Ultrashort laser pulse wafer scribing

A method of scribing a wafer having a plurality of integrated circuits formed thereon or therein, the integrated circuits separated by one or more streets, the method comprising:

• generating a beam of laser pulses, the laser pulses having a pulse width selected so as to minimize an ablation threshold of a target material;
• shaping the generated beam of laser pulses through diffraction to convert the laser pulses into flat laser pulses with substantially uniform spatial irradiance profiles, wherein the shaping produces, at the wafer, a series of laser spots with edges that are flattened, each including an asymmetrical aspect ratio with a first dimension being longer than a second dimension, the shaping spatially spreading the energy of each of the laser pulses as the aspect ratios of the respective laser spots change from symmetrical to asymmetrical;
• aligning the longer first dimension of each laser spot in a cutting direction along the wafer so as to distribute the energy of each laser pulse in the cutting direction;
• and
• providing relative movement, in the cutting direction, between the beam and the wafer so as to ablate a portion of the target material with the beam at a pulse repetition frequency in a range between approximately 5.1 MHz and approximately 100 MHz.

A method of scribing a wafer having a plurality of integrated circuits formed thereon or therein, the integrated circuits separated by one or more streets, the method comprising:

• generating a beam of one or more laser pulses, the laser pulses each having a pulse width in a range between approximately 0.6 picosecond and approximately 190 picoseconds;
• shaping the generated beam of laser pulses through diffraction to convert the laser pulses into flat laser pulses with substantially uniform spatial irradiance profiles, wherein the shaping produces, at the wafer, a series of laser spots with edges that are flattened, each including an asymmetrical aspect ratio with a first dimension being longer than a second dimension, the shaping spatially spreading the energy of each of the laser pulses as the aspect ratios of the respective laser spots change from symmetrical to asymmetrical;
• aligning the longer first dimension of each laser spot in a cutting direction along the wafer so as to distribute the energy of each laser pulse in the cutting direction;
• and
• providing relative movement, in the cutting direction, between the beam and the wafer so as to ablate a portion of the target material with the beam.

A method of scribing a wafer having a plurality of integrated circuits formed thereon or therein, the integrated circuits separated by one or more streets, the method comprising:

• generating a beam of one or more laser pulses, the laser pulses having a pulse width in a range between approximately 210 picoseconds and approximately 1000 picoseconds;
• shaping the generated beam of laser pulses to through diffraction convert the laser pulses into flat laser pulses with substantially uniform spatial irradiance profiles, wherein the shaping produces, at the wafer, a series of laser spots that each include an asymmetrical aspect ratio with a first dimension being longer than a second dimension, the shaping spatially spreading the energy of each of the laser pulses as the aspect ratios of the respective laser spots change from symmetrical to asymmetrical;
• aligning the longer first dimension of each laser spot in a cutting direction along the wafer so as to distribute the energy of each laser pulse in the cutting direction;
• and
• providing relative movement, in the cutting direction, between the beam and the wafer so as to ablate a portion of the target material with the beam, the relative movement including a bite size comprising an overlap offset between successive laser spots at the wafer, the bite size based on an overall depth of the ablated portion such that the overall depth of the ablated portion equals a pulse ablation depth of a single laser pulse multiplied by a ratio of the first dimension to the bite size.