Laser processing of amorphous semiconductors induces crystallinity, whereby the material's electrical properties can be precisely controlled. This process is often used for making thin-film transistors that can be used for flat panel displays; however, treating large areas is time consuming. Previous approaches to process large films by treating only specific regions of interest lack uniformity. This technology is a laser annealing system that uses a non-periodic pulsing pattern for processing large films. Instead of a constant repetition rate, the laser fires pairs of pulses at specified locations, altering the heating/cooling cycle of the material. This enables shorter processing times while maintaining the necessary consistency across large films.
## Non-periodic laser pulsing increases throughput
To achieve uniformity, multiple scans across the material are usually required because subsequent scans reduce inhomogeneities. By using a non-periodic pulsing pattern, the material undergoes multiple melting cycles on each scan, reducing the required number of laser scans. The pulses may occur at different energies to tailor to desired crystal structures. Increasing the size of flat panel displays results in more space between pixels; therefore, to increase processing speed, only these regions are irradiated. Another benefit of irradiating selected regions is that inhomogeneities caused by the edges of the beam are outside of the regions of interest.
This process has been experimentally verified on silicon films using transient reflectance methods and transmission electron microscopy. Estimates have shown that throughput may be increased by nearly 2.5 times over traditional methods.
Patent Pending (US 20130105807)
Tech Ventures Reference: IR M10-044
