vertically propagating cracks 108 or laterally propagating cracks 109 vertically propagating cracks 108 tend to emanate from the trench bottom 119 in a direction substantially parallel with the trench sidewalls 118 while horizontally propagating cracks 109 emanate from the sidewalls 118 or trench bottom 119 in a direction non parallel with the trench sidewalls 118 for the hybrid scribing methods described herein where a plasma etch subsequent to the laser ablation of trench 112 will advance the trench bottom 119 through the substrate with anisotropic etch the vertically propagating cracks 108 will be eliminated horizontally propagating cracks 109 however pose a risk of surviving an anisotropic etch process which does not significantly etch the trench sidewall 118 because the trench 112 may be just below a device thin film layer 104 horizontally propagating cracks 109 which survive the singulation process pose a risk of continuing to run out laterally non parallel to the sidewall 118 and adversely affect product die adjacent to the trench 112 while it has been found by the inventor and his associates that a femtosecond laser advantageously reduces the occurrence of all microcracks in the substrate the inventor has further found that of the fewer remaining microcracks the ratio of vertically oriented microcracks to horizontally oriented microcracks can be increased significantly when a centrally peaked spatial power profile is employed fig2 a is a graph illustrating the femtosecond laser beam has a centrally peaked.