Methods and apparatuses for performing wafer level characterization of a plasmon element
Improved pump-probe testing methods and apparatuses for measuring the performance of a plasmon element at wafer level are provided. In one embodiment, the apparatus includes a light source configured to output a first light beam on a grating located at a first end of a waveguide, the waveguide being configured to couple energy of the first light beam to the plasmon element located at a second end of the waveguide, and an optical probe assembly positioned above a top surface of the wafer. The optical probe assembly is configured to direct a second light beam on an area of the wafer including the plasmon element and detect a portion of the second light beam reflected from the area.
1. An apparatus for measuring performance of a plasmon element on a wafer, the apparatus comprising:
a light source configured to output a first light beam on a grating located at a first end of a waveguide, the waveguide being configured to couple energy of the first light beam to the plasmon element located at a second end of the waveguide; and
an optical probe assembly positioned above a top surface of the wafer and configured to:
direct a second light beam on an area of the wafer including the plasmon element; and
detect a portion of the second light beam reflected from the area.
2. The apparatus of claim 1 , wherein the detected portion is used to determine a coupling efficiency of the plasmon element, and the coupling efficiency corresponds to an amount of the energy of the first light beam transferred to the plasmon element.
3. The apparatus of claim 1 , wherein the first light beam has a wavelength between about 700 nm and about 1000 nm, inclusive.
4. The apparatus of claim 1 , wherein the first light beam is modulated at a first frequency, and the optical probe assembly is configured to detect a variation of the portion of the second light at the first frequency.
5. The apparatus of claim 1 , wherein the optical probe assembly is configured to detect a change in reflectivity of the area induced by the energy of the first light beam coupled to the plasmon element.
6. The apparatus of claim 5 , wherein the change in the reflectivity of the area correlates to a temperature change of the plasmon element.
7. The apparatus of claim 1 , wherein the optical probe assembly is configured to output the second light beam incident upon a surface of the area at an angle substantially normal to the surface.
8. The apparatus of claim 1 , wherein the area including the plasmon element is a fabricated surface at an angle with respect to the top surface of the wafer, and the plasmon element is exposed at the fabricated surface.
9. The apparatus of claim 1 , wherein the plasmon element comprises a near-field transducer.
10. The apparatus of claim 1 , wherein the optical probe assembly comprises an objective lens spaced apart from the area at a distance of about 1 mm to about 10 mm, inclusive.
11. The apparatus of claim 10 , wherein the objective lens is spaced apart from the area at about 6 mm.
12. The apparatus of claim 1 , wherein the first light beam is incident on the grating at an angle with respect to the top surface of the wafer between about 10 degrees and about 80 degrees, inclusive.
13. A method for measuring performance of a plasmon element on a wafer, the method comprising:
outputting from a light source a first light beam on a grating located at a first end of a waveguide, the waveguide being configured to couple energy of the first light beam to the plasmon element located at a second end of the waveguide;
positioning an optical probe assembly above a top surface of the wafer; and
operating the optical probe assembly to:
direct a second light beam on an area of the wafer including the plasmon element; and
detect a portion of the second light beam reflected from the area.
14. The method of claim 13 , further comprising determining a coupling efficiency of the plasmon element using the detected portion, wherein the coupling efficiency corresponds to an amount of the energy of the first light beam transferred to the plasmon element.
15. The method of claim 14 , wherein the coupling efficiency of the energy of the first light beam coupled to the plasmon element is measured before dicing the wafer.
16. The method of claim 15 , wherein the wafer was formed using a preselected manufacturing process, the method further comprising modifying the preselected manufacturing process for a subsequent wafer based on a result of the measured coupling efficiency.
17. The method of claim 13 , wherein the first light beam has a wavelength between about 700 nm and about 1000 nm, inclusive.
18. The method of claim 13 , wherein the first light beam is modulated at a first frequency, and wherein the operating the optical probe assembly further comprises detecting a variation of the portion of the second light beam at the first frequency.
19. The method of claim 13 , wherein the operating the optical probe assembly further comprises detecting a change in reflectivity of the area induced by the energy of the first light beam coupled to the plasmon element.
20. The method of claim 19 , wherein the change in the reflectivity of the area correlates to a temperature change of the plasmon element.
21. The method of claim 13 , wherein the operating the optical probe assembly further comprises outputting the second light beam incident upon a surface of the area at an angle substantially normal to the surface.
22. The method of claim 13 , wherein the area including the plasmon element is a fabricated surface at an angle with respect to the top surface of the wafer, and the plasmon element is exposed at the fabricated surface.
23. The method of claim 13 , wherein the plasmon element comprises a near-field transducer.
24. The method of claim 13 , wherein the optical probe assembly comprises an objective lens spaced apart from the area at a distance of about 1 mm to about 10 mm, inclusive.
25. The method of claim 24 , wherein the objective lens is spaced apart from the area at about 6 mm.
26. The method of claim 13 , wherein the first light beam is incident on the grating at an angle with respect to the top surface of the wafer between about 10 degrees and about 80 degrees, inclusive.
27. The method of claim 13 , wherein the coupling efficiency of the energy of the first light beam coupled to the plasmon element is measured before dicing the wafer.
28. The method of claim 13 , wherein the wafer was formed using a preselected manufacturing process, the method further comprising modifying the preselected manufacturing process for a subsequent wafer based on a result of the measured coupling efficiency.