Electron Beam Exposure Apparatus Stage Velocity Interpolation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional electron beam exposure apparatuses face challenges in deflecting the electron beam accurately at high wafer stage velocities, leading to significant errors in stage feedback, which limits throughput as the stage moves faster.
Innovation Solution
An electron beam exposure apparatus with a stage position detector and a computing unit that calculates the movement velocity of the wafer stage and interpolates positional changes within shorter time cycles, allowing for precise deflection of the electron beam to match the wafer stage's movement, thereby reducing feedback errors and increasing throughput.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the wafer stage moves at higher velocity to increase throughput, then productivity is improved, but measurement precision of stage position deteriorates due to insufficient sampling frequency
Solution Approach 1:
The patent applies preliminary action by calculating the stage velocity and interpolating position changes before the actual exposure writing process. The controller computes the amount of stage movement during the measurement cycle and uses this pre-calculated information to guide the electron beam deflection, ensuring accurate tracking even at high stage velocities where direct measurement would be insufficient.
Solution Approach 2:
The patent introduces an intermediary calculation process between the stage position measurement and the electron beam deflection control. The controller acts as an intermediary that receives stage position data, calculates velocity and interpolated position changes, and then uses these calculated values to control the electron beam deflector, bridging the gap between measurement frequency limitations and the need for high-precision tracking at high speeds.
2Measurement precision
If the measurement cycle is kept at 100 nanoseconds to maintain position accuracy, then measurement precision is improved, but the electron beam cannot be deflected in time at high velocities, causing feedback errors
Solution Approach 1:
The patent performs preliminary calculation of stage velocity and position interpolation during the measurement cycle itself. By computing the amount of stage movement in advance based on the measured position change and elapsed time, the system prepares the deflection information needed before the exposure process begins, eliminating time delays in the feedback loop.
Solution Approach 2:
The patent implements dynamic adjustment of the electron beam deflection based on calculated stage velocity. Rather than using fixed deflection parameters, the system continuously updates the deflection amount based on the real-time calculated velocity and interpolated position changes, allowing the beam to dynamically track the stage movement even at varying high speeds.
3Device complexity
If conventional feedback control is used at high stage velocities, then device complexity is minimized, but manufacturing precision deteriorates due to 10-nm feedback errors
Solution Approach 1:
The patent applies preliminary action by calculating the stage velocity and interpolated position changes before the actual exposure writing process. The controller computes the amount of stage movement during the measurement cycle and uses this pre-calculated information to guide the electron beam deflection, ensuring accurate tracking even at high stage velocities where direct measurement would be insufficient.
Solution Approach 2:
The patent changes the parameter used for feedback control from direct position measurement to calculated velocity-based interpolation. By using the elapsed time and position change to compute stage velocity and then interpolating position at shorter time intervals, the system achieves higher effective measurement precision without requiring a complete overhaul of the feedback control architecture.
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 accurate deflection of the electron beam even at high wafer stage velocities, reducing positional errors to below 1 nm and enhancing writing throughput by calculating and adjusting the electron beam deflection in synchronization with the wafer stage's movement.
Implementation Method 1
The laser interferometer 20 reads the position of the wafer stage 15
Implementation Method 2
The electron gun 13 is to emit an electron beam 12
Implementation Method 3
The deflector 14 is to deflect the electron beam 12
Data Source
AI summary
An electron beam exposure apparatus includes: an electron gun for generating an electron beam; a deflector for deflecting the electron beam; a wafer stage; a stage position detector for detecting a position of the wafer stage; and a stage position computing unit for calculating a movement velocity of the wafer stage. On a basis of the movement velocity, the stage position computing unit calculates an amount of positional change of the wafer stage with respect to an interpolation time, and subsequently calculates an amount of positional movement of the wafer stage by sequentially adding the amount of positional change to the position of the wafer stage in synchronism with the interpolation time. Thus, the stage position computing unit calculates an amount of deflection of the electron beam corresponding to the amount of the positional movement of the wafer stage.