The present invention is directed to an upper chamber design of a plasma CVD chamber which provides more uniform conditions for forming thin CVD films on a substrate. Embodiments of the invention improve temperature control of the upper chamber and improve particle performance by reducing or minimizing the temperature fluctuations on the dome between the deposition and non-deposition cycles. In accordance with an aspect of the present invention, an apparatus for processing semiconductor substrates comprises a chamber defining a plasma processing region therein. The chamber includes a bottom, a side wall, and a dome disposed on top of the side wall. The dome has a substantially flat dome top. A top RF coil is disposed above the dome top, and has an outer loop which is larger in size than the substrates to be processed in the chamber. A cold plate is disposed above the top RF coil, and is larger in size than the substrates to be processed in the chamber.