Status on ALD deposition of NbN / AlN at Grenoble (WP12-2.2)

1. Status on ALD deposition of NbN/AlN at Grenoble (WP12-2.2) M. Benz, F. Weiss, E. Blanquet, C. Jiménez, A. Mantoux SIMaP/LMGP (Grenoble INP) matthieu.benz@simap.grenoble-inp.fr

2. Introduction ALD technique AlNdeposition Future plans Conclusion      Motivations RF cavities: bulk niobium Functionalcoating (inside the cavity)  Enhancement of the quality factor and reduction of the electomagneticlosses A. Gurevich, "Enhancement of RF breakdown field of SC by multilayer coating". Appl. Phys.Lett., 2006. 88 Challenge : conformaldeposition on complexshape Atomic Layer Deposition

3. Introduction ALD technique AlNdeposition Future plans Conclusion   Thermal ALD vs Plasma enhanced ALD • Sequential introduction of the precursors, surface saturation : conformalprocess • Mono-atomiclayers(ideally in the « ALD window ») • Higherreactivity, lowerdepositiontemperaturethan ALD • Slightlylessconformalthan thermal ALD

4. Introduction ALD technique AlNdeposition Future plans Conclusion   State of the art • Most common settings in plasma ALD* : • Al source : TMA • N source : NH3 plasma • Temperature : 350°C • Thermal ALD issue : • NH3 reactiveabove 350°C • TMA decompositionabove375°C • -> smallprocessingwindow TMA New depositionstrategy : use of a hydrogen plasma for precursorreduction *Banerjee et al.,Phys. StatusSolidi C 12, No. 7, 1036–1042 (2015)

5. Introduction ALD technique AlNdeposition Future plans Conclusion   Experimental conditions • Constant parameters : • 1000 cycles • 8 hPa in pressure • Pulses time • Studiedparameters : • Temperature • Plasma power Most criticalparameter : temperature

6. Introduction ALD technique AlNdeposition Future plans Conclusion   Temperature influence on thickness • @ 2800W or high temperatures : • Lowoxygen contamination • Lowroughness • Good cristallinity 85nm AlN sustrate • Good processing conditions • Above 400°C @ 500W • Above 350°C @ 1000W • Above 250°C @ 2800W • Depositionsuccessful on niobium

7. Introduction ALD technique AlNdeposition Future plans Conclusion    Niobium nitridedeposition • Tested • No transport • Homemade • Currentlytested • Transport @ 150°C • Currentlytested PDMAN Modified PDMAN TBTDEN General strategy : niobium reduction NbV(precursor) → NbIII(NbN)

8. Introduction ALD technique AlNdeposition Future plans Conclusion  Conclusion • AlNsuccessfullydeposited at 250°C • Additionalcharacterizationongoing to publishresults • Resultspresentedduring 3 conferences : • ALD 2015 • EuroCVD 2015 • RAFALD 2015 (best poster award) • Nextstep : NbNdeposition (ongoing)