EUV Plasma Position Control via Dual-Pulse Feedback

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Solution Overview

Problem

Conventional laser-produced plasma (LPP) EUV lithography light sources have low conversion efficiencies due to the inability to fix the plasma position within the vacuum chamber, leading to reduced precision and increased energy consumption.

Innovation Solution

Implementing a feedback control system that calculates the droplet and plasma positions using the return beams of both pre-pulse and main pulses to adjust the time delay and optics, ensuring the plasma position remains fixed at a target position by minimizing the difference between observed and target positions.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If conventional LPP EUV lithography light sources are used without feedback control, then the system structure is simpler, but the plasma position cannot be fixed leading to low conversion efficiency

Engineering Contradiction:

Improveconversion efficiencyVSAvoidsystem complexity

Core Design Contradiction:

ProductivityVSDevice complexity

Solution Approach 1:

The patent implements a feedback control system that continuously measures the actual plasma position using sensors and compares it to the target position. The control system then adjusts the droplet generator timing and laser pulse parameters based on this feedback to maintain optimal plasma position, thereby fixing the plasma position and improving conversion efficiency despite the increased system complexity

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The patent replaces manual or open-loop mechanical positioning with an automated feedback control system that uses sensors and algorithms to dynamically adjust the droplet ejection timing and laser pulse delivery. This substitution of mechanical positioning with intelligent control systems enables precise plasma position fixation while maintaining operational flexibility

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Manufacturing precision

If plasma position is not fixed, then the system operation is easier, but the precision of EUV radiation generation is reduced

Engineering Contradiction:

Improveplasma position precisionVSAvoidsystem operation simplicity

Core Design Contradiction:

Manufacturing precisionVSEase of operation

Solution Approach 1:

The feedback control system enables the system to self-correct plasma position deviations automatically. The control system continuously monitors plasma position and self-adjusts droplet ejection timing and laser pulse parameters without requiring manual intervention, thereby maintaining high precision while keeping the operation process simple and automated

Inventive Principle:

Principle #25Self-service

Solution Approach 2:

The system uses real-time feedback from position sensors to automatically adjust operating parameters. This closed-loop control maintains precise plasma positioning through continuous correction, eliminating the need for complex manual adjustments while ensuring manufacturing precision

Inventive Principle:

Principle #23Feedback

3Loss of energy

If plasma position varies, then the system is more adaptable to conditions, but energy consumption increases due to reduced efficiency

Engineering Contradiction:

Improveenergy consumptionVSAvoidplasma position stability

Core Design Contradiction:

Loss of energyVSStability of the object's composition

Solution Approach 1:

The feedback control system maintains stable plasma position by continuously monitoring and adjusting droplet ejection timing and laser pulse parameters. This stability ensures consistent EUV radiation generation efficiency, preventing energy waste that would occur with plasma position variations, thereby reducing overall energy consumption

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The system dynamically adjusts operational parameters such as droplet ejection timing, laser pulse energy, and pulse timing based on feedback from position sensors. These parameter changes optimize the energy conversion efficiency at different operating conditions while maintaining stable plasma position, thereby reducing energy loss

Inventive Principle:

Principle #35Parameter changes

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

This approach enhances the conversion efficiency of EUV light sources by maintaining a stable plasma position, reducing the effects of laser beam drift and changes in plasma position, thereby improving the precision and reducing energy consumption.

Implementation Method 1

When the laser pulses hit a droplet, the droplet is vaporized into a plasma which emits the EUV radiation

Methodology Applied

Scientific EffectLaser ablation: Laser Ablation

Implementation Method 2

the droplet is vaporized into a plasma which emits the EUV radiation

Methodology Applied

Scientific EffectPlasma emission: Plasma

Data Source

PatentUS12130556B2Plasma position control for extreme ultraviolet lithography light sources

Publication Date: 2024.10.29 TAIWAN SEMICONDUCTOR MANUFACTURING CO LTD

AI summary

A method includes dispensing a droplet into a vacuum chamber; firing a pre-pulse laser to the droplet; sensing a first image of a return beam of the pre-pulse laser from the droplet; after firing the pre-pulse laser, firing a main-pulse laser to the droplet, wherein when the main-pulse laser hits the droplet, the droplet is vaporized into a plasma that emits extreme ultraviolet radiation; after sensing the first image and firing the main-pulse laser, sensing a second image of a return beam of the main-pulse laser from the droplet; and adjusting a plasma position in the vacuum chamber according to at least the second image.