Laser-assisted atomic layer deposition of HfO2 for thin film electronics
Kujansuu, Aregaw (2024)
2024
Sähkötekniikan DI-ohjelma - Master's Programme in Electrical Engineering
Informaatioteknologian ja viestinnän tiedekunta - Faculty of Information Technology and Communication Sciences
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Hyväksymispäivämäärä
2024-11-26
Julkaisun pysyvä osoite on
https://urn.fi/URN:NBN:fi:tuni-2024111310185
https://urn.fi/URN:NBN:fi:tuni-2024111310185
Tiivistelmä
This study investigates the effect of laser pulses on hafnium oxide thin films produced through Atomic Layer Deposition. Laser experiments were conducted with varying energies (from 20 mJ to 220 mJ), pulse intervals (from 50 ms to 250 ms), and process temperatures (from 120 °C to 200°C). The objective was to examine the influence of laser pulses on film uniformity, crystallinity, and stoichiometry. The application of laser pulses is expected to enhance film properties by promoting densification, improving film uniformity, and potentially inducing crystallization, which may lead to improved electrical and optical properties of the films.
The ellipsometer measurements indicate that the thickness and refractive index of laser-treated film regions depend significantly on process parameters, with thickness ranging from 85.7 Å to 120.2 Å and refractive index from 1.993 to 2.299 under varying deposition conditions. The laser-treated regions were generally thinner and exhibited higher refractive indices than untreated regions, suggesting film densification. XRD measurements did not reveal structural differences between treated and untreated regions, likely due to insufficient film thickness for conventional XRD analysis. To further investigate crystallinity, additional analysis using grazing incidence XRD (GIXRD) is recommended.
XPS measurements showed high carbon content (from 21.61% to 64.48%) in the laser-treated regions, likely from contamination caused by a marker used to designate the laser-treated areas. Two of the three samples suggest that the reference regions exhibited lower carbon content relative to the laser-treated areas, implying that laser energy may contribute to the presence of carbon. Interestingly, increasing laser energy from 20 mJ to 220 mJ corresponded with a decrease in carbon content in both the reference and treated regions: carbon in untreated regions dropped from 42.13% to 21.61%, while in treated regions, it decreased from 48.8% to 36.36%. This inverse correlation between laser energy and carbon content implies that higher energy levels may reduce unwanted carbon species, though these findings could be influenced by inhomogeneous film properties or measurement inconsistencies.
Response Surface Methodology (RSM) analysis indicated that the laser pulse interval has a negligible effect on film thickness and refractive index, whereas laser energy has a pronounced impact on thickness. Temperature-energy contour plots at a constant chamber temperature of 120 °C and 50 ms laser pulse interval reveal that applying laser energy between 73 and 220 mJ produces the greatest thickness reduction, with over a 20% decrease observed in treated regions. At a chamber temperature of 160 °C and 50 ms pulse interval, maximum thickness reduction occurred when laser energy was between 114 and 181 mJ, with reductions reaching up to 15%. The results suggest that applying laser pulses may be beneficial; however, due to several erroneous factors, the experiment needs to be replicated to confirm the effect of the laser.
The ellipsometer measurements indicate that the thickness and refractive index of laser-treated film regions depend significantly on process parameters, with thickness ranging from 85.7 Å to 120.2 Å and refractive index from 1.993 to 2.299 under varying deposition conditions. The laser-treated regions were generally thinner and exhibited higher refractive indices than untreated regions, suggesting film densification. XRD measurements did not reveal structural differences between treated and untreated regions, likely due to insufficient film thickness for conventional XRD analysis. To further investigate crystallinity, additional analysis using grazing incidence XRD (GIXRD) is recommended.
XPS measurements showed high carbon content (from 21.61% to 64.48%) in the laser-treated regions, likely from contamination caused by a marker used to designate the laser-treated areas. Two of the three samples suggest that the reference regions exhibited lower carbon content relative to the laser-treated areas, implying that laser energy may contribute to the presence of carbon. Interestingly, increasing laser energy from 20 mJ to 220 mJ corresponded with a decrease in carbon content in both the reference and treated regions: carbon in untreated regions dropped from 42.13% to 21.61%, while in treated regions, it decreased from 48.8% to 36.36%. This inverse correlation between laser energy and carbon content implies that higher energy levels may reduce unwanted carbon species, though these findings could be influenced by inhomogeneous film properties or measurement inconsistencies.
Response Surface Methodology (RSM) analysis indicated that the laser pulse interval has a negligible effect on film thickness and refractive index, whereas laser energy has a pronounced impact on thickness. Temperature-energy contour plots at a constant chamber temperature of 120 °C and 50 ms laser pulse interval reveal that applying laser energy between 73 and 220 mJ produces the greatest thickness reduction, with over a 20% decrease observed in treated regions. At a chamber temperature of 160 °C and 50 ms pulse interval, maximum thickness reduction occurred when laser energy was between 114 and 181 mJ, with reductions reaching up to 15%. The results suggest that applying laser pulses may be beneficial; however, due to several erroneous factors, the experiment needs to be replicated to confirm the effect of the laser.