Laser Control System Trapezoidal Window Energy Dose Calculation
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Solution Overview
Problem
Current MOPA laser systems face challenges in tonal disturbances and require further sharpening of timing and energy control to improve operation, particularly in high-repetition rate applications like integrated circuit lithography.
Innovation Solution
The implementation of a laser control system with an oscillator gas chamber and an amplifier gas chamber, utilizing a trapezoidal window for energy dose calculation and a feedback control loop to modify voltage inputs, along with advanced control algorithms such as feed-forward, energy servo, dither cancellation, and MopaOpPoint compensation to refine energy and timing control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional square window method is used for energy dose calculation, then the calculation is simple, but tonal disturbances occur and energy control precision deteriorates
Solution Approach 1:
The patent changes the calculation window shape from square to trapezoidal, modifying the temporal parameters of the integration function. This parameter change eliminates tonal disturbances in the energy dose calculation while maintaining computational simplicity, directly resolving the contradiction between precision and harmful factors.
2Measurement precision
If feedback control loop is implemented, then energy control precision is improved, but system complexity increases
Solution Approach 1:
The patent implements a feedback control loop that continuously monitors the actual energy dose delivered and compares it with the target dose, then adjusts the laser discharge parameters accordingly. This feedback mechanism improves energy control precision while the use of trapezoidal window calculation keeps the computational aspect manageable, balancing precision improvement with acceptable system complexity.
3Measurement precision
If voltage input is modified to improve timing control, then timing precision is improved, but energy delivery stability may deteriorate
Solution Approach 1:
The patent applies preliminary action by pre-calculating the optimal voltage waveform shape (trapezoidal) before the laser discharge occurs. This pre-planned voltage profile ensures both precise timing control and stable energy delivery, as the waveform characteristics are determined in advance to simultaneously satisfy both timing and stability requirements, avoiding the need for real-time adjustments that could compromise stability.
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 the precision and stability of laser energy delivery, reducing energy dose errors by approximately 25% and improving timing control, leading to more efficient and accurate operation in high-repetition rate environments.
Implementation Method 1
a first voltage input is delivered operatively in the form of electrical pulses to a first pair of electrodes within an oscillator gas chamber and a second pair of electrodes within an amplifier gas chamber
Data Source
AI summary
A laser control system contains an oscillator gas chamber and an amplifier gas chamber. A first voltage input is operatively connected to deliver electrical pulses to a first pair of electrodes within the oscillator gas chamber and a second pair of electrodes within the amplifier gas chamber. An output of the gas chambers is an energy dose calculated by a trapezoidal window. A control circuit connects to the first voltage input for modifying the first voltage input. A feedback control loop communicates an output of the gas chambers to the control circuit for modifying the first voltage input.