Method and apparatus for cutting devices from substrates
View Patent ↗A method and system for cutting a wafer comprising a semiconductor substrate attached to an array of integrated devices includes placing the wafer on a stage such as a movable X-Y stage including a vacuum chuck having a porous mounting surface, and securing the wafer during and after cutting by vacuum pressure through the pores. The wafer is cut by directing UV pulses of laser energy at the substrate using a solid-state laser having controlled polarization. An adhesive membrane can be attached to the separated die to remove them from the mounting surface, or the die can otherwise be removed after cutting from the wafer.
1. A method for manufacturing die from a substrate comprising a material, comprising;
mounting the substrate on a stage;
directing pulses of laser energy at a surface of the substrate, the pulses having a wavelength, an energy density, a spot size, a repetition rate and a pulse duration sufficient to induce ablation of said material;
causing the pulses to impact the substrate in a scribe pattern to cut scribe lines in the substrate;
controlling polarization of the laser pulses with respect to direction of scribe lines in the scribe pattern; and
separating die defined by the scribe pattern.
2. The method of claim 1 , wherein the wavelength is less than about 560 nanometers.
3. The method of claim 1 , including using a solid state UV laser to generate the pulses.
4. The method of claim 1 , wherein the scribe pattern includes scribe lines parallel to first and second axes, including controlling the polarization so that the polarization is linear and arranged in a first direction for scribe lines parallel to the first axis and arranged in a second direction for scribe lines parallel to the second axis.
5. The method of claim 1 , including causing overlap of successive pulses.
6. The method of claim 1 , wherein the wavelength is between about 150 and 560 nanometers.
7. The method of claim 1 , wherein the repetition rate is between about 10 kHz and 50 kHz.
8. The method of claim 1 , wherein said energy density is between about 10 and 100 joules per square centimeter, said pulse duration is between about 10 and 30 nanoseconds, and the spot size is between about 5 and 25 microns.
9. The method of claim 1 , wherein the substrate has a thickness, and the scribe lines are cut to a depth of more than about one half said thickness.
10. The method of claim 1 , wherein the spot size is less than 20 microns.
11. The method of claim 1 , including causing overlap of successive pulses, and wherein the overlap is in a range from 50 to 99 percent.
12. The method of claim 1 , wherein the substrate has an active surface and a back side, and including causing the laser pulses to impact the back side.
13. The method of claim 1 , wherein the stage comprises a movable x-y stage, and said causing the pulses to impact the substrate in a scribe pattern, includes moving the substrate on the x-y stage.
14. The method of claim 1 , wherein said controlling polarization includes aligning polarization of the pulses parallel to the scribe line being scribed.
15. The method of claim 1 , wherein said material comprises a semiconductor.
16. The method of claim 1 , wherein the wavelength is between about 150 and 560 nanometers, and the repetition rate is greater that 50 kHz.