DIFFERENT SPUTTERING CONFIGURATIONS FOR COATING 1,5 GHz COPPER CAVITIES

Transcription

1 13th nternational Workshop on RF uperconductivity FFRT PUTTRG CFGURT FR CTG 1,5 GHz CPPR CVT G.Lanza,.emporad, F.Carassiti,.eambrosis,. Patron, C.Pira, M.ebastiani,.tark and H.Padamsee, V.Palmieri

2 s it possible: to improve the b/cu cavities performances? to straighten the Q-slope of iobium thin films?

3 ntroduction MGTR HGH FUTUR TU

4 ensify the puttering ischarge Positive electrode insert in the diode configuration Target ubstrate - + Positive ions bombardment of the growing film mpurities are preferentially removed relative to the atoms of the main film ensification of the crystal structure ncreasing of the coating hardness dhesion improvement FUTUR TU

5 Techniques Comparison Magnet iased Grid +100 V Cathode -420 V TR CR MGTR FUTUR TU

6 ensify the puttering ischarge Feed the magnetron with an electrons extra source Hollow Cathode eposition rate increases Less direzionality of the ions Planar Magnetron FUTUR TU

7 Hollow Cathode Magnetron Current () V curve HC = 1 HC = 2 HC = 3 HC = 4 HC = 5 HC = 6 HC = hollow cathode magnetron characteristics Voltage (V) plane magnetron characteristic FUTUR TU

8 High onized Plasma...let s try heating directly the post-magnetron n the termoelectronic emission regime the cathode emits avalanches of electrons that feed and densify the plasma FUTUR TU

9 High onized Plasma...let s try heating directly the post-magnetron n the termoelectronic emission regime the cathode emits avalanches of electrons that feed and densify the plasma FUTUR TU

10 Techniques comparison TR CR HGLY FUTUR TU

11 High onized Plasma Results: till low RRR: electronic bombardment of the substrate high heating of the chamber and successively degassing mpurities from isolators on homogeneous thickness 3,0 distribution Thickness (μm) 2,5 2,0 1,5 1,0 0,5 0,0 Cav 1 Cav 2 Cav 3 Cav 4 Cav 5 Cav 6 Position FUTUR TU

12 ias Results: RRR eq. UP eq. W eq. UP eq. W eq. UP UP eq. W eq. UP UP eq. W Run Run 3020 Run Run Run U Position U Tc always higher than T c bulk FUTUR TU

13 Focused on eam FG-M 3 kv 80000x, after F sectioning TM F X after F lamella thinning b on Cu FUTUR TU

14 M-FM urface nalysis M 20 kv 40000x M 20 kv 40000x Contact Mode FM Contact Mode FM b on Cu U b on Cu FUTUR TU

15 Roughness Ra and RM Peak to Peak (nm) U LL-772 Q-771 R-768 YY Peak to Peak value RM value Ra value FUTUR TU

16 Vickers ndentation Unbiased M = 54,33 GPa iased M = 88,95 GPa FUTUR TU

17 Hardness comparison HV film hardness mean value J-H model LL-772 Q-771 R-768 YY-767 Unbiased M iased M FUTUR TU

18 RF measures on 1,5 GHz cavities Rs (nhm) 100 ias LL 2007 Qo= 1,5x10 9 problem of several vacuum break Unbias LL 2007 Qo= 2,6x acc (MV/m) FUTUR TU

19 Results iased films show: Higher surface roughness Higher hardeness denser structure Lower mean crystallite size RRR lower than unbiased film first RF measure of biased cavity had problems of vacuum breaks and test will be repeated FUTUR TU

20 Future tudies Combine both techniques ncrease film thickness Use Kripton as sputtering gas pply new cleaning treatment technique Check all cavities preparation steps FUTUR TU

21 Thanks

22 TT FUTUR TU

23 High onized Plasma...let s try heating directly the post-magnetron with holes inside it FUTUR TU

24 High onized Plasma...let s try heating directly the post-magnetron with holes inside it n the termoelectronic emission regime the cathode emits avalanches of electrons that feed and densify the plasma FUTUR TU

25 Vickers indentation at different loads FUTUR TU

26 MP: Critical Temperature 9,60 Critical Temperature Tc (K) 9,50 9,40 9,30 9,20 9,10 eq. UP eq. W eq. UP eq. W eq. UP eq. W eq. UP eq. W Run 20 Run 21 Run 30 Run 31 Position U

27 MP: Thickness 3,0 Thickness (μm) 2,5 2,0 1,5 1,0 0,5 Run 20 iased Run 21 iased Run 30 Unbiased Run 31 Unbiased 0,0 eq. Up Position eq.own

28 tate-of-the-art at 1500 MHz K single cell Rs [nhm] Q 1x10 15 MV/m acc [MV/m] Q 3x10 20 MV/m 28 MV/m reached in a large LP cryostat (He evaporation at large power)

29 Cu substrate Micro morphology unbiased M biased M

30 Results THCK RUGH (7,5 µm 2 investigated) deposition mode # [µm] RM R a peak- to peak [nm] ,73 8,2 6,5 55,7 unbiased M ,61 7,1 5, (±0,1) 7,6 6, ,9 (±0,2) 8,2 6,6 43,5 Q , biased M LL-772 0,98 9,4 7,4 59,3 YY-767 1,3 11,8 9,7 62 R-768 0,9 (±0,1) 12,5 10,2 68

31 puttering Parameters CR type F- LL Cathode Current () 7 7 Cathode Power (kw) ias Voltage (V) Pressure (mbar) 2x10-3 3x10-3 Time (min) FUTUR TU