Production of large area VHF plasma using ladder-shaped electrode

A VHF SiH4/H2 plasma was produced using a ladder-shaped electrode of 1200 mm×141 mm. In this case, VHF power up to 200 W was fed to the ladder-shaped electrode through the matching box. The plasma parameters in mixture gas plasma of SiH4/H2 were measured with a heated Langmuir probe and examined as a function of gas mixture rate. A uniform VHF plasma was achieved over 1 m at the frequency of 60 MHz. Furthermore, when the concentration of SiH4 gas was increased, the ion saturation current decreased while the electron temperature increased.