Scientific Reports (May 2023)

Millisecond flash lamp curing for porosity generation in thin films

  • Ahmed G. Attallah,
  • Slawomir Prucnal,
  • Maik Buttering,
  • Eric Hirschmann,
  • Nicole Koehler,
  • Stefan E. Schulz,
  • Andreas Wagner,
  • Maciej O. Liedke

DOI
https://doi.org/10.1038/s41598-023-34748-x
Journal volume & issue
Vol. 13, no. 1
pp. 1 – 10

Abstract

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Abstract Flash lamp annealing (FLA) with millisecond pulse durations is reported as a novel curing method for pore precursor's degradation in thin films. A case study on the curing of dielectric thin films is presented. FLA-cured films are being investigated by means of positron annihilation spectroscopy (PAS) and Fourier-transform infrared (FTIR) spectroscopy in order to quantify the nm-scale porosity and post-treatment chemistry, respectively. Results from positron annihilation reveal the onset of the formation of porous voids inside the samples at 6 ms flash treatment time. Moreover, parameter's adjustment (flash duration and energy density) allows for identifying the optimum conditions of effective curing. Within such a systematic investigation, positron results indicate that FLA is able to decompose the porogen (pore precursors) and to generate interconnected (open porosity) or isolated pore networks with self-sealed pores in a controllable way. Furthermore, FTIR results demonstrate the structural evolution after FLA, that help for setting the optimal annealing conditions whereby only a residual amount of porogen remains and at the same time a well-densified matrix, and a hydrophobic porous structures are created. Raman spectroscopy suggests that the curing-induced self-sealing layer developed at the film surface is a graphene oxide-like layer, which could serve as the outside sealing of the pore network from intrusions.