Method of correcting deviations of critical dimensions of patterns formed on a wafer in a EUVL process
An embodiment includes a method of correcting deviations of critical dimensions of patterns formed on a wafer in an extreme ultraviolet lithography (EUVL) process. The embodiment includes preparing a reflection photo mask having a reflection layer and absorption patterns that are formed on the reflection layer to define reflection regions therebetween. An exposure process is performed using the reflection photo mask, thereby forming the patterns on the wafer. Critical dimensions of the patterns are measured. A reference critical dimension is set based on the measured critical dimensions of the patterns. Critical dimension deviations are determined by comparing the measured critical dimensions of the patterns with the reference critical dimension. Energy beams having energies corresponding to the critical dimension deviations are locally irradiated onto the reflection layer, thus locally varying the thickness of the reflection layer.
1. A method of correcting deviations of critical dimensions of patterns formed on a wafer in an extreme ultraviolet lithography process, the method comprising:
preparing a reflection photo mask having a reflection layer; and
locally varying the thickness of the reflection layer by locally irradiating an energy beam onto the reflection layer.
2. The method according to claim 1 , wherein locally varying the thickness of the reflection layer includes locally reducing the thickness of the reflection layer.
3. The method according to claim 2 , wherein locally reducing the thickness of the reflection layer includes locally lowering the reflectance of the reflection layer.
4. The method according to claim 1 , wherein the energy beam is an electron beam, an ion beam, or an electromagnetic radiation beam.
5. The method according to claim 1 , wherein the energy beam is a focused electron beam.
6. The method according to claim 1 , wherein the reflection layer is a multiple layer obtained by alternately laminating two different kinds of layers.
7. The method according to claim 1 , wherein the reflection layer is a multiple layer obtained by alternately laminating a molybdenum layer and a silicon layer.
8. The method according to claim 1 , wherein the reflection photo mask includes:
a mask substrate on which the reflection layer is formed; and
absorption patterns disposed on the reflection layer.
9. The method according to claim 8 , wherein the reflection photo mask further includes:
a capping layer interposed between the absorption patterns and the reflection layer; and
a buffer layer interposed between the capping layer and the absorption patterns.
10. A method of correcting deviations of critical dimensions of patterns formed on a wafer in an extreme ultraviolet lithography process, the method comprising:
preparing a reflection photo mask having a reflection layer and absorption patterns that are formed on the reflection layer to define reflection regions therebetween;
forming the patterns on the wafer by performing an exposure process using the reflection photo mask;
measuring critical dimensions of the patterns;
setting a reference critical dimension based on the measured critical dimensions of the patterns;
determining critical dimension deviations by comparing the measured critical dimensions of the patterns with the reference critical dimension; and
locally varying the thickness of the reflection layer by locally irradiating an energy beam, which has an energy corresponding to the critical dimension deviations, onto the reflection layer.
11. The method according to claim 10 , wherein locally varying the thickness of the reflection layer includes locally reducing the thickness of the reflection layer.
12. The method according to claim 11 , wherein locally reducing the thickness of the reflection layer includes locally lowering the reflectance of the reflection layer.
13. The method according to claim 12 , wherein when the measured critical dimensions of the patterns are critical dimensions of clear patterns transferred from the reflection regions, and the reference critical dimension is set to a minimum of the measured critical dimensions of the patterns.
14. The method according to claim 12 , wherein when the measured critical dimensions of the patterns are critical dimensions of dark patterns transferred from the absorption patterns, and the reference critical dimension is set to a maximum of the measured critical dimensions of the patterns.
15. The method according to claim 10 , wherein the energy beam is an electron beam, an ion beam, or an electromagnetic radiation beam.
16. The method according to claim 10 , wherein the energy beam is a focused electron beam.
17. The method according to claim 10 , wherein the reflection layer is a multiple layer obtained by alternately laminating two or more different kinds of layers.
18. The method according to claim 10 , wherein the reflection layer is a multiple layer obtained by alternately laminating a molybdenum layer and a silicon layer.
19. The method according to claim 10 , wherein the reflection photo mask further includes:
a capping layer interposed between the absorption patterns and the reflection layer; and
a buffer layer interposed between the capping layer and the absorption patterns.
20. A method of varying critical dimensions of patterns formed on a wafer, the method comprising:
providing a reflection photo mask having a reflection layer; and
locally modifying the reflection layer by locally irradiating an energy beam onto the reflection layer.
21. The method according to claim 20 , wherein locally modifying the reflection layer includes locally changing the reflectance of the reflection layer.
22. The method according to claim 20 , wherein locally modifying the reflection layer includes thermally activating a portion of the reflection layer.