EUV Pre-Pulse Laser Targeting with Dual-Feedback Alignment
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Solution Overview
Problem
Inconsistent EUV radiation generation and reduced efficiency in semiconductor manufacturing due to inaccuracies in targeting the pre-pulse laser beam, leading to incomplete exposure of semiconductor substrates and inefficient use of target material.
Innovation Solution
A dual-feedback control system using a quad-cell sensor and a camera sensor to adjust the target position of the pre-pulse laser beam, ensuring precise alignment and synchronization with the disc-shaped droplet of target material.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a pre-pulse laser beam is used to deform droplets into disc-shaped targets, then EUV radiation generation efficiency is improved, but targeting accuracy deteriorates due to position drift
Solution Approach 1:
The patent employs a dual-feedback control system using a quad-cell sensor for fast position detection and a camera sensor for slow position detection. The quad-cell sensor provides high-frequency feedback to correct rapid position drift, while the camera sensor provides low-frequency feedback to correct slower drift, ensuring the pre-pulse laser beam consistently targets the correct position on the disc-shaped droplet despite thermal and mechanical drift.
Solution Approach 2:
The pre-pulse laser beam is used to deform the droplet into a disc-shaped target before the main pulse arrives. This preliminary action creates an optimized target geometry that enhances EUV radiation generation efficiency when the main pulse strikes the deformed droplet.
2Manufacturing precision
If dual-feedback control system is implemented, then targeting precision is improved, but device complexity increases
Solution Approach 1:
The control system is segmented into two independent feedback loops: a fast feedback loop using the quad-cell sensor for high-frequency position corrections, and a slow feedback loop using the camera sensor for low-frequency position corrections. This segmentation allows each sensor to operate in its optimal frequency range without interfering with the other, managing complexity through functional separation.
Solution Approach 2:
The dual-feedback system operates with periodic actions at different frequencies. The quad-cell sensor operates at a high frequency to detect and correct rapid position drift, while the camera sensor operates at a lower frequency to detect and correct slower drift, creating a multi-frequency control rhythm that manages system complexity.
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
Maintains accurate EUV radiation dose, improves yield rate and quality of semiconductor devices, and optimizes target material usage by enhancing the alignment and synchronization of laser beams.
Implementation Method 1
A dual-feedback control system using a quad-cell sensor and a camera sensor to adjust the target position of the pre-pulse laser beam
Implementation Method 2
A dual-feedback control system using a quad-cell sensor and a camera sensor to adjust the target position of the pre-pulse laser beam
Implementation Method 3
The EUV radiation is produced from a laser produced plasma (LPP) that is generated by exposing droplets of tin (Sn) to a carbon dioxide (CO2)-based laser
Implementation Method 4
The EUV radiation is produced from a laser produced plasma (LPP) that is generated by exposing droplets of tin (Sn) to a carbon dioxide (CO2)-based laser
Data Source
AI summary
Some implementations described herein provide a dual-feedback control system for laser beam targeting in a lithography system such as an EUV lithography system. In addition to using feedback from a high-frequency quad-cell sensor to adjust a target position of the pre-pulse laser beam based on a first portion of a phase of a wavefront of the pre-pulse laser beam, the dual-feedback control system uses feedback from a low-frequency camera sensor to adjust the target position of the pre-pulse laser beam based on a second portion of the phase of the wavefront.