Membrane Cleaning via Electrostatic Field and Oscillation
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Solution Overview
Problem
Current methods for cleaning pellicles in lithographic apparatuses are inadequate, as they risk rupturing thin, flexible membranes and may introduce heat-related stress, limiting their operational lifetime and effectiveness in removing particles that can cause pattern errors in substrates.
Innovation Solution
A membrane cleaning apparatus that uses an electric field generating mechanism, including collector electrodes and a mechanism for inducing mechanical oscillations, to dislodge and transport particles from the membrane surface, employing pulsed electrostatic pressure and controlled voltage applications to avoid membrane rupture and ensure efficient cleaning.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional cleaning methods are used on the pellicle, then particles may be removed, but the thin membrane risks rupturing and heat-related stress is introduced
Solution Approach 1:
The patent replaces conventional mechanical cleaning methods (such as brushes, wipes, or liquid cleaners) with an electrostatic field-based cleaning system. The electrostatic field exerts forces on charged particles to remove them from the pellicle surface without physical contact, thereby avoiding mechanical stress that could rupture the thin membrane while still achieving effective particle removal.
Solution Approach 2:
The patent changes the physical state or parameters of the cleaning approach by using electrostatic fields instead of mechanical forces. By controlling the voltage and field strength parameters, the system achieves particle removal through electrostatic forces that do not compromise membrane integrity, resolving the contradiction between cleaning effectiveness and membrane safety.
2Manufacturing precision
If the pellicle is spaced from the patterning device to prevent particle imaging, then particles on the pellicle may still cause local hot spots and be transferred to the patterning device
Solution Approach 1:
The patent applies preliminary cleaning action to the pellicle using electrostatic field forces before particles can cause harmful effects. By continuously or periodically removing particles from the pellicle surface through electrostatic forces, the system prevents particles from migrating to the patterning device or creating local hot spots, thereby maintaining pattern accuracy without requiring the pellicle to be in direct contact with the patterning device.
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
The apparatus effectively removes particles from the membrane without causing rupture, maintaining the membrane's integrity and improving the cleanliness of the pellicle, thereby reducing pattern errors and extending the pellicle's operational lifetime.
Implementation Method 1
an electric field generating mechanism for generating an electric field in the vicinity of the membrane when supported by the membrane support
Implementation Method 2
The electric field generating mechanism can be used to generate an electric field in the vicinity of the membrane when supported by the membrane support so as to dislodge particles from a surface of the membrane
Implementation Method 3
the electric field generating mechanism can be used to generate an electric field in the vicinity of the membrane when supported by the membrane support so as to transport particles away from a surface of the membrane
Implementation Method 4
a mechanism for inducing mechanical oscillations in the membrane when supported by the membrane support
Data Source
AI summary
A membrane cleaning apparatus for removing particles from a membrane, the apparatus including a membrane support and an electric field generating mechanism. The membrane support is for supporting the membrane. The electric field generating mechanism is for generating an electric field in the vicinity of the membrane when supported by the membrane support. The electric field generating mechanism may include: one or more collector electrodes; and a mechanism for applying a voltage across a membrane supported by the membrane support and the or each of the one or more collector electrodes.