Method for reduction of gap fill defects
A method of electrodepositing a conductor to form a defect-free conductor layer on a wafer surface including features. The wafer surface including the features is lined with a nucleation film. The conductor is electrodeposited onto the nucleation layer from a process solution having an additive that adsorbs strongly on the already deposited conductor and weakly on the exposed portions of the nucleation layer. As a result, the conductor selectively deposits on the still exposed portions of the nucleation layer and covers them with the conductor, thereby forming the defect-free conductor layer on the wafer surface.
1 . A method of electrodepositing a conductor to form a defect-free layer on a wafer surface including at least one cavity, wherein the wafer surface including the at least one cavity is lined with a continuous conductive film, the method comprising:
electrodepositing the conductor onto the continuous conductive film from a process solution including at least one inhibiting additive configured to adsorb strongly on the conductor and weakly on the continuous conductive film being electrodeposited, wherein electrodepositing the conductor forms a discontinuous layer exposing a surface portion of the continuous conductive film;
having a first concentration of the at least one inhibiting additive adsorbed on the discontinuous layer while having a second concentration of the at least one inhibiting additive adsorbed on the exposed surface portion of the continuous conductive film, wherein the first concentration is higher than the second concentration; and
continuing electrodepositing the conductor wherein the conductor electrodeposits on the surface portion of the continuous conductive film at a higher rate than on the discontinuous layer, thus forming a defect-free layer.
2 . The method of claim 1 , wherein the defect-free layer is a conformal layer lining the continuous conductive film.
3 . The method of claim 1 , further comprising electrodepositing onto the defect-free layer to fill the at least one cavity with the conductor.
4 . The method of claim 3 , further comprising continuing electrodepositing the conductor, wherein continuing electrodepositing is performed using an other process solution comprising an other additive.
5 . The method of claim 4 , wherein the other additive comprises accelerator molecules.
6 . The method of claim 1 , wherein the inhibiting additive comprises suppressor molecules.
7 . The method of claim 1 , wherein the continuous conductive film is a nucleation layer.
8 . The method of claim 7 , wherein the nucleation layer comprises ruthenium.
9 . The method of claim 7 , wherein the nucleation layer comprises a material selected from the group consisting of W, Mo, MoN, and WCN.
10 . The method of claim 1 , wherein the conductor is copper.
11 . The method of claim 1 , wherein the inhibiting additive comprises leveler molecules.
12 . The method of claim 1 , wherein the inhibiting additive comprises suppressor and leveler molecules.
13 . A method of forming a defect-free conformal conductive layer coating a surface of a wafer surface including at least one cavity, the wafer surface including the at least one cavity being lined with a nucleation layer, the method comprising:
electrodepositing a conductive layer onto the nucleation layer, wherein the conductive layer partially exposes a portion of the nucleation layer;
applying a solution onto the conductive layer and the exposed portion of the nucleation layer, wherein the solution includes at least one additive configured to adsorb strongly on the conductive layer and weakly on the nucleation layer;
adsorbing a first concentration of the at least one additive on the conductive layer while adsorbing a second concentration of the at least one additive on the portion of the nucleation layer; and
electrodepositing a conductor on the conductive layer and the portion of the nucleation layer to form a defect-free conformal conductive layer thereon, wherein the conductor electrodeposits on the exposed portion of the nucleation layer at a higher rate than on the conductive layer.
14 . The method of claim 13 , further comprising depositing the nucleation layer onto the wafer surface including the at least one cavity using atomic layer deposition process prior to electrodepositing the conductive layer onto the nucleation layer.
15 . The method of claim 13 , wherein the first concentration of the at least one additive is higher than the second concentration of the at least one additive.
16 . The method of claim 13 , wherein the conductor is copper.
17 . The method of claim 13 , wherein the at least one additive comprises suppressor molecules.
18 . The method of claim 13 , wherein the at least one additive comprises leveler molecules.
19 . The method of claim 13 , wherein the at least one additive comprises leveler and suppressor molecules.
20 . A method of electrodepositing a conductor on a wafer surface having at least one cavity, wherein the wafer surface is lined with a nucleation layer, the method comprising electrodepositing a conductive layer on the nucleation layer, wherein electrodepositing comprises applying a solution to the wafer surface and the solution comprises at least one suppressor or leveler configured to adsorb strongly on material of the conductive layer and weakly on material of the nucleation layer.
21 . The method of claim 20 , wherein electrodepositing on any exposed portion of the nucleation layer takes place at a higher rate than electrodepositing on the conductive layer.
22 . The method of claim 21 , wherein a first concentration of the at least one suppressor or leveler on the conductive layer is higher than a second concentration of the at least one suppressor or leveler on any exposed portion of the nucleation layer.
23 . The method of claim 20 , wherein the at least one suppressor or leveler comprises suppressor molecules.
24 . The method of claim 20 , wherein the at least one suppressor or leveler comprises leveler molecules.