Electrostatic Clamp Intermediate Electrode Voltage Segmentation
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Solution Overview
Problem
Conventional electrostatic clamps in lithographic apparatuses experience breakdown failures due to high voltage across barriers, leading to reduced clamping force and throughput in semiconductor manufacturing.
Innovation Solution
An electrostatic clamp design featuring intermediate electrodes held at voltages between the primary electrode and ground, reducing the voltage across barriers and distributing voltage through resistive networks to minimize breakdown risks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If conventional electrostatic clamps use high voltage across barriers to generate clamping force, then clamping force is sufficient, but breakdown failure rate increases
Solution Approach 1:
The single high-voltage barrier is segmented into multiple lower-voltage barriers by introducing intermediate electrodes. The voltage is distributed across these segmented barriers, reducing the voltage stress on each individual barrier while maintaining the overall clamping force through the cumulative effect of multiple electrostatic fields.
Solution Approach 2:
Intermediate electrodes are introduced as mediator elements between the high-voltage electrode and ground. These intermediaries divide the voltage potential into steps, creating multiple lower-voltage barriers that reduce breakdown risk while still generating sufficient electrostatic clamping force through their combined effect.
2Force
If voltage is concentrated across few barriers, then clamping force is high, but breakdown risk increases
Solution Approach 1:
The voltage distribution is segmented across multiple barriers created by intermediate electrodes. This segmentation concentrates the clamping force generation across distributed electrostatic fields while reducing the harmful breakdown risk by limiting the voltage across any single barrier.
Solution Approach 2:
The voltage parameter is changed from a single high-voltage application across few barriers to a distributed voltage application across multiple barriers. The intermediate electrodes are held at voltages between the high-voltage electrode and ground, creating a stepped voltage distribution that reduces breakdown risk while maintaining clamping force.
3Reliability
If intermediate electrodes are added to reduce voltage across barriers, then breakdown failure rate decreases, but device complexity increases
Solution Approach 1:
Intermediate electrodes serve as mediator elements that simplify the overall system reliability by reducing breakdown risk. While they add structural elements, they eliminate the need for extremely high-voltage insulation and reduce the probability of failure, providing a net simplification in terms of operational reliability.
Solution Approach 2:
The voltage parameter distribution is changed to reduce the maximum voltage across any single barrier. This parameter change reduces the complexity of insulation requirements and barrier design, even though additional electrodes are introduced, because the operational voltage stress on each component is reduced.
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 design significantly reduces breakdown failure rates, maintaining high clamping force and improving the throughput of lithography systems by evenly distributing voltage across multiple barriers.
Implementation Method 1
An electrostatic clamp may be provided to electrostatically clamp an object, such as a mask or a substrate (wafer) to an object support
Implementation Method 2
The electrodes include a first electrode configured in use to be held at a first voltage, at least one intermediate electrode configured in use to be held at a second voltage
Data Source
AI summary
An electrostatic clamp configured to, in use, hold an article, such as a reticle or a wafer in a lithographic apparatus. The clamp includes a lower portion; an upper portion formed of a dielectric material, and a plurality of electrodes disposed between the lower portion and the upper portion. The electrodes include a first electrode configured in use to be held at a first voltage, at least one intermediate electrode configured in use to be held at a second voltage, and a ground electrode. The at least one intermediate electrode is located between the first electrode and the ground electrode and the second voltage is between the first voltage and ground to reduce the voltage across a barrier between the electrodes and so reduce the risk of high-voltage breakdown.