Dielectric deposition and etch back processes for bottom up gapfill
Methods to reduce film cracking in a dielectric layer are described. The methods may include the steps of depositing a first dielectric film on a substrate and removing a top portion of the first dielectric film by performing an etch on the film. The methods may also include depositing a second dielectric film over the etched first film, and removing a top portion of the second dielectric film. In addition, the methods may include annealing the first and second dielectric films to form the dielectric layer, where the removal of the top portions from the first and the second dielectric films reduces a stress level in the dielectric layer.
1. A method for filling a trench in a substrate with a dielectric material, the method comprising:
filling the trench with a film of the dielectric material, wherein the dielectric film is formed by:
combining a first fluid stream comprising atomic oxygen with a second fluid stream comprising a silicon-containing precursor, and
reacting the atomic oxygen and the silicon-containing precursor in a deposition chamber having an internal pressure of less than about 10 Torr to form the dielectric film in the trench, wherein dielectric material initially deposited near the top of the trench flows towards the bottom of the trench while the substrate is held at a temperature of about 30° C. to about 75° C.;
removing a top portion of the dielectric film by etching the film; and
annealing the etched film.
2. The method of claim 1 , wherein the dielectric film is etched back below the top of the trench.
3. The method of claim 2 , wherein a capping layer is deposited on the etched back dielectric film.
4. The method of claim 3 , wherein the capping layer comprises the same dielectric material as the dielectric film.
5. The method of claim 1 , wherein the etching of the film is performed as a wet etch or a dry etch.
6. The method of claim 1 , wherein the etching of the film is a dry etch performed by exposing the film to a etch gas comprising a fluorine compound.