Light emitting diode chip having distributed Bragg reflector and method of fabricating the same
View Patent ↗Exemplary embodiments of the present invention disclose a light emitting diode chip including a substrate having a first surface and a second surface, a light emitting structure arranged on the first surface of the substrate and including an active layer arranged between a first conductive-type semiconductor layer and a second conductive-type semiconductor layer, a distributed Bragg reflector arranged on the second surface of the substrate, the distributed Bragg reflector to reflect light emitted from the light emitting structure, and a metal layer arranged on the distributed Bragg reflector, wherein the distributed Bragg reflector has a reflectivity of at least 90% for light of a first wavelength in a blue wavelength range, light of a second wavelength in a green wavelength range, and light of a third wavelength in a red wavelength range.
1. A method of fabricating a light emitting diode chip, the method comprising:
forming a light emitting structure on a first surface of a substrate, the light emitting structure comprising:
a first conductive-type semiconductor layer;
a second conductive-type semiconductor layer; and
an active layer disposed between the first conductive-type semiconductor layer and the second conductive-type semiconductor layer;
removing a portion of the substrate by grinding a second surface of the substrate;
after the grinding, reducing the surface roughness of the second surface of the substrate by lapping the substrate; and
forming a distributed Bragg reflector on the second surface of the substrate,
wherein the distributed Bragg reflector comprises a first material layer comprising TiO 2 , a second material layer comprising SiO 2 , a third material layer comprising TiO 2 , and a fourth material layer comprising SiO 2 , and
wherein the first material layer has an optical thickness that is different from an optical thickness of the third material layer.
2. The method of claim 1 , further comprising forming a reflective metal layer or a protective layer on the distributed Bragg reflector.
3. The method of claim 1 , wherein the surface roughness of the second surface of the substrate comprises a root-mean-square (RMS) value of 3 nm or less before forming the distributed Bragg reflector.
4. The method of claim 1 , wherein the distributed Bragg reflector comprises a reflectivity of at least 90% for light of a first wavelength in a blue wavelength range, light of a second wavelength in a green wavelength range, and light of a third wavelength in a red wavelength range.
5. The method of claim 1 , wherein the surface roughness of the second surface of the substrate comprises a root-mean-square (RMS) value of 1 nm or less before forming the distributed Bragg reflector.
6. The method of claim 1 , further comprising polishing the second surface of the substrate by a chemical mechanical polishing process after performing the lapping.
7. The method of claim 5 , further comprising polishing the second surface of the substrate using a chemical mechanical polishing process.
8. The method of claim 1 , wherein forming the distributed Bragg reflector comprises using ion assisted deposition.