Electron Beam Apparatus Proximity Effect Correction
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Solution Overview
Problem
Conventional electron beam apparatuses face challenges in achieving high accuracy and throughput due to the proximity effect, which causes overexposure and loss of linearity in pattern drawing, and also suffer from electrostatic charge and contamination issues during inspection, leading to reduced accuracy.
Innovation Solution
The solution involves adjusting the dose of electron beams based on pattern density to correct the proximity effect, using inverse filtering to enhance contrast, and irradiating electron beams selectively around the edges of patterns to minimize negative charge and contamination, while utilizing a single column to integrate drawing and inspection functions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If electron beams are irradiated uniformly across the pattern area, then the drawing speed is high, but the proximity effect causes overexposure and reduces manufacturing precision
Solution Approach 1:
The patent applies local quality by varying the electron beam dose according to the local pattern density. Areas with high pattern density receive reduced dose to prevent overexposure from scattered electrons, while areas with low density receive full dose. This localized dose adjustment resolves the contradiction by maintaining both drawing speed and pattern accuracy through spatially adaptive exposure control.
Solution Approach 2:
The patent changes the dose parameter of electron beams based on pattern density calculations. By dynamically adjusting the beam intensity parameter in different regions, the system achieves both high drawing speed and manufacturing precision, resolving the trade-off between productivity and accuracy.
2Productivity
If electron beams are used for inspection, then inspection speed is high, but electrostatic charge and contamination occur reducing measurement precision
Solution Approach 1:
The patent applies preliminary anti-action by irradiating electron beams specifically around the edges of patterns before formal inspection. This pre-irradiation prevents electrostatic charge accumulation and contamination that would otherwise occur during subsequent inspection, thereby maintaining both high inspection speed and measurement precision.
Solution Approach 2:
The patent converts the potentially harmful effect of electron beam irradiation (which causes charge and contamination) into a beneficial pre-treatment step. By strategically applying beams around edges, the harmful effects are prevented before they can degrade inspection accuracy, while the inspection speed remains high.
3Productivity
If multiple electron beams are used for high-speed drawing, then productivity increases, but device complexity increases
Solution Approach 1:
The patent segments the electron beam into multiple beams that can be controlled independently. This segmentation enables high-speed parallel drawing while using a single column structure, thereby increasing productivity without proportionally increasing device complexity. The multiple beams are generated and controlled within one column, avoiding the need for multiple complete column assemblies.
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 improves the accuracy and throughput of pattern drawing by reducing overexposure and enhancing contrast, and enhances inspection accuracy by minimizing electrostatic charge and contamination, allowing for high-speed and cost-effective operation with reduced hardware requirements.
Implementation Method 1
an error arises in a pattern to be exposed, due to a phenomenon called a proximity effect of electron beams even if electron beam is irradiated thereon by using the desired drawing pattern to be drawn. The finer patterns to be exposed are, the greater errors relatively become.
Implementation Method 2
electron beams, which have reached a wafer, not only expose a resist but also pass through the resist, then scatter inside the wafer, and thus expose the resist again
Implementation Method 3
an electron beam apparatus which irradiates electron beams on a periphery of edges of a pattern to be inspected on a wafer, thereby preventing occurrence of electrostatic charges and improving inspection accuracy
Implementation Method 4
an electron beam apparatus which inspects patterns drawn on the wafer by observing secondary electrons emitted from the wafer irradiated with electron beams
Data Source
AI summary
High-contrast exposure is performed by use of a small dose of electron beams, a pattern is formed on a wafer with high accuracy, and high-precision inspection is performed. In pattern formation, proximity effect correction processing is performed. Moreover, exposure of electron beams is performed based on a result of filtering using an inverse characteristic of exposure characteristics of the electron beams. Furthermore, in pattern inspection, electron beams are irradiated based on a result of filtering for obtaining a peripheral region of an edge of the pattern formed.