Patent ID: 7255806

Claim:
A substrate processing method comprising: a step of shaping a laser beam emitted from a laser beam source into a beam having a focal depth larger than a maximum value of variation in thickness of a processing area portion of a substrate to be processed and larger than a maximum value of variation in bend of the processing area portion by making the laser beam pass through a surface-relief diffractive optical element for performing phase modulation on a wavefront of the laser beam, the shaped beam having a sectional area smaller than that of the laser beam before the shaping step, the surface-relief diffractive optical element having a surface with concentric patterns of an uneven saw-tooth sectional shape, and the concentric patterns being formed at equivalent intervals on the surface according to a preselected period based on the maximum value of variation in thickness of the processing area portion and the maximum value of variation in bend of the processing area portion; a step of forming plural etching holes by irradiating the shaped beam onto a film formed on the substrate to remove the film; and a step of forming plural recessed portions by etching the substrate through the plural etching holes.