Dual-Pulse Laser Lithography Light Source Efficiency
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing methods for generating extreme ultraviolet (EUV) light in lithography processes have limitations in power conversion efficiency from input energy for ionization, which affects the performance and complexity of semiconductor manufacturing.
Innovation Solution
A dual-pulse laser-produced plasma (LPP) mechanism is employed in a lithography system, where a fuel target generator produces tin droplets that are irradiated by a pre-pulse and main pulse laser to generate EUV light, with a monitoring system adjusting parameters to optimize flow velocity and laser frequency for improved power conversion efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If a single-pulse laser is used to generate EUV light, then the device complexity is reduced, but the power conversion efficiency is insufficient
Solution Approach 1:
The laser pulse is divided into two distinct pulses: a pre-pulse (first pulse) that creates a plasma channel and a main pulse (second pulse) that generates EUV radiation. This segmentation allows optimization of each pulse's function, with the pre-pulse preparing the medium and the main pulse producing high-efficiency EUV light, thereby improving overall power conversion efficiency without requiring complex additional components
Solution Approach 2:
The pre-pulse is applied before the main pulse to pre-ionize the gas medium and create an optimal plasma channel structure. This preliminary action prepares the medium in advance, ensuring that when the main pulse arrives, it can generate EUV radiation with maximum efficiency. The timing and energy of the pre-pulse are optimized to create the ideal conditions for subsequent EUV generation without adding complex control systems
2Use of energy by moving object
If higher laser power is used to improve EUV generation efficiency, then the power conversion efficiency increases, but contamination of the system increases
Solution Approach 1:
A gas medium (such as xenon or krypton) is introduced as an intermediary between the laser and the target material. The pre-pulse ionizes this gas to create a controlled plasma channel that guides and confines the main pulse's energy. This intermediary plasma channel allows high-power laser interaction to occur in a controlled manner, improving EUV generation efficiency while containing contaminants within the plasma region, preventing them from contaminating the broader system
Solution Approach 2:
The system uses an inert gas environment (vacuum or inert gas-filled chamber) to contain the plasma and prevent contamination of surrounding components. The inert atmosphere isolates the high-power laser-plasma interaction zone, allowing efficient EUV generation while preventing reactive byproducts and debris from contaminating optical surfaces and other sensitive system components
3Use of energy by moving object
If the laser pulse duration is extended to improve ionization completeness, then the power conversion efficiency improves, but the temporal resolution of the process decreases
Solution Approach 1:
The laser interaction is structured as a periodic two-pulse sequence with optimized timing. The pre-pulse duration and intensity are optimized to create the plasma channel in a specific time window, followed by the main pulse that generates EUV radiation within a controlled temporal window. This periodic structure ensures complete ionization occurs within the pre-pulse timeframe, while the main pulse delivers EUV radiation in a short, well-defined temporal window, maintaining high temporal resolution for lithography applications
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 enhances power conversion efficiency and reduces contamination, enabling more precise and efficient EUV light generation for advanced lithography processes, such as those used in FinFET manufacturing.
Implementation Method 1
LPP technology produces EUV light by focusing a high-power laser beam onto small fuel droplet targets to form highly ionized plasma that emits EUV radiation
Implementation Method 2
highly ionized plasma that emits EUV radiation with a peak of maximum emission at 13.5 nm
Data Source
AI summary
A method for generating light is provided. The method further includes measuring a period of time during which one of targets from a fuel target generator passes through two detection positions. The method also includes exciting the targets with a laser generator so as to generate plasma that emits light. In addition, the operation of exciting the targets with the laser generator includes: irradiating a pre-pulse laser on the targets to expand the targets; detecting conditions of expanded targets; and adjusting at least one parameter of the laser generator according to the measured period of time and the conditions when the measured period of time is different from a predetermined value. The parameter of the laser generator which is adjusted according to the measured period of time includes a frequency for generating a laser for illuminating the targets.