Semiconductor light emitting apparatus and its manufacturing method

• US 20050230698A1
• Filed: 03/01/2005
• Published: 10/20/2005
• Est. Priority Date: 03/02/2004
• Status: Active Grant

• Current Assignee: Kabushiki Kaisha Toshiba (Toshiba Corporation)
• Original Assignee: Kabushiki Kaisha Toshiba (Toshiba Corporation)
• Inventors: Sakai, Takayuki
• Granted Patent: US 7,242,031 B2
• Time in Patent Office: Days
• US Class Current: 257/98
• CPC Class Codes: H01L 2224/48472 the other connecting portion not on the bonding area also being a wedge bond, i.e. wedge-to-wedge
• CPC Class Codes: H01L 2924/01012 Magnesium [Mg]
• CPC Class Codes: H01L 2924/12041 LED
• CPC Class Codes: H01L 33/44 characterised by the coatings, e.g. passivation layer or anti-reflective coating

Abstract

A semiconductor light emitting apparatus comprises: a semiconductor light emitting device; resin that seals the semiconductor light emitting device; and antireflective coating provided on a surface of the resin. The antireflective coating is made of material having an intermediate refractive index between the refractive index of the resin and the refractive index of air.

Claims

1. A semiconductor light emitting apparatus comprising:

a semiconductor light emitting device;

a resin that seals the semiconductor light emitting device; and

antireflective coating provided on a surface of the resin, the antireflective coating being made of material having an intermediate refractive index between the refractive index of the resin and the refractive index of air.

2. The semiconductor light emitting apparatus as claimed in claim 1, wherein the antireflective coating is provided with a film thickness that generally conforms to an equation:

T=(m−

½

)λ

/2n

where λ

is a wavelength of light, m is an integer, n is the refractive index of the antireflective coating, and T is the film thickness.

3. The semiconductor light emitting apparatus as claimed in claim 2, wherein the antireflective coating has a thickness in a range of plus or minus 30 nanometers from the film thickness that conforms to the equation.

4. The semiconductor light emitting apparatus as claimed in claim 1, wherein the refractive index n₁ of the antireflective coating generally conforms to an equation:

n₁={square root}{square root over (n₀n₂)}

where n₀ is the refractive index of the air, and n₂ is the refractive index of the resin.

5. The semiconductor light emitting apparatus as claimed in claim 1, wherein the antireflective coating is made from a material selected from a group consisting of polymers, oxides and fluorides.

6. The semiconductor light emitting apparatus as claimed in claim 1, wherein the resin has a light extraction surface that controls a distribution of a light emitted from the semiconductor light emitting device.

7. The semiconductor light emitting apparatus as claimed in claim 1, further comprising a fluorescent material that absorbs a light emitted from the semiconductor light emitting device and converts its wavelength.

8. A semiconductor light emitting apparatus comprising:

a semiconductor light emitting device; and

a resin that seals the semiconductor light emitting device,

at least a portion of the surface of the resin being provided with asperities having an average pitch less than ½

of a wavelength of light emitted through the resin.

9. The semiconductor light emitting apparatus as claimed in claim 8, wherein the wavelength λ

of the light, an average width a of projections of the asperities, an average width b of recesses of the asperities, a refractive index n₁ of the resin and a refractive index n₂ of air generally satisfy a following condition;

10. The semiconductor light emitting apparatus as claimed in claim 8, wherein an effective refractive index at the asperities continuously varies from a refractive index of the resin to a refractive index of air.

11. The semiconductor light emitting apparatus as claimed in claim 8, wherein the asperities have a plurality of projections protruding in a curved configuration.

12. The semiconductor light emitting apparatus as claimed in claim 8, wherein the asperities have a plurality of projections with oblique side surfaces.

13. The semiconductor light emitting apparatus as claimed in claim 8, wherein the asperities have a plurality of projections having generally perpendicular side surfaces and arranged periodically or irregularly.

14. The semiconductor light emitting apparatus as claimed in claim 8, wherein the resin has a light extraction surface that controls a distribution of a light emitted from the semiconductor light emitting device.

15. The semiconductor light emitting apparatus as claimed in claim 8, further comprising a fluorescent material that absorbs a light emitted from the semiconductor light emitting device and converts its wavelength.

16. A method of manufacturing a semiconductor light emitting apparatus comprising:

mounting a semiconductor light emitting device on a mounting member;

molding the semiconductor light emitting device by a resin having asperities on at least a part of a surface thereof, the asperities having an average pitch less than ½

of a wavelength of light emitted through the resin.

17. The method of manufacturing a semiconductor light emitting apparatus as claimed in claim 16, wherein the molding the semiconductor light emitting device includes pouring a fluid resin into a mold that has transfer asperities on its inner surface, and forming the asperities corresponding to the transfer asperities on the resin by curing the resin while the semiconductor light emitting device is dipped in the resin.

18. The method of manufacturing a semiconductor light emitting apparatus as claimed in claim 16, wherein the molding the semiconductor light emitting device includes forming the asperities on the surface of the resin by imprinting transfer asperities formed on a stamper onto the surface of the resin.

19. The method of manufacturing a semiconductor light emitting apparatus as claimed in claim 16, wherein the molding the semiconductor light emitting device includes:

applying block copolymer onto the surface of the resin;

disgregating the block copolymer into a first phase and a second phase;

removing the first phase; and

forming the asperities by selectively etching the surface of the resin by using the second phase of the block copolymer as masks.

20. The method of manufacturing a semiconductor light emitting apparatus as claimed in claim 19, wherein the block copolymer is composed of polystyrene and polymethyl methacrylate.