Gapfill of variable aspect ratio features with a composite PEALD and PECVD method
Provided herein are methods and apparatus for filling one or more gaps on a semiconductor substrate. The disclosed embodiments are especially useful for forming seam-free, void-free fill in both narrow and wide features. The methods may be performed without any intervening etching operations to achieve a single step deposition. In various implementations, a first operation is performed using a novel PEALD fill mechanism to fill narrow gaps and line wide gaps. A second operation may be performed using PECVD methods to continue filling the wide gaps.
1. A method comprising:
(a) introducing a first reactant in vapor phase into a reaction chamber having a substrate therein, the substrate comprising a gap to be filled and allowing the first reactant to adsorb onto a substrate surface;
(b) introducing a second reactant in vapor phase into the reaction chamber;
(c) exposing the substrate surface to plasma to drive a surface reaction between the first and second reactants on the substrate surface;
(d) sweeping or purging the reaction chamber;
(e) repeating (a)-(d) one or more times to deposit a first dielectric film in the gap;
(f) introducing at least a third reactant in vapor phase into the reaction chamber; and
(g) generating a plasma from at least the third reactant to drive a gas phase reaction, wherein the gas phase reaction produces a second dielectric film, and wherein the second dielectric film is deposited on the first dielectric film.
2. The method of claim 1 , wherein the plasma in operation (g) is a capacitively coupled plasma.
3. The method of claim 1 , wherein operation (f) further comprises introducing a fourth reactant in vapor phase into the reaction chamber while introducing the third reactant into the reaction chamber.
4. The method of claim 1 , wherein the first dielectric film deposited in (e) comprises the same material as the second dielectric film deposited in (g).
5. The method of claim 1 , wherein the first dielectric film completely fills the gap.
6. The method of claim 1 , wherein the first dielectric film forms an indentation over the gap.
7. The method of claim 1 , wherein the first dielectric film and the second dielectric film are silicon oxide.
8. The method of claim 1 , wherein the reaction chamber is a multi-station chamber.
9. The method of claim 1 , wherein a gas used to generate the plasma in (c) comprises the second reactant.
10. The method of claim 1 , wherein the third reactant is the same as one of the first reactant and the second reactant.
11. The method of claim 1 , wherein the first reactant is a first silicon-containing reactant and the third reactant is a second silicon-containing reactant.
12. The method of claim 10 , wherein the first reactant and the third reactant are different.
13. The method of claim 12 , wherein the first reactant is an aminosilane.
14. The method of claim 13 , wherein the third reactant is tetra-ethoxy-silane (TEOS) or silane (SiH 4 ).