Bonding type semiconductor substrate, semiconductor light emitting element, and preparation process thereof

• US 6,465,809 B1
• Filed: 06/08/2000
• Issued: 10/15/2002
• Est. Priority Date: 06/09/1999
• Status: Expired due to Term

• Current Assignee: Kabushiki Kaisha Toshiba (Toshiba Corporation)
• Original Assignee: Kabushiki Kaisha Toshiba (Toshiba Corporation)
• Inventors: Akaike, Yasuhiko, Furukawa, Kazuyoshi, Yoshitake, Shunji
• Primary Examiner(s): Jackson, Jr., Jerome
• Assistant Examiner(s): NGUYEN, JOSEPH H
• Application Number:
  US09/589,452
• Time in Patent Office: 859 Days
• Field of Search: 257/190, 257/201, 257/103, 257/94-97, 257/189
• US Class Current: 257/94
• CPC Class Codes: H01L 21/187 by direct bonding
• CPC Class Codes: H01L 2224/04042 Bonding areas specifically adapted for wire connectors, e.g. wirebond pads
• CPC Class Codes: H01L 2224/48463 the connecting portion on the bonding area of the semiconductor or solid-state body being a ball bond
• CPC Class Codes: H01L 24/05 of an individual bonding area
• CPC Class Codes: H01L 2924/00 Indexing scheme for arrangements or methods for connecting or disconnecting semiconductor or solid-state bodies as covered by H01L24/00
• CPC Class Codes: H01L 2924/12041 LED
• CPC Class Codes: H01L 2924/351 Thermal stress
• CPC Class Codes: H01L 33/0093 Wafer bonding; Removal of the growth substrate
• CPC Class Codes: H01L 33/10 with a light reflecting structure, e.g. semiconductor Bragg reflector
• CPC Class Codes: H01L 33/16 with a particular crystal structure or orientation, e.g. polycrystalline, amorphous or porous
• CPC Class Codes: H01L 33/20 with a particular shape, e.g. curved or truncated substrate

Abstract

The process comprises a step of growing epitaxially mixed crystals of a compound semiconductor represented by the composition formula In_x(Ga_1−yAl_y)_1−xP on a GaAs substrate 12 to form an epi-wafer having an n-type cladding layer 14 (0.45<x<0.50, 0≦y≦1), an active layer 15, a p-type cladding layer 16 and a cover layer 17; a step of removing the cover layer 17 by etching to expose the surface of the p-type cladding layer 16; a step of integrally joining a mirror-polished GaP substrate 11 on the p-type cladding layer 16 by placing the GaP substrate on the cladding layer at room temperature so that the mirror-polished surface of the GaP substrate may come into contact with the p-type cladding layer 16; a step of the subjecting the resultant laminate to a heat treatment; a step of carrying out an etching treatment from the side of the GaAs substrate 12 to expose the n-type cladding layer 14; and a step of forming electrodes 19 on the surface of the n-type cladding layer 14 and on the back surface of the GaP substrate 11, respectively.

Claims

1. A semiconductor light emitting element comprising:

a first epitaxial growth layer formed from mixed crystals of a compound semiconductor on a first semiconductor substrate, said first epitaxial growth layer including a first cladding layer formed by selecting a composition ratio of the mixed crystals so as to match a lattice constant of said first semiconductor substrate, an active layer formed on said first cladding layer, and a second cladding layer formed on said active layer;

said first semiconductor substrate being removed from the first epitaxial growth layer;

a second semiconductor substrate whose a main surface is mirror-polished and which is directly bonded to said first epitaxial growth layer via the mirror-polished surface or a second epitaxial growth layer grown on the mirror-polished surface; and

electrodes which are formed on the front side of said first cladding layer and on the back side of said second semiconductor substrate and which supplies an electric current to said active layer,

said first semiconductor substrate being formed from GaAs,

said first epitaxial growth layer being represented by the composition formula In_x(Ga<sub>1−

y</sub>Al_y)<sub>1−

x</sub>P,

a composition ratio of said first cladding layer in said composition formula being 0.45<

x<

0.50 and 0≦

y≦

1,

said second semiconductor substrate being formed from GaP, and

said second epitaxial growth layer containing GaP as a main component.

2. The semiconductor light emitting element according to claim 1, wherein a thermal expansion coefficient of said first epitaxial growth layer is close to the thermal expansion coefficient of said second semiconductor substrate.

3. A bonding type semiconductor substrate comprising:

a first semiconductor substrate whose at least one surface is mirror-polished; and

a second semiconductor substrate whose at least one surface is mirror-polished and which is integrally joined to said mirror-polished surface of said first semiconductor substrate via the mirror-polished surface,

a crystal orientation of the bonded surface of said second semiconductor substrate being much the same as a crystal orientation of the back surface which is opposite to the bonded surface of the first semiconductor substrate.

4. The bonding type semiconductor substrate according to claim 3, wherein said first semiconductor substrate and said second semiconductor substrate are bonded and integrated so that normal-mesa directions on the joined surfaces may cross each other at right angles.

5. The bonding type semiconductor substrate according to claim 3, wherein said first semiconductor substrate has a surface inclining in a direction of from a (100) plane toward a (111) group III gallium plane direction at a first inclining angle, and

said second semiconductor substrate has a surface inclining in a direction of from (100) plane toward a (111) group V phosphorus plane direction at a second inclining angle.

6. The bonding type semiconductor substrate according to claim 5, wherein said first inclining angle is much the same as said second inclining angle.

7. A semiconductor light emitting element comprising:

a first conductive type cladding layer;

an active layer formed on said first conductive type cladding layer, emitting light by current injection, and having a band gap smaller than that of said first conductive type cladding layer;

a second conductive type cladding layer formed on said active layer and having a band gap greater than that of said active layer; and

a transparent second conductive type semiconductor bonding substrate having an inside surface and an outside surface, of which at least the inside surface is mirror-polished, the inside surface being bonded to said second conductive type cladding layer via no layer or via one of a second epitaxial growth layer of a second conductive type semiconductor grown on the inside surface and a bonding layer of a second conductive type semiconductor grown on said second conductive type cladding layer, being transparent to the light emitted from said active layer, and a lattice constant and a material of said transparent second conductive type semiconductor bonding substrate being different from those of said first conductive type cladding layer, said active layer, and said second conductive type cladding layer.

8. The semiconductor light emitting element according to claim 7, wherein a thermal expansion coefficient of said second conductive type cladding layer is close to the thermal expansion coefficient of said transparent second conductive type semiconductor bonding substrate.

9. The semiconductor light emitting element according to claim 7, wherein said first conductive type cladding layer, said active layer, and said second conductive type cladding layer include In_x(Ga₁₋

3Al_y)<sub>1−

x</sub>P (0.45<

x<

0.50, 0≦

y≦

1), and said transparent second conductive type semiconductor bonding substrate is formed of GaP.

14. The semiconductor light emitting element according to claim 7, wherein an area of the inside surface of said transparent second conductive type semiconductor bonding substrate is larger than an area of said active layer.

15. The semiconductor light emitting element according to claim 7, wherein an area of the inside surface of said transparent second conductive type semiconductor bonding substrate is smaller than an area of the outside surface of said transparent second conductive type semiconductor bonding substrate.

16. The semiconductor light emitting element according to claim 7, further comprising a transparent first conductive type semiconductor bonding substrate having an inside surface and an outside surface, of which at least the inside surface is mirror-polished, the inside surface being bonded to said second conductive type cladding layer via no layer or via one of a third epitaxial growth layer of a first conductive type semiconductor grown on the inside surface and a bonding layer of a first conductive type semiconductor grown on said first conductive type cladding layer, being transparent to the light emitted from said active layer, a lattice constant and a material of said transparent first conductive type semiconductor bonding substrate being different from said first conductive type cladding layer, said active layer, and said second conductive type cladding layer.

10. A semiconductor light emitting element comprising:

A first epitaxial growth layer formed from mixed crystals of a compound semiconductor on an inside surface of an opaque semiconductor substrate having the inside surface and an outside surface, said first epitaxial growth layer including a first conductive type cladding layer formed by selecting a composition ratio of the mixed crystals so as to match a lattice constant of said opaque semiconductor substrate, an active layer formed on said first conductive type cladding layer and emitting light by current injection, a second conductive type cladding layer formed on said active layer;

said opaque semiconductor substrate being opaque to the light emitted from said active layer and being removed from the first epitaxial growth layer; and

a transparent second conductive type semiconductor bonding substrate having an inside surface and an outside surface, of which at least the inside surface is mirror-polished, the inside surface being bonded to said second conductive type cladding layer via no layer or via one of a second epitaxial growth layer of a second conductive type semiconductor grown on the inside surface and a bonding layer of a second conductive type semiconductor grown on said second conductive type cladding layer, being transparent to the light emitted from said active layer, a lattice constant and a material of said transparent second conductive type semiconductor bonding substrate being different from those of said first epitaxial growth layer, and a crystal orientation of the inside surface being substantially the same as that of the outside surface of said opaque semiconductor substrate.

11. The semiconductor light emitting element according to claim 10, further comprising:

a first electrode formed on said first conductive type cladding layer via no layer or via bonding layer of a first conductive type semiconductor; and

a second electrode formed on said outer surface of said transparent second conductive type semiconductor bonding substrate.

12. The semiconductor light emitting element according to claim 10, wherein in the inside surface of said opaque semiconductor substrate, a (111)A plane or a (111)B plane preferentially appears, and in the inside surface of said transparent second conductive type semiconductor bonding substrate, a (111)B plane or a (111)A plane preferentially appears.

13. The semiconductor light emitting element according to claim 10, wherein said first conductive type cladding layer, said active layer, and said second conductive type cladding layer include In_x(Ga₁₋

yAl_y)<sub>1−

x</sub>P (0.45<

x<

0.50, 0≦

y ≦

1), and said transparent second conductive type semiconductor bonding substrate is formed of GaP.