A high plasma density chemical vapor deposition (CVD) is used to fill high aspect ratio spaces in-situ concurrent with a deposit to achieve gap fill. High plasma density CVD is also used for etching. In high density CVD a potential is coupled inductively to ionize a gas (plasma) in a CVD chamber. Once ionized the plasma is referred to as an inductively coupled plasma (ICP). In one application ICP is used to deposit dielectric films for gap fill.
One problem encountered when using an ICP process is the inability to adequately clean residue from the chamber after each deposition run or after each etch. In non-inductive systems chamber cleaning is accomplished using capacitive coupling of an electrical potential to a cleaning plasma which has been injected into the chamber. When using the inductively coupled design it is necessary to eliminate capacitive coupling during the inductive coupling, thereby making it difficult for plasmas to clean the chamber surfaces, since without capacitive coupling efficient cleaning is not possible.