Electrostatic Chuck Shield Electrodes for Lithography
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Solution Overview
Problem
The degradation of channels and external apparatus in contact with temperature conditioning fluid in lithographic chucks over time, and the difficulty in compensating for sudden changes in dissipated power during unmounting and mounting of patterning devices or substrates, lead to temperature fluctuations and performance issues in lithographic apparatuses.
Innovation Solution
Incorporating shield electrodes connected to ground to reduce electrolysis effects, and using compensating electrodes to maintain consistent electric fields and power dissipation, along with a channel heater to manage temperature gradients, within the chuck's temperature conditioning fluid channels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If temperature conditioning fluid is used to control chuck temperature, then temperature stability is improved, but channel degradation occurs over time
Solution Approach 1:
A shield electrode is introduced as an intermediary component between the drive electrode and the temperature conditioning fluid channels. This shield electrode, connected to ground, prevents direct electrical interaction between the high-voltage drive electrode and the fluid channels, thereby preventing electrolysis and degradation of the channels while allowing the temperature conditioning function to continue operating effectively.
2Force
If electrostatic clamping is used to hold patterning device, then holding force is improved, but sudden power changes cause temperature fluctuations
Solution Approach 1:
Compensating electrodes are pre-configured in the chuck structure and connected to a power supply that can provide compensating current. When the drive electrode power is suddenly changed during unmounting or mounting operations, the compensating electrodes automatically provide compensating current to maintain stable power dissipation and temperature, preventing temperature fluctuations caused by the sudden power changes.
Solution Approach 2:
The compensating electrodes work as a feedback mechanism to counteract sudden power changes. The power supply monitors the drive electrode power and automatically adjusts the compensating electrode power to maintain constant total power dissipation, thereby stabilizing the chuck temperature during dynamic operations like unmounting and mounting patterning devices.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Prevents degradation of chuck components, maintains stable temperature control, and improves the accuracy of thermo-mechanical corrections, enhancing the performance and overlay precision of lithographic apparatuses.
Implementation Method 1
shield electrodes connected to ground to reduce electrolysis effects
Implementation Method 2
channel heater to manage temperature gradients
Implementation Method 3
The chuck may be configured to hold the patterning device or substrate by electrostatic attraction
Implementation Method 4
driving a temperature conditioning fluid through channels formed within the chuck
Implementation Method 5
channels formed within the chuck
Data Source
Figure 1~2
Figure 3~4
Figure 5~6
AI summary
A chuck, chuck control system, lithographic apparatus and method of using a chuck are disclosed. In an embodiment, there is provided a chuck (43) for use in holding a patterning device (MA) or a substrate (W) onto a supporting table (MT, WT) of a lithography apparatus (100) by electrostatic force, in which the patterning device is for imparting a radiation beam (B) with a pattern in its cross-section to form a patterned radiation beam, and the substrate is for receiving the patterned radiation beam; said chuck comprising: a dielectric member (45); a temperature conditioning fluid channel (48) formed within the chuck; a drive electrode (40, 42) for applying a potential difference between the drive electrode and the patterning device or substrate across the dielectric member in order to electrostatically attract the patterning device or substrate towards the drive electrode; and a first shield electrode (60) for reducing or preventing the development of an electric field across temperature conditioning fluid in the temperature conditioning fluid channel due to a voltage applied to the drive electrode, in order to reduce or prevent electrolysis in the fluid.