| 摘要 |
Intended is to suppress the warpage of a working target at a laser working time. Inside of a wafer (11), there is formed a modified area (M2), from which cracks (a2, b2) parallel to the thickness direction of the wafer (11) and extending in a direction inclined with respect to a plane containing a line (5) are formed. Inside of the wafer (11), there is formed a modified area (M3), from which a crack (a3) parallel to the thickness direction of the wafer (11) and extending in a direction inclined with respect to the plane containing the line (5) is formed to be connected to the crack (b2). In short, the cracks (a2, a3, b2) are formed to be connected. At the laser working time, therefore, those cracks cause the portions of the two sides across the cutting line (5) in the wafer (11) to mesh each other, so that the internal stress, which is established by forming the modified areas in parallel with the thickness direction of the wafer (11) and in the direction normal to the plane containing the line (5), can be reduced. |
