Apparatus and method to improve resist line roughness in semiconductor wafer processing
View Patent ↗A process for prohibiting amino group transport from the top surface of a layered semiconductor wafer to a photoresist layer introduces a thin film oxynitride over the silicon nitride layer using a high temperature step of nitrous oxide (N 2 O) plus oxygen (O 2 ) at approximately 300° C. for about 50 to 120 seconds. By oxidizing the silicon nitride layer, the roughness resulting from the adverse affects of amino group transport eliminated. Moreover, this high temperature step, non-plasma process can be used with the more advanced 193 nanometer technology, and is not limited to the 248 nanometer technology. A second method for exposing the silicon nitride layer to an oxidizing ambient, prior to the application of antireflective coating, introduces a mixture of N 2 H 2 and oxygen (O 2 ) ash at a temperature greater than or equal to 250° C. for approximately six minutes. This is followed by an O 2 plasma clean and/or an Ozone clean, and then the subsequent layering of the ARC and photoresist.
1. A method of applying a photoresist to a semiconductor substrate in a process chamber comprising:
providing said substrate having a silicon nitride layer thereon;
depositing an oxynitride layer directly over and in contact with said silicon nitride layer, as a means to prevent amino group transport;
depositing an antireflective coating on said oxynitride layer, such that said oxynitride layer is directly between and in contact with said silicon nitride layer and said antireflective coating;
introducing a photoresist mask directly over and in contact with said antireflective coating;
applying N 2 H 2 combined with O 2 ash at a temperature exceeding 250° C. and exposing said semiconductor substrate to a plasma for six minutes, prior to depositing said antireflective coating and introducing said photoresist and
further processing said substrate with said photoresist mask to form a pattern having dimensions that are unaffected by said amino group transport.
2. The method of claim 1 further comprising depositing said oxynitride layer at a thickness of less than 100 angstroms.
3. The method of claim 1 further comprising depositing said oxynitride layer at a thickness of less than 10 angstroms.
4. The method of claim 1 further comprising depositing said oxynitride layer at a thickness of approximately 5 to 10 angstroms.
5. The method of claim 1 comprising depositing said oxynitride layer having a compound of the form SiO x N y .
6. The method of claim 1 wherein said antireflective coating is either an organic or inorganic material.
7. The method of claim 1 further comprising depositing said antireflective coating using spin-coating.
8. The method of claim 1 wherein said photoresist is exposed to radiation in the ultraviolet regime.
9. The method of claim 1 wherein said step of depositing an oxynitride layer comprises converting said silicon nitride layer to SiO x N y via oxidation.
10. The method of claim 1 further comprising depositing said oxynitride layer at a thickness of approximately 10 to 20 angstroms.
11. The method of claim 1 wherein said oxynitride layer is deposited using an LPCVD process.