Conductive Reticle Cleaning Layer for Vacuum Charge Dissipation
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Solution Overview
Problem
Lithographic apparatus reticle stages become contaminated over time, leading to patterning errors and defects, and current charge dissipation methods require venting to atmospheric pressure, reducing efficiency and yield.
Innovation Solution
A conductive reticle stage cleaning apparatus with a conductive layer and optional second layer, generating electrostatic fields to dissipate charge and remove particles without venting, using a conductive polymer like doped polyimide and insulating polymers, with a thickness of up to 8 microns to maintain efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a separate conductive device is disposed between each load of the RTC device to dissipate charge, then charge dissipation is improved, but scanning ability and overall efficiency are reduced due to the need for two devices
Solution Approach 1:
The patent combines the charge dissipation function and particle removal function into a single RTC device. The conductive layer is integrated directly into the RTC device structure, eliminating the need for a separate conductive device. This merging allows the device to dissipate charge and remove particles simultaneously, maintaining scanning ability and efficiency while improving reliability.
Solution Approach 2:
The RTC device is designed with multi-functionality, serving both as a charge dissipation mechanism and a particle removal mechanism. The conductive layer enables charge dissipation, while the electrostatic field generated by the conductive layer also removes particles. This universal design improves productivity by using one device for multiple functions rather than requiring separate devices.
2Object-affected harmful factors
If manual cleaning is performed on the reticle stage, then contamination is removed, but the lithographic apparatus must be vented to atmospheric pressure and partially disassembled, reducing yield
Solution Approach 1:
The patent replaces the mechanical manual cleaning system with an electrostatic field-based cleaning system. Instead of requiring physical contact and manual intervention, the conductive layer generates an electrostatic field that automatically removes particles from the reticle stage. This substitution eliminates the need to vent the apparatus to atmospheric pressure and disassemble components, thereby maintaining vacuum conditions and improving yield.
Solution Approach 2:
The RTC device performs self-service cleaning by generating its own electrostatic field through the conductive layer. The system automatically removes particles without requiring external manual intervention or system shutdown. This self-service capability allows continuous operation under vacuum, preventing yield reduction associated with venting and disassembly.
3Object-generated harmful factors
If an insulating top coating is used on the RTC device, then particle removal is enabled, but charge accumulates over multiple cycles causing the device to stick to the reticle stage
Solution Approach 1:
The patent uses a composite structure with a conductive layer integrated into the RTC device. The conductive layer works in conjunction with the insulating top coating to prevent charge accumulation while maintaining particle removal capability. The conductive layer dissipates charge that would otherwise accumulate on the insulating surface, preventing the sticking problem while preserving the electrostatic field necessary for particle removal.
Solution Approach 2:
The conductive layer is strategically positioned at specific locations where charge accumulation occurs, such as contact surfaces with the reticle stage. This local quality approach allows charge dissipation at critical points while maintaining the insulating properties of the top coating in other areas where electrostatic field generation is needed for particle removal.
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
Efficient charge dissipation and particle removal on reticle stages improve scanning ability and overall yield in lithographic apparatuses, maintaining operational efficiency under vacuum without partial disassembly.
Implementation Method 1
remove particles on the reticle stage via an electrostatic field generated between the conductive layer and the reticle stage
Implementation Method 2
remove particles on the reticle stage via an electrostatic field generated between the conductive layer and the reticle stage
Implementation Method 3
dissipate charge on the reticle stage
Data Source
AI summary
A reticle stage cleaning apparatus for a reticle stage in a lithographic apparatus includes a substrate having a frontside and a backside opposite the frontside and a conductive layer disposed on the frontside of the substrate. The conductive layer is configured to contact the reticle stage to dissipate charge on the reticle stage and to remove particles on the reticle stage via an electrostatic field generated between the conductive layer and the reticle stage. The substrate can include a plurality of grooves and the conductive layer can be disposed on the frontside of the substrate and on a bottom surface of the plurality of grooves. The reticle stage cleaning apparatus can include a second conductive layer configured to remove particles on the reticle stage via a second electrostatic field and be disposed atop the conductive layer in the bottom surface of the plurality of grooves.