Patent ID: 7741131
Filing Date: 2010-06-22
Classification: H01L

Abstract:
1. A method of laser processing a light reflective structure that has a major surface and includes a multilayer passivation structure and target material supported on a substrate, the light reflective structure characterized by a nonuniform distribution of passivation layer thickness across the major surface, comprising: obtaining prior knowledge about the nonuniform distribution of the passivation layer thickness across the major surface; performing a first light beam reflection measurement on a first region of the light reflective structure at a location where a portion of the target material is present, the measurement being performed at a first light beam wavelength while leaving operationally undamaged the first region and the substrate; performing a second light beam reflection measurement on a second region of the light reflective structure in a vicinity of the first region and at a location where a portion of the multilayer passivation structure is present and where the target material is not present, the measurement being performed at a second light beam wavelength while leaving operationally undamaged the second region and the substrate and, the first and second light beam wavelengths being the same; and processing the first and second light beam reflection measurements to calculate absorption difference corresponding to the first and second light beam reflection measurements and the prior knowledge to determine a processing laser output parameter for laser processing a selected portion of target material in proximal location to the first and second regions.