Method for manufacturing semiconductor light emitting device
According to one embodiment, a semiconductor light emitting device includes a stacked structure body and an electrode. The stacked structure body has a first conductivity type first semiconductor layer including a nitride-based semiconductor, a second conductivity type second semiconductor layer including a nitride-based semiconductor, and a light emitting layer provided between the first and second semiconductor layers. The electrode has first, second and third metal layers. The first metal layer is provided on the second semiconductor layer and includes silver or silver alloy. The second metal layer is provided on the first metal layer and includes at least one element of platinum, palladium, rhodium, iridium, ruthenium, osmium. The third metal layer is provided on the second metal layer. A thickness of the third metal layer along a direction from the first toward the second semiconductor layer is equal to or greater than a thickness of the second metal layer.
1. A method for manufacturing a semiconductor light emitting device, the device including a semiconductor layer including a nitride semiconductor, the semiconductor layer including a light emitting section, the method comprising:
forming a first metal layer on a first surface of the semiconductor layer, the first metal layer including silver or silver alloy, forming a second metal layer on the first metal layer, the second metal layer including at least one element of platinum, palladium, rhodium, iridium, ruthenium and osmium, and forming a third metal layer on the second metal layer, a thickness of the third metal layer along a direction from the first metal layer toward the second metal layer being not less than a thickness of the second metal layer along the direction; and
performing sinter processing on the semiconductor layer, the first metal layer, the second metal layer and the third metal layer in an atmosphere including oxygen after the forming the first, second and third metal layers.
2. The method according to claim 1 , wherein
the first metal layer includes a plurality of particles including silver,
the first metal layer has a first average diameter of the particles before the sinter processing,
the first metal layer has a second average diameter of the particles after the sinter processing,
the second average diameter is not less than the first average diameter, and
the second average diameter is not more than three times the first average diameter.
3. The method according to claim 1 , wherein
a work function of the third metal layer is higher than a work function of aluminum and is higher than a work function of titanium.
4. The method according to claim 1 , wherein
a diffusion coefficient of the third metal layer to silver is smaller than a diffusion coefficient of the second metal layer to silver.
5. The method according to claim 1 , further comprising
forming a fourth metal layer on the third metal layer, and
a diffusion coefficient of the third metal layer to the fourth metal layer being smaller than a diffusion coefficient of the second metal layer to the fourth metal layer.
6. The method according to claim 1 , wherein
the first metal layer is a single layer film including silver.
7. The method according to claim 1 , wherein
a first region including a boundary between the first metal layer and the second metal layer includes an element included in the second metal layer,
the first metal layer includes a second region apart from the boundary, and
a first concentration of the element in the first region is higher than a second concentration of the element in the second region.
8. The method according to claim 1 , wherein
a peak wavelength of light emitted from the light emitting layer is 370 nanometers or more and 400 nanometers or less.
9. The method according to claim 1 , wherein
an oxygen concentration in the atmosphere in the sinter processing is 20% or more.
10. A method for manufacturing a semiconductor light emitting device, the device including a semiconductor layer including a nitride semiconductor, the semiconductor layer including a light emitting section, the method comprising:
forming a first metal layer on a first surface of the semiconductor layer, the first metal layer including silver or silver alloy, forming a second metal layer on the first metal layer, the second metal layer including at least one element of platinum, palladium, rhodium, iridium, ruthenium and osmium, and forming a third metal layer on the second metal layer; and
performing sinter processing on the semiconductor layer, the first metal layer, the second metal layer and the third metal layer in an atmosphere including oxygen after the forming the first, second and third metal layers,
the third metal layer having an internal stress smaller than an internal stress of the second metal layer.
11. The method according to claim 10 , wherein
a work function of the third metal layer is higher than a work function of aluminum and is higher than a work function of titanium.
12. The method according to claim 10 , wherein
a diffusion coefficient of the third metal layer to silver is smaller than a diffusion coefficient of the second metal layer to silver.
13. The method according to claim 10 , further comprising
forming a fourth metal layer on the third metal layer, and
a diffusion coefficient of the third metal layer to the fourth metal layer being smaller than a diffusion coefficient of the second metal layer to the fourth metal layer.
14. The method according to claim 10 , wherein
the first metal layer is a single layer film including silver.
15. The method according to claim 10 , wherein
a first region including a boundary between the first metal layer and the second metal layer includes an element included in the second metal layer,
the first metal layer includes a second region apart from the boundary, and
a first concentration of the element in the first region is higher than a second concentration of the element in the second region.
16. The method according to claim 10 , wherein
the first metal layer includes a plurality of particles including silver,
the first metal layer has a first average diameter of the particles before the sinter processing,
the first metal layer has a second average diameter of the particles after the sinter processing,
the second average diameter is not less than the first average diameter, and
the second average diameter is not more than three times the first average diameter.
17. The method according to claim 10 , wherein
an oxygen concentration in the atmosphere in the sinter processing is 20% or more.