Cleaning solution for removing damaged portion of ferroelectric layer and cleaning method using the same
A cleaning solution for use in removing a damaged portion of a ferroelectric layer, and a cleaning method using the solution. The cleaning solution includes a fluoride, an organic acid with carboxyl group, an alkaline pH adjusting agent and water.
1. A method of cleaning an integrated circuit having a ferroelectric layer, the method comprising:
providing an integrated circuit substrate having an exposed ferroelectric layer with a damage portion; and
selectively removing a damaged portion of the exposed ferroelectric layer with a cleaning solution by contacting the exposed ferroelectric layer with said cleaning solution, wherein said cleaning solution comprises a fluoride, an organic acid having a carboxyl group, an alkaline pH adjusting agent, and water.
2. The method of claim 1 , wherein the exposed ferroelectric layer includes a surface of the ferroelectric layer passed through annealing after deposition on the integrated circuit substrate, and the step of contacting the exposed ferroelectric layer with said cleaning solution includes etching back the ferroelectric layer by about 100 Å to about 500 Å from a top portion of the ferroelectric layer.
3. The method of claim 1 , wherein the exposed ferroelectric layer is interposed between upper and lower electrode layers, and the method further comprises forming a capacitor by patterning the upper electrode layer, the ferroelectric layer and the lower electrode layer, before contacting the exposed ferroelectric layer with said cleaning solution.
4. The method of claim 1 , wherein the pH of the cleaning solution is greater than 5 to about 6.0.
5. The method of claim 1 , wherein the fluoride is hydrogen fluoride, hydroboron tetrafluoride or ammonium fluoride.
6. The method of claim 1 , wherein the organic acid is formic acid, acetic acid or citric acid.
7. The method of claim 1 , wherein the alkaline pH adjusting agent is ammonium hydroxide, potassium hydroxide, tetramethylammonium hydroxide or tetraethylammonium hydroxide.
8. The method of claim 1 , wherein the content of the fluoride is about 0.01% to about 1% by weight based on the total weight of said cleaning solution.
9. The method of claim 1 wherein the content of the organic acid with carboxyl group is about 1% to about 50% by weight based on the total weight of said cleaning solution.
10. The method of claim 1 , wherein the content of the alkali pH adjusting agent is about 0.25% to about 15% by weight based on the total weight of said cleaning solution.
11. A method of cleaning an integrated circuit, the method comprising:
providing an integrated circuit having an exposed ferroelectric layer; and
selectively removing a damaged portion of the exposed ferroelectric layer with a cleaning solution by contacting the exposed ferroelectric layer with said cleaning solution, wherein said cleaning solution comprises a fluoride, an organic acid having a carboxyl group, an alkaline pH adjusting agent, and water, and wherein the organic acid dissolves a reduced metallic component of the ferroelectric layer.
12. The method of claim 11 , further comprises the step of:
depositing and annealing the ferroelectric layer prior to selectively removing the damage portion of the ferroelectric layer.
13. The method of claim 11 , wherein the step of selectively removing the damage portion of the ferroelectric layer includes removing a semi-stable pyrochlore structure that appears from a top portion of the ferroelectric layer to a predetermined depth.
14. The method of claim 11 , wherein the pH of the cleaning solution is greater than 5 to about 6.0.
15. The method of claim 11 , wherein contacting the exposed ferroelectric layer with said cleaning solution includes the exposed ferroelectric layer in contact with said cleaning solution for about 30 to about 600 seconds such that the damaged portion of the ferroelectric layer is completely removed.
16. The method of claim 11 , wherein the exposed ferroelectric layer includes a surface of the ferroelectric layer passed through annealing after deposition on the integrated circuit substrate, and the step of contacting the exposed ferroelectric layer with said cleaning solution includes etching back the ferroelectric layer by about 100 Å to about 500 Å from a top portion of the ferroelectric layer.
17. The method of claim 11 , wherein the exposed ferroelectric layer is interposed between upper and lower electrode layers, and the method further comprises forming a capacitor by patterning the upper electrode layer, the ferroelectric layer and the lower electrode layer, before contacting the exposed ferroelectric layer with said cleaning solution.
18. The method of claim 11 , wherein the fluoride is hydrogen fluoride, hydroboron tetrafluoride, or ammonium fluoride.
19. The method of claim 11 , wherein the organic acid is formic acid, acetic acid, or citric acid.
20. The method of claim 11 , wherein the alkaline pH adjusting agent is ammonium hydroxide, potassium hydroxide, tetramethylammonium hydroxide, or tetraethylammonium hydroxide.
21. The method of claim 11 , wherein the content of the fluoride is about 0.01% to about 1% by weight based on the total weight of said cleaning solution.
22. The method of claim 11 , wherein the content of the organic acid with carboxyl group is about 1% to about 5 0 % by weight based on the total weight of said cleaning solution.
23. The method of claim 11 , wherein the content of the alkali pH adjusting agent is about 0.25% to about 15% by weight based on the total weight of said cleaning solution.
24. The method of claim 11 , wherein the ferroelectric layer is formed of a STO, a BST, a PZT, or a PLZT layer.