Detecting the cleanness of wafer after post-CMP cleaning

1. A method comprising:

performing a Chemical Mechanical Polish (CMP) process on a wafer;

performing a post-CMP cleaning process on the wafer using a chemical solution;

rinsing the wafer with water;

drying the wafer; and

after the drying the wafer, determining cleanness of the wafer by generating a Fourier Transform Infrared Spectroscopy (FTIR) spectrum or a Raman spectrum from the wafer.

2. The method of claim 1 , wherein the determining cleanness of the wafer comprises comparing characteristic peaks of the FTIR spectrum or the Raman spectrum with characteristic peaks stored in a database to find a material of a brush used in the post-CMP cleaning process.

3. The method of claim 2 , wherein the determining cleanness of the wafer further comprises comparing characteristic peaks of the FTIR spectrum or the Raman spectrum with characteristic peaks of aluminum oxide.

4. The method of claim 2 , wherein the determining cleanness of the wafer comprises comparing characteristic peaks of the FTIR spectrum or the Raman spectrum with characteristic peaks of Polyvinyl Alcohol (PVA).

5. The method of claim 2 , wherein the determining cleanness of the wafer comprises comparing characteristic peaks of the FTIR spectrum or the Raman spectrum with characteristic peaks of the material of the brush that comprises Polyvinyl chloride (PVC).

6. The method of claim 2 , wherein the determining cleanness of the wafer comprises comparing characteristic peaks of the FTIR spectrum or the Raman spectrum with characteristic peaks of the material of the brush that comprises Benzotriazole (BTA).

7. The method of claim 1 , wherein the determining cleanness of the wafer comprises generating the FTIR spectrum.

8. The method of claim 7 further comprising:

projecting an infrared light on the wafer;

receiving a reflected light reflected from the wafer into a detecting unit; and

providing the reflected light to a processing unit to generate the FTIR spectrum.

9. The method of claim 1 , wherein the determining cleanness of the wafer comprises generating the Raman spectrum.

10. The method of claim 9 further comprising:

projecting a laser beam on the wafer;

receiving a reflected laser beam reflected from the wafer into a detecting unit; and

providing the reflected laser beam to generate the Raman spectrum.

11. A method comprising:

performing a Chemical Mechanical Polish (CMP) process on a wafer;

performing a post-CMP cleaning process on the wafer using a brush;

rinsing the wafer with water;

projecting an infrared light on a surface of the wafer to generate a reflected infrared light;

generating a Fourier Transform Infrared Spectroscopy (FTIR) spectrum from the reflected infrared light; and

comparing characteristic peaks in the FTIR spectrum with stored characteristic peaks to determine materials left on the surface of the wafer, wherein the determined materials comprise a material of the brush.

12. The method of claim 11 , wherein characteristic peaks of water in the FTIR spectrum are excluded when the characteristic peaks in the FTIR spectrum are compared to the stored characteristic peaks.

13. The method of claim 11 , wherein characteristic peaks of carbon dioxide in the FTIR spectrum are excluded when the characteristic peaks in the FTIR spectrum are compared to the stored characteristic peaks.

14. The method of claim 11 , wherein the infrared light is projected on the wafer in a direction not perpendicular to the surface of the wafer.

15. A method comprising:

performing a Chemical Mechanical Polish (CMP) process on a wafer using a slurry;

performing a post-CMP cleaning process on the wafer using a brush;

drying the wafer; and

finding a material of the brush on a surface of the wafer to determine cleanness of the surface of the wafer.

16. The method of claim 15 , wherein the finding the material further comprises finding the material in the slurry.

17. The method of claim 15 , wherein the finding the material comprises:

projecting an infrared light on a surface of the wafer to generate a reflected infrared light;

generating a Fourier Transform Infrared Spectroscopy (FTIR) spectrum from the reflected infrared light; and

comparing characteristic peaks in the FTIR spectrum with stored characteristic peaks of the material in the brush.

18. The method of claim 15 , wherein the finding the material comprises:

projecting a laser beam on a surface of the wafer to generate a reflected laser beam;

generating a spectrum from the reflected laser beam; and

comparing characteristic peaks in the spectrum with stored characteristic peaks of the material of the brush.

19. The method of claim 15 , wherein the material of the brush comprises Polyvinyl Alcohol (PVA), Polyvinyl chloride (PVC), or Benzotriazole (BTA).

20. The method of claim 2 , wherein the brush contacts the wafer, and is rotated in the post-CMP cleaning process.