Nitride semiconductor light emitting element

1. A nitride semiconductor light emitting element comprising:

a sapphire substrate; and

a light emitting element structure portion that has a plurality of nitride semiconductor layers formed on the sapphire substrate,

wherein

the nitride semiconductor light emitting element is a back-surface-emitting type nitride semiconductor light emitting element that outputs light from the light emitting element structure portion to an outside of the element through the sapphire substrate, the nitride semiconductor light emitting element being divided into a chip whose planarly-viewed shape is a square or a rectangle,

an average length of sides of the planarly-viewed shape of the chip is 400 μm or greater, and

a thickness of the sapphire substrate is 0.45 to 1 times the average length.

2. The nitride semiconductor light emitting element according to claim 1 , wherein

the light emitting element structure portion includes:

a base structure portion that includes an AlGaN-based semiconductor layer formed on the sapphire substrate; and

a light emitting laminated portion formed on a crystal surface of the base structure portion, the light emitting laminated portion including an n-type clad layer being an n-type AlGaN-based semiconductor layer, an active layer having an AlGaN-based semiconductor layer, and a p-type clad layer being a p-type AlGaN-based semiconductor layer.

3. The nitride semiconductor light emitting element according to claim 1 , wherein the thickness of the sapphire substrate is 0.5 times or greater the average length.

4. The nitride semiconductor light emitting element according to claim 1 , wherein the thickness of the sapphire substrate is 0.8 times or less the average length.

5. The nitride semiconductor light emitting element according to claim 1 , wherein the chip is obtained from a wafer being divided by stealth dicing.

6. The nitride semiconductor light emitting element according to claim 1 , wherein the average length is 500 μm or greater.

7. A method for manufacturing a nitride semiconductor light emitting element, the method comprising:

forming a light emitting element structure portion having a plurality of nitride semiconductor layers on a sapphire substrate as a wafer having a first thickness;

polishing a back surface of the sapphire substrate as the wafer on which the light emitting element structure portion is formed, so as to reduce a thickness of the sapphire substrate to a second thickness being smaller than the first thickness; and

dividing the wafer in which the light emitting element structure portion is formed on the sapphire substrate having its thickness reduced into a chip of a nitride semiconductor light emitting element whose planarly-viewed shape is a square or a rectangle,

wherein

the nitride semiconductor light emitting element is a back-surface-emitting type light emitting element that outputs light emitted from the light emitting element structure portion to an outside of the element through the sapphire substrate,

an average length of sides of the planarly-viewed shape of the nitride semiconductor light emitting element is 400 μm or greater, and

the second thickness is 0.45 to 1 times the average length.

8. The method for manufacturing the nitride semiconductor light emitting element according to claim 7 , wherein

the forming the light emitting element structure portion includes:

forming a base structure portion including an AlGaN-based semiconductor layer on the sapphire substrate as the wafer having the first thickness; and

forming, on a crystal surface of the base structure portion, a light emitting laminated portion that includes an n-type clad layer being an n-type AlGaN-based semiconductor layer, an active layer having an AlGaN-based semiconductor layer, and a p-type clad layer being a p-type AlGaN-based semiconductor layer.

9. The method for manufacturing the nitride semiconductor light emitting element according to claim 7 , wherein, in the dividing the wafer into the chip, stealth dicing is performed.

10. The method for manufacturing the nitride semiconductor light emitting element according to claim 9 , wherein, in the performing the stealth dicing, a plurality of focal points of a laser beam used in the stealth dicing are set in a thickness direction of the sapphire substrate.