Gap fill using carbon-based films
Provided herein are methods of filling gaps using high density plasma chemical vapor deposition (HDP CVD). According to various implementations, carbon-containing films such as amorphous carbon and amorphous carbide films are deposited by HDP CVD into gaps on substrates to fill the gaps. The methods may involve using high hydrogen-content process gasses during HDP CVD deposition to provide bottom-up fill. Also provided are related apparatus.
1. A method comprising:
introducing a process gas to a high density plasma chemical vapor deposition (HDP CVD) chamber that houses a substrate having a gap, wherein the process gas includes a hydrocarbon reactant and has a H:C ratio of at least 4:1; and
filling the gap with an amorphous carbon (a-C) film by an HDP CVD reaction of the process gas.
2. The method of claim 1 , wherein the gap is filled in a single deposition operation with no intervening etch operations.
3. The method of claim 1 , wherein the hydrocarbon reactant has a H:C ratio of at least 3:1.
4. The method of claim 1 , wherein the hydrocarbon reactant has a H:C ratio of at least 4:1.
5. The method of claim 1 , wherein the process gas includes molecular hydrogen (H 2 ).
6. The method of claim 1 , further comprising generating a plasma including hydrogen radicals.
7. The method of claim 1 , wherein the filling the gap comprises a hydrogen radical etch at a top of the gap during the HDP CVD reaction.
8. The method of claim 1 , wherein filling the gap with an amorphous carbon film comprises two or more deposition stages and one or more intervening etch operations.
9. The method of claim 8 , wherein the one or more intervening etch operations are hydrogen-based etches.
10. The method of claim 9 , wherein transitioning from a deposition stage to an intervening etch operation comprises stopping flow of the hydrocarbon reactant to the HDP CVD chamber while maintaining flow of hydrogen (H 2 ) to the HDP CVD chamber.
11. The method of claim 1 , wherein the hydrocarbon reactant is selected from ethane and methane.
12. The method of claim 1 , wherein the hydrocarbon reactant is acetylene.
13. The method of claim 1 , wherein neutral species preferentially etch material deposited at a top of the gap with respect to material deposited at a bottom of the gap during gap fill.