Docstoc

Fundamentals II

Document Sample
Fundamentals II Powered By Docstoc
					Ion Implantation Machines


                              Russell Gwilliam
                              Director of Technology
                              Surrey Ion Beam Centre

          Ion Implant Workshop 2009-
       R.Gwilliam Surrey Ion Beam Centre
                        Contents
• Ion Implanters
   – Historical and Modern
  Beam G
• B           i
       Generation
   – Ion sources and Source precursers
• Beam Identification
   – Mass Scans
• Dose Control and Quality
   – Charge Integration and Faraday systems
• Low Energy Lens
   – Energy Contamination and Uniformity Issues
                     pp
• Niche Markets and Applications
   – Process and Machine Requirements
• Surrey Ion Beam Centre Facilities
                        Ion Implant Workshop 2009-
                     R.Gwilliam Surrey Ion Beam Centre
            CMOS Process Window

• Implanter market is driven by the Si Industry
  High              hi    h    b    d l df i
• Hi h current machines have been developed for increased  d
  throughput
• Ultra low energy implanters (sub 1keV) are required for
  the formation of Ultra Shallow Junctions. (this has also
  driven the development of rapid thermal and laser
  annealing)
     g       gy                                      p
• High Energy machines are available with limited operation
  capability focussed on the CMOS market.
• Very high beam purity required for certain applications
                      Ion Implant Workshop 2009-
                   R.Gwilliam Surrey Ion Beam Centre
                   p
The “Silicon Roadmap”



                                    International Technology
                                          Roadmap for
                                     Semiconductors (ITRS)
                                  p //            /      /     p
                               http://www.itrs.net/Common/2004Update
                                          /2004Update.htm




   Ion Implant Workshop 2009-
R.Gwilliam Surrey Ion Beam Centre
                                                                    Gate Stack




                                                                      Oxide
                                                           source    Channel     drain




The down scaling of the device geometries is certainly a non-trivial task!!
                             Ion Implant Workshop 2009-
It is not micro           R.Gwilliam longer, we Centre
                  electronics any Surrey Ion Beam are in   the nano regime!!
                               Scaling Issues

   de ices
As devices geometries are scaled ‘Short Channel Effects’ can dominate
   Excessive device Leakage, punch-through, ‘parasitic’ devices, loss of control…




                                               Source/Drain Extensions (SDE) are a
                                                 y     p                  g
                                               key component in reducing ‘Short
                                               Channel Effects’




                            Ion Implant Workshop 2009-
                         R.Gwilliam Surrey Ion Beam Centre
  p           g    y
Implanter Design: My Favourite




            Ion Implant Workshop 2009-
         R.Gwilliam Surrey Ion Beam Centre
       Implantation at Bell Labs: 1954



                                                                   Ion source plasma
         Walter Brattain
William Shockley John Bardeen
               y                                                   Target ( a bit of Ge)




  Bell Labs1947Ge transistor
                                  Ion Implant Workshop 2009-
                               R.Gwilliam Surrey Ion Beam Centre
               Beamlines: 1943-2000




                     Calutron “f b” 1944
                     C l t    “fab”;




Calutron Isotope Separators:                       Eaton Ultra-low Energy Beamline:
           1943-45
           1943 45                                               ~2000

                             Ion Implant Workshop 2009-
                          R.Gwilliam Surrey Ion Beam Centre
Harwell Isotope Separator: ~1965




             Ion Implant Workshop 2009-
          R.Gwilliam Surrey Ion Beam Centre
Varian DF-4: ~1976




      Ion Implant Workshop 2009-
   R.Gwilliam Surrey Ion Beam Centre
                Tools from the 70’s and 80’s
                                               Varion/Extrion DF4
                                               Single wafer presentation single end station
                                               Medium current (around 100uA)
                                               Corner Faraday cups




Varion/Extrion 350D
Twin end station introduced to
enhance throughput but still single
wafer load in atmosphere.



                                   Ion Implant Workshop 2009-
                                R.Gwilliam Surrey Ion Beam Centre
  Beam Purity: Sensitive Regions
Multimer breakup                                           “Mass” resolution
(energy, dose)                                             (ions, energy)
Charge exchange
(ions, energy, dose)



                                                            Molecular breakup
                                                            (    gy)
                                                            (energy)
                                                            Charge exchange
                                                            (energy, dose)




                          Ion Implant Workshop 2009-
                       R.Gwilliam Surrey Ion Beam Centre
                            Magnet Equation
Uniform, circular, non-fringing                                Linear magnet:
magnetic field                                                 B = k* Imagnet

                                                               Circular field region:
    Ion path                     Rmagnet
                                                               Rcurvature = Rmagnet*cot(Θ /2)

                                                               Magnetic bending:
               Rcurvature
                                   Bending angle, Θ            Rcurvature = [m*v/ne]*B
                                                                          = [m/ne*B]*(2E/m)1/2
                                                                          = [m/ne*B]*(2ne*U/m)1/2
       Mass selection
                                                  Magnet equation
                                                  M    t     ti
       slits
m = ion mass
                                                  (m/n)*U = (k*Rmagnet*cot(Θ/2))1/2) * I2
     ion h
ne = i charge
v    = ion velocity                               (m/n)*U = k’ *I2
                 p
U = acceleration potential
B    = magnetic field strength
                                       Ion Implant Workshop 2009-
                                    R.Gwilliam Surrey Ion Beam Centre
Ion (M /Ch    )*”E t ti ”
I (Mass/Charge)*”Extraction”
        Spectrum




           Ion Implant Workshop 2009-
        R.Gwilliam Surrey Ion Beam Centre
Isotope Identification and Purity




        Ion Implant Workshop 2009-
     R.Gwilliam Surrey Ion Beam Centre
                               Dose Measurement
                              Ground
               E3   E2   E1
                                         Charge = Dose x e x Area
                                         Implant Time = Dose x e x Area/Ibeam
                                         Average dose rate =Dose/Implant Time
                                         Average beam current density = Ibeam /Scan Area
                                         Instant b        t d it           /Beam Area
                                         I t t beam current density = Ibeam/B    A



E1 biased negative wrt to ground to
remove secondary electrons from aperture.
                                                          130V
E2 biased negative wrt integrator to collect
             g             g                                              110V
circulating currents                                                                    I Int




                                   Ion Implant Workshop 2009-
                                R.Gwilliam Surrey Ion Beam Centre
     Implant Requirements
CMOS I l t R i         t




         Ion Implant Workshop 2005-
      R.Gwilliam Surrey Ion Beam Centre
  q                  p g
Requirements: CMOS Doping
130 nm CMOS Technology node (≈70 nm gates)

Dose U if
D           it
     Uniformity                           0 5%
                                         <0.5%

Energy Accuracy                          <1.0%
                                         (<0 1% energy contamination)
                                         (<0.1%

Angular Accuracy                         <1o (<0.1o for wells)

Metallic Contamination                   <1x1011 atoms /cm2
                                         (<0.01% monolayer)

Particle Contamination                   <0.10 /cm2
                                         for particles >0.16um


                     Ion Implant Workshop 2009-
                  R.Gwilliam Surrey Ion Beam Centre
  Requirements: Productivity
Throughput                                         >200 wafers/hour
                                                   (for low doses)

Ion Source Lifetime                                >100-500 hours

Tune Time (ion or energy change)                   <3 minutes

Mean time before failure (MTBF)                    >200 hours

Availability (“uptime”)                            >95 %




                       Ion Implant Workshop 2009-
                    R.Gwilliam Surrey Ion Beam Centre
Beamline Implanter Design




                                           Axcelis ULE3


          Ion Implant Workshop 2009-
       R.Gwilliam Surrey Ion Beam Centre
     High Current Beamline: AMAT
        Accel/decel
                    xR80
          electrodes
      Wafer            Mass
                       resolving slits

Faraday
cup                            Magnet




                                    Ion
                                    source



                               Ion Implant Workshop 2009-
                            R.Gwilliam Surrey Ion Beam Centre
               Spinning Wheels
                               50-90
                Radial speeds: 50 90 m/s



                                                     Stationary ion beam


Scan speeds:
1-10 cm/s                                            Spinning Wheels:
                                                     Lower Temperature
                                                     Lower Charging
                                                     Dose Scanning



                    Ion Implant Workshop 2009-
                 R.Gwilliam Surrey Ion Beam Centre
Broken Gates: Particles and Spinning Wheels

                                                                                     p y
                                                       Model describes collisions of poly-lines on
                                                       wafers into particles.
                            Damage captured
                            on blanket wafers
                            (Al and PR covered)
                                                                                   g
                                                                              Damage as
                            1-3o                                               seen on
                                                                              patterned
                                                                                wafers
                            Film/wafer

                           Particle and
                           direction of
      Direction of the
                           impact
      particle strike
                                                                            Particle and
           Crater
                           Directions of impact                             direction of
           maximum
                                                                            impact           Center
           depth=0.13 um   typically in the
                                                                                             of the
5um                        range of +15-45o                                                  wheel
                           around the spin
                           direction
           0.5-1um

                           Damage is worse for thinner poly
                           lines and fast spin speeds.
                                               speeds                               y
                                                                                M.Taylor, IIT04

                                Ion Implant Workshop 2009-
                             R.Gwilliam Surrey Ion Beam Centre
   Less Poly Breakage at Slower Wheel Speeds




                                                                   atio
                                                    hesion energy ra
                                                              10.0

Poly damage avoidance                                                     8.0
mandates reduction of spin




                                      sion energy/adh
                                                                          6.0
                                                                                         0.25 um
speeds from 900- 1250 RPM                                                                0.18 um
(90 m/s) to <200 RPM.                                                     4.0            0.13 um

                                                                          2.0




                                 Collis
                                                                                                           R ti 1 --> hi h probablity of d
                                                                                                           Ratio>1       high   b blit f damage
                                                                                                           Ratio<1 --->low probablity of damage
                                                                          0.0
                                                                             100   300    500           700         900     1100       1300
                                                                                                   Spin speed (rpm)

But… slower wheel speeds means:
  1. Less beam overlap at same scan speed: poor micro-uniformity
  2. Larger charge deposition per pass: higher charging levels
  3. Less centripetal clamping f
  3 L         ti t l l               less h t t
                            i force: l              f hotter    f
                                          heat transfer, h tt wafers
  4. Risk of wheel vibration problems at some speeds: hub wear, pitched wafers
So, many process and machine adjustments are needed……..or….
                                                                                                                          M.Taylor,
                                                                                                                          M Taylor IIT04

                              Ion Implant Workshop 2009-
                           R.Gwilliam Surrey Ion Beam Centre
 Ribbon beams: Varian VIISTA80
                       Mass
                       selection                     Beam
Mass selection         slits                         bending
                                                     b di
magnet                                               magnet




                                                        Wafer
                      Accel/
 Ribbon beam                                            scan
                      decel
 ion source           electrodes


                    Ion Implant Workshop 2009-
                 R.Gwilliam Surrey Ion Beam Centre
       VIISta-3000: High-energy,
       VIISta 3000: High energy
              Single wafer
                              Charge exchange channel
                     Negative        (0-750 keV)
                     i path
                     ion th
                                   Positive
                                   ion path




Varian Tandem accelerator beam line
10 keV to 3.75 MeV




                        Ion Implant Workshop 2009-
                     R.Gwilliam Surrey Ion Beam Centre
High Energy: LINAC (LINear ACcelerator)

   RF LINAC concept         90° Mass                 RF Resonators
                            Analyzing
                            Magnet
                                                               58 5° Final
                                                               58.5
                                                               Energy Magnet



                                 Quadrupole LensRF Electrode
                                                   El t d




                                                   Axcelis HE3
                  Ion Implant Workshop 2009-
               R.Gwilliam Surrey Ion Beam Centre
                   High Energy: LINAC/Single Wafer
                                 ( l         il bl )
                   AMAT: SWIFT(no longer available)
Boron:
Drift from 10 keV to 100 keV as B+
Boosted 100 keV to 400 keV as B+
Boosted 400 keV to 850 keV as B++

Phosphorus:
Drift from 10 keV to 100 keV as P+
Drift 100 keV to 200 keV as P ++
Boosted 200 keV to 850 keV as P ++
Boosted 850 keV to 1700 keV as P+++

Arsenic:
Drift from 10 keV to 80 keV as As+
Drift 80 keV to 200 keV as As ++
D ift 200 k V t 300 k V as A +++
Drift     keV to     keV    As

Indium, Antimony: (with optional vaporizers)
Drift 10 keV to 50 keV as In+ or Sb+
Drift 50 keV to 200 keV as In ++ or Sb ++
Drift 200 keV to 300 keV as In +++ or Sb +++

Tilt angle control: 0 to 60o ±0.1o




                                          Ion Implant Workshop 2009-
                                       R.Gwilliam Surrey Ion Beam Centre
SIMOX: Oxygen f SOI wafers
SIMOX O       for     f
 RF ion source                                       Hot (550-600C)
                                                     wafer wheel




                                 IBIS 1000

                    Ion Implant Workshop 2009-
                 R.Gwilliam Surrey Ion Beam Centre
         Thermal Processing
         Th    lP       i
(or how to get something useful from your implant!!)

Solid Phase Epitaxial Regrowth
– Furnace anneal
     p
– Rapid Thermal Anneal
– Spike Anneal
– Flash Anneal
– Laser Anneal
Liquid Phase Epitaxial Regrowth
  Q switched
                  Ion Implant Workshop 2009-
               R.Gwilliam Surrey Ion Beam Centre
     Implant Requirements
CMOS I l t R i         t




         Ion Implant Workshop 2009-
      R.Gwilliam Surrey Ion Beam Centre
                Tools from the 70’s and 80’s
                                                      Eaton NV6200 Implanter
                                                      Robotic handling through a load lock
                                                      introduced along with high tilt angle and
                                                      auto wafer twist.




Varion E-220
Scan compensation introduced
through hybrid scanning system
giving incident angle control across
wafer.


                                   Ion Implant Workshop 2009-
                                R.Gwilliam Surrey Ion Beam Centre
  g
High Current Batch Tools
          A new tool concept was introduced by Applied Materials in
          1986 with a high current (30mA) batch processor using
          mechanical scanning of multiple wafers - the so called
          spinning disc. Varian and Eaton followed.
          Beam current was monitored during the off phase of the
          implant when the wheel was retracted




     Ion Implant Workshop 2009-
  R.Gwilliam Surrey Ion Beam Centre
                                High Energy Implantation
                                                Eaton NV1002
                                                Eaton were first to use RFQ technology to access
                                                the MeV implant area. The mechanical sample
                                                            p                              p
                                                scanning was retained as power loading can be
                                                high due to the increased energy.
                                                                             q
                                                AMAT now use a similar technique on their latest
                                                SWIFT high energy tool




General Ionex IX1500
Tandem design of accelerator requiring
the generation of negative ion species.
This design is currently used by Varian
for their high energy machines

                                       Ion Implant Workshop 2009-
                                    R.Gwilliam Surrey Ion Beam Centre
                       Scan Incident Angle Correction
                                                  Nissin NH20SP
                                                  Use of double electrostatic plates giving kick-
                                                  back f the b     di           f
                                                  b k of th beam divergence from scanning  i
                                                  and producing neutral and charge filtration




Varian VIISta 80
Current state of the art 300mm capability
using a corrector magnet with multiple
p pieces for beam uniformity tuning in
pole p                        y       g
the horizontal and mechanical vertical
scanning on air bearings with He cooled
chuck.


                                 Ion Implant Workshop 2009-
                              R.Gwilliam Surrey Ion Beam Centre
   Ion Implant Workshop 2009-
R.Gwilliam Surrey Ion Beam Centre
               Current State of the Art from AMAT 300mm Single wafer
                                    and Batch Tools




                       Differential    MRS
                     Lens System      Vanes
                                              MRS Turbo
                                              Pump (300 l/s)
                                                                        Analyzing Magnet      Energy
                                                                                                                  Beam Collimator
                                                                                              Resolving
                                                   Small Radius
                                                                                              System
                                                   Analyzing Magnet

    Large
 Diameter   Wafer                                    Dual Range                                                                     Wafer
Beam Stop                                            Power Supplies
                                                     & HiRes TEM

      High Density
     Plasma Flood                                                     Ion Source/
           System                                                     Extraction                      Beam Scanner
                                                                                    Beam
                                                                                    Booster
                                                     Tetrode
                        IHC                          Extraction
                     Source                                                                               Whisper Scan


                                                   Ion Implant Workshop 2009-
                                                R.Gwilliam Surrey Ion Beam Centre
           p
General Purpose Research Machines

                                          Long beam lines to
                                          achieve high mass
                                          resolution.
                                          Very flexible
                                          60+ Ion Species Run
                                          10mA to 1nA beam
                                          current
                                          Any size sample to
                                          400mm x 400mm
                                          Implant
                                          I l target
                                          temperature from 20 to
                                          1400k.
                                          L cost of ownership
                                          Low     f       hi




         Ion Implant Workshop 2009-
      R.Gwilliam Surrey Ion Beam Centre
                   Ion sources

  Freeman                                       Chordis




Bernas         Ion Implant Workshop 2009-                 IHC
            R.Gwilliam Surrey Ion Beam Centre
  More Sources




   Ion Implant Workshop 2009-
R.Gwilliam Surrey Ion Beam Centre
Commercial Implanter Source Lifetime




           Ion Implant Workshop 2009-
        R.Gwilliam Surrey Ion Beam Centre
Ions and Source Precursers (Chordis)




            Ion Implant Workshop 2009-
         R.Gwilliam Surrey Ion Beam Centre
                                Beam Transport
Constant Density Field Varied


                                               For constant plasma density, increasing
                                               the t ti fi ld d h            th b
                                               th extraction field and hence the beam
                                               current the plasma becomes depleted
                                               and has a concave boundary.
                                               As the density is increased for a given
                                               extraction field, and hence beam
                                               current, the plasma grows and hence has
Constant Field Density Varied                  a convex boundary.


                                                 hi       id    i              i l
                                               This provides an important optical
                                               element in the optics of the ion
                                               transport.




                              Ion Implant Workshop 2009-
                           R.Gwilliam Surrey Ion Beam Centre
                  Effect of Plasma Boundary Shape
 G1=5 kV

       G2=        G3= -8 kV               G4=0V
        10
       -10                                                                  keV
                                                                          5k VB
       KV                                                                 IB=17 mA
                                                                          Plasma saddle: 0.05




                                                                  40 mm

G1=5 kV
      G2=-10 kV
                   G3=-8 kV                                               5 keV B
                                                G4=0
                                                G4 0 V
                                                                          IB=17 mA
                                                                          Plasma saddle: 0.15




                                                                  40 mm

                                 Ion Implant Workshop 2009-
                              R.Gwilliam Surrey Ion Beam Centre
                              Effect of Space Charge
                   G3=-8 kV
       G2=-10
G1=    kV
5kV                                 G4=0V
                                                                B 5 keV
                                                                IB=17 mA
                                                                Plasma saddle: 0.1mm



                                                  40 m


                                                           As energy dropped beam blows up
1 kV
       - 10 kV   - 5 kV
                               0V
                                                                    B 1 keV
                                                                    IB=15 mA
                                                                    Plasma saddle: 0.1mm




                                   Ion Implant Workshop 2009-
                                R.Gwilliam Surrey Ion Beam Centre
                                         3 keV B (AMU 11) beam
                                         decelerated from 6 keV.
                                         IB=0.7 mA




                                    As Ibeam increased beam
                                    blows upp



                                         3 keV B (11 AMU) beam
                                          decelerated from 6 keV.
                                         IB=7 mA




   Ion Implant Workshop 2009-
R.Gwilliam Surrey Ion Beam Centre
Beam Contamination




     Ion Implant Workshop 2009-
  R.Gwilliam Surrey Ion Beam Centre
Metals Contamination




   Ion Implant Workshop 2009-
R.Gwilliam Surrey Ion Beam Centre
Target Charging and Neutralisation




            Ion Implant Workshop 2009-
         R.Gwilliam Surrey Ion Beam Centre
Target Temperature




    Ion Implant Workshop 2009-
 R.Gwilliam Surrey Ion Beam Centre
    Surrey Decel Lens




   Ion Implant Workshop 2009-
R.Gwilliam Surrey Ion Beam Centre
Plasma Immersion Ion Implantation: PIII




                                                    wafer target
                                                                             plasma

                                                                    sheath




                                                                    -V +
                                    positive ion   electron        neutral

     Varian PLAD

                Ion Implant Workshop 2009-
             R.Gwilliam Surrey Ion Beam Centre
Alternatives to Standard Ion Implant


                           PIII
                           No mass analysis however very
                           high beam currents available.
                             g
                           Purity and dosimetry issues
                           Cheap and very attractive for
                           synthesis
                           Also use PSII




           Ion Implant Workshop 2009-
        R.Gwilliam Surrey Ion Beam Centre
Cluster Implantation




     Ion Implant Workshop 2009-
  R.Gwilliam Surrey Ion Beam Centre
      Facilities at the Ion Beam Centre
Accelerator Facilities at the Ion Beam Centre
  –   2MV implanter (High Voltage Eng. Europe, 1991)
  –   200 kV implanter (Danfysik, 1997)
  –                 ( g         g    g     p ,
      2MV Tandem (High Voltage Eng. Europe, 2002) )
  –   Implanters: Class 100 cleanroom
  –   Analysis: Microbeam, channelling goniometer
Implantation
Process
Measurement
Analysis

                     Ion Implant Workshop 2009-
                  R.Gwilliam Surrey Ion Beam Centre
Elemental Implants Available
El      lI l       A il bl




           Ion Implant Workshop 2009-
        R.Gwilliam Surrey Ion Beam Centre
        Facilities at the Ion Beam Centre
Implantation
Process
  –   Photolithography (0.5um optical)
  –   A     li (RTA l          df
      Annealing (RTA, laser and furnace) )
  –   Metal and dielectric deposition (thermal, sputter and e-beam)
  –   Plasma deposition and etch
  –   FIB and e-beam direct write

Measurement
Analysis


                         Ion Implant Workshop 2009-
                      R.Gwilliam Surrey Ion Beam Centre
            Facilities at the Ion Beam Centre
Implantation
Process
Measurement
Electrical
    – Hall effect (differential and temperature dependent)
    – CV-IV (HP4160) and ECV (BioRad)
               d
    – DLTS and FRS
    – 4PP static and mapping
Optical
    – EL and PL
    – Thermawave (Jenaoptic mapping)
                   (    p      pp g)
    – Elipsometry (Plasmos mapping)
Analysis
                           Ion Implant Workshop 2009-
                        R.Gwilliam Surrey Ion Beam Centre
        Facilities at the Ion Beam Centre
Implantation
Process
Measurement
Analysis
  –   RBS depth profiling
  –   PIXE and PIGE trace element imaging
  –   ERD/NRA hydrogen isotope p
                  y g                    g
                               p profiling
  –   IBIC transport measurement
  –   3 dimensional elemental mapping (1um resolution)
          –From 2007 resolution improved to <30nm



                        Ion Implant Workshop 2009-
                     R.Gwilliam Surrey Ion Beam Centre
                     Applications
Accelerator Facilities at the Ion Beam Centre
Implantation
I l t ti
   –   Doping (Si, C, SiC, III-V)
   –   Un-Doping (carrier removal in III V s)
       Un Doping                      III-V’s)
   –   Ion Beam Synthesis (SIMOX, βFeSi2 etc, MgB2)
   –   Dislocation Engineering (light from silicon)
   –   Surface Treatment (anti-fouling)
   –   Topography (direct writing, MEMS)
Process
Measurement
Analysis


                        Ion Implant Workshop 2009-
                     R.Gwilliam Surrey Ion Beam Centre
                   Conclusions

• Implant has moved a long way since the 1960’s
  however it has been dragged there by the
  h         i h b      d       d h b h
  requirement of the Si industry so tools have
  b                        i li d f hi       li i
  become ever more specialised for this application.
• Other material systems have not had the financial
  clout to enable specific tool development to take
  place however as has been shown in Si, implant
  can be adapted and honed to fit very stringent
  requirements when needed.
                    Ion Implant Workshop 2009-
                 R.Gwilliam Surrey Ion Beam Centre

				
DOCUMENT INFO
Shared By:
Categories:
Tags:
Stats:
views:16
posted:10/14/2011
language:English
pages:62