Method and device for separating a flat workpiece into a plurality of sections

A method of separating a workpiece into a plurality of sections, the method comprising:

• generating one or a plurality of lines of modified material along one or a plurality of predefined separating lines in the workpiece in a first step by local material processing using a first laser beam through a surface of the workpiece such that the first laser beam generates a reduction of breaking stress of the workpiece along the one or a plurality of predefined separating lines, and
• dividing, in a second step, the workpiece into the sections along the one or a plurality of predefined separating lines by thermal laser beam separation by directing a second laser beam that generates a heating zone onto the workpiece and, near the heating zone or partly overlapping the heating zone, applying a cooling medium to the surface to generate a cooling zone,
• wherein the generating the one or the plurality of lines of modified material generates the one or the plurality of lines of modified material 1) in portions at a distance from the surface in the workpiece, and 2) such that each one of the one or the plurality of lines of modified material start at the surface of the workpiece and then extend at varying distances with respect to the surface along the one or a plurality of predefined separating lines in the workpiece, and guiding the one or the plurality of lines of modified material in a region of surface structures or a surface metalization on the one or a plurality of predefined separating lines which would obstruct a coupling of laser radiation for the thermal laser beam separation into the workpiece to the surface to locally remove said surface structures or said surface metalization on the one or a plurality of predefined separating lines using the first laser beam.