Laser annealing process of ITO thin films using beam shaping technology

In this study, we develop a laser annealing system for In 2O 3Sn (ITO) to carry out heat treatment on oxides with high melting temperature on substrates with low melting temperature. It is known that the working temperature of traditional heat treatments is usually limited by the melting point of the substrate materials. To overcome this problem, we apply a laser annealing technique to modify the film properties, and to measure the electrical and surface properties, we use Hall measurement, a four-point probe, and an atomic force microscope in our experiment. We will discuss how the annealing is affected by the laser machining parameters, including the beam profile, intensity distribution, laser spot overlap, and laser operation mode. We will further show through experimental results that the beam profile greatly affects the surface roughness of the ITO films. With the use of a uniform beam profile with proper laser intensity, the surface roughness and the sheet resistance of the ITO films can be reduced from 23 nm to 4.2 nm and from 417 Ω/sq to 400.4 Ω/sq, respectively. ► Laser annealing process can alter physical property of high melting temperature oxide films on low melting temperature substrate. ► Using beam shaping technology with symmetric intensity supply, laser annealing process can obtain better surface roughness. ► Compared with the dots-scanning method, the vector-scanning method achieved a better annealing effect.