Plasma-enhanced atomic layer deposition of AlPO4/AlPxOy: comparing dual source and supercycle approaches for composition control

Preischel, Florian; Zanders, D.; Glauber, J.-P.; Rönnby, K.; Rogalla, D.; Gemming, Thomas; Dement, Peter; Nolan, M.; Devi, A.

Plasma-enhanced atomic layer deposition of AlPO4/AlPxOy: comparing dual source and supercycle approaches for composition control

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Files

d5dt02282g.pdf(2.34 MB)

Date

2025-10-31

Authors

Preischel, Florian

Zanders, D.

Glauber, J.-P.

Rönnby, K.

Rogalla, D.

Gemming, Thomas

Dement, Peter

Nolan, M.

Devi, A.

Publisher

Royal Society of Chemistry

Published Version

10.1039/d5dt02282g

Abstract

In pursuit of developing a plasma-enhanced atomic layer deposition (PEALD) process for AlPO4, we explored two different approaches, both employing an O2 plasma as the co-reactant. First-principles density functional theory (DFT) calculations indicate that TMA-phosphine adducts are stable, with ethyl or isopropyl groups on the phosphine. The adducts were thermally characterized, with the newly synthesized [Me3AlPiPr3] (TMAPIP) featuring a promising one-step evaporation. Therefore, it was tested as a dual-source precursor at 120 °C, providing both Al and P atoms for the resulting AlPxOy layers, thereby simplifying the process design. Although the P content of the PEALD-deposited films was limited to a few percent, this might be advantageous for P doping of Al2O3. The second approach, therefore, involved a supercycle (SC) process design, in which the number of phosphorus reagent sub-cycles using P(NMe2)3 as the precursor was varied alongside a single Al2O3 cycle with TMA; in both cases, O2 plasma was used as the co-reactant. Simple gas-phase DFT calculations show that P(NMe2)3 reacts favorably with the chemisorbed Al species present in the second sub-cycle. The SC method enabled the incorporation of significantly higher amounts of P over a broad temperature range from 60 °C to 240 °C. The deposition of stoichiometric AlPO4 was ultimately achieved by varying the number of phosphorus cycles, allowing the composition to be precisely adjusted via the deposition temperature.

Keywords

AlPO4 , PEALD , Plasma-enhanced atomic layer deposition (PEALD) process , [TyndallMicroNano]

Citation

Preischel, F, Zanders, D, Glauber, J-P, Rönnby, K, Rogalla, D, Gemming, T, Dement, P, Nolan, M & Devi, A 2025, 'Plasma-enhanced atomic layer deposition of AlPO4/AlPxOy: comparing dual source and supercycle approaches for composition control', Dalton Transactions, vol. 54, no. 47, pp. 17507-17520. https://doi.org/10.1039/d5dt02282g