Ion Beam Induced Deposits of Pt Composition, Voldose and

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					Ion Beam Induced Deposits of Pt:

Composition, Vol/dose and electrical transport
                 properties



 A. Fernández-Pacheco, R. Córdoba, J.M de Teresa,
             O. Montero, M. R. Ibarra
                                                       Outline
   • Dual beam equipment in Zaragoza (Spain): Induced
     deposition


   • Pt IBID deposition: Composition, Vol/dose

   • Transport measurements
      – As a funtion of T
          – During deposition: microprobes

          Results shown: De Teresa et al, Microelectronical engineering, submitted
                        Preprint available on request



A. Fernández-Pacheco --- Pt IBID: Composition, Vol/dose & Electrical transport measurements --- EFUG 2007- Arcachon
                              Dual Beam in Zaragoza
                                         Nova 200 NanoLab by FEI


    EDX DETECTOR                                                                                         FEG 30 keV ELECTRON
   (Oxford Instruments)                                                                                        COLUMN


                                                                                                       30 keV Ga+3 ION COLUMN
   STEM DETECTOR
      (not visible)
                                                                                                        TLD (THROUGH-LENS)
                                                                                                       DETECTOR (secondary and
 EBL LITHOGRAPHY
                                                                                                         backscattered electrons)
(Raith Elphy Plus) (not
         visible)
                                                                                                             OMNIPROBE
                                                                                                          NANOMANIPULATOR

  4 MICROPROBES FOR
      ELECTRICAL                                                                                              5 GAS
  MEASUREMENTS (not                                                                                      INJECTORS (GIS)
         visible)


                                                                                                          CDEM DETECTOR
                                                                                                          (secondary ions and
                                                                                                               electrons)




 A. Fernández-Pacheco --- Pt IBID: Composition, Vol/dose & Electrical transport measurements --- EFUG 2007- Arcachon
   Ion & electron beam induced deposition
  IBID & EBID of metallic materials is one major application of dual beam systems:

 Controllable lateral size (EBID~5nm; IBID ~1-10nm) & thickness (10nm-10µm)

 Applications: Reparation of optical masks & integrated circuits, fabrication of 3d-
 nanostructures, protection layers for lamella preparation, creation of electronic
 devices, fabrication of nanoelectrodes & nanocontacts, transport studies of NW, etc
                                                                                  Materials in Zaragoza:
                      Injector
    Precursor                                   Beam
       gas                 h~ 50 µm                                        METAL                             GAS
                                                                                Pt                  (CH3)3Pt(CpCH3)
                                                                                W                          W(CO)6
  z~ 150 µm                                                                    Co                         Co2(CO)8
                                                                           (only EBID)

                                  Substrate                                 Problems:
                                                                            - High ρ (amorphous carbon matrix)
   Process:    Beam    “breaks”    the                                      - Ga implantation (IBID)
   molecules, inducing a deposit (CVD)
A. Fernández-Pacheco --- Pt IBID: Composition, Vol/dose & Electrical transport measurements --- EFUG 2007- Arcachon
                                 Pt IBID- OBJECTIVE
                   High conductivity deposits are desired!!
IBID depositions in 5 x 5 mm2 areas on a Si substrate- influence of:
                           - Ion current: 100pA- 2.5nA
                           - Beam energy: 5- 30keV
                                                                                                                      7keV, 1.8nA




 Study of the Vol/dose                          Study of the Pt content                           Study of the resistivity
    (cross sections)                                (EDX analysis)
                                                                                                    - R(Temperature) ex situ
                                                                                                    - R(time) in situ
                                                                % Pt = 23.21 ± 0.24
                                                                % C = 65.99 ± 0.24
                                                                % Ga = 10.81 ± 0.29




      20keV, 0.21nA                                     20keV, 0.21nA
A. Fernández-Pacheco --- Pt IBID: Composition, Vol/dose & Electrical transport measurements --- EFUG 2007- Arcachon
                                                           Pt IBID: Vol/dose
                               Vol/dose (current) decreases from                              Vol/dose (beam energy) increases
                                          0.65 down to    0.45µm3/nC                                                           sligthtly
                                0.8                                                                           1




                                                                                  Volume per dose (µm /nC)
    Volume per dose (µm /nC)




                                                  incident energy= 10 keV




                                                                                  3
   3




                                0.7                                                                          0.8

                                0.6                                                                          0.6

                                0.5                                                                          0.4

                                0.4                                                                          0.2

                                0.3                                                                           0
                                      0     0.5      1    1.5      2    2.5   3                                    0      5    10    15    20    25    30
                                                  Ion beam current (nA)                                                  Incident ion beam energy (keV)

  Ga+


                                                                                                               2ary e-
Precursor
molecules                                                                                                                                       ~50nm in
                                                                                                                                                all E range
                                                                       !!
                                                                MILLING!!


 A. Fernández-Pacheco --- Pt IBID: Composition, Vol/dose & Electrical transport measurements --- EFUG 2007- Arcachon
                                            Pt IBID: Pt content
                    Pt content (current) ~ constant                                          Pt content (beam energy)
                                                                                     decreases from 27% down to 17%.
                                                                                    [TRIM: Pt sputtering yield increases]

                     24

                     22                                                             40
                                            Pt
       % (atomic)




                     20
                                                                                    30
                     18           Incident energy=20kV                                              Pt




                                                                         % atomic
                     16

                     14                                                             20
                     12                     Ga                                                      Ga
                     10                                                             10
                     8

                          0.0   0.5   1.0        1.5   2.0   2.5   3.0               0
                                Ion beam current (nA)                                    0      5    10   15   20     25   30
                                                                                              Incident ion beam energy (keV)

       Ga content (beam energy) increases                                            Ga content (beam energy) ~10%
               sligthly (from 8% up to 12% at 20kV)                                    [TRIM: Penetration depth of
                             [MILLING]                                                       Ga+ ~constant]


A. Fernández-Pacheco --- Pt IBID: Composition, Vol/dose & Electrical transport measurements --- EFUG 2007- Arcachon
                  Transport measurements: resistance
                           as a function of T
                  Al                                                                             Optical lithographyŁ 12 µm
                                                                                                                    Ł
                                                                                                 gap between metal electrodes.

                                                              IBID Pt                              FIB deposits permit 4W
                  Si3N4 //Si
                                                                                                   electrical measurements




                 40
RESISTANCE (Ω)




                                                                                       R weakly                dependent    on
                 35                                                                    temperature.
                                                                                                    µΩ⋅
                                                                                                500 µΩ⋅cm:




                                                                                            ≈
                                                                                        ρ
                 30
                           30keV, 1nA, tdwell=200ns
                           thickness~500nm                                             Lower than other values reported
                 25
                                                                                       in literature but still 50 times
                 20
                                                                                       higher than bulk Pt
                      50    100      150          200        250         300
                                           T(K)
      A. Fernández-Pacheco --- Pt IBID: Composition, Vol/dose & Electrical transport measurements --- EFUG 2007- Arcachon
                        Transport measurements: in situ
                            control of the resistance

                        6
                       10                                                                        Different R ranges




                                                                                      
                        5
                                10keV,0.54nA, tdwell=1µs       Rfinal=23.5M
                       10
                                                                                                   (non) percolation
     Resistance (kΩ)




                        4
                       10                                                                         of Pt islands (+Ga)
                                                  electron-beam-induced
    Microprobes by Kleindiek
            3
                                                  Pt deposition         In situ 2W-R measurements
         10
                      Thickness(both deposits)~160nm
                        2
                       10         30keV,10pA,
                                  tdwell=200ns    ion-beam-induced
                                                  Pt deposition                                     EBID (~10% Pt)




                                                                                  
                        1
                       10                                         Rfinal=1k

                        0
                       10
                            0       2         4            6     8          10
                                           Time (a.u.)
                                                                                                     IBID (~20% Pt)


A. Fernández-Pacheco --- Pt IBID: Composition, Vol/dose & Electrical transport measurements --- EFUG 2007- Arcachon
                      CONCLUSIONS & OUTLOOK
     Study as a function of Ebeam & Ibeam of Pt- ion induced deposits
          –    Vol/dose (current) decreases (milling increases)
          –    Vol/dose (beam energy) increases sligthly (more SE generated)
          –    %Pt (current) ~ constant
          –    %Ga (current) increases sligthly (milling increases)
          –    %Pt (beam energy) decreases (sputtering yield of Pt increases)
          –    %Ga (beam energy) ~ constant (interaction volume does not change much)

     Preliminary transport results
                500µ ⋅cm (50 times larger than bulk Pt)
                               




           –
                      ≈
                  ρ




           – R weakly dependent with temperature
           – Possible to measure in situ the resistance during deposition

     Next…
           – Study of different parameters: tdwell, trefresh, gas flux,…
           – Annealing procedures to increase Pt content
           – Sistematic study of , 4W in situ measurements, …
                                                ρ




A. Fernández-Pacheco --- Pt IBID: Composition, Vol/dose & Electrical transport measurements --- EFUG 2007- Arcachon

				
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