Process for improving photoresist pillar adhesion during MRAM fabrication
A method for improving photo resist adhesion to an underlying hard mask layer. The method includes a cleaning step that includes applying tetramethylammonium hydroxide (TMAH) to coat a hard mask layer of a wafer. The method further includes puddle developing the wafer for a first desired amount of time, and rinsing the wafer in running water for a second desired amount of time. The method further includes spin drying the wafer, and baking the wafer for a third desired amount of time. The method concludes with the proceeding of subsequent photolithographic processes on the wafer.
1. A method for improving photo resist adhesion to an underlying hard layer, comprising:
cleaning the surface of the hard layer by applying tetramethylammonium hydroxide (TMAH) to coat a hard mask layer of the wafer;
puddle developing the wafer for a first desired amount of time;
rinsing the wafer for a second desired amount of time;
spin drying the wafer;
baking the wafer for a third desired amount of time; and
proceeding with subsequent photolithographic processes on the wafer, which fabricates pillars therein.
2. The method of claim 1 , wherein the first desired amount of time is approximately 2 minutes.
3. The method of claim 1 , wherein the second desired amount of time is approximately 1 minute.
4. The method of claim 1 , wherein the third desired amount of time is approximately 5 minutes.
5. The method of claim 1 , wherein the rinsing uses running water and the water is deionized water.
6. The method of claim 1 , further comprising cooling on a chilled plate for approximately one minute subsequent to the baking.
7. The method of claim 1 , further comprising treating the wafer with hexamethyldisilazane (HMDS) subsequent to the baking.
8. The method of claim 1 , wherein the underlying hard mask layer is tantalum nitride (TaN).
9. A method for improving photo resist pillar adhesion to a wafer, the method comprising:
cleaning a surface of tantalum nitride hard layer by applying tetramethylammonium hydroxide (TMAH) to coat the tantalum nitride hard layer of the wafer;
puddle developing the wafer for a first desired amount of time;
rinsing the wafer in running water for a second desired amount of time;
spin drying the wafer;
baking the wafer for a third desired amount of time; and
proceeding with subsequent photolithographic processes on the wafer.
10. The method of claim 9 , wherein the first desired amount of time is approximately 2 minutes.
11. The method of claim 9 , wherein the second desired amount of time is approximately 1 minute.
12. The method of claim 9 , wherein the third desired amount of time is approximately 5 minutes.
13. The method of claim 9 , wherein the water is deionized water.
14. The method of claim 9 , further comprising treating the wafer with hexamethyldisilazane (HMDS) subsequent to the baking.
15. The method of claim 9 , wherein the wafer is treated with hexamethyldisilazane (HMDS) subsequent to the baking.
16. A method for manufacturing an MRAM device, the method comprising:
applying tetramethylammonium hydroxide (TMAH) to coat a tantalum nitride hard layer of a wafer;
submerging the wafer in a dish of TMAH for a first desired amount of time;
rinsing the wafer in running water for a second desired amount of time;
spin drying the wafer;
baking the wafer for a third desired amount of time; and
proceeding with subsequent photolithographic processes on the wafer.
17. The method of claim 16 wherein the applying is a cleaning process and wherein the first desired amount of time is approximately 2 minutes.
18. The method of claim 17 , wherein the second desired amount of time is approximately 1 minute.
19. The method of claim 18 , wherein the third desired amount of time is approximately 5 minutes.
20. The method of claim 16 , wherein the water is deionized water.