High throughput hot testing method and system for high-brightness light-emitting diodes

Patent metadata

Field	Value
Publication number	US-8927944-B2
Application number	US-201213673947-A
Country	US
Kind code	B2
Filing date	Nov 9, 2012
Priority date	Nov 14, 2011
Publication date	Jan 6, 2015
Grant date	Jan 6, 2015

Abstract

A method of performing a hot test of a wafer-level, packaged high-brightness phosphor converted light-emitting diode (pc-HBLED) includes selectively heating portions of the phosphor layer using a laser to provide a predetermined temperature gradient in the phosphor layer. The selective heating can directly heat the silicone in a silicone-based phosphor layer, or directly heat the active ion(s) of the phosphor in a Lumiramic™-based phosphor or even the active ion(s) of a silicone-based phosphor layer. A current is applied to the InGaN film to establish a predetermined temperature at the InGaN film junction, the film junction being adjacent to the phosphor layer. Photometric measurements are performed on the HBLED after the selective heating and during the applied electroluminescent current. This method quickly establishes the temperatures and temperature gradients in the HBLED consistent with those of an operating, product-level HBLED, thereby ensuring accurate binning of the HBLED.

First claim

The invention claimed is:

1. A method of performing a hot test of a high-brightness light-emitting diode (HBLED), the HBLED including an indium-gallium-nitride (InGaN) film, a phosphor layer formed on the InGaN film, and a lens formed over the phosphor layer and the InGaN film, the method comprising:
selectively heating portions of the phosphor layer using a laser to provide a predetermined temperature gradient in the phosphor layer;
applying current to the InGaN film to establish a predetermined temperature in the InGaN film; and
performing photometric measurements on the HBLED.

2. The method of claim 1 , wherein the selectively heating directly heats silicone in the phosphor layer.

3. The method of claim 1 , wherein the selectively heating is performed with a mid-infra-red (mid-IR) laser.

4. The method of claim 1 , wherein the selectively heating is performed with a tunable laser.

5. The method of claim 1 , wherein the selectively heating directly heats active phosphor ions.

6. The method of claim 1 , wherein the selectively heating is performed with an optically pumped semiconductor laser (OPSL) to excite absorption bands near 460 nm.

7. A system for hot testing of high-brightness light-emitting diodes (HBLEDs), each HBLED including an indium-gallium-nitride (InGaN) film, a phosphor layer formed on the InGaN film, and a lens formed over the phosphor layer and the InGaN film, the system comprising:
a laser positioned to direct its light onto an HBLED, the laser configured to selectively heat portions of the phosphor layer;
a probe tester configured to apply current to the InGaN film of the HBLED to establish a predetermined in the InGaN film and to provide electroluminescence;
an integrating sphere configured to collect light emitted by the HBLED during testing; and
a spectrometer system configured to perform photometric measurements on light collected by the integrating sphere.

8. The system of claim 7 , further including timing electronics coupled to the laser and the probe tester to synchronize operation of the laser and the probe tester.

9. The system of claim 7 , wherein the laser is positioned to direct its light through the integrating sphere onto the HBLED.

10. The system of claim 7 , wherein the integrating sphere includes a collar configured to minimize entry of extraneous light into the integrating sphere during testing and to collect a totality of light emitted by the HBLED.

11. The system of claim 7 , further including a moveable wafer carrier for positioning the HBLED.

12. A method of performing a hot test of a high-brightness light-emitting diode (HBLED), the HBLED including an indium-gallium-nitride (InGaN) film, a phosphor layer formed on the InGaN film, and a lens formed over the phosphor layer and the InGaN film, the method comprising:
using a first excitation source to establish a first predetermined operating condition of the phosphor layer;
using a second excitation source to establish a second predetermined operating condition of the InGaN film; and
performing photometric measurements on the HBLED after establishing the first and second predetermined operating conditions.

13. The method of claim 12 , wherein establishing the first predetermined operating condition includes providing a predetermined temperature gradient for the phosphor layer, and establishing the second predetermined operating condition includes providing a predetermined temperature for the InGaN film.

14. The method of claim 12 , wherein using the first excitation source includes targeting excitation of silicone used as a binder in the phosphor layer.

15. The method of claim 12 , wherein using the first excitation source includes targeting excitation of active phosphor ions in the phosphor layer.

16. The method of claim 12 , wherein using the first excitation source includes using an optical light source to selectively excite vibrational modes of silicone in the phosphor layer, thereby generating a temperature gradient in the phosphor layer.

17. The method of claim 12 , wherein using the first excitation source includes using an optical light source to selectively excite vibrational modes of one of methanol and a hydrocarbon wetting agent in the phosphor layer, thereby generating a temperature gradient in the phosphor layer.

18. The method of claim 12 , wherein the second excitation source includes applying a current to the InGaN film.

19. A system for hot testing of high-brightness light-emitting diodes (HBLEDs), each HBLED including an indium-gallium-nitride (InGaN) film, a phosphor layer formed on the InGaN film, and a lens formed over the phosphor layer and the InGaN film, the system comprising:
a first excitation source configured to establish a first predetermined operating condition of the phosphor layer;
a second excitation source configured to establish a second predetermined operating condition of the InGaN film;
an integrating sphere for positioning over the HBLED, the integrating sphere configured to collect light emitted by the HBLED during testing; and
a spectrometer system configured to perform photometric measurements on light collected by the integrating sphere.

20. The system of claim 19 , wherein the first excitation source includes one of an optical parametric oscillator and a Cr+3 insulating crystal laser, the first excitation source configured to excite silicone used as a binder in the phosphor layer.

21. The system of claim 19 , wherein the first excitation source includes an optically pumped semiconductor laser, the first excitation source configured to excite active phosphor ions in the phosphor layer.

22. The system of claim 19 , wherein the first excitation source includes a coherent light source, the first excitation source configured to excite active phosphor ions in the phosphor layer.

23. The system of claim 19 , wherein a wavelength of the first excitation source is between 2.0 microns and 3.5 microns, and an average power of the coherent source is between 100 watts and 12 watts for selectively exciting either one of silicone and methanol dopant wetting agents of the phosphor layer.

24. The system of claim 19 , wherein a wavelength of the first excitation source is between 0.45 microns and 0.53 microns, and an average power of the coherent source is between 100 watts and 12 watts.

25. The system of claim 19 , further including a plurality of first excitation sources, which in combination provide an average coherent power of 12 watts.

26. The system of claim 19 , wherein the second excitation source includes an electrical probe tester.

27. The system of claim 19 , further including a plurality of second excitation sources.

Assignees

• Kla Tencor Corp

Inventors

• Solarz Richard W

Classifications

• H10H20/825

  containing nitrogen, e.g. GaN · CPC title

• H10H20/84

  Coatings, e.g. passivation layers or antireflective coatings · CPC title

• G01R31/44 Primary

  Testing lamps · CPC title

• H05B33/10 Primary

  Apparatus or processes specially adapted to the manufacture of electroluminescent light sources · CPC title

• G01R31/2635

  Testing light-emitting diodes, laser diodes or photodiodes · CPC title