Semiconductor chip for optoelectronics

• US 20040195641A1
• Filed: 05/07/2004
• Published: 10/07/2004
• Est. Priority Date: 04/27/2001
• Status: Active Grant

• Current Assignee: Osram Opto Semiconductors GmbH (Ams-Osram AG)
• Original Assignee: Osram Opto Semiconductors GmbH (Ams-Osram AG)
• Inventors: Wirth, Ralph
• Granted Patent: US 7,145,181 B2
• Time in Patent Office: Days
• US Class Current: 257/433
• CPC Class Codes: H01L 33/20 with a particular shape, e.g. curved or truncated substrate
• CPC Class Codes: H01L 33/38 with a particular shape

Abstract

A semiconductor chip, in particular a light-emitting diode, has a substrate (2), on which a sequence of semiconductor layers (3) with an active zone (5) has been applied. Above the sequence of semiconductor layers (3) there is a stepped window layer (6), which is structured in the manner of a Fresnel lens and has with regard to the coupling out of radiation the function of a hemispherical lens (7). This produces a semiconductor chip with particularly high coupling-out efficiency.

Claims

1. A semiconductor chip for optoelectronics with a substrate (2), on which there is arranged a sequence of semiconductor layers (3) with a photon-emitting active zone (5) and with a following window layer (6), characterized in that the window layer (6) is structured in one region in the manner of a Fresnel lens, so that in the region radiation emitted from the active zone (5) impinges on interfaces of the window layer (6) with respect to the surrounding medium that are inclined toward the active zone (5).

2. The semiconductor chip as claimed in claim 1, characterized in that the structured region of the window layer is constructively obtained by portioned projection of surface regions of an imaginary lens (7) in the form of a hemisphere in the direction of its center point, centered on the active zone (5).

3. The semiconductor chip as claimed in claim 2, characterized in that the following applies for the diameter d_A of the active zone:

4. The semiconductor chip as claimed in claim 2, characterized in that the structured region of the window layer (6) is approximated in cross section to a polygon.

5. The semiconductor chip as claimed in claim 1, characterized in that the semiconductor chip has a central contact point arranged above the active zone (5).

6. The semiconductor chip as claimed in claim 1, characterized in that the semiconductor chip has a contact point (9) outside the window layer (6).

7. The semiconductor chip as claimed in claim 6, characterized in that from the contact point (9) a contact bridge (11) leads to the active zone.

8. The semiconductor chip as claimed in claim 1, characterized in that a reflective layer is arranged between the active zone (5) and the substrate (2).

9. A method for producing a semiconductor chip for optoelectronics, in which firstly a semiconductor layer (3) with an active zone (5) and a following window layer (6) is applied to a substrate (2), characterized by the following method steps for forming a surface of the window layer (6) that is structured in the manner of a Fresnel lens:

applying a photoresist layer on the window layer (6),

exposing the photoresist layer with the aid of a gray-scale mask,

developing the photoresist layer for forming a stepped surface structure in the photoresist layer, and

transferring the surface structure of the photoresist layer onto the window layer (6) lying underneath it with the aid of an anisotropic etching operation.