Agilent TechnologiesAgilent Technologies
Scanning Microwave Microscopy (SMM)Microscopy (SMM)
Expanding Impedance M h N lMeasurements to the Nanoscale: Coupling the Power of Scanning Probe Microscopy with the PNA
Presented by:
Craig Wall PhDProduct Manager – Agilent AFMProduct Manager – Agilent AFM,Nanomeasurements Division
Scanning Microwave Microscopy
12/15/2008
OutlineOutline
IntroductionIntroduction
Principle
Instrument setup
Experiments
SummarySummary
12/15/2008
Scanning Microwave Microscopy
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IntroductionAvailable SPM-based techniques to probe materials electric properties:
Scanning near-field microwave microscopy (SNMM)Scanning capacitance microscopy (SCM)Scanning capacitance microscopy (SCM)Scanning spreading resistance microscopy (SSRM)Electrostatic force microscopy (EFM)Current-sensing (or conductive) AFM (CSAFM)Current-sensing (or conductive) AFM (CSAFM)Kelvin force microscopy (KFM)More …
Scanning Probe Microscopy, edited by S. Kalinin and A. Gruverman, Springer, New York, 2007.
Vector network analyzer + AFMimpedancecapacitance
Scanning Probe Microscopy, edited by S. Kalinin and A. Gruverman, Springer, New York, 2007.
capacitancedopant densitymore …
Scanning Microwave Microscopy
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Scanning Microwave Microscopy (SMM)
Z
AFM Basic ConfigurationAFM Basic ConfigurationZ
XY
AFM tip monitors surface Closed loop scanner (xyz) or stageS ith ti ith lScan with tip or with sampleVideo access
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Scanning Microwave Microscopy
12/15/2008
AFM Imaging Modes
Contact Mode AFM (1986)Dynamic in x and yDynamic in x and yTip is in contact or near contact with the surfaceSmall vertical force, but the probe dragged over the surface exerting lateral force.Weakly bound or soft samples move easily.Lower lateral resolution.
AC Mode AFM (1993)Dynamic in x, y, and zIntermittent contact. Soft surfaces are stiffened by viscoelastic response. Impact is predominately vertical, therefore large vertical force, but no lateral force.Higher lateral resolutionHigher lateral resolution.
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Scanning Microwave Microscopy
12/15/2008
PrincipleZZ
complex reflection coefficient
incident transmitted0
0
ZZZZ
L
L
+−
=Γ
REFLECTION
ReflectedIncident
REFLECTION
AR
=
Optical analogy
reflectedSWR
S P t I d
ReturnLoss
incident transmitted
Optical analogy S-ParametersS11, S22 Reflection
Coefficient
Impedance, Admittance
R+jX, G+jB Γ, ρ
incident transmitted
reflectedScanning Microwave Microscopy
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Microwave transmission
Schematic
SSource
Half wave lengthCoaxial resonator 50 Ohm
Probe
Scanning Microwave Microscopy
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Instrument setup
professional network analyzerAFM
For dC/dV measurements, a low-frequency modulation is added to the microwave. Demodulated signal is detected by an ac mode controller with built-in digital lock-in amplifiers.
Scanning Microwave Microscopy
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Agilent 5400 Based SMM
Scanning Microwave Microscopy
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Agilent 5400 Based SMM
Load DiplexerLoad Diplexer
RF to PNA
Scanner headScanner head With Conductive Tip
Scanning Microwave Microscopy
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Scanner assembly, cantilever
Cantilever holder
Pt/Ir cantilever
Scanner assembly Al substrate
Scanning Microwave Microscopy
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Scanning Microwave Microscopy
Agilent PerformanceVector Network Analyzer
PNA
SignalConditioning
Conductive tip
Conditioning
Agilent 5400SPM Instrument
Agilent PrecisionMachining and ProcessTechnologies to deliver
Scanning Microwave Microscopy
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gRF/MW to the conductive tip
PNA Controls from PicoView
Agilent General Audience
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Experiments – frequency sweep
Agilent General Audience
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DRAMDRAM
Agilent General Audience
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SMM image of SRAM
A – topographyB – capacitanceB capacitanceC – dC/dV
Schematic of 6-FET unit cell of SRAM
Agilent General Audience
Schematic of 6 FET unit cell of SRAM
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0
2.50
2.5
0
2.5
Topography Phase Surface Potential
Kelvin Force Microscopy of Semiconductor Surfaces1st Eigen/10kHz
5
7.5
10
12.5
15
17.5
5
7.5
10
12.5
15
17.5
5
7.5
10
12.5
15
17.5
SiGe
µm
20
22.5
µm
20
22.5
µm
20
22.5
0
5
10
0
5
10
0
5
1010
15
20
25
30
35
10
15
20
25
30
35
10
15
20
25
30
35
SRAM
40
45
50
40
45
50
40
45
50
Surface Potential Surface Potential Surface Potential
25 μm40 μm40 μm
Agilent General Audience(70kHz/10kHz) (70kHz/425kHz) (425kHz/70kHz)
25 μm40 μm40 μm
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Images of an SDRAM
• Very high sensitivity• Can see semiconductor, insulators and conductors• Can be calibrated
Agilent General Audience
• Can also get inductance and reactance
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SMM image of SRAM
Topography dC/dVTopography dC/dV
Zoomed scans of a transistor.
Agilent General Audience
Line feature of 10 – 20 nm in width can be seen in the dC/dV image
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Carriers at 0V bias in SRAM
Scanning Microwave Microscopy
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Sample 1
Optical images of sample 1. The failed 48th transistor is marked with a blue circle.Optical images of sample 1. The failed 48 transistor is marked with a blue circle.
Agilent General Audience
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Sample 1
Topography (top), dopant concentration (middle), and capacitance (bottom) images of scans across FETs 43 46 (right) and FETs 45 48 (left) Dopant density images (middle) clearly show a difference on the 48th FET– 46 (right) and FETs 45 – 48 (left). Dopant density images (middle) clearly show a difference on the 48th FET
from all others (43 – 47). The missing dark area (p dopant) indicates a problem in the channel of the 48th FET.
Agilent General Audience
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Sample 1
Topography (top), dopant concentration (middle), and capacitance (bottom) images of scans across FETs 47 – 50 (right) and FETs 49 – 52 (left). Like the last slide, dopant concentration images also show a
ti bl diff th 48th FET f ll th C it i f th 48th FETnoticeable difference on the 48th FET from all others. Capacitance image of the 48th FET appears some difference from others as well. The result here is consistent with the observation obtained on July 10.
Agilent General Audience
12/15/2008Page 23
SiGe device
Topography Capacitance dC/dV
Scanning Microwave Microscopy
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InGaP/GaAs heterojunction bipolar transistor
Topography Impedance1 4 7 1 4 7
Different regions from the emitter-side contact layer (7 and 8) to the subcollector layer (1) with different doping levels were clearly resolved in the impedance image. (Sample courtesy of T. Low)
Scanning Microwave Microscopy
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Biological sample
Bacteria cells of geobacter sulfurreducens
Topography Impedance
Sample courtesy of N Hansmeier T Chau R Ros and S Lindsay at Arizona State University
Scanning Microwave Microscopy
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Sample courtesy of N. Hansmeier, T. Chau, R. Ros, and S. Lindsay at Arizona State University.
SummaryA new technique, which integrates AFM with a professional network analyzer, has been developed.
scanning microwave microscopy— scanning microwave microscopy
Mapping impedance, capacitance, dielectric constants, etc.— SNMMSNMM
Measuring two-dimensional dopant density of semiconductors.— SCM
High sensitivity with resolution ultimately limited by the probe.
Metals, semiconductors, dielectric materials, ferroelectric materials, insulators, and even biological samples.
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Scanning Microwave Microscopy
Agilent Technologies = Innovation in Measurements
We are presenting a state of the art AFM/SMMWe are presenting a state of the art AFM/SMM microscope to enable material measurements at the Nanoscale
+ =
Coaxial cableCoaxial Resonator
Sample scanning AFM in X and YNetwork Analyzer
SampleThe MW diplexer
Ground/Shield
Scanning Microwave Microscopy
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Sample scanning AFM in X and Y and Z (closed loop)
Analyzer