PROPERTIES OF THIN FILMS MADE BY ION BEAM
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 0 1 0 2 3 4 5 6 7 Computer simulation: Displacement of Cu atoms due to the impact of 1. 5 ke. V 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)
Ion incidence angle effects on emitted particles from the target Less efficiency Cone angle exit particles More efficiency Uniform direction exit particles RCGD - Bari, May 13 -14 A. Valentini
DUAL ION BEAM SPUTTERING SCHEME ASSISTANCE ION SOURCE (Ar/H 2/O 2) TARGET 1 TARGET 2 Ar Ar SUBSTRATE QCM ION BEAM SOURCE 1 ION BEAM SOURCE 2 PUMPING GROUP RCGD - Bari, May 13 -14 A. Valentini
DUAL GRIDS ION SOURCE High Energy GRIDLESS ION SOURCE 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 sp 3 bonds, which gives the structure properties similar to those of diamond. Variable features with % of sp 2 bonds RCGD - Bari, May 13 -14 A. Valentini
DLC IBS PREVIOUS ACTIVITY 2007 -2008 IB SPUTTERING ASSISTANCE I beam V beam (V) Ar (sccm) CH 4 (sccm) I beam V beam Ar (V) (sccm) 0745 60 1200 2, 5 / 18, 8 100 0752 60 800 2, 5 / 20 0753 60 800 2, 5 / 0801 60 800 2, 5 0803 60 800 0804 60 0805 Temp CH 4 (sccm) H 2 (sccm) T (°C) 1 / 4 905 100 1 / 4 700 19, 1 100 1 / 4 900 / off / / 300 2 2 off / / 300 800 2 2 off / / 600 60 800 2 2 off / / Amb 0806 60 800 2, 5 / off / / Amb 0807 60 800 2, 5 / 20 90 2 2 / 300 0808 60 800 2, 5 / 20 90 2 2 / 900 0809 25 300 2, 5 / 20 100 1 3 / 600 0810 25 300 2, 5 / 20 100 1 3 / 300 0853 25 300 2, 5 / 20 100 1 3 / 300 0854 25 300 2, 5 / 20 100 1 3 / 150 (m. A) RCGD - Bari, May 13 -14 A. Valentini
CHEMICAL ANALYSIS RESULTS XPS DLC CVD DIAMOND Campioni sp 2 sp 3 SAMPLES sp 2 sp 3 F 4 - 82 0803 17 48 F 5 - 81 0805 14 51 F 6 - 86 0807 28 40 0808 22 54 0810 20 49 0853 23 48 0808 Ib Vb Ar / Ia Va Ar CH 4 / Tsub 60 800 2, 5 / 20 90 2 2 / 900 RCGD - Bari, May 13 -14 A. Valentini
APPLICATIONS In order to stabilize the photoemissive properties of the Cs. I 1, 5 nm of IBS DLC on 20 nm of Thermal Evaporated Cs. I on Conductive Silicon substrate RCGD - Bari, May 13 -14 A. Valentini
APPLICATIONS Conductive Layer for Cs. I – Head-On 2016 Sample Material Thickness (nm) 1532 ITO 10 1533 ITO 5 1533 ox ITOox 5 1534 Ni 5 1534 C 5 1535 Ni 3 1536 Ni. C+ Ni 3+0. 5 1537 C+Ni 2. 5+0. 5 1538 Ni 1 1538 Ni 3 Ion Beam Sputtering RCGD - Bari, May 13 -14 A. Valentini
RESULTS Conductive layer UV Transmittance Selected Layer (C 2. 5 nm + Ni 0. 5 nm) RCGD - Bari, May 13 -14 A. Valentini
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=150 V - Ib=1 A - (5 sccm Ar + 4 sccm H 2) Scotch tape test results: Copper on Kapton DLC on Kapton No Pretreatment Scotch tape RCGD - Bari, May 13 -14 A. Valentini
ION BEAM SPUTTERING DEPOSITION PARAMETERS Vbeam = 600 -1200 V Sputtering gas: Ar (2. 5 sccm) Vass = 50 – 150 V Ibeam = 50 - 60 m. A -----------Iass = 0. 05 – 1. 2 A Assistance gas : Ar – Ar+N 2 – Ar+H 2 -------------Film thickness = 50 – 100 nm Dep. rate = 0. 010 0. 017 nm/sec ----------------Sample size 6 x 6 cm 2 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 cm 3 D = 6 cm; L = 5 cm Sample on soft tissue (mouse pad) increase contact under pressure. Orientations: Horizontal & Vertical. Insulation Tester: Megger MIT 410 Multimeter: Agilent 34401° to Four Point Probe S=2 mm Circular Tool Radii r 1=1 cm & r 2= 2 cm RCGD - Bari, May 13 -14 A. Valentini
Sheet Resistance _ Results RCGD - Bari, May 13 -14 A. Valentini
Chemical Analysis _ Results XPS 1928 1929 298 296 294 292 290 288 286 284 282 280 Binding Energy (e. V) Sputt. 800 V 50 m. A Assist. 80 V 70 m. A Gas assist. (sccm) 2. 1 Ar 1 H 2 298 296 294 292 290 288 286 284 282 280 Binding Energy (e. V) 1928 1929 BE /e. V ± 0. 1 Abb% C–C (sp 3) 284. 7 79 C– O 285. 9 13 286. 0 12 C=O 287. 2 5 287. 3 5 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. 1 3. 4 1. 0 ü Surface contaminations ü Any (or very low) contribution of Csp 2 at the surface RCGD - Bari, May 13 -14 A. Valentini
IB contribution in DLC formation -The carbon atoms Ion Sputtered from Graphite target are more likely to form sp 2 -hybridezed carbon bonding - The Nitrogen in Assistance Beam - encreases sp 2 - hybridized carbon bonding - encreases the localized states at the Fermi level that favor the cunduction by hopping mechanisms Higher content of sp 2 -hybridized carbon bonding and hopping will reduce the film resistivity !! --------- The Hydrogen in Assiatance Beam facilitates the formation of sp 3 carbon strucuture as sum of bonds Csp 3 -Csp 3 or Csp 3 -H 1 s - 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 ü Higher Sputtering Energy Increases sp 3/sp 2 Higher Rs ü N 2 assistance Does not change significantly sp 3/sp 2 üH 2 assistance Control sp 3/sp 2 The Lowest Rs Control Rs * • Rs values nearest the 100 M /Square RCGD - Bari, May 13 -14 A. Valentini
Large Area Ion Beam Deposition System 400 mm in diameter substrates 6 x 22/30 cm RF Ion Beam Source 16 cm RF deposition source and RF neutralizers 12 cm RF assist ion source. RCGD - Bari, May 13 -14 A. Valentini
Summary 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 ü Chemical Analysis on DLC deposited on Kapton (Raman) ü XPS in depth analysis ü Tests on the effects of CH 4 in the Assistance Beam ü RCGD - Bari, May 13 -14 A. Valentini
Thanks for the attention RCGD - Bari, May 13 -14 A. Valentini
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