Thermal annealing of thin films using fiber lasers via the spot-beam annealing method

48‐3: Invited Paper: Fiber‐Laser Processing of Si and IGZO Films for Advanced AMOLED Displays on Gen 8 Substrates

“…In other words, according to our current physical understanding and model of the ELA method [16][17][18], as long as we create equivalent local heating and melting-and-solidification cycles while also using a sufficiently coherent beam (so as to induce the LIPSS effect [1], particularly near the late stage of the process), it should be possible to produce the "ELA-Si" films even using a set of substantially different technical elements and schemes. The results also indicate that the individual-pulse-created thermal spikes [7,19], which are intrinsic to the SBA method (and the extent of which can be adjusted (i.e., amplified or reduced)), at least to the extent manifested in the present work, apparently do not significantly affect the overall melt-mediated crystallization and microstructure evolution transpiring in the films during the process.…”

“…Based on the current experimental results that show that fiber-laserbased SBA can generate highly grain-ordered polycrystalline Si films suitable for manufacturing LTPS-and LTPO-based AMOLED displays, as well as based on the consideration of the method's unusual and flexible technical characteristics and capabilities [4], we identify the following future R&D activities as being sensible options for the technology: (1) development and utilization of the next-level SBA systems for further research and optimization of the method, (2) targeted investigation pertaining to the use of the method to conduct spot-beam-based SLS of Si films [8,20,21], and (3) general exploration regarding the heat treatment of thin-film materials (e.g., SBA of a-IGZO thin films to induce topological and compositional short-range ordering for improving the stability of the films [14,19]).…”

“…In this paper, we suggest that the SBA method can be identified as an unusually flexible and capable approach for solid-phase thermal annealing of thin films, in general, and for improving the physical stability and properties of amorphous thin films, in particular. This suggestion regarding the stability enhancement of amorphous films via SBA is based on simultaneously considering the physical changes that are expected to transpire in amorphous materials at elevated temperatures [14], as well as based on the results obtained from thermal analysis of thin films during SBA (the results of which show, as expected, the presence of distinct individual-pulse generated short-lived temperature spikes that are superimposed on top of a multiple-pulse defined and generated overall thermal profile at a point in the irradiated films [7,19]). Specifically, the combination of the following three factors leads us to note that the SBA method is likely well suited for improving the stability and properties of amorphous thin films on high-processingtemperature-intolerant substrates: (1) the flexibility of the SBA method (in terms of varying the overall multiple-pulse-defined beam dwell time, as well as the ability to tune and engineer the degree to which the temperature spikes are manifested), (2) the kinetic nature of thermodynamically driven local topological and compositional changes involving a range of activation enthalpies that take place in amorphous materials during thermal treatments (the changes that must improve the stability of the amorphous materials), and (3) the need to kinetically avoid either the solidphase or melt-mediated crystallization of the materials (as well as to avoid inducing any damage to the high-temperature-processingintolerant substrates or subs-structures and devices).…”

“…For these and some additional reasons, we suggest that the SBA technology may be useful in identifying and optimizing a beneficial laser-annealing treatment of a-IGZO films for enhancing the configurational stability of the films to commensurately improve the device stability and performance of the resulting a-IGZO films (above and beyond the level attainable using the conventional furnace, RTA, or laser annealing of the films). Note that the flexible and unusual characteristics of the SBA method should also permit, ironically, an efficient investigation and tailored optimization of either the solid-phase or melt-mediated crystallization of a-IGZO films [19].…”

67‐4: Uniform Polycrystalline Si Films Obtained via the Fiber‐laser‐based Spot‐Beam‐Annealing Method

“…The flexible nature of the SBA method in terms of its ability to spatially and temporally control the deposition of laser energy can also be leveraged in order to enable the method to perform and execute other laser crystallization schemes that may potentially be better suited for future display products and applications [9][10][11][12][13]18].…”