Scribing sapphire substrates with a solid state UV laser
View Patent ↗A process and system scribe sapphire substrates, by performing the steps of mounting a sapphire substrate, carrying an array of integrated device die, on a stage such as a movable X-Y stage including a vacuum chuck; and directing UV pulses of laser energy directed at a surface of the sapphire substrate using a solid-state laser. The pulses of laser energy have a wavelength below about 560 nanometers, and preferably between about 150 in 560 nanometers. In addition, energy density, spot size, and pulse duration are established at levels sufficient to induce ablation of sapphire. Control of the system, such as by moving the stage with a stationary beam path for the pulses, causes the pulses to contact the sapphire substrate in a scribe pattern at a rate of motion causing overlap of successive pulses sufficient to cut scribe lines in the sapphire substrate.
1. A method for manufacturing die from a sapphire substrate, comprising:
producing a laser beam having a wavelength below about 560 nanometers;
coupling the laser beam into a sapphire substrate by absorption sufficient to induce ablation of the sapphire substrate;
moving the laser beam relative to the sapphire substrate in a first direction to create via the ablation a first scribe line in the substrate that extends in the first direction;
moving the laser beam relative to the sapphire substrate in a second direction different from the first direction to create via the ablation a second scribe line in the substrate that extends in the second direction;
linearly polarizing the laser beam in a direction parallel to the first direction as the first scribe line is created; and
linearly polarizing the laser beam in a direction parallel to the second direction as the second scribe line is created.
2. The method of claim 1 , wherein the moving of the laser beam relative to the sapphire substrate in the first and second directions includes mounting the sapphire substrate on a stage and moving the stage relative to the laser beam.
3. The method of claim 1 , wherein the first direction is generally orthogonal to the second direction.
4. The method of claim 1 , wherein the sapphire substrate has a thickness, and the first and second scribe lines are created with a depth of more than about half of said thickness.
5. A method for manufacturing die from a sapphire substrate, comprising;
mounting the sapphire substrate on a stage, the sapphire substrate having a surface;
producing pulsed laser energy having a wavelength below about 560 nanometers using a Q-switched Nd:YVO 4 laser;
coupling a sequence of pulses of the pulsed laser energy directly into the surface of the sapphire substrate by absorption sufficient to induce ablation of sapphire at the surface;
causing the sequence of pulses to impact the sapphire substrate in a scribe pattern comprising a plurality of intersecting scribe lines, so that the ablation cuts the plurality of intersecting scribe lines which extend in at least first and second directions in the sapphire substrate, and so that pulses in the sequence of pulses overlap spatially with previous and following pulses; and
linearly polarizing the laser energy in a direction parallel to the first direction while cutting the scribe lines extending in the first direction, and changing the polarization to a direction parallel to the second direction while cutting the scribe lines extending in the second direction.
6. The method of claim 5 , wherein the sapphire substrate has a thickness, and the scribe lines are cut to a depth of about one half, or more, of said thickness.