Control of bevel etch film profile using plasma exclusion zone rings larger than the wafer diameter
A method of cleaning a bevel edge of a semiconductor substrate is provided. A semiconductor substrate is placed on a substrate support in a reaction chamber of a plasma processing apparatus. The substrate has a dielectric layer overlying a top surface and a bevel edge of the substrate, the layer extending above and below an apex of the bevel edge. A process gas is introduced into the reaction chamber and energized into a plasma. The bevel edge is cleaned with the plasma so as to remove the layer below the apex without removing all of the layer above the apex.
1. A method of cleaning a bevel edge of a semiconductor substrate, comprising:
placing a semiconductor substrate on a substrate support in a reaction chamber of a plasma processing apparatus, the substrate having a dielectric layer overlying a top surface and a bevel edge of the substrate, the layer extending above and below an apex of the bevel edge;
introducing a process gas into the reaction chamber;
energizing the process gas into a plasma; and
cleaning the bevel edge with the plasma so as to remove the layer below the apex without removing all of the layer above the apex;
wherein the layer is not etched at portions of the top surface of the substrate extending inwardly from the bevel edge.
2. The method of claim 1 , wherein cleaning the bevel edge with the plasma further comprises etching the layer with a higher etch rate at the apex than inwardly of the apex along the upper portion of the bevel edge.
3. The method of claim 1 , wherein the layer is an interlayer dielectric; and the plasma processing apparatus is a bevel etcher.
4. The method of claim 1 , wherein the process gas comprises an oxygen-based gas selected from O 2 and CO 2 .
5. The method of claim 4 , wherein the process gas further comprises a fluorine-based gas.
6. The method of claim 5 , wherein the fluorine-based gas includes CF 4 , SF 6 , NF 3 or C 2 F 6 .
7. The method of claim 1 , wherein the cleaning removes etch byproducts on the bevel edge and/or on a backside of the substrate.
8. The method of claim 1 , wherein the substrate is a semiconductor wafer and the cleaning is carried out with a bevel etch plasma processing apparatus, wherein a portion of an upper plasma exclusion zone ring closest to the wafer has an outer diameter equal to or greater than an outer diameter of the wafer.
9. The method of claim 1 , wherein the substrate is a 300 mm diameter silicon wafer.
10. The method of claim 1 , wherein the layer is a low-k or high-k dielectric layer.
11. The method of claim 1 , wherein the layer is silicon oxide, organosilicate glass (OSG), fluorinated silica glass (FSG), carbon-doped oxide, mesoporous and/or nanoporous glass, organic polymer, borophosphosilicate glass (BPSG) or tetraethylorthosilicate (TEOS).