LED fabrication via ion implant isolation

Abstract

A semiconductor light emitting diode includes a semiconductor substrate, an epitaxial layer of n-type Group III nitride on the substrate, a p-type epitaxial layer of Group III nitride on the n-type epitaxial layer and forming a p-n junction with the n-type layer, and a resistive gallium nitride region on the n-type epitaxial layer and adjacent the p-type epitaxial layer for electrically isolating portions of the p-n junction. A metal contact layer is formed on the p-type epitaxial layer. Some embodiments include a semiconductor substrate, an epitaxial layer of n-type Group III nitride on the substrate, a p-type epitaxial layer of Group III nitride on the n-type epitaxial layer and forming a p-n junction with the n-type layer, wherein portions of the epitaxial region are patterned into a mesa and wherein the sidewalls of the mesa comprise a resistive Group III nitride region for electrically isolating portions of the p-n junction. In method embodiments disclosed, the resistive border is formed by forming an implant mask on the p-type epitaxial region and implanting ions into portions of the p-type epitaxial region to render portions of the p-type epitaxial region semi-insulating. A photoresist mask or a sufficiently thick metal layer may be used as the implant mask. In some method embodiments, a mesa is formed in the epitaxial region prior to implantation. During implantation, the epiwafer is mounted at an angle such that ions are implanted directly into the sidewalls of the mesa, thereby rendering portions of the mesa semi-insulating. The epiwafer may be rotated during ion implantation.

Description

[0001] This application claims priority from application No. 60 / 519,197 filed Nov. 12, 2003 for “LED Fabrication via Ion Implant Isolation.”BACKGROUND OF THE INVENTION [0002] The present invention relates to the manufacture and packaging of semiconductor light emitting diodes (“LED”). An LED is a semiconductor device that emits light whenever current passes through it. In its simplest form, a light emitting diode includes a p-type portion and an n-type portion to define a p-n junction diode. When mounted on a lead frame and encased in an encapsulant (usually a polymer), the overall LED package is also referred to as a “lamp.”[0003] Because of the high reliability, long life and generally low cost of LEDs, they have gained wide acceptance in a variety of lighting applications in many fields of application. [0004] LED lamps are extremely tough. They typically do not include glass and avoid filaments entirely. As a result, LED lamps can take abuse far beyond that of the incandescent la...

AI Technical Summary

Problems solved by technology

LED lamps are extremely tough.

Additionally, the passivation layer (typically silicon nitride) that is often added to protect the diode can crack following thermal or mechanical stress and thus provide additional possibilities for the development of undesired contacts to the epitaxial layers of the device.

The process of die separation may be harmful to exposed p-n junction regions.

In particular, when the purpose of the patterning step is to define an etch pattern in a GaN-based layer, GaN's chemical, physical, and thermal stability (which are favorable characteristics in finished devices) can cause additional difficulties if the etchant removes the resist before fully removing the desired pattern of material.

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