Method of Fabricating Light Emitting Device and Thus-Fabricated Light Emitting Device

• US 20070224714A1
• Filed: 04/13/2005
• Published: 09/27/2007
• Est. Priority Date: 04/27/2004
• Status: Active Grant

• Current Assignee: Shin-Etsu Handotai Co., Ltd. (Shin-Etsu Chemical Company Limited)
• Original Assignee: Shin-Etsu Handotai Co., Ltd. (Shin-Etsu Chemical Company Limited)
• Inventors: Ikeda, Hitoshi, Nakamura, Akio, Suzuki, Kingo
• Granted Patent: US 7,663,151 B2
• Time in Patent Office: Days
• US Class Current: 438/26
• CPC Class Codes: H01L 33/0093 Wafer bonding; Removal of the growth substrate
• CPC Class Codes: H01L 33/0095 Post-treatment of devices, e.g. annealing, recrystallisation or short-circuit elimination
• CPC Class Codes: H01L 33/22 Roughened surfaces, e.g. at the interface between epitaxial layers
• CPC Class Codes: H01L 33/30 containing only elements of Group III and Group V of the Periodic Table

Abstract

A light emitting device chip is obtained by dicing a light emitting device wafer having a light emitting layer section 24 based on a double heterostructure in which a first-conductivity-type cladding layer 6, an active layer 5 and an second-conductivity-type cladding layer 4, each of which being composed of a compound semiconductor having a composition allowing lattice matching with GaAs, out of compound semiconductors expressed by formula (Al_xGa_1-x)_yIn_1-yP (where, 0≦x≦1, 0≦y≦1), are stacked in this order, and having the (100) surface appeared on the main surface thereof, and GaP transparent semiconductor layers 20, 90 stacked on the light emitting layer section 24 as being agreed with the crystal orientation thereof, so that the {100} surfaces appear on the side faces of the GaP transparent semiconductor layer. Accordingly, there can be provided a method of fabricating a light emitting device having the AlGaInP light emitting layer section and the GaP transparent semiconductor layers, less causative of failures such as edge chipping during the dicing.

Claims

1. A method of fabricating a light emitting device obtaining a light emitting device by dicing a light emitting device wafer having a light emitting layer section based on a double heterostructure in which a first-conductivity-type cladding layer, an active layer and an second-conductivity-type cladding layer, each of which being composed of a compound semiconductor having a composition allowing lattice matching with GaAs, out of compound semiconductors expressed by formula (Al_xGa_1-x)_yIn_1-yP (where, 0≦

x≦

1, 0≦

y≦

1), are stacked in this order, and having the (100) surface appeared on the main surface thereof, and a GaP transparent semiconductor layer stacked on said light emitting layer section as being agreed with the crystal orientation thereof, so that the {100} surfaces appear on the side faces of said GaP transparent semiconductor layer.

2. The method of fabricating a light emitting device as claimed in claim 1, further comprising a step of etching the side faces of said GaP transparent semiconductor layer composed of the {100} surface exposed by said dicing to thereby form thereon surface roughening projections, using an etching solution for surface roughening containing acetic acid, hydrofluoric acid, nitric acid, iodine and water amounted to a total content of 90% by mass or more, and having a total content by mass of acetic acid, hydrofluoric acid, nitric acid and iodine larger than the content by mass of water.

3. The method of fabricating a light emitting device as claimed in claim 2, wherein said etching solution for surface roughening contains:

acetic acid (on CH₃COOH basis);

37.4% by mass or more and 94.8% by mass or less;

hydrofluoric acid (on HF basis);

0.4% by mass or more and 14.8% by mass or less;

nitric acid (on HNO₃ basis);

1.3% by mass or more and 14.7% by mass or less; and

iodine (on I₂ basis);

0.12% by mass or more and 0.84% by mass or less,

and has a water content of 2.4% by mass or more and 45% by mass or less.

4. The method of fabricating a light emitting device as claimed in claim 2, wherein said etching solution for surface roughening contains:

acetic acid (on CH₃COOH basis);

45.8% by mass or more and 94.8% by mass or less;

hydrofluoric acid (on HF basis);

0.5% by mass or more and 14.8% by mass or less;

nitric acid (on HNO₃ basis);

1.6% by mass or more and 14.7% by mass or less; and

iodine (on I₂ basis);

0.15% by mass or more and 0.84% by mass or less,

and has a water content of 2.4% by mass or more and 32.7% by mass or less.

5. The method of fabricating a light emitting device as claimed in claim 2, wherein said GaP transparent semiconductor layer is formed to as thick as 10 μ

m or more on said light emitting device wafer.

6. The method of fabricating a light emitting device as claimed in claim 2, wherein said surface roughening projections are formed by removing, after said dicing step, a process-induced damage layer formed in said side faces of said GaP transparent semiconductor layer using an etching solution for removing damage composed of an aqueous sulfuric acid/hydrogen peroxide solution, and then by further etching the exposed surface by said etching solution for surface roughening.

7. The method of fabricating a light emitting device as claimed in claim 2, wherein said surface roughening projections formed by the anisotropic etching using said etching solution for surface roughening are further rounded by etching using an isotropic etching solution.

8. A light emitting device comprising:

a light emitting layer section based on a double heterostructure in which a first-conductivity-type cladding layer, an active layer and an second-conductivity-type cladding layer, each of which being composed of a compound semiconductor having a composition allowing lattice matching with GaAs, out of compound semiconductors expressed by formula (Al_xGa_1-x)_yIn_1-yP (where, 0≦

x≦

1, 0≦

y≦

1), stacked in this order, and having the (100) surface appeared on the main surface thereof; and

a GaP transparent semiconductor layer stacked on said light emitting layer section as being agreed with the crystal orientation thereof,

being formed by dicing so that the {100} surfaces appear on the side faces of said GaP transparent semiconductor layer as the side faces of the device.

9. The light emitting device as claimed in claim 8, wherein said GaP transparent semiconductor layer has surface roughening projections formed on the side faces thereof by anisotropic etching.

10. The light emitting device as claimed in claim 9, wherein said surface roughening projections are rounded to have curved surfaces on the end portion side thereof.

11. The light emitting device as claimed in claim 10, wherein each of said surface roughening projections has a main body composing the projection base and thinned towards the end side thereof, and a swelled tip portion integrated with said main body, as being swelled out in a ball form on the end side thereof.

12. The light emitting device as claimed in claim 8, wherein said light emitting layer section is obtained as being epitaxially grown on a GaAs substrate having the principal crystal axis with an off-angle of 1°

to 25°

, both ends inclusive, away from the <

100>

direction, and the crystal orientation of said GaP transparent semiconductor layer is agreed with said off-angled light emitting layer section.

13. The light emitting device as claimed in claim 12, wherein a plurality of said surface roughening projections formed as being distributed on said side faces show a polyhedral form having a plurality of planes surrounding the outer surface of at least the projection bases, and the majority of said projections are formed as having both of φ

1 and φ

2 of 30°

or more, satisfying φ

1>

φ

2, where φ

1 and φ

2 are acute angles respectively held between each of two opposing surfaces of the same projection and the first main surface of said GaP transparent semiconductor layer in a predetermined direction on said side faces.

14. The light emitting device as claimed in claim 9, wherein said surface roughening projections are such as those having a basic geometry obtained by anisotropic etching, and further rounded using an isotropic etching solution.

15. The light emitting device as claimed in claim 8, wherein said GaP transparent semiconductor layer is formed as a GaP light extraction layer formed on a first main surface side, which falls on the light extraction side, of said light emitting layer section.

16. The light emitting device as claimed in claim 8, wherein said GaP transparent semiconductor layer is formed as a GaP transparent substrate layer formed on a second main surface side, which falls on the opposite side of the light extraction side, of said light emitting layer section.