and the Trees: XRD and AFM for Compound … · XRD and AFM for Compound Semiconductors and Solar...
Transcript of and the Trees: XRD and AFM for Compound … · XRD and AFM for Compound Semiconductors and Solar...
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Welcome
Assunta ViglianteHead of Business Development,Semiconductor Industry
Today’s Topics:Overview on X-ray diffraction (XRD) solutions for compound semiconductorsX-ray characterization and metrology for solar cellsAtomic Force Microscopy (AFM) applicationsBruker Nano AFMsQ&A
David SampsonProduct Manager, AFM
First, See the Forest…
XRD – Bulk material properties• thickness• orientation• roughness• epitaxy• composition• phase
AFM – Surface material properties• surface roughness• grain size• uniformity• surface potential• electrical fields• capacitance• work function• spreading resistance
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Compound Semiconductor Industries
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Material Systems Devices Applications InP
InGaAs InAlAs
InGaAlAs InGaAsP InGaAsN
1.3/1.55um Lasers LEDs
VCSELs Detectors
HBTs
Optical fibre communications Sensors
IR cameras Wireless communications
GaAs AlGaAs InGaAs
InGaAlAs InGaAsP
Solar Cells Detectors VCSELs HEMTs FETs
Fibre amplifiers Medicine
Solid state laser pumps CD, Minidisc
Gigabit Ethernet GPS, Automotive
Satellite
InGaP InAlP
InGaAlP GaN
InGaN InGaAlN
Visible Lasers UHB LEDs
Visible VCSELs InGaP HBTs
Doudle Junction Solar Cells White LEDs
Display illumination Solid-state lighting
DVD lasers Pointers, bar code
Wireless communications Satellite Medicine
Si SiGe
MOSFETs Solar Cells
HEMTs Virtual Substrates
Wireless communications Solar power
Inexpensive starting material for III-V´s Computers
Data Processing
ZnSe White LEDs Display illumination Solid-state lighting
Please use your mouse to answer the question on the right of your screen:
What types of materials do you currently analyze? (Check all that apply.)
Thin film solarCrystalline or polycrystalline SiDye sensitized solarLEDsLasersCIGS/CdTe
Audience Poll
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Pseudomorphic Layers Compression and Tension
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Substrate Substrate Substrate
Layer underCompression
Layer without Strain
Layer underTension
Sample 1460: XRR and HRXRD Measurement Consistent Data Analysis with LEPTOS
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GaN(000) GaN(002) GaN(004)
One sample-model
Multiple measurements
Sample 1460: Fast Reciprocal Space Mapping Using the LynxEye 1D-Detector
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Δt = 3.84s / point T = 418 min Δt = 1.92s / point T = 39 min
GaN(104+)GaN(002)
Conversion to reciprocal
space units using LEPTOS
Sample 1460: Fast Reciprocal Space Mapping Using the LynxEye 1D-Detector
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Δt = 3.84s / point T = 418 min Δt = 1.92s / point T = 39 min
GaN(104+)GaN(002)
Conversion to reciprocal
space units using LEPTOS
• RSM with the LynxEye are collected by looping 2theta-scans. The data are converted afterwards to RSU using the Leptos software.•Instead measuring the (105+) reflection, the (104+) reflection was chosen because of the smaller beam footprint and resulting in a better resolution.•A further reduction of the measurement time may be achieved by reducing the measurement time per point and reducing mapped area.
Changing to the In-Plane Geometry
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Quick and easy change of the setup:
• Rotate the tube by 90°• Remove the PBO• Mount the soller-slits
(0.23°) on the primaryand secondary side
• Ready to measure
What is IP-GID ?
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• Scattering geometry combining Bragg condition with total external reflection from crystal surface (non coplanar geometry)
• Penetration depth of x-rays reduced by 3 orders of magnitude (from 1-10 μm in standard Bragg condition to 1-10 nm at critical angle and below)
⇒ Surface sensitive technique
Sample 1504: Depth-Dependent Determination of the In-Plane Lattice Parameter of the Surface-Near AlInN Layer Using In-Plane Diffraction
0,40 0,45 0,50 0,55 0,60 0,65 0,700
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inte
nsity
[c
ps]]
incidence angle [deg]
Peak @ 115,4° Peak @ 113,7°
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2 peak positions at the AlxIn1-xN(300) reflection :
115,05° ± 0,2° a = 3,162Å113,66° ± 0,1° a = 3,188Å
Lateral mismatch: Δa/a = -0.0082 h - position at (104+) reflection : 1.0082l - position : 4.082αi = 0.4°
αi = 0.7°
Cu-Kα1
Cu-Kα2
surface
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HRXRD SimulationExample: Si1-xGex - Si Structure
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Fit results
Concentration cx = 39.67 %
Thickness SiGe layer = 2.5 nm
Thickness Si layer = 80.83 nm
Sample courtesy of Uni Duisburg / IPAG
Si
Si1-xGex
Si
D8 DISCOVER with 2D HI-STAR Detector
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ω scan
2D detector used in fixed position
ω scanned for one frame for half of the 2θ range of the detector
HI-STAR
Cu LFF2.2 kW
Laser Video Scope
Homogeneity maps with µXRD
D8 DISCOVER for Material Research µ-HRXRD - Homogeneity Mapping
(In0.12Ga)N(100nm)/GaN(2000nm)/Al2O3
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Time: 2 sec.2θ (d-spacing)
χ (mosaic)
InGaNGaN
Measured areaGaN InGaN
D8 DISCOVER for Material Research µ-HRXRD - Homogeneity Mapping(In0.12Ga)N(100nm)/GaN(2000nm)/Al2O3
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Solar CellsHigh Efficiency
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Satellites and Space Explorations Applications
Epitaxial layers
GaAs, Ge, InP substrate
Efficiency 40.7%
XRD Requirements:
HRXRD on 6“ wafers
Solar Cells for Commercial Applications
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• Bulk Si (90%of the solar cells market)
• CdTe thin film on glass• CuInSe2 CIS and CuInxGa(1-x)Se2 thin film on glass
• New materials in R&D Organic films, films on flexible tapes, nanocrystals...
X-ray Solutions:
• Basic XRD PhaseAnalysis• Texture/preferredorientation
• µXRF elemental composition
• µXRF can be in line
ARTAX Technique
CCDX-raytube
Detector
Laser
Probe
Capillary optics Ranging from 25µm to 100 µmEnergy range From few KeV to 25 KeV
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Analysis of Functional Coatings Solar Cells (1)
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Structure of the solar cell system
Coating Thickness Ranges
Layer Coating [µm]
ZnO 0.80 - 1.80CdS 0.05 - 0.10CuInGaSe 1.50 - 2.0Mo 0.30 - 0.40
Quality control of CIGS-Modules (30x30cm²)
with Micro X-ray Fluorescence
Results:Elemental distribution in the CIGS-layer; Coating thickness distribution of Mo, CIGS, CdS and ZnOInfluence of module curvature No influence on layer composition Influence to coating thickness small (approx. 3% per mm)
µXRF Capabilities
Mo Micro-focus source and capillary optics
µXRF evaluation software (qualitative and quantitative multilayers analysis with fundamental parameters)
Automated height alignment and measurement scripts
Spot size can be chosen according to the collimator or capillary optics
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Acknowlegements
Martin Zimmerman, Bruker AXS, Karlsruhe, Germany
Wayne Lin, Bruker AXS, China
Keisuke Saito, Bruker AXS, Japan
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Now, See the Trees…
XRD – Bulk material properties• thickness• orientation• roughness• epitaxy• composition• phase
AFM – Surface material properties• surface roughness• grain size• uniformity• surface potential• electrical fields• capacitance• work function• spreading resistance
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Cantilever Detection: The Industry Norm
Laser Beam Bounce Detection
advantage:
simple setup, cheap
disadvantage:
alignment procedure,
larger head design
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The Bruker Difference
Interferometric Detection
advantage:
Compact design, accurate tip delfection infromation, No laser alignment –Easier to use
disadvantage:
Slightly more complex deflection detection system
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Bruker Nano Products
N8 NEOS - The Workhorse in Surface Inspection
• excellent time-to-result performance
• rigid combination of optical microscopy and AFM/SPM
• simple switching between techniques
• flexible sample handling
• resolution below 1 nm
Design ObjectiveObjective based AFM that combines a research quality optical microscope with a research quality AFM
Maintaining all AFM functionality and angstrom level noise floor
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What Does Roughness Mean?
PbSe Thin Film
Sa – Average Roughness 64.6 nmSq – RMS Roughness 78.8 nmSsk – Skewness -0.39Sku – Kurtosis 2.84..S10z- Ten Point Height 650 nm..Sdr - Surface Area Ratio
69%..Srwi - Radial Wave Index 0.09
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Sa
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%SAD
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2.0 nm
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AFM as a Local Surface Probe
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Surface PotentialElectrical FieldsCapacitanceWork FunctionConductivity
Dopant ProfilingBand StructureDefect DetectionSurface Uniformity
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Electrical Measurements
Electrostatic Force Microscopy
Scanning Surface Potential Microscopy (Kelvin)
Scanning Spreading Resistance or Conductive AFM
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Three choices: Amplitude, Phase or Frequency
F = C (Vtip – Vsurface)2
Δφ = -arcsin[(Q/2k)(d2C/dz2)ΔV)Q = quality factor k = spring Constant
Electrostatic Force Microscopy
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Scanning Surface Potential
• AC mode• Measures the work function between the tip and the sample• Can map the band bending and doping
• AC voltage applied to tip• Nulling voltage applied to minimize oscillations• Nulling voltage is ≈ ΔWork function
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Electrical Measurements
MeasurementElectronics
Conductance AFM – High Current
Tunneling AFM – Low Current
Scanning Spreading Resistance – Logarithmic Amplifier
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Photo Assisted AFM
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Lock InAmplifier
Signal Generator
Controller
Raw data to lock inSeparated data back to controller
Please use your mouse to answer the question on the right of your screen:
What technique do you feel would best complement AFM?
RamanIRConfocalXRFEllipsometry
Audience Poll
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04.06.2009Bruker Confidential66
NANOS
We have created a easy to use, customizable high resolution metrology solution that couples research quality microscopy with state of the art scanning probe technology. Whether you need a basic research system or a 300 millimeter highly automated system, Bruker has a AFM that will meet your needs.
04.06.2009Bruker Confidential67
Bruker Nano Instruments
NANOS N8 NEOS
N8 ARGOS
N8 RADOS
N8 TITANOS
upgrade AFM √
routine lab instrument
√ √
routine lab instrument, automated
√
localized objects, defect inspection
√ √ √ √
sample sizes up to 50 mm
√ √ √ √
sample sizes up to 100 mm
√ (√) √
sample sizes up to 150 mm
(√) (√) √
sample sizes up to 300 mm
√
application in liquids
√ √ √
04.06.2009Bruker Confidential68
Bruker Nano Instruments
NANOS N8 NEOS
N8 ARGOS
N8 RADOS
N8 TITANOS
req. resolution ~ 1 nm
√ √ √ √ √
req. resolution ~ 0.1 nm
√ √ √ √
req. resolution > 0.05 nm
√ √ √
quasi atomic resolution
√
semiconductor industry
√ √
Industry, R&D, QA √ √
basic research √ √
automated systems
√ √
teaching instrument
√ √
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