Processing method and processing apparatus for workpiece
Disclosed is a processing method for a workpiece. The processing method includes a holding step of holding the workpiece on a holding table, a grinding step of grinding the workpiece that is held on the holding table at and around its center by a grinding wheel, so that a recess portion is formed at and around the center of the workpiece and an annular projection portion is formed surrounding the recess portion at and along an outer periphery of the workpiece, and a fusion step of applying a laser beam to a surface of the workpiece, the surface having been ground in the grinding step, so that the ground surface is fused. A processing apparatus for a workpiece is also disclosed.
1 . A processing method for a workpiece, comprising:
a holding step of holding the workpiece on a holding table;
a grinding step of grinding the workpiece that is held on the holding table at and around a center thereof by a grinding wheel, so that a recess portion is formed at and around the center of the workpiece, an annular projection portion is formed surrounding the recess portion at and along an outer periphery of the workpiece, and an inner side surface is formed between the recess portion and the annular projection portion; and
a fusion step of applying a laser beam to a boundary region including the inner side surface and a bottom surface of the recess portion, so that the boundary region is fused.
2 . The processing method according to claim 1 , wherein the boundary region includes at least one of an inner side surface of the annular projection portion and an outer peripheral portion of the recess portion, the outer peripheral portion being continuous with the inner side surface.
3 . The processing method according to claim 1 , wherein the grinding step includes
a vertical direction grinding step of relatively moving the grinding wheel in a vertical direction with respect to the holding table, and
a horizontal direction moving step of relatively moving the grinding wheel with respect to the holding table in a horizontal direction toward the center of the workpiece,
wherein by the vertical direction grinding step and the horizontal direction moving step, an oblique surface is formed inclined in a step shape or a slope shape from a side of an inner periphery of an upper surface of the annular projection portion toward a center of the recess portion, and
the boundary region includes the oblique surface.
4 . The processing method according to claim 1 , wherein the laser beam is output by a laser oscillator and separated into a first laser beam and a second laser beam, and
the first laser beam is applied to the bottom surface of the recess portion, and the second laser beam is applied to the inner side surface of the recess portion.
5 . The processing method according to claim 4 , wherein the first laser beam is emitted from a first optical system and the second laser beam is emitted from a second optical system.