nanostation 300: system for scanning probe metrology on larger … · - system for spm metrology on...
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Physikalisch-Technische Bundesanstalt, Braunschweig und BerlinWorking group 5.22 in cooperation with Surface Imaging Systems
Nanostation 300: System for scanning probe metrology on larger objects
Travel range: 300 mm x 550 mm; el.-magnetic linear direct drives
Feedback control by encoder systems with < 10 nm resolution
Position deviations after correction of reproducible errors: < 1 µm
Objectives:
- System for SPM metrology on 300 mm objects
- Sample navigation: opt. microscopes and SPM
- Automatic measurement incl. tip reconstruction
- Use of air bearing x-y-stage and stable granite base
- Flexibility with respect to different SPM modi
- System upgradeable: 6 axis piezo scanning stage
- System upgradeable: x-y-laser interferometry
Nanostation 300 in PTB clean room centre Nanostation 300: SPM z-stability
SPM tip reconstruction
Microscopic structure localisation
SPM contact mode measurements on etched Si (111) faces
Use of non-contact SPM mode with EBD C-needle cantilever:
Control paramater setting influences obtainable edge resolution
Wrong setting of control parameters can damage sensitive tips
Edge measurement requires application of dedicated scanning modi
Different microscopes for structure localization:
Coarse ( and fine microscope (0.7
High resolution microscope: 85 µm x 65 µm, 117 nm pixelsize
Optical feature localisation to define batch AFM measurements
4 mm x 3 mm) mm x 0.5 mm)
Stage characteristics
Straightness deviation in y-direction: 1.2´´, hysteresis of 0.4´´
Straightness deviation in x-direction: 4´´, no hysteresis
Stage positioning noise at target position currently 70 nm (2s)
Further decrease possible by controlled reduction of air gap
yaw vs. position along y-axis
-0,8
-0,4
0
0,4
0,8
-0,3 -0,15 0 0,15 0,3
y position [m]
yaw
[arc
sec]
yaw vs. position along x-axis
-4
-2
0
2
-0,15 -0,1 -0,05 0 0,05 0,1 0,15
x position [m]
yaw
[arc
sec]
Profile through atomic Si steps
-0,2
-0,1
0
0,1
0,2
0 1000 2000 3000 4000 5000x position [nm]
heig
ht
[nm
]
sensor noise in z
-0.06
-0.04
-0.02
0
0.02
0.04
0.06
0 0.2 0.4 0.6 0.8 1
position [nm]
he
igh
t[n
m]
SPM measurement in contact: z- noise < 0.06 nmspot mode
Edge detection and control parameters
2D Graph 4
X Position [nm]
-20 -10 0 10 20
Z[n
m]
0
2
4
6
8
10
SPM tip reconstruction method by use of Au nanospheres:
Reconstruct the 3D tip shape from several 1D profiles
Scanning probe microscope
Reference samples
Optical microscope
Mask object
Object frame
Air bearing x-y-stage
26,7° 24,1°26,7° 24,1°
49,2° 46,9°49,2° 46,9°
59,3° 61,7°
artefact
59,3° 61,7°
artefact
Use of carbon-needle cantilever,variation of damping parameters:above: 60% remaining amplitude => low resolutionmiddle: 53% => optimum resolutionbottom: 50% => severe tip wear