Thin-Film Substrate Holder for Electrostatic Clamping and Temperature Control
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Solution Overview
Problem
In high-throughput lithographic apparatuses, conventional substrate holders face challenges in securely clamping substrates due to high accelerations, especially in extreme ultraviolet (EUV) radiation lithography where vacuum clamping is not feasible, and temperature control is critical to prevent thermal stress and overlay errors from liquid evaporation effects.
Innovation Solution
A substrate holder with a thin-film stack forming electronic or electric components, including burls for substrate support, integrated with real-time temperature measurement and heating capabilities, allowing for secure clamping via electrostatic forces and precise temperature control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If vacuum clamping is used to secure substrates, then clamping reliability is improved, but it cannot be applied in EUV lithography where vacuum conditions are not feasible
Solution Approach 1:
The patent replaces the vacuum-based clamping mechanism with an electrostatic clamping mechanism. The substrate holder includes an electrostatic clamp that uses electrostatic forces to secure the substrate, eliminating the need for vacuum conditions. This allows the same clamping function to be performed in atmospheric conditions suitable for EUV lithography while maintaining high clamping reliability during high-acceleration operations.
2Manufacturing precision
If liquid immersion is used to increase numerical aperture, then imaging resolution is improved, but temperature control becomes critical to prevent thermal stress and overlay errors
Solution Approach 1:
The substrate holder integrates real-time temperature measurement capabilities with heating elements. Temperature sensors continuously monitor the substrate temperature, and this feedback is used to control the heating elements, maintaining optimal temperature conditions. This prevents thermal stress and overlay errors that would otherwise occur due to liquid evaporation during immersion lithography, thereby preserving imaging resolution.
Solution Approach 2:
The system actively controls the temperature parameter of the substrate and immersion liquid to maintain stability. By adjusting and maintaining optimal temperature conditions through integrated heating and monitoring, the system prevents thermal expansion and contraction that would cause overlay errors, thereby preserving the high imaging resolution enabled by liquid immersion.
3Device complexity
If conventional substrate holders are used without integrated temperature control, then device complexity is reduced, but thermal stress and overlay errors increase
Solution Approach 1:
The patent merges the temperature control functionality directly into the substrate holder structure. The substrate holder integrates heating elements, temperature sensors, and electrostatic clamping mechanisms into a single unified device. This combination allows precise temperature control and overlay accuracy to be achieved without significantly increasing overall system complexity, as the temperature control is built into the existing substrate holder architecture.
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 substrate holder effectively secures substrates during high accelerations and maintains accurate temperature control, reducing thermal stress and overlay errors in lithographic processes.
Implementation Method 1
a thin-film stack provided on the surface and forming an electronic or electric component
Implementation Method 2
allowing for secure clamping via electrostatic forces
Implementation Method 3
integrated with real-time temperature measurement and heating capabilities
Data Source
AI summary
A substrate holder for a lithographic apparatus has a main body having a thin-film stack provided on a surface thereof. The thin-film stack forms an electronic or electric component such as an electrode, a sensor, a heater, a transistor or a logic device, and has a top isolation layer. A plurality of burs to support a substrate are formed on the thin-film stack or in apertures of the thin-film stack.