Laser processing method for cutting a wafer-like object by using a laser to form modified regions within the object

A laser processing method, comprising:

• irradiating a wafer-like object to be processed with laser light with a light-converging point located therewithin to form a first modified region within the object and separated from a surface of the object on a laser light entrance face side toward inside by a first predetermined distance, the first modified region functioning as a starting point for cutting of the object;
• and
• irradiating the wafer-like object to be processed with laser light with a light-converging point located therewithin to form a second modified region within the object and separated from a surface of the object on a laser light entrance face side toward inside by a second predetermined distance different from the first predetermined distance by changing a position of the light converging point of the laser light in the direction which the laser light enters into the object, the second modified region functioning as a starting point for cutting of the object.

A laser processing method comprising:

• irradiating a wafer-like object to be processed with laser light with a light-converging point located therewithin under a condition with a peak power density of at least 1×108 (W/cm2) at the light-converging point and a pulse width of 1 μs or less to form a first modified region within the object and separated from a surface of the object on a laser light entrance face side toward inside by a first predetermined distance, the first modified region functioning as a starting point for cutting of the object;
• and
• irradiating the wafer-like object to be processed with laser light with a light-converging point located therewithin under a condition with a peak power density of at least 1×108 (W/cm2) at the light-converging point and a pulse width of 1 μs is or less to form a second modified region caused by multiphoton absorption within the object and separated from a surface of the object on a laser light entrance face side toward inside by a second predetermined distance different from the first predetermined distance by changing a position of the light converging point of the laser light in the direction which the laser light enters into the object, the second modified region functioning as a starting point for cutting of the object.

A laser processing method, comprising:

• irradiating a wafer-like object to be processed and made of semiconductor material with laser light with a light-converging point located therewithin to form a first molten processed region within the object and separated from a surface of the object on a laser light entrance face side toward inside by a first predetermined distance, the first molten processed region functioning as a starting point for cutting of the object;
• and
• irradiating the wafer-like object to be processed and made of semiconductor material with laser light with a light-converging point located therewithin to form a second molten processed region within the object and separated from a surface of the object on a laser light entrance face side toward inside by a second predetermined distance different from the first predetermined distance, by changing a position of the light converging point of the laser light in the direction which the laser light enters into the object, the second molten processed region functioning as a starting point for cutting of the object.

A method of manufacturing a semiconductor device formed using a laser processing method, the manufacturing method comprising:

• irradiating a wafer-like object to be processed with laser light with a light-converging point located therewithin to form a first modified region within the object and separated from a surface of the object on a laser light entrance face side toward inside by a first predetermined distance, the first modified region functioning as a starting point for cutting of the object;
• and
• irradiating the wafer-like object to be processed with laser light with a light-converging point located therewithin to form a second modified region within the object and separated from a surface of the object on a laser light entrance face side toward inside by a second predetermined distance different from the first predetermined distance by changing a position of the light converging point of the laser light in the direction which the laser light enters into the object, the second modified region functioning as a starting point for cutting of the object, to facilitate cutting of the object along a line along which the object is intended to be cut in order to provide at least one manufactured semiconductor device.

A method of manufacturing a semiconductor device formed using a laser processing method, the manufacturing method comprising:

• irradiating a wafer-like object to be processed and made of semiconductor material with laser light with a light-converging point located therewithin to form a first molten processed region within the object and separated from a surface of the object on a laser light entrance face side toward inside by a first predetermined distance, the first molten processed region functioning as a starting point for cutting of the object;
• and
• irradiating the wafer-like object to be processed and made of semiconductor material with laser light with a light-converging point located therewithin to form a second molten processed region within the object and separated from a surface of the object on a laser light entrance face side toward inside by a second predetermined distance different from the first predetermined distance, by changing a position of the light converging point of the laser light in the direction which the laser light enters into the object, the second molten processed region functioning as a starting point for cutting of the object, to facilitate cutting of the object along a line along which the object is intended to be cut in order to provide at least one manufactured semiconductor device.