Mask Exposure Beam Deflection for Thermal Placement Correction
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Solution Overview
Problem
The increasing precision requirements for semiconductor photomasks lead to positional accuracy issues due to temperature differences between the mask and the exposure chamber, causing pattern placement errors that can result in wafer defects if not corrected.
Innovation Solution
A mask exposure system and method that includes temperature sensors for the mask and chamber, a deflector to adjust the electron beam's position based on voltage, and a controller to correct the beam's direction and degree of deflection, predicting and compensating for temperature-induced distortions in real-time to maintain accurate pattern placement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the mask is exposed immediately after entering the chamber without thermal equilibrium, then productivity is improved, but manufacturing precision deteriorates due to thermal expansion/contraction
Solution Approach 1:
The system performs preliminary measurement of the mask temperature and chamber temperature before the exposure process, and calculates the thermal expansion/contraction amount in advance. This allows the exposure position to be pre-compensated, enabling immediate exposure without waiting for thermal equilibrium while maintaining pattern placement accuracy.
Solution Approach 2:
The system changes the exposure position parameters based on the measured temperature difference between the mask and chamber. By dynamically adjusting the exposure position according to the thermal state, the system compensates for thermal expansion/contraction effects and maintains manufacturing precision while improving productivity.
2Manufacturing precision
If the mask waits for thermal equilibrium before exposure, then manufacturing precision is improved, but productivity deteriorates due to exposure time loss
Solution Approach 1:
The system replaces the mechanical waiting process (thermal equilibrium time) with a computational compensation process. Instead of physically waiting for temperature equalization, the system uses temperature measurements and calculations to determine and apply position corrections, dramatically reducing the time required while maintaining precision.
Solution Approach 2:
The system introduces temperature measurement and calculation as an intermediary between the mask entering the chamber and the exposure process. This intermediary step provides the necessary information to compensate for thermal effects without requiring the mask to physically reach thermal equilibrium, thus maintaining precision while improving productivity.
3Manufacturing precision
If temperature measurement and correction systems are added, then manufacturing precision is improved, but device complexity increases
Solution Approach 1:
The system integrates temperature measurement and position correction functions into the existing exposure apparatus. The temperature sensors and correction mechanisms are incorporated as additional functions of the same device, avoiding the need for separate independent systems and minimizing the increase in overall device complexity.
Solution Approach 2:
The system implements a feedback loop where temperature measurements are continuously taken, and the exposure position is automatically adjusted based on the measured thermal state. This closed-loop control ensures high manufacturing precision while using a relatively simple structure that leverages the existing control capabilities of the exposure apparatus.
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 solution effectively corrects mask placement errors due to temperature differences, ensuring precise pattern exposure without waiting for thermal equilibrium, thereby enhancing productivity and reducing wafer defects.
Implementation Method 1
a deflector configured to adjust a position at which the electron beam is irradiated on the mask by deflecting the electron beam based on a voltage level applied to the deflector
Implementation Method 2
A constituent material of the mask may expand or contract depending on a temperature change, such that the mask may expand or contract until the temperature of the mask entering the chamber attains thermal equilibrium with the internal temperature of the chamber
Data Source
AI summary
A mask exposure system includes a chamber, a stage configured to receive a mask, one or more mask temperature sensors, a beam source configured to irradiate an electron beam on the mask, a deflector configured to adjust a position at which the electron beam is irradiated on the mask by deflecting the electron beam based on a voltage level applied to the deflector, in the chamber, a chamber temperature sensor configured to measure an internal temperature of the chamber, and a controller configured to control a direction of deflection and a degree of deflection of the electron beam the deflector. The controller is configured to correct the voltage level applied to the deflector based on a difference between the temperature of the mask and the chamber.