Mechanically forming crack initiation defects in thin glass substrates using an abrasive surface

A method for forming an initiation defect in a glass substrate to facilitate separating the glass substrate into a plurality of substrates is provided. The method includes providing the glass substrate and contacting a broad surface of the glass substrate with an abrasive surface thereby forming a field of initiation defects in the broad surface of the glass substrate. The field of initiation defects has a width of at least about three millimeters between outermost initiation defects. At least one initiation defect is heated with a laser source. The at least one initiation defect is cooled with a cooling fluid such that a crack initiates from the at least one initiation defect, the crack extending through a thickness of the glass substrate and propagating across the glass substrate to separate the glass substrate into the plurality of substrates.