| 摘要 |
PURPOSE:To obtain enough needed for fusion and to obtain slow strength distribution so as to remove scattering of Si by providing an optical system for laser beam reduction between a laser oscillator and a condensing lens, when making fused marks at the rear of an Si wafer by irradiation with excimer laser beams so as to form a strain field. CONSTITUTION:The long-side of the beam cross-section of a laser beam which is emitted from an excimer laser oscillator 1 is reduced with a cylindrical reducer 2. If the output energy of the oscillator 1 is about 100mT per pulse, the reduction ratio is made about 1/3-2/3. Also, the short-side of the reduced laser beam is condensed with a cylindrical lens 3 and is made a long and narrow beam, which is applied to the rear of a wafer 4 so as to yield a strain field. If it is done this way, it can make uniform fused marks with enough strength while removing the scattering of Si, and the strain field becomes uniform. |
