Melt detection systems and methods of using the same
High bandwidth time-and-space resolved phase transition microscopy systems configured to detect melt onset in a wafer being processed by laser annealing systems with ultra-short dwell times and spot size.
1. A method of detecting the onset of melt in a region of interest of a semiconductor surface during a laser annealing process, the method comprising:
irradiating the semiconductor surface with pulses of radiation during the laser annealing process;
capturing, with a pixelated image sensor, an image that captures a portion of the radiation that has reflected off of the semiconductor surface; and
processing the image to detect a new discontinuity in an intensity of the reflected radiation in a region of interest of the image, the new discontinuity indicating the onset of melt of the semiconductor in the region of interest;
wherein the processing includes the detection of an intensity in a captured image frame that exceeds a threshold value, the threshold value corresponding to a maximum reflectivity of the semiconductor in the solid phase, or a reflectivity of the semiconductor on a melt-side of a solid-liquid phase transition.
2. The method of claim 1 , wherein the laser annealing process includes performing sequential sweeps across the semiconductor surface at a sweep frequency, f sweep , wherein the irradiating includes emitting pulses of radiation at a pulse frequency, f Probe , wherein f Probe <f sweep .
3. The method of claim 2 , wherein f Probe is a rational beat frequency of f sweep .
4. The method of claim 2 , wherein f Probe is synchronized with f sweep , and multiple pulses of radiation are captured in a single image frame by the pixelated image sensor.
5. The method of claim 1 , wherein the irradiating includes emitting a random distribution of pulses and the processing includes applying broadband statistics to the captured images to detect the new discontinuity.
6. The method of claim 1 , wherein the pixelated image sensor is a CCD or CMOS image sensor.
7. The method of claim 1 , wherein the processing includes application of one or more of fitting algorithms, edge detection algorithms, eigenbasis decompositions, or feed-forward classifiers.
8. The method of claim 1 , wherein the radiation is blue light.
9. The method of claim 1 , wherein the radiation has a wavelength in the telecom band.
10. The method of claim 1 , wherein the processing the image to detect a new discontinuity includes processing the image to detect a moving pair of discontinuities in the intensity of the reflected radiation that correspond to a melted region of the semiconductor.
11. The method of claim 10 , further comprising determining a melt phase time duration from the detected pair of discontinuities and comparing the determined melt phase time duration to a target melt phase time duration.
12. A method of detecting the onset of melt in a region of interest of a semiconductor surface during a laser annealing process, the method comprising:
irradiating the semiconductor surface with pulses of radiation;
capturing, with a pixelated image sensor, an image that captures a portion of the radiation that has reflected off of the semiconductor surface; and
processing the image to detect a new discontinuity in an intensity of the reflected radiation in a region of interest of the image, the new discontinuity indicating the onset of melt of the semiconductor in the region of interest;
wherein the processing includes application of one or more of fitting algorithms, edge detection algorithms, eigenbasis decompositions, feed-forward classifiers, or the detection of any intensity in a captured image frame that exceeds a threshold value.
13. The method of claim 12 , wherein the laser annealing process includes performing sequential sweeps across the semiconductor surface at a sweep frequency, f sweep , wherein the irradiating includes emitting pulses of radiation at a pulse frequency, f Probe , wherein f Probe <f sweep .
14. The method of claim 13 , wherein f Probe is a rational beat frequency of f sweep .
15. The method of claim 13 , wherein f Probe is synchronized with f sweep , and multiple pulses of radiation are captured in a single image frame by the pixelated image sensor.
16. The method of claim 12 , wherein the irradiating includes emitting a random distribution of pulses and the processing includes applying broadband statistics to the captured images to detect the new discontinuity.
17. The method of claim 12 , wherein the radiation is blue light or has a wavelength in the telecom band.
18. The method of claim 12 , wherein the processing the image to detect a new discontinuity includes processing the image to detect a moving pair of discontinuities in the intensity of the reflected radiation that correspond to a melted region of the semiconductor.
19. The method of claim 18 , further comprising determining a melt phase time duration from the detected pair of discontinuities and comparing the determined melt phase time duration to a target melt phase time duration.
20. A method of detecting the onset of melt in a region of interest of a semiconductor surface during a laser annealing process, the method comprising:
irradiating the semiconductor surface with pulses of radiation;
capturing, with a pixelated image sensor, an image that captures a portion of the radiation that has reflected off of the semiconductor surface; and
processing the image to detect a new discontinuity in an intensity of the reflected radiation in a region of interest of the image, the new discontinuity indicating the onset of melt of the semiconductor in the region of interest;
wherein the processing the image to detect a new discontinuity includes processing the image to detect a moving pair of discontinuities in the intensity of the reflected radiation that correspond to a melted region of the semiconductor.
21. The method of claim 20 , wherein the laser annealing process includes performing sequential sweeps across the semiconductor surface at a sweep frequency, f sweep , wherein the irradiating includes emitting pulses of radiation at a pulse frequency, f Probe , wherein f Probe <f sweep .
22. The method of claim 21 , wherein f Probe is a rational beat frequency of f sweep .
23. The method of claim 21 , wherein f Probe is synchronized with f sweep , and multiple pulses of radiation are captured in a single image frame by the pixelated image sensor.
24. The method of claim 20 , wherein the irradiating includes emitting a random distribution of pulses and the processing includes applying broadband statistics to the captured images to detect the new discontinuity.
25. The method of claim 20 , wherein the radiation is blue light or has a wavelength in the telecom band.
26. The method of claim 20 , further comprising determining a melt phase time duration from the detected pair of discontinuities and comparing the determined melt phase time duration to a target melt phase time duration.