Spring Substrate Restrainers for Electrode Coverage and Cleaning
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Solution Overview
Problem
Existing substrate restraining systems in lithographic apparatuses using electrostatic clamps face challenges in ensuring the substrate fully covers the electrodes to prevent electrostatic breakdown while allowing for effective cleaning of the substrate table, as they often restrict access and create contamination issues.
Innovation Solution
A substrate restraining system with circumferentially arranged cantilever springs that allow radial displacement to prevent substrate uncovering of electrodes, featuring a base-end stop configuration that facilitates cleaning and reduces contamination by minimizing contact points and friction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a substrate restraining system with fixed restrainers is used to prevent substrate uncovering of electrodes, then electrode protection is improved, but cleaning access to the substrate table is restricted
Solution Approach 1:
The restrainers are designed as spring-loaded components that can dynamically change position. During normal operation, the springs maintain restrainers in a position that prevents substrate uncovering of electrodes. During cleaning operations, the springs allow restrainers to be displaced or repositioned to provide access to the substrate table surface, thus resolving the contradiction between protection and accessibility.
Solution Approach 2:
The spring mechanism allows the restrainers to change their positional parameter based on operational requirements. The spring force and displacement characteristics can be adjusted to provide appropriate restraint during substrate handling while allowing sufficient movement during cleaning operations, thus enabling both electrode protection and cleaning access.
2Manufacturing precision
If traditional clamp structures are used to restrain the substrate, then substrate positioning is improved, but contamination risk increases due to multiple contact points
Solution Approach 1:
The spring mechanism extracts the friction and contact issues from the substrate restraint system. By using spring-loaded restrainers that contact the substrate minimally and temporarily only when needed for positioning or preventing uncovering, the system reduces continuous contact points and associated contamination risks while maintaining positioning precision.
Solution Approach 2:
The spring components act as flexible elements that can conform to the substrate surface with minimal contact pressure and area. This flexible restraint approach maintains substrate positioning accuracy while reducing the number and duration of contact points, thereby minimizing contamination risk compared to rigid clamp structures.
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 system enables efficient cleaning of the substrate table without exposing electrodes, maintains substrate centering, and reduces contamination by minimizing contact surfaces and friction, thus enhancing the operational reliability of the lithographic apparatus.
Implementation Method 1
The spring has a proximal end and a distal end. The distal end of the spring is radially displaceable. A base of the proximal end of the spring is fixed to the substrate table at a fixing location. The spring is operable to prevent the substrate uncovering the switched on electrodes.
Data Source
AI summary
A substrate restraining system comprising: a substrate table and a plurality of circumferentially arranged restrainers each comprising a spring, wherein the spring has a proximal end and a distal end, wherein the distal end of the spring is radially displaceable, and wherein a base of the proximal end of the spring is fixed to the substrate table at a fixing location.