Material cutting using laser pulses
A method of cutting a semiconductor material by irradiating the semiconductor material with laser energy, includes providing a laser source adapted to emit successive pulses of laser beams, each laser beam pulse having a pulse width of 100 picoseconds or less, emitting laser beam pulses from the laser source, guiding the emitted laser beam pulses to irradiate semiconductor material to be cut, and moving the semiconductor material relative to the irradiating laser beam pulses to cut the semiconductor material along a cutting line. The semiconductor material is irradiated by a plurality of laser beam pulses with a pulse repetition frequency in the range from 0.1 GHz to 5000 GHz.
1. A method of cutting a semiconductor material by irradiating the semiconductor material with laser energy, comprising the steps of:
i) providing a laser source adapted to emit successive pulses of laser beams,
ii) emitting laser beam pulses from the laser source,
iii) guiding the emitted laser beam pulses to irradiate semiconductor material to be cut, and
iv) moving the semiconductor material relative to the irradiating laser beam pulses to cut the semiconductor material along a cutting line,
wherein the laser source is adapted to emit laser beam pulses having a pulse width of 100 picoseconds or less, and in step iii), the semiconductor material is irradiated by a plurality of laser beam pulses with a pulse repetition frequency in the range from 0.5 GHz to 50 GHz,
wherein the plurality of laser beam pulses are emitted in at least two successive bursts of pulses, each burst comprising a plurality of laser beam pulses, and
wherein an inter-burst frequency, being a frequency of a first laser beam pulse within successive bursts, is in the range of 0.1 kHz to 1,000 kHz.
2. The method of claim 1 , wherein each of the plurality of laser beam pulses has a respective pulse energy, and the method comprises a step of controlling the laser source such that a pulse energy of a first laser beam pulse within the plurality has a different pulse energy to a second laser beam pulse within the plurality.
3. The method of claim 1 , wherein each burst comprises between 2 and 100,000 laser beam pulses.
4. The method of claim 3 , wherein each burst comprises between 2 and 1000 laser beam pulses.
5. The method of claim 1 , wherein the inter-burst frequency is in the range of 1 kHz to 100 kHz.
6. The method of claim 1 , comprising the step of controlling the laser source such that the energy transmitted in successive bursts is different.
7. The method of claim 6 , wherein each of the plurality of laser beam pulses has a respective pulse energy, and the method comprises the step of controlling the laser source such that a pulse energy of a pulse within a first burst is different to a pulse energy of a pulse within a second burst.
8. The method of claim 1 , comprising a step of controlling the laser source such that successive bursts have different pulse repetition frequencies.
9. The method of claim 1 , comprising a step of controlling the polarisation of the emitted laser beam pulses, such that the laser beam pulses of different bursts have different laser beam polarisation states.
10. The method of claim 1 , wherein step iii) comprises splitting the laser beam pulses into a plurality of spatially separated sub-beams to produce a pattern of irradiation spots on the semiconductor material, and wherein the laser beam pulses of successive bursts are split such that the pattern of irradiation spots associated with a first burst is different to the pattern of irradiation spots associated with the next burst.
11. The method of claim 10 , wherein the irradiation spots produced during successive bursts are respectively spatially separated, to irradiate different cutting lines in the semiconductor material.
12. Laser cutting apparatus for performing the method of claim 1 .
13. A laser cutting apparatus for cutting a semiconductor material, comprising:
a laser source adapted to emit successive pulses of laser beams, each laser beam pulse having a pulse width of 100 picoseconds or less, the laser beam pulses having a pulse repetition frequency in the range from 0.5 GHz to 50 GHz, the pulses of laser beams being emitted in at least two successive bursts of pulses, each burst comprising a plurality of laser beam pulses, wherein an inter-burst frequency, being a frequency of a first laser beam pulse within successive bursts, is in a range of 0.1 kHz to 1,000 kHz; and
a laser beam guiding assembly for directing the laser beam pulses from the laser source to irradiate a semiconductor material to be cut, and a driving assembly for relatively moving the semiconductor material and the irradiating laser beam pulses.