EUV Lithography Dose Margin Control for Plasma Instability
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Solution Overview
Problem
Existing EUV lithography systems face challenges in maintaining consistent EUV intensity due to plasma instability, leading to variations in exposure dosage and reduced throughput, as the current method provides a generic dose margin regardless of exposure dosage and plasma instability.
Innovation Solution
The system dynamically determines the dose margin per wafer based on exposure dosage and plasma instability, using a method that adjusts the number of margin droplets and implements inter-compensation between bursts to ensure consistent EUV energy delivery, optimizing the dose margin for each wafer and enhancing throughput.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a generic dose margin is used for all wafers, then the system is simple to operate, but the exposure dosage consistency deteriorates due to plasma instability
Solution Approach 1:
The patent implements dynamic determination of dose margin per wafer based on real-time plasma instability measurements. The dose margin is adjusted dynamically according to the measured plasma conditions for each specific wafer, transforming the static generic approach into a dynamic adaptive system that maintains exposure dosage consistency while accounting for plasma variations
Solution Approach 2:
The system measures plasma instability and uses this feedback to adjust the dose margin for each wafer. The plasma instability measurement feeds into the dose margin calculation, creating a closed-loop control system that automatically compensates for plasma variations to maintain consistent exposure dosage
2Manufacturing precision
If the number of margin droplets is increased to compensate for plasma instability, then the exposure dosage consistency improves, but the throughput deteriorates due to excessive margin droplets
Solution Approach 1:
The patent changes the parameter of dose margin from a fixed generic value to a variable value determined by plasma instability measurements. By adjusting the dose margin parameter dynamically based on actual plasma conditions, the system achieves the minimum necessary margin droplets for each wafer, avoiding excessive margin droplets that would reduce throughput while maintaining exposure dosage consistency
3Productivity
If the dose margin is optimized per wafer based on plasma instability, then the throughput improves by reducing excessive margin droplets, but the system complexity increases
Solution Approach 1:
The system performs self-characterization by measuring its own plasma instability and using this information to determine the appropriate dose margin for each wafer. The EUV source essentially serves itself by providing the plasma instability measurements that directly inform the dose margin calculation, reducing the need for external complex characterization systems
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 ensures that the EUV lithography process maintains consistent exposure dosage while optimizing throughput by dynamically adjusting the dose margin according to plasma stability, reducing the need for excessive margin droplets and maintaining high EUV energy delivery.
Implementation Method 1
a laser operable to heat the target material to a temperature sufficient to generate plasma
Implementation Method 2
heat the target material to a temperature sufficient to generate plasma
Implementation Method 3
an EUV source configured to deliver a predetermined amount of EUV energy to a wafer
Data Source
AI summary
Lithography methods and corresponding lithography apparatuses are disclosed herein for improving throughput of lithography exposure processes. An exemplary lithography method includes generating a plurality of target material droplets and generating radiation from the plurality of target material droplets based on a dose margin to expose a wafer. The dose margin indicates how many of the plurality of target material droplets are reserved for dose control. In some implementations, the plurality of target material droplets are grouped into a plurality of bursts, and the lithography method further includes performing an inter-compensation operation that designates an excitation state of target material droplets in one of the plurality of bursts to compensate for an energy characteristic of another one of the plurality of bursts.