Patent ID: 6194239
Filing Date: 2001-02-27
Classification: H01L,Y02E,Y02P,Y10S

Abstract:
A method for making a light emitting diode, comprising the steps of:providing a single crystal semi-conductor substrate doped with a first type of impurity having a surface;introducing a second type of impurity into said surface to define a surface layer doped with a second type of impurity adjacent the surfaceanodizing the surface layer to define a first porous layer having a first porosity along a surface of the surface layer;anodizing the substrate to form a second porous layer adjacent the first porosity layer and traversing the surface layer, and having a second porosity less than said first porosity;anodizing the substrate to form a third porous layer in the second porous layer, the third porous layer having a third porosity greater than the second porosity;providing a plurality of parallel spaced electrodes on said first porous layer;attaching a transparent support substrate to the surface and electrodes with a transparent binder material;separating the second porous layer from the semi-conductor substrate along a line of weakness defined in the third porous layer or at or adjacent and interface defined between said second porous layer and the third porous layer to form a separated LED substrate;providing a like second plurality of parallel spaced electrodes on an exposed surface of said second porous layer opposite the surface layer;attaching a second transparent support substrate to the exposed surface and electrodes with a transparent binder material to form an LED assembly; andthereafter, subdividing the LED assembly between the spaced electrodes to define a plurality of LED devices.