Electron temperature control with a small mesh number grid in inductively coupled plasmas

Abstract

The electron temperature is controlled to 0.6 eV with a small mesh number (the number of the grid wire per 2.54 cm) grid in Ar 1.3 Pa inductively coupled plasma. The key factor in determining the electron temperature is different for different mesh numbers: when the mesh number is large, the key factor is the potential difference between the plasma potential in region II and the grid bias voltage, but when the mesh number is small the plasma potential difference between regions I and II is the key factor. Furthermore, in such cases, the electron density in region II increases with discharge pressure, which is the opposite of what occurs when the mesh number is large. The measured electron energy probability functions show a bump structure for some conditions. This could be explained by the low electron–electron or electron–neutral collision frequencies due to the low electron density and operating pressure.