Laser processing method
AssigneeHamamatsu Photonics K.K.
InventorsTakeshi Sakamoto, Kenichi Muramatsu
Life of this patent
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Abstract
A laser processing method for preventing particles from occurring from cut sections of chips obtained by cutting a silicon wafer is provided. An irradiation condition of laser light L for forming modified regions 77 to 712 is made different from an irradiation condition of laser light L for forming the modified regions 713 to 719 such as to correct the spherical aberration of laser light L in areas where the depth from the front face 3 of a silicon wafer 11 is 335 μm to 525 μm. Therefore, even when the silicon wafer 11 and a functional device layer 16 are cut into semiconductor chips from modified regions 71 to 719 acting as a cutting start point, twist hackles do not appear remarkably in the areas where the depth is 335 μm to 525 μm, whereby particles are hard to occur.
Claims10
A laser processing method of converging laser light within a silicon wafer having a thickness t (500 μm <t) with a condenser lens so as to form a plurality of rows of modified regions to become a cutting start point within the silicon wafer along a cutting line for cutting the silicon wafer, the method comprising the steps of:
- forming a first modified region along the cutting line in a first area having a depth of 350 μm to 500 μm from a laser light entrance surface of the silicon wafer by locating a converging point of the laser light in the first area;
- and
- forming a second modified region along the cutting line in a second area having a depth of 0 μm to 250 μm from the laser light entrance surface by locating the converging point in the second area;
- wherein, when forming the first modified region, the laser light is converged within the silicon wafer so as to cancel a spherical aberration to occur in response to a depth from the laser light entrance surface, and in the laser light emitted from the condenser lens, the converging position of center rays and converging position of marginal rays are restrained from deviating from each other in the thickness direction of the silicon wafer, and thereby an the influence of the spherical aberration is reduced.
A laser processing method of converging laser light within a silicon wafer having a thickness t (350 μm <t≦500 μm) with a condenser lens so as to form a plurality of rows of modified regions to become a cutting start point within the silicon wafer along a cutting line for cutting the silicon wafer, the method comprising the steps of:
- forming a first modified region along the cutting line in a first area having a depth of 350 μm to t μm from a laser light entrance surface of the silicon wafer by locating a converging point of the laser light in the first area;
- and
- forming a second modified region along the cutting line in a second area having a depth of 0 μm to 250 μm from the laser light entrance surface by locating the converging point in the second area;
- wherein, when forming the first modified region, the laser light is converged within the silicon wafer so as to cancel a spherical aberration to occur in response to a depth from the laser light entrance surface, and in the laser light emitted from the condenser lens, the converging position of center rays and converging position of marginal rays are restrained from deviating from each other in the thickness direction of the silicon wafer, and thereby an influence of the spherical aberration is reduced.
A laser processing method of converging laser light within a silicon wafer having a thickness t (500 μm <t) with a condenser lens so as to form a plurality of rows of modified regions to become a cutting start point within the silicon wafer along a cutting line for cutting the silicon wafer, the method comprising the steps of:
- forming a first modified region along the cutting line in a first area having a depth of 350 μm to 500 μm from a laser light entrance surface of the silicon wafer by locating a converging point of the laser light in the first area;
- and
- forming a second modified region along the cutting line in a second area having a depth of 0 μm to 250 μm from the laser light entrance surface by locating the converging point in the second area;
- wherein, when forming the first modified region, the laser light is converged within the silicon wafer so as to cancel a spherical aberration to occur in response to a depth from the laser light entrance surface, and thereby an influence of the spherical aberration is reduced;
- and
- wherein, when forming the first modified region, a member which acts to cancel the spherical aberration to occur in response to the depth from the laser light entrance surface is arranged between the condenser lens and the silicon wafer, and thereby, in the laser light emitted from the condenser lens, the converging position of center rays and converging position of marginal rays are restrained from deviating from each other in the thickness direction of the silicon wafer, and the influence of the spherical aberration is reduced.
A laser processing method of converging laser light within a silicon wafer having a thickness t (500 μm <t) with a condenser lens so as to form a plurality of rows of modified regions to become a cutting start point within the silicon wafer along a cutting line for cutting the silicon wafer, the method comprising the steps of:
- forming a first modified region along the cutting line in a first area having a depth of 350 μm to 500 μm from a laser light entrance surface of the silicon wafer by locating a converging point of the laser light in the first area;
- and
- forming a second modified region along the cutting line in a second area having a depth of 0 μm to 250 μm from the laser light entrance surface by locating the converging point in the second area;
- wherein, when forming the first modified region, the laser light is converged within the silicon wafer so as to cancel a spherical aberration to occur in response to a depth from the laser light entrance surface, and thereby an influence of the spherical aberration is reduced;
- and
- wherein, when forming the first modified region, the condenser lens which can change a lens performance so as to cancel the spherical aberration to occur in response to the depth from the laser light entrance surface is used, and thereby, in the laser light emitted from the condenser lens, the converging position of center rays and converging position of marginal rays are restrained from deviating from each other in the thickness direction of the silicon wafer, and the influence of the spherical aberration is reduced.
A laser processing method of converging laser light within a silicon wafer having a thickness t (350 μm <t≦500 μm) with a condenser lens so as to form a plurality of rows of modified regions to become a cutting start point within the silicon wafer along a cutting line for cutting the silicon wafer, the method comprising the steps of:
- forming a first modified region along the cutting line in a first area having a depth of 350 μm to t μm from a laser light entrance surface of the silicon wafer by locating a converging point of the laser light in the first area;
- and
- forming a second modified region along the cutting line in a second area having a depth of 0 μm to 250 μm from the laser light entrance surface by locating the converging point in the second area;
- wherein, when forming the first modified region, the laser light is converged within the silicon wafer so as to cancel a spherical aberration to occur in response to a depth from the laser light entrance surface, and thereby an influence of the spherical aberration is reduced;
- and
- wherein, when forming the first modified region, a member which acts to cancel the spherical aberration to occur in response to the depth from the laser light entrance surface is arranged between the condenser lens and the silicon wafer, and thereby, in the laser light emitted from the condenser lens, the converging position of center rays and converging position of marginal rays are restrained from deviating from each other in the thickness direction of the silicon wafer, and the influence of the spherical aberration is reduced.
A laser processing method of converging laser light within a silicon wafer having a thickness t (350 μm <t≦500 μm) with a condenser lens so as to form a plurality of rows of modified regions to become a cutting start point within the silicon wafer along a cutting line for cutting the silicon wafer, the method comprising the steps of:
- forming a first modified region along the cutting line in a first area having a depth of 350 μm to t μm from a laser light entrance surface of the silicon wafer by locating a converging point of the laser light in the first area;
- and
- forming a second modified region along the cutting line in a second area having a depth of 0 μm to 250 μm from the laser light entrance surface by locating the converging point in the second area;
- wherein, when forming the first modified region, the laser light is converged within the silicon wafer so as to cancel a spherical aberration to occur in response to a depth from the laser light entrance surface, and thereby an influence of the spherical aberration is reduced;
- and
- wherein, when forming the first modified region, the condenser lens which can change a lens performance so as to cancel the spherical aberration to occur in response to the depth from the laser light entrance surface is used, and thereby, in the laser light emitted from the condenser lens, the converging position of center rays and converging position of marginal rays are restrained from deviating from each other in the thickness direction of the silicon wafer, and the influence of the spherical aberration is reduced.
Dependencies are inferred from the claim text.