RADIATION EMITTING SEMICONDUCTOR DEVICE

• US 20030173575A1
• Filed: 02/12/2001
• Published: 09/18/2003
• Est. Priority Date: 02/15/2000
• Status: Active Grant

• Current Assignee: OSRAM GmbH (Ams-Osram AG)
• Original Assignee: Osram Opto Semiconductors GmbH (Ams-Osram AG)
• Inventors: Strauss, Uwe, Eisert, Dominik, Zehnder, Ulrich, Mundbrod-Vangerow, Manfred, Haerle, Volker, Kuehn, Frank
• Granted Patent: US 6,730,939 B2
• Time in Patent Office: Days
• US Class Current: 257/95
• CPC Class Codes: H01L 2224/32245 the item being metallic
• CPC Class Codes: H01L 2224/32257 the layer connector connecting to a bonding area disposed in a recess of the surface of the item
• CPC Class Codes: H01L 2224/48091 Arched
• CPC Class Codes: H01L 2224/48247 connecting the wire to a bond pad of the item
• CPC Class Codes: H01L 2224/48465 the other connecting portion not on the bonding area being a wedge bond, i.e. ball-to-wedge, regular stitch
• CPC Class Codes: H01L 2224/73265 Layer and wire connectors
• 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 2924/00014 the subject-matter covered by the group, the symbol of which is combined with the symbol of this group, being disclosed without further technical details
• CPC Class Codes: H01L 2924/10155 being other than a cuboid
• CPC Class Codes: H01L 33/0093 Wafer bonding; Removal of the growth substrate
• CPC Class Codes: H01L 33/20 with a particular shape, e.g. curved or truncated substrate
• CPC Class Codes: H01L 33/22 Roughened surfaces, e.g. at the interface between epitaxial layers
• CPC Class Codes: H01L 33/38 with a particular shape
• CPC Class Codes: H01L 33/405 Reflective materials
• CPC Class Codes: H01L 33/60 Reflective elements

Abstract

Radiation-emitting semiconductor device, method for fabricating same and radiation-emitting optical device

A radiation-emitting semiconductor device with a multilayer structure (100) comprising a radiation-emitting active layer (10), with electrical contacts (30, 40) for impressing a current in the multilayer structure (100) and with a radiotransparent window layer (20). The window layer is arranged exclusively on the side of the multilayer structure (100) facing away from a main direction of radiation of the semiconductor device and has at least one side wall that includes a first side wall portion (20a) which extends obliquely, concavely or in a stepwise manner toward a central axis of the semiconductor device lying perpendicular to the multilayer sequence. In its subsequent extension toward the back side, viewed from the multilayer structure, the side wall changes over into a second side wall portion (20b) that extends perpendicularly to the multilayer structure, that is, parallel to the central axis, and the portion of the window layer (20) encompassing the second side wall portion (20b) forms a mounting pedestal for the semiconductor device. The first and second side wall portions are fabricated especially preferably by means of a saw blade having a shaped edge. In a preferred optical device, the semiconductor device is mounted window layer downward in a reflector cup. “Light-Emitting Diodes Based on Geometrically Deformed Chips”, SPIE Conference On Light-Emitting Diodes, San Jose, Calif.,

Claims

1. A radiation-emitting semiconductor device comprising

a multilayer structure (100) that contains a radiation-emitting active layer (10),

electrical contacts (30, 40) for impressing a current in the multilayer structure (100), and

a radiotransparent window layer (20), which

is disposed exclusively on the side of said multilayer structure (100) facing away from a main direction of radiation of the semiconductor device,

has at least one side wall comprising a first side wall portion (20a) which extends obliquely, concavely or in a stepwise manner with respect to a central axis of the semiconductor device lying perpendicular to the multilayer sequence, and which in its subsequent extension toward the back side, viewed from said multilayer structure, changes over into a second side wall portion (20b) that extends perpendicularly to said multilayer structure, that is, parallel to said central axis, and

the portion² of said window layer (20) encompassing said second side wall portion (20b) forms a mounting pedestal for said semiconductor device.

²TRANSLATOR'"'"'S NOTE:

Loss of parallel grammatical structure sic.

2. The semiconductor device as recited in claim 1,

wherein [said] window layer (20) is fabricated from the epitaxial substrate used to grow said multilayer sequence (100).

3. The semiconductor device as recited in any of the foregoing claims, wherein the refractive index of the material of said window layer (20) is higher than the refractive index of the material of said multilayer sequence (100), particularly of said active layer (10).

4. The semiconductor device as recited in any of the foregoing claims, wherein said window layer (20) is made of silicon carbide or is SiC-based and said multilayer sequence is fabricated of nitride-based semiconductor materials, particularly of GaN-based semiconductor materials.

5. The semiconductor device as recited in any of the foregoing claims, wherein all the lateral sides of said window layer (20) comprise a first side wall portion (20a) and a second side wall portion (20b).

6. The semiconductor device as recited in any of the foregoing claims, wherein said first side wall portion (20a) is a planar oblique surface that forms with said central axis (50) an angle (α

) that is between 20°

inclusively and 30°

inclusively.

7. The semiconductor device as recited in claims 4, 5 and 6 and having a square lateral cross section, and wherein all four sides of said window layer (20) comprise a planar, oblique, first side wall portion (20a) and wherein the ratio of the edge length of said multilayer structure (100) to the edge length of said mounting pedestal is between 1.5 inclusively and 2 inclusively, especially preferably about 1.35.

8. The semiconductor device as recited in any of the foregoing claims, wherein at least said first side wall portion (20a) is roughened.

9. A radiation-emitting optical device with a radiation-emitting semiconductor device as recited in any of claims 1 to 8, comprising a reflector cup (410) that has oblique or parabaloid side walls (350) and in which said semiconductor device is mounted in such a way that said window layer (20) is oriented toward the floor (430) of said reflector cup.

10. A radiation-emitting optical device as recited in claim 9, wherein said side walls of said reflector cup are coated with reflection-increasing material.

11. The radiation-emitting optical device as recited in claim 9 or 10, wherein said side walls of said reflector cup are realized in such manner that the radiation emitted backwardly by said semiconductor device is reflected upwardly to said active layer, predominantly in one and the same direction, by the oblique side walls.

12. A method for fabricating a radiation-emitting semiconductor device as recited in any of claims 1 to 8, comprising the following steps:

fabricating a plurality of mutually adjacent multilayer structures (100) on a large-area substrate wafer (20),

sawing into said substrate wafer (20) from the back of the substrate, with a saw blade (80) having a shaped edge (R) that has the negative shape of the intended shape of said first side wall portions (20a), to a predetermined depth at which the blade-shaped portion of said saw blade saws into said substrate,

dividing said wafer along said sawcuts, and

processing the separated devices further.

13. The method as recited in claim 12, wherein the dividing is done by means of a breaking method or a second sawcut.

14. The method as recited in claim 12 or 13, wherein before the back of said substrate is sawn into, metal contacts are produced on the unoccupied surfaces of said substrate or said multilayer structure.

15. The method as recited in any of claims 12 to 14, wherein the sawing is performed with a saw blade having a V-shaped edge.