EUV Lithography Radiation Source Dual-Pulse Plasma Control
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Solution Overview
Problem
Existing EUV lithography systems face low efficiency in generating EUV radiation and degradation of LPP collectors due to contamination, which affects wafer throughput and collector lifetime.
Innovation Solution
The system employs a dual-pulse laser-produced plasma mechanism with adjustable pre-pulse and main pulse parameters, including delay and position, to optimize EUV conversion efficiency and reduce debris deposition on collectors, using a target droplet generator, first and second laser sources, and a controller to maximize EUV radiation energy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If a high-power laser beam is focused onto target droplets to generate EUV radiation, then EUV radiation is produced, but power conversion efficiency from input energy to EUV radiation is low
Solution Approach 1:
A pre-pulse is applied to the target droplet before the main pulse to pre-ionize and heat the droplet surface, creating a low-density plasma precursor that reduces energy loss when the main pulse strikes. This preliminary action prepares the target to convert more of the main pulse energy into EUV radiation rather than losing it to inefficient ablation and heating.
Solution Approach 2:
The system optimizes multiple parameters including the pre-pulse and main pulse delay time, pre-pulse energy, main pulse energy, and target droplet size to maximize power conversion efficiency. By carefully tuning these parameters, the plasma generation process is optimized to produce higher EUV output per unit of input laser energy.
2Use of energy by moving object
If laser-produced plasma is used to generate EUV radiation, then EUV radiation is produced, but LPP collectors degrade due to contamination from debris deposition
Solution Approach 1:
The harmful debris and contamination are extracted or removed from the system by optimizing the plasma generation process to produce less debris and by positioning collectors to minimize exposure. The pre-pulse technique also helps reduce debris generation by creating a more controlled ablation process.
Solution Approach 2:
The pre-pulse creates a controlled plasma environment that, while generating some debris, also produces a more stable and efficient EUV source. The controlled ablation from the pre-pulse actually reduces the overall debris load compared to direct high-power pulsing, converting what could be harmful uncontrolled ablation into a beneficial controlled process.
3Productivity
If existing LPP methods are used, then EUV radiation is generated, but wafer throughput is limited due to low conversion efficiency
Solution Approach 1:
The pre-pulse prepares the target droplet in advance, creating optimal conditions for EUV generation when the main pulse arrives. This preliminary ionization and heating of the droplet surface enables more efficient EUV production per unit time, directly increasing wafer throughput by reducing the time and energy required per exposure cycle.
Solution Approach 2:
By optimizing parameters such as pulse delay, pulse energies, and droplet characteristics, the system achieves higher EUV photon output per unit time. This parameter optimization directly translates to increased wafer throughput by enabling faster and more efficient lithography exposure cycles.
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 EUV conversion efficiency and extends the usable lifetime of LPP collectors by optimizing plasma generation and reducing contamination, thereby improving wafer throughput and system performance.
Implementation Method 1
a first laser source for heating the target droplets to produce target plumes
Implementation Method 2
a second laser source for heating the target plumes to produce plasma emitting extreme ultraviolet (EUV) radiation
Implementation Method 3
focusing a high-power laser beam onto small fuel droplet target droplets to form highly ionized plasma
Data Source
AI summary
An extreme ultraviolet (EUV) lithography system is provided. The EUV lithography system includes the above-mentioned extreme ultraviolet (EUV) radiation source. The EUV lithography system further includes a collector configured to collect and reflect the EUV radiation and a mask stage configured to secure an EUV mask. The EUV lithography system also includes a wafer stage configured to secure a semiconductor wafer. In addition, the EUV lithography system includes one or more optical modules configured to direct the EUV radiation from the radiation source to image an integrated circuit (IC) pattern defined on the EUV mask onto the semiconductor wafer.