Patterned laser annealing of silicon oxide films

Abstract

UV-absorbing silicon monoxide (SiO x , x ≈ 1) thin films on fused silica substrates are irradiated by an ArF excimer laser (wavelength 193 nm) in the sub-ablation threshold regime. Multi-pulse irradiation of films with ∼200-nm thickness at a fluence of about 100 mJ/cm 2 leads to a significant increase of the UV transmission, indicating the oxidation of SiO x to SiO 2 . The quality of the obtained films after this laser annealing process depends on the oxygen content of the environment. Irradiation in air at atmospheric pressure leads to the formation of sub-micron-sized oxide particles on top of the film. Structured illumination is applied either to form areas of the film with changed transmission and refractive index, or for the formation of regular particle patterns with sub-micron periods. These processes can be utilized for the fabrication of phase masks or for various types of surface functionalization.

Theoretical Study on Laser Annealing of Non-Stoichiometric SiOX films

“…It was shown [17] that at the temperatures of 1470 and 1620 K the Si nanocrystals were formed during 1 s and 20 ms respectively. Although the surface temperature of the sample between laser beams increases with decreasing distance between the beams but it is not enough to stimulate the phase transition of SiO x film into nanocomposite SiO 2 (Si) film with Si nanocrystals which agrees well with the experimental data obtained in [19]. As a result, silicon nanoparticles will be formed accurately at the positions of the peak intensity of the laser radiation.…”

Formation of Periodic Structures on the Solid Surface under Laser Irradiation

“…In work [41], the attention was focused on the formation of periodic structures in non-stoichiometric films of SiO ( < 2). The cited authors analyzed conditions for the production of oxide films using the laser annealing.…”

“…They demonstrated a possibility to perform the process of patterned (spatially selective) oxidation. Unlike other methods applied to the spatially selective functionalization of the surface -e.g., chemical or plasma treatments, which demand multistage procedures (deposition of a masking layer, patterned masks, etching or plasma treatment, mask removal, and so on) -the treatment used by the authors of work [41] is carried out as a one-stage process. Therefore, the spatially selective oxidation of SiO films can be done, by using an excimer laser ( Fig.…”

“…Image of the specimen surface morphology obtained using the atomic-force microscopy (AFM) method [40] (d) SEM images of a two-dimensional interference pattern composed of nanoparticles formed structural irradiation of SiO film 400 nm in thickness. Parameters of laser irradiation:= 193 nm, = 100 mJ/cm 2 , = 5 Hz, and = 2000 pulses[41]…”

Theoretical Evaluation of the Temperature Field Distribution in the Silicon Periodic Nanostructures During Thermal Annealing

“…Now, creation of periodic surface structures and properties of these structures are analyzed in great scale with various methods [8][9][10][11] for using in practical work [12][13][14][15].…”