Distribution Function

By: Tsanko Vaskov TSANKOV*

11 April 2019

Figure 1 Schematic representation of the discharge chamber with diagnostics. Dimensions are in mm.

Feature Article

Author(*) Information: Senior researcher,Chair for plasma and atomic physics,Ruhr University Bochum,Ph.D.

The high level of miniaturization and degree of integration of modern integral circuits based on semiconductor technology would be unthinkable without the use of various plasma-based processing steps during manufacturing, such as deposition and etching. These processes, their quality and efficiency depend critically on a number of plasma parameters, such as flux, density and energy of the ions. To optimize and control the semiconductor processing it is therefore desirable to be able to measure these quantities without affecting the plasma, its homogeneity and the quality of the ongoing surface treatment process.This is now possible with the method developed by us. It is an extension of the well-known mass spectrometry diagnostics. The method uses the distribution in velocities of the ions, measured at the wall of the process chamber by an energy resolved mass spectrometer, to obtain the plasma characteristics in the plasma volume. The parameters that can be determined include the velocity distribution of the ions in the plasa, their density, flux, mean energy and temperature.

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