To enable a substrate to be protected against chipping and easily positioned at dicing.
A substrate of a light emitting device composed of an N+ layer, an N layer, a light emitting layer, and a P layer all formed of III group nitride semiconductor is cut off through such a method that cutting lines 20 of prescribed line width are left like a lattice on the substrate, the surface of the N+ layer is exposed in the boundary region of the cutting line 20 and a region where the electrode of the N layer is provided, the latticed cutting lines 20 are pattern-recognized as dicing lines, the substrate is diced along the cutting lines 20 with a blade which is wider than the width of the cutting line 20 till grooves are formed on its surface removing the layers of the cutting line 20, and the rear side of the substrate is scribed corresponding to the grooves provided to the front side, whereby the substrate is separated into unit chips. As the cutting lines 20 are formed protruding, the pattern recognition of the cutting lines can easily be made, and the blade can easily be positioned by control. The P layer and the light emitting layer are removed in the vicinity of the blade, mechanical vibrations are restrained from being transmitted to the light emitting layer, so that the light emitting layer is protected against mechanical distortion at dicing.
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