Method for analyzing metal element on surface of wafer
View Patent ↗Various kinds of metal elements existing on the surface of a wafer are analyzed with higher sensitivity. A high concentration HF solution is dropped onto a surface of a wafer. By providing the droplets of high concentration HF solution, the native oxide film on the surface of the wafer is dissolved into the solution, and the metal elements or compounds thereof existing in vicinity of the surface of the wafer are eliminated from the wafer and are incorporated into the high concentration HF solution. The droplets formed by agglomerating the high concentration HF solution are aggregated at a predetermined position on the surface of the wafer. Then, the recovered droplet of the high concentration HF solution is dried. The aggregated material is irradiated with X-ray at an angle for promoting total reflection, and the total reflection X-ray fluorescence spectrometry is conducted to detect the emitted X-ray.
1. A method for analyzing a metal element, comprising:
dropping a liquid on a surface of a semiconductor wafer having an oxide film formed thereon to dissolve said oxide film in said liquid, thereby incorporating a metal element contained in said semiconductor wafer into said liquid, said liquid containing hydrofluoric acid at a concentration of equal to or greater than 20 wt %;
aggregating said liquid incorporating said metal element on said semiconductor wafer;
drying said aggregated liquid to obtain an aggregated material containing said metal element on said semiconductor wafer; and
analyzing said metal element by detecting fluorescent X-ray emitted from said semiconductor wafer, said fluorescent X-ray being emitted by irradiating X-ray upon said semiconductor wafer at an incident angle of providing a total reflection thereof.
2. The method according to claim 1 , wherein said semiconductor wafer is a silicon wafer.
3. The method according to claim 1 , wherein said metal element contains one, two or more element(s) selected from the group consisting of Ti, Fe, In, Ce, Zr, Hf, Y, La, Ru, Pt, Ir, Rh, Pd and Os.
4. The method according to claim 1 , wherein said analyzing said metal element includes analyses of:
at least one element selected from a group (i) consisting of Ti, Fe and In; and
at least one element selected from a group (ii) consisting of Ce, Zr, Hf, Y, La, Ru, Pt, Ir, Rh, Pd and Os simultaneously.
5. The method according to claim 1 , wherein the concentration of said hydrofluoric acid in said liquid is equal to or greater than 40 wt %.
6. The method according to claim 1 , wherein said aggregated material containing said metal element is incorporated within a spot of said X-ray irradiating on the surface of said semiconductor wafer.
7. The method according to claim 1 , wherein said metal element is a metal element contained in a metal impurity adhered onto the surface of said semiconductor wafer.
8. The method according to claim 7 , wherein said metal impurity contains a component that is not soluble into said liquid.
9. The method according to claim 1 , wherein said liquid contains H 2 O 2 .
10. The method according to claim 1 , wherein a line flux of the x-ray is about 10 mm φ, and a volume of the liquid is from 50 μL to 1000 μL.
11. The method according to claim 1 , wherein said aggregating is performed with recovery bar.
12. The method according to claim 11 , wherein said recovery bar comprises polytetrafluoroethylene.
13. The method of claim 11 , wherein the recovery bar moves from a peripheral portion toward a center portion of the semiconductor wafer while rotating the semiconductor wafer.
14. The method according to claim 1 , wherein said drying is performed at about 100° C. for 1 to 10 minutes.
15. The method according to claim 1 , wherein the irradiating X-ray is a WLβ ray, a AgKα ray or a MoKα ray.