Laser Wavelength Separation Control Near Resonance Frequencies

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Existing lithography systems face challenges in achieving stable wavelength control, particularly at resonance frequencies, leading to slow transient responses and overshoots when operating in multifocal imaging mode, which limits the ability to efficiently produce multiple focal images for 3D NAND lithography.

Innovation Solution

A laser system incorporating a wavelength controller and a model reference adaptive control system to stabilize wavelength separation, using a piezoelectric transducer for precise control of laser radiation, enabling stable operation even at critical repetition rates near resonance frequencies.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If a piezoelectric transducer is used for wavelength control in multifocal imaging mode, then wavelength separation can be achieved, but unstable operation and overshoot occur at resonance frequencies

Engineering Contradiction:

Improvewavelength separation stabilityVSAvoidoperation stability at resonance frequencies

Core Design Contradiction:

Manufacturing precisionVSReliability

Solution Approach 1:

The patent implements dynamic control by detecting the repetition rate of the laser pulses and adjusting the drive waveform of the piezoelectric transducer in real-time. When the repetition rate approaches a resonance frequency, the system dynamically modifies the waveform to avoid excitation of resonant modes, thereby maintaining stable operation across varying operating conditions while preserving wavelength separation capability.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The patent employs feedback control by detecting the actual repetition rate of the laser pulses and using this information to adjust the drive waveform of the piezoelectric transducer. This closed-loop approach allows the system to respond to changing operating conditions and prevent instability at resonance frequencies, ensuring reliable wavelength separation.

Inventive Principle:

Principle #23Feedback

2Device complexity

If traditional wavelength control is used, then system simplicity is maintained, but transient response is slow and exhibits overshoot

Engineering Contradiction:

Improvecontrol system simplicityVSAvoidtransient response speed

Core Design Contradiction:

Device complexityVSSpeed

Solution Approach 1:

The patent applies preliminary action by pre-calculating and storing optimal drive waveforms for the piezoelectric transducer corresponding to different repetition rates. When the detected repetition rate approaches a resonance frequency, the system proactively switches to a pre-determined corrective waveform that prevents overshoot and accelerates transient response, rather than reacting after the problem occurs.

Inventive Principle:

Principle #10Preliminary action

3Manufacturing precision

If multiple exposure passes are used for different wavelengths, then depth of focus requirement is met, but productivity decreases

Engineering Contradiction:

Improvedepth of focusVSAvoidexposure throughput

Core Design Contradiction:

Manufacturing precisionVSProductivity

Solution Approach 1:

The patent enables continuous wavelength switching within a single exposure pass by implementing rapid, stable wavelength control through piezoelectric transducer modulation. This allows the lithography system to alternate between different wavelengths continuously during one exposure sequence, eliminating the need for multiple separate exposure passes and thereby maintaining high productivity while achieving the required depth of focus.

Inventive Principle:

Principle #20Continuity of useful action

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

Enables rapid and stable switching between multiple focal images during a single exposure pass, enhancing depth of focus and exposure latitude for 3D NAND lithography without the limitations of traditional systems.

Implementation Method 1

Methodology Applied

Scientific EffectPiezoelectric effect: Piezoelectric Effect

Data Source

PatentUS20260081397A1Apparatus for and method of control for spectrum separation

Publication Date: 2026.03.19 CYMER INC

AI summary

Apparatus for and methods of rapidly achieving a target peak wavelength separation in a system for producing laser radiation at more than one wavelength in which one or more actuators control wavelength in response to being supplied with a waveform. The characteristics of the waveform are determined using a model reference control system.