Laser processing method and laser processing apparatus

A laser processing method comprising the step of:

• irradiating an object having a wafer shape to be processed with laser light with a light-converging point located within the object to form a modified region including a crack region within the object under a condition with a peak power density of at least 1×108 (W/cm2) at the light-converging point and a pulse width 1 μs or less, to form a starting point, from which cutting of the object starts, constituted by the modified region in a region separated from a surface of said object a laser light entrance face side toward inside by a predetermined distance, along a line along which the object is intended to be cut.

A laser processing method comprising the step of:

• irradiating an object having a wafer shape to be processed with laser light with a light-converging point located within the object to form a modified region including a molten processed region within the object under a condition with a peak power density of at least 1×108 (W/cm2) at the light-converging point and a pulse width 1 μs or less, to form a starting point, from which cutting of the object starts, constituted by the modified region in a region separated from a surface of said object a laser light entrance face side toward inside by a predetermined distance, along a line along which the object is intended to be cut.

A laser processing method comprising the step of:

• irradiating an object having a wafer shape to be processed with laser light with a light-converging point located within the object to form a modified region including a refractive index change region which is a region with a changed refractive index within the object under a condition with a peak power density of at least 1×108 (W/cm2) at the light-converging point and a pulse width 1 μs or less, to form a starting point, from which cutting of the object starts, constituted by the modified region in a region separated from a surface of said object a laser light entrance face side toward inside by a predetermined distance, along a line along which the object is intended to be cut.

A laser processing method comprising the step of:

• irradiating an object made of a semiconductor material and having a wafer shape to be processed with laser light with a light-converging point located within the object to form a modified region within the object under a condition with a peak power density of at least 1×108 (W/cm2) at the light-converging point and a pulse width 1 μs or less, to form a starting point, from which cutting of the object starts, constituted by the modified region in a region separated from a surface of said object a laser light entrance face side toward inside by a predetermined distance, along a line along which the object is intended to be cut.

A laser processing method comprising the step of:

• irradiating an object made of a piezoelectric material and having a wafer shape to be processed with laser light with a light-converging point located within the object to form a modified region within the object under a condition with a peak power density of at least 1×108 (W/cm2) at the light-converging point and a pulse width 1 μs or less, to form a starting point, from which cutting of the object starts, constituted by the modified region in a region separated from a surface of said object a laser light entrance face side toward inside by a predetermined distance, along a line along which the object is intended to be cut.

A laser processing method comprising the step of:

• irradiating an object made of a semiconductor material and having a wafer shape to be processed with laser light with a light-converging point located within the object to form a molten processed region within the object, to form a starting point, from which cutting of the object starts, constituted by the modified region, in a region separated from a surface of said object a laser light entrance face side toward inside by a predetermined distance, along a line along which the object is intended to be cut.

A laser processing method comprising the step of:

• irradiating an object having a wafer shape to be processed with laser light with a light-converging point located within the object to form a modified region caused by multiphoton absorption within the object along a line along which the object is intended to be cut and along laser light entrance face of the object, to cut the object.

A laser processing method comprising the step of:

• irradiating an object having a wafer shape to be processed with laser light with a light-converging point located within the object under a condition with a peak power density of at least 1×108 (W/cm2) at the light-converging point and a pulse width 1 μs or less, to form a modified region including a crack region within the object along a line along which the object is intended to be cut and along laser light entrance face of the object, to cut the object.

A laser processing method comprising the step of:

• irradiating an object having a wafer shape to be processed with laser light with a light-converging point located within the object under a condition with a peak power density of at least 1×108 (W/cm2) at the light-converging point and a pulse width 1 μs or less, to form a modified region including a molten processed region within the object along a line along which the object is intended to be cut and along laser light entrance face of the object, to cut the object.

A laser processing method comprising the step of:

• irradiating an object having a wafer shape to be processed with laser light with a light-converging point located within the object under a condition with a peak power density of at least 1×108 (W/cm2) at the light-converging point and a pulse width 1 μs or less, to form a modified region including a refractive index change region which is a region with a changed refractive index within the object along a line along which the object is intended to be cut and along laser light entrance face of the object, to cut the object.

A laser processing method comprising the step of:

• irradiating an object made of a semiconductor material and having a wafer shape to be processed with laser light with a light-converging point located within the object under a condition with a peak power density of at least 1×108 (W/cm2) at the light-converging point and a pulse width 1 μs or less, to form a modified region within the object along a line along which the object is intended to be cut and along laser light entrance face of the object, to cut the object.

A laser processing method comprising the step of:

• irradiating an object made of a piezoelectric material and having a wafer shape to be processed with laser light with a light-converging point located within the object under a condition with a peak power density of at least 1×108 (W/cm2) at the light-converging point and a pulse width 1 μs or less, to form a modified region within the object along a line along which the object is intended to be cut and along laser light entrance face of the object, to cut the object.

A laser processing method comprising the step of:

• irradiating an object made of a semiconductor material and having a wafer shape to be processed with laser light with a light-converging point located within the object, to form a molten processed region within the object along a line along which the object is intended to be cut and along laser light entrance face of the object, to cut the object.