# PowerPoint-presentatie

Analysis and Performance of a lightweight
over-actuated 450mm wafer chuck
R. Boshuisen, PME
09-06-2010
Rein Boshuisen, PME
Titel van de presentatie
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Contents
• Introduction
• Problem Description
• Principle of Over-actuation
• Test Setup and Analysis
• Improvements on the Current Setup
• Conclusions
Over-actuation
of a wafer chuck
Titel van de presentatie
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Problem description
Typically wafer chucks are actuated as rigid bodies. Larger wafers leads
to heavier wafer stages:
Z
X
200 mm Wafer
Width: 1.5
300 mm Wafer
Thickn: 1.5
450 mm Wafer
Y
Depth 1.5
Depth 1.5
m kg
Width: 1.5
&gt; 3 x m kg
Thickn: 1.5
&gt; 11 x m kg
Modal
analysis
Over-actuation
of Modal
a wafer
analysis
chuck
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Problem description
Desire to have a LARGE chuck with LOW
Mass and HIGH internal modes
Z
X
Drawbacks of large wafers and chucks:
• Larger actuation forces and deformation
• Larger power dissipation and thermal load
• Internal modes still critical to performance
Modal
analysis
Over-actuation
of Modal
a wafer
analysis
chuck
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Y
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Alternative: Over-Actuation
z
Fz
ALTERNATIVE means of ACTUATOR placement
Challenge deal with infinitely many modes, without
adding as many actuators and control complexity
Fz
Fz
Actuation in nodes
Fz
Fz
Fz
Symmetrical actuation
Over-actuation
of a wafer chuck
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Eigenmodes of a chuck
Modal
analysis
Over-actuation
of Modal
a wafer
analysis
chuck
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First eigenmode - Example
Over-actuation
of a wafer chuck
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Eigenmodes of a chuck
Modal
analysis
Over-actuation
of Modal
a wafer
analysis
chuck
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Eigenmodes of a chuck
• Actuators on nodeline?
• Change nodelines?
Modal
analysis
Over-actuation
of Modal
a wafer
analysis
chuck
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Topology optimization1 of chuck
y
x
1Langelaar
Over-actuation
of a wafer chuck
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TU Delft
Optimization Strategy
Modal Coordinates
B

T
 1
 ms 2

 0

 0

0
1
ms  k
0
2

0

0




C
Mechanics
Physical Coordinates
Minimize the contribution by varying actuator position
a and cavity diameter d :
2
2
2
5
5
5
T
T
T

min   f 1  f Bz   f 1  f BRx   f 1  f BRy 


Z
Rx
Ry
Over-actuation
of a wafer chuck
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Optimization result I
Modal
analysis
Over-actuation
of Modal
a wafer
chuck
Titel van de presentatie
analysis
12
Eigenmodes of a chuck
184 Hz
270 Hz
270 Hz
Actuator location
Green zero displacement
349 Hz
521 Hz
Over-actuation
of a wafer chuck
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Optimization result II
Modal
analysis
Over-actuation
of Modal
a wafer
analysis
chuck
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Optimization result II
Modal
analysis
Over-actuation
of Modal
a wafer
analysis
chuck
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Realized Test Setup
Three linear encoders
Frame
Z
X
Y
Folded Flexures (3x),
Actuator assembly (5x)
Fixing Rz, X and Y
Wafer chuck demonstrator
motions in Z, Rx, and Ry
Modal
analysis
Over-actuation
of Modal
a wafer
analysis
chuck
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Realized Test Setup
Conventional actuation around COG
Over-actuation around COG
Over-actuation
of a wafer chuck
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Measured Result I
Modal
analysis
Over-actuation
of Modal
a wafer
analysis
chuck
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Measured Result II
Modal
analysis
Over-actuation
of Modal
a wafer
analysis
chuck
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Control of the chuck
3 Sensors
Chuck
Dynamics
Z
RX
3 PID
controllers
Actuation
matrix
Loc -&gt;CoG
RY
Control with standard industrial controller Bosch-RexRoth NYCe 4000
Over-actuation
of a wafer chuck
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Performance of the setup
Conventional
Bandwidths:
Z
RX
RY
Standstill Performance
RMS
Z
RX
RY
50 Hz
60 Hz
50 Hz
Over-Actuated
Factor 2 in bandwidth,
4 in stiffness
102 Hz
100 Hz
100 Hz
Factor 5 improvement
30 nm
7 nm
Over-Actuation shows clear benefits
compared to conventional actuation!
Over-actuation
of a wafer chuck
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Why still excitation of the modes??
Modal
analysis
Over-actuation
of Modal
a wafer
analysis
chuck
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Mode excitation analysis
• Improved model
• No Symmetry – Possible causes
•
•
•
•
Actuator 5
Gravity Compensators
Plate springs
Chuck
The analysis only partially explains the mode excitations
Over-actuation
of a wafer chuck
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Improvements of the current setup
• Sensor-placement / Over-Sensing
Over-actuation
of a wafer chuck
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Control of the chuck
3 Sensors
Chuck
Dynamics
Z
RX
3 PID
controllers
Actuation
matrix
Loc -&gt;CoG
RY
Control with:
Over-actuation
of a wafer chuck
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Over-Sensing
Adjust Sensorposition such, that the excitation of
the modes is not converted to CoG movement
• Place sensor in a node
• Symmetric sensor placement
Over-actuation
of a wafer chuck
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Over-Sensing
Over-actuation
of a wafer chuck
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Over-Sensing
• This sensor placement can distinguish the first and second
eigenmode from the rigid body movement
• Active damping of first eigenmode!
Over-actuation
of a wafer chuck
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Over-Sensing - Performance
Conventional
Over-Actuated + first
mode active damping
Bandwidths:
Z
RX
RY
100 Hz
100 Hz
100 Hz
200 Hz
150 Hz
150 Hz
Standstill Performance
RMS
Sensor 1
Sensor 2
Sensor 3
Sensor 4
4.0 nm
5.8 nm
4.6 nm
4.6 nm
1.8 nm
1.9 nm
1.9 nm
1.9 nm
Over-actuation
of a wafer chuck
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Conclusion
• Over-actuation is succesfully implemented on a wafer chuck with
an increased performance as result.
• Symmetry is critical for the positions of the nodelines on the
diagonals
• Include sensor position optimization in the design phase
• Use four sensors to be able to actively damp the first eigenmode
Over-actuation
of a wafer chuck
Titel van de presentatie
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Analysis and Performance of a lightweight
over-actuated 450mm wafer chuck
R. Boshuisen, PME
09-06-2010
Rein Boshuisen, PME
Titel van de presentatie
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Over-actuation
of a wafer chuck
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Dynamic Analysis –
effect of rotated chuck
Over-actuation
of a wafer chuck
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Dynamic Analysis –
effect of Gravity Compensator
Over-actuation
of a wafer chuck
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Damping
• Chuck is very lightly damped, increasing damping, reduces
maximum peak-hight, leading to less sensitivity of the actuator
placement
Over-actuation
of a wafer chuck
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