Inspection method for semiconductor light-emitting device and manufacturing method for semiconductor light-emitting device
An inspection method for a semiconductor light-emitting device includes an image capturing step for irradiating light to the semiconductor light emitting device so as to excite an active layer and capturing an image of photoluminescence released from the active layer, an inspection region extracting step for extracting an inspection region of the captured image, a luminance average determination step for, determining as defective when a luminance average is smaller than a predetermined threshold, a luminance variance determination step for determining as defective when a luminance variance is larger than a predetermined threshold, and a total determination step for totally determining the semiconductor light-emitting device as defective when determined the semiconductor light emitting device as defective in at least one of the two determination results.
1. A method of inspecting a semiconductor light-emitting device having an active layer, the method comprising:
irradiating the semiconductor light-emitting device with light of a shorter wavelength than light emitted from the active layer, using an irradiating light source;
capturing an image of photoluminescence emitted from the active layer upon the irradiation of the semiconductor light-emitting device, using an image sensor;
extracting a region of the semiconductor light-emitting device from the captured image, as an inspection region, using a computer;
calculating an average value of a photoluminescence intensity over pixels in the inspection region, using the computer;
calculating a variation value indicating a degree of variation of the photoluminescence intensity over the pixels in the inspection region, using the computer; and
determining that the semiconductor light-emitting device is defective upon determining that at least one of (i) the average value of the photoluminescence intensity is smaller than a predetermined first threshold, and (ii) the variation value is larger than a predetermined second threshold, using the computer.
2. The method according to claim 1 , wherein
the inspection region is a region other than predetermined non-emitting regions of the semiconductor light-emitting device.
3. The method according to claim 2 , wherein
the captured image is a color image composed of color components of red, green and blue, and the photoluminescence intensity is given by using a luminance value which is calculated as a weighted average obtained by providing predetermined weighting to the color components.
4. The method according to claim 3 , wherein
the step of capturing an image of photoluminescence emitted from the active layer comprises capturing an image of a plurality of semiconductor light-emitting devices at once, and
wherein the step of extracting a region of the semiconductor light-emitting device comprises separately extracting a region of each of the semiconductor light-emitting devices from the extracted image, as an inspection region.
5. The method according to claim 4 , wherein
the variation value is determined based on any one of variance, standard deviation, average deviation and coefficient of variation of photoluminescence intensity in the inspection region.
6. The method according to claim 5 , wherein
the average value of the photoluminescence intensity and the variation value are calculated in parallel.
7. The method according to claim 2 , wherein
the captured image is a color image composed of color components of red, green and blue, and the photoluminescence intensity is given by using a pixel value of a color component having the highest sensitivity to light of wavelength emitted from the active layer excited by the irradiation light.
8. The method according to claim 7 , wherein
the step of capturing an image of photoluminescence emitted from the active layer comprises capturing an image of a plurality of semiconductor light-emitting devices at once, and
wherein the step of extracting a region of the semiconductor light-emitting device comprises separately extracting a region of each of the semiconductor light-emitting devices from the extracted image, as an inspection region.
9. The method according to claim 8 , wherein
the variation value is determined based on any one of variance, standard deviation, average deviation and coefficient of variation of photoluminescence intensity in the inspection region.
10. The method according to claim 9 , wherein
the average value of the photoluminescence intensity and the variation value are calculated in parallel.
11. The method according to claim 2 , wherein
the step of capturing an image of photoluminescence emitted from the active layer comprises capturing an image of a plurality of semiconductor light-emitting devices at once, and
wherein the step of extracting a region of the semiconductor light-emitting device comprises separately extracting a region of each of the semiconductor light-emitting devices from the extracted image, as an inspection region.
12. The method according to claim 2 , wherein
the variation value is determined based on any one of variance, standard deviation, average deviation and coefficient of variation of photoluminescence intensity in the inspection region.
13. A method for manufacturing a semiconductor light-emitting device, the method comprising:
forming a semiconductor light-emitting device;
inspecting the semiconductor light-emitting device formed in the step of forming the semiconductor light-emitting device to determine whether or not the semiconductor light-emitting device is defective; and
determining that the semiconductor light-emitting device is an acceptable device when the semiconductor light-emitting device is not determined as defective in the step of inspecting the semiconductor light-emitting device,
wherein the step of inspecting the semiconductor light-emitting device is implemented according to the inspection method defined in claim 2 .
14. The method according to claim 1 , wherein
the captured image is a color image composed of color components of red, green and blue, and the photoluminescence intensity is given by using a luminance value which is calculated as a weighted average obtained by providing predetermined weighting to the color components.
15. The method according to claim 1 , wherein
the captured image is a color image composed of color components of red, green and blue, and the photoluminescence intensity is given by using a pixel value of a color component having the highest sensitivity to light of wavelength emitted from the active layer excited by the irradiation light.
16. The method according to claim 1 , wherein
the step of capturing an image of photoluminescence emitted from the active layer comprises capturing an image of a plurality of semiconductor light-emitting devices at once, and
wherein the step of extracting a region of the semiconductor light-emitting device comprises separately extracting a region of each of the semiconductor light-emitting devices from the extracted image, as an inspection region.
17. The method for according to claim 1 , wherein
the variation value is determined based on any one of variance, standard deviation, average deviation and coefficient of variation of photoluminescence intensity in the inspection region.
18. The method according to claim 1 , wherein
the average value of the photoluminescence intensity and the variation value are calculated in parallel.
19. A method of manufacturing a semiconductor light-emitting device, the method comprising:
forming a semiconductor light-emitting device;
inspecting the semiconductor light-emitting device formed in the step of forming the semiconductor light-emitting device to determine whether or not the semiconductor light-emitting device is defective; and
determining that the semiconductor light-emitting device is an acceptable device when the semiconductor light-emitting device is not determined as defective in the step of inspecting the semiconductor light-emitting device,
wherein the step of inspecting the semiconductor light-emitting device is implemented according to the inspection method defined in claim 18 .
20. A method of manufacturing a semiconductor light-emitting device, the method comprising:
forming a semiconductor light-emitting device;
inspecting the semiconductor light-emitting device formed in the step of forming the semiconductor light-emitting device to determine whether or not the semiconductor light-emitting device is defective; and
determining that the semiconductor light-emitting device is an acceptable device when the semiconductor light-emitting device is not determined as defective in the step of inspecting the semiconductor light-emitting device,
wherein the step of inspecting the semiconductor light-emitting device is implemented according to the inspection method defined in claim 1 .