Angled etch for surface smoothing
Methods of processing a feature on a semiconductor workpiece are disclosed. The method is performed after features have been created on the workpiece. An etching species may be directed toward the workpiece at a non-zero tilt angle. In certain embodiments, the tilt angle may be 30° or more. Further, the etching species may also be directed with a non-zero twist angle. In certain embodiments, the etching species may sputter material from the features, while in other embodiments, the etching species may be a chemically reactive species. By adjusting the tilt and twist angles, as well as the flow rate of the etching species and the exposure time, the LER and LWR of a feature may be reduced with minimal impact of the CD of the feature.
1. A method of processing a feature on a workpiece, comprising:
patterning a resist layer disposed on the workpiece;
etching the workpiece while the resist layer is in place to define the feature on the workpiece, wherein the feature comprises a critical dimension, a line width roughness, and line edge roughness; and
performing an etch process using a twist angle up to 10° and a high tilt angle, wherein ions are directed toward the feature and the high tilt angle is between 30° and 80°, and wherein after the etch process, the critical dimension of the feature is changed by less than 2 nanometers and the line width roughness and the line edge roughness of the feature are each reduced by at least 15%.
2. The method of claim 1 , wherein the high tilt angle is between 50° and 65°.
3. The method of claim 1 , wherein the etch process utilizes a sputtering species.
4. The method of claim 1 , wherein the etch process utilizes a chemically reactive species.
5. The method of claim 1 , wherein the line width roughness and the line edge roughness are each reduced by at least 20%.
6. The method of claim 1 , wherein a non-zero twist angle is used during the etch process.
7. A method of processing a feature on a workpiece, wherein the feature comprises at least two layers of different materials, comprising:
patterning a resist layer disposed on the workpiece;
etching the workpiece while the resist layer is in place to define the feature on the workpiece, wherein the feature comprises a critical dimension, a line width roughness, and line edge roughness;
performing a first etch process using a first species, a first twist angle and a first high tilt angle, wherein ions of the first species directed toward the feature, the first twist angle is up to 10° and the first high tilt angle between 30° and 80°; and
performing a second etch process using a second species, a second twist angle and a second high tilt angle, wherein ions of the second species are directed toward the feature, the second twist angle is up to 10° and the second high tilt angle is between 30° and 80°, and wherein after the first etch process and second etch process, the critical dimension of the feature is chanced by less than 2 nanometers and the line width roughness and the line edge roughness of the feature are each reduced by at least 15%.
8. The method of claim 7 , wherein one of the first species and the second species is selected to selectively etch one of the at least two layers of the feature.
9. The method of claim 7 , wherein the first high tilt angle is different from the second high tilt angle.
10. The method of claim 7 , wherein at least one of the first species or the second species comprises a sputtering species.
11. The method of claim 7 , wherein at least one of the first species or the second species comprises a chemically reactive species.
12. The method of claim 7 , wherein the first high tilt angle is between 50° and 65°.
13. The method of claim 7 , wherein the second high tilt angle is between 50° and 65°.
14. The method of claim 7 , wherein the line width roughness and the line edge roughness are each reduced by at least 20%.
15. The method of claim 7 , wherein a non-zero twist angle is used during at least one of the first etch process and the second etch process.