Pulse Radiation Feedback Control for Rapid Wavelength Switching
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Solution Overview
Problem
Current lithographic systems face challenges in rapidly switching between different wavelengths of radiation due to settling time issues, which complicates the creation of complex 3D structures with high-aspect-ratio features in 3D NAND fabrication, requiring improved depth of focus and process uniformity.
Innovation Solution
A radiation system that uses a feedback loop to control bursts of pulses, where the control signal for a given pulse is dependent on the determined characteristic of previous pulses, incorporating a sensor, optical element, and actuator to adjust the wavelength dynamically, allowing for oscillation between multiple wavelengths to enhance depth of focus.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the wavelength is changed rapidly between pulses, then the ability to create complex 3D structures with high-aspect-ratio features is improved, but transient effects and settling time issues worsen
Solution Approach 1:
The patent implements a feedback control system where the control signal for a given pulse in a given burst is dependent on the determined characteristic of a corresponding pulse from at least one previous burst. This feedback mechanism allows the system to compensate for transient effects and settling time issues by continuously adjusting the wavelength based on previous pulse characteristics, thereby maintaining process uniformity while enabling rapid wavelength switching for complex 3D structure fabrication.
2Manufacturing precision
If multiple exposure passes are made with different wavelengths, then the depth of focus is improved, but the complexity of the manufacturing process increases
Solution Approach 1:
The patent enables continuous wavelength switching within a burst of pulses, allowing the system to perform multiple exposure passes with different wavelengths in a continuous manner rather than requiring separate, discrete exposure steps. This continuity approach maintains the beneficial depth of focus effects while reducing overall process complexity by integrating multiple wavelength exposures into a single operational sequence.
3Productivity
If the control signal changes rapidly to switch wavelengths, then the productivity is improved, but the stability of the radiation characteristic worsens
Solution Approach 1:
The patent employs preliminary action by using feedback from previous burst characteristics to pre-adjust the control signal for upcoming pulses. This allows the system to anticipate and compensate for potential instability before it occurs, enabling rapid wavelength switching for high productivity while maintaining wavelength stability through proactive control adjustments based on historical data.
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 enables rapid and precise control of radiation wavelength, reducing transient effects and improving process uniformity, particularly beneficial for 3D NAND lithography by increasing depth of focus and maintaining stability across multiple exposure passes.
Implementation Method 1
an optical element configured to interact with the pulses of radiation to control a characteristic of the pulses of radiation, the characteristic of the pulses of radiation being dependent on a configuration of the optical element
Data Source
AI summary
A radiation system for controlling bursts of pulses of radiation comprises: an optical element; a controller; an actuator; and a sensor. The optical element is configured to interact with the pulses of radiation to control a characteristic of the pulses of radiation, the characteristic of the pulses of radiation being dependent on a configuration of the optical element. The controller is operable to generate a control signal. The actuator is configured to receive the control signal from the controller and to control a configuration of the optical element in dependence on the control signal. The sensor is operable to determine the characteristic of pulses having interacted with the optical element. The control signal for a given pulse in a given burst is dependent on the determined characteristic of a corresponding pulse from a previous burst.