High density plasma CVD chamber

The present invention is directed to the design of a plasma CVD chamber which provides more uniform conditions for forming thin CVD films on a substrate. In one embodiment, 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 dome top and having a side portion defining a chamber diameter. A top RF coil is disposed above the dome top. A side RF coil is disposed adjacent the side portion of the dome. The side RF coil is spaced from the top RF coil by a coil separation. A ratio of the coil separation to the chamber diameter is at least about 0.15, more desirably about 0.2-0.25.