PROPERTIES OF THIN FILMS MADE BY ION BEAM DEPOSITION Resistive Coating for Gaseous Detectors May 13-14 Bari – Italy Diamond-Like Carbon and related resistive coatings for Micro-Pattern Gaseous Detectors Antonio Valentini

Ion – Solid Interactions SPUTTERING PROCESS Ion Target RCGD - Bari, May 13-14 A. Valentini

Simulated Trajectories Computer simulation: Displacement of Cu atoms due to the impact of 1.5 keV Argon ions (a) Trajectories within the entire volume of collision cascade for 10 incident particles (b,c) Transport of target atoms out of and into the designated layer (20 incident particles) (d) Trajectories of sputtered atoms (50 incident particles) 0 1 2 3 4 5 6 7 2 3 0 12 1.5 KeV Ar+ RCGD - Bari, May 13-14 A. Valentini

Ion incidence angle effects emitted particles from the target Less efficiency More efficiency Cone angle exit particles Uniform direction exit particles RCGD - Bari, May 13-14 A. Valentini

DUAL ION BEAM SPUTTERING SCHEME   DUAL ION BEAM SPUTTERING SCHEME Ar PUMPING GROUP ION BEAM SOURCE 1 (Ar/H2/O2) ASSISTANCE ION SOURCE TARGET 1 SUBSTRATE QCM TARGET 2 ION BEAM SOURCE 2 RCGD - Bari, May 13-14 A. Valentini

High Energy High Current DUAL GRIDS ION SOURCE GRIDLESS ION SOURCE High Energy High Current e- ION BEAM RCGD - Bari, May 13-14 A. Valentini

DIAMOND-LIKE CARBON (DLC) Metastable form of amorphous carbon, containing a significant fraction of sp3 bonds, which gives the structure properties similar to those of diamond. Variable features with % of sp2 bonds RCGD - Bari, May 13-14 A. Valentini

DLC IBS PREVIOUS ACTIVITY 2007-2008 IB SPUTTERING ASSISTANCE   IB SPUTTERING ASSISTANCE Temp I beam (mA) V beam (V) Ar (sccm) CH4 (sccm) I beam (mA) H2 (sccm) T (°C) 0745 60 1200 2,5 / 18,8 100 1 4 905 0752 800 20 700 0753 19,1 900 0801 off 300 0803 2 0804 600 0805 Amb 0806 0807 90 0808 0809 25 3 0810 0853 0854 150 RCGD - Bari, May 13-14 A. Valentini

CHEMICAL ANALYSIS RESULTS XPS DLC CVD DIAMOND Campioni sp2 sp3 F4 - 82 F5 81 F6 86 SAMPLES sp2 sp3 0803 17 48 0805 14 51 0807 28 40 0808 22 54 0810 20 49 0853 23 Ib Vb Ar / Ia Va CH4 Tsub 0808 60 800 2,5 / 20 90 2 900 RCGD - Bari, May 13-14 A. Valentini

APPLICATIONS In order to stabilize the photoemissive properties of the CsI 1,5 nm of IBS DLC on 20 nm of Thermal Evaporated CsI Conductive Silicon substrate RCGD - Bari, May 13-14 A. Valentini

Conductive Layer for CsI – Head-On APPLICATIONS Conductive Layer for CsI – Head-On 2016 Ion Beam Sputtering Sample Material Thickness (nm) 1532 ITO 10 1533 5 1533ox ITOox 1534 Ni C 1535 3 1536 NiC+ Ni 3+0.5 1537 C+Ni 2.5+0.5 1538 1 RCGD - Bari, May 13-14 A. Valentini

Conductive layer UV Transmittance RESULTS Conductive layer UV Transmittance Selected Layer (C 2.5 nm + Ni 0.5 nm) RCGD - Bari, May 13-14 A. Valentini

Good adhesion of DLC on Kapton Sheet Resistance of about 100 M APPLICATIONS ION BEAM SPUTTERING APPLIED FOR DLC FORMATION ON KAPTON The goals! Good adhesion of DLC on Kapton Sheet Resistance of about 100 M RCGD - Bari, May 13-14 A. Valentini

Good adhesion of DLC on Kapton To improve adhesion: Chemical surface cleaning Surface pretreatment with Ion Beam: Vb=150V - Ib=1A - (5 sccm Ar + 4 sccm H2) Scotch tape test results: Copper on Kapton DLC on Kapton No Pretreatment Pretreatment Pretreatment Scotch tape Scotch tape RCGD - Bari, May 13-14 A. Valentini

ION BEAM SPUTTERING DEPOSITION PARAMETERS Vbeam = 600 -1200 V Ibeam = 50 - 60 mA Sputtering gas: Ar (2.5 sccm) ---------------------- Vass = 50 – 150 V Iass = 0.05 – 1.2 A Assistance gas : Ar – Ar+N2 – Ar+H2 --------------------------- Film thickness = 50 – 100 nm Dep. rate = 0.010  0.017 nm/sec --------------------------------- Sample size 6x6 cm2 At now 22 samples and Parameter values have been setted for each one Starting from The Sheet Resistance values obtained on previous samples RCGD - Bari, May 13-14 A. Valentini

SHEET RESISTANCE MEASUREMENTS Two Probe Cu-bars: 6 x 0.5 x 0.5 cm3 D = 6 cm; L = 5 cm Sample on soft tissue (mouse pad) to increase contact under pressure. Orientations: Horizontal & Vertical. Insulation Tester: Megger MIT 410 Multimeter: Agilent 34401° Four Point Probe S=2 mm Circular Tool Radii r1=1 cm & r2= 2 cm RCGD - Bari, May 13-14 A. Valentini

Sheet Resistance _ Results RCGD - Bari, May 13-14 A. Valentini

Chemical Analysis _ Results XPS 1928 280 282 284 286 288 290 292 294 296 298 Binding Energy (eV) 1929 280 282 284 286 288 290 292 294 296 298 Binding Energy (eV) Sputt. 800 V 50 mA Assist. 80 V 70 mA Gas assist. (sccm) 2.1 Ar 1 H2 1928 1929 BE /eV ± 0.1 Abb% C–C (sp3) 284.7 79 C– O 285.9 13 286.0 12 C=O 287.2 5 287.3 COOH 288.6 3 288.5 4 RCGD - Bari, May 13-14 A. Valentini

Chemical Analysis _ Results XPS %C %O %N %Si %Ar %Cu 1928 78.8 14.5 2.5 3.1 1.1 -- 1929 75.1 16.4 3.4 1.0 Surface contaminations Any (or very low) contribution of Csp2 at the surface RCGD - Bari, May 13-14 A. Valentini

IB contribution in DLC formation Csp3-Csp3 or Csp3-H1s The carbon atoms Ion Sputtered from Graphite target are more likely to form sp2-hybridezed carbon bonding The Nitrogen in Assistance Beam encreases sp2- hybridized carbon bonding encreases the localized states at the Fermi level that favor the cunduction by hopping mechanisms Higher content of sp2-hybridized carbon bonding and hopping will reduce the film resistivity !! ----------------- The Hydrogen in Assiatance Beam facilitates the formation of sp3 carbon strucuture as sum of bonds Csp3-Csp3 or Csp3-H1s As the energy of Ar ions used for sputtering encreases the graphite sputtering rate encreases RCGD - Bari, May 13-14 A. Valentini

Sheet Resistance Values and Film Properties Preliminary results from Raman Analysis Rs = 0.5 M/Square  > 50 G/Square Higher Sputtering Energy Increases sp3/sp2 Higher Rs N2 assistance Does not change significantly sp3/sp2 The Lowest Rs H2 assistance Control sp3/sp2 Control Rs * Rs values nearest the 100 M/Square RCGD - Bari, May 13-14 A. Valentini

400mm in diameter substrates 16cm RF deposition source Large Area Ion Beam Deposition System 400mm in diameter substrates 16cm RF deposition source and RF neutralizers 12cm RF assist ion source. 6 x 22/30 cm RF Ion Beam Source RCGD - Bari, May 13-14 A. Valentini

Summary DLC films with controlled properties Next Step Assisted Ion Beam Sputtering has many indipendent parameters to be set and More tests are necessary but The technique is promising to grow DLC films with controlled properties Next Step Tests on the reproducibility Chemical Analysis on DLC deposited on Kapton (Raman) XPS in depth analysis Tests on the effects of CH4 in the Assistance Beam RCGD - Bari, May 13-14 A. Valentini

Thanks for the attention RCGD - Bari, May 13-14 A. Valentini