Electron Beam Lithography Pattern Correction via Iterative Scattering Simulation
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Solution Overview
Problem
Current electron gun writing systems for integrated circuits face challenges in accurately forming patterns due to electron scattering phenomena, leading to significant shape differences between the desired and obtained patterns, especially with complex shapes and proximity effects.
Innovation Solution
A method that breaks down a pattern into elementary outlines with standardized shapes, applies simulation patterns to account for electron scattering, and iteratively adjusts the work pattern using displacement vectors to minimize shape differences, ensuring faithful reproduction of the desired pattern.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If electron beam insolation is applied to form patterns on resin layer, then pattern formation is achieved, but electron scattering phenomena cause significant shape differences between desired and obtained patterns
Solution Approach 1:
The patent applies preliminary action by performing simulation calculations before actual pattern formation to predict electron scattering effects. The method calculates the distribution of secondary electrons and backscattered electrons in advance, then uses these predictions to pre-compensate the insolation dose distribution, thereby correcting shape distortions before they occur in the final pattern.
Solution Approach 2:
The patent implements feedback by using simulation results to inform and adjust the insolation process. The simulated electron scattering patterns provide feedback information that is used to optimize the insolation conditions, creating a closed-loop system where measurement (simulation) informs control (insolation dosing) to achieve the desired pattern accuracy.
2Manufacturing precision
If insolation conditions are optimized to account for electron scattering, then pattern fidelity improves, but calculation and simulation time increases
Solution Approach 1:
The patent applies segmentation by dividing the pattern formation process into discrete computational steps: initial pattern definition, simulation of electron scattering, calculation of dose compensation, and iterative refinement. This segmentation allows the complex optimization problem to be broken down into manageable stages, reducing overall computational burden while maintaining accuracy.
Solution Approach 2:
The patent uses partial action by applying electron scattering correction selectively to critical pattern regions rather than uniformly across the entire pattern. The simulation and compensation focus on areas where electron scattering has the most significant impact on shape accuracy, thereby reducing calculation time while maintaining pattern fidelity where it matters most.
3Manufacturing precision
If proximity effects between neighboring patterns are corrected through dose adjustment, then shape accuracy improves, but exposure time increases significantly
Solution Approach 1:
The patent applies local quality by implementing spatially varying insolation conditions tailored to specific regions of the pattern. Different dose levels and exposure parameters are applied locally depending on the position relative to neighboring patterns, rather than using uniform correction across the entire field. This localized approach corrects proximity effects accurately while minimizing overall exposure time.
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 method significantly reduces shape differences between the desired and final patterns, improving the accuracy and faithfulness of pattern formation by iteratively correcting for scattering effects and proximity issues, thereby enhancing the precision of electron beam writing systems.
Implementation Method 1
electrically-charged particles are projected onto the surface of a layer, commonly called resin. The electronic radiation causes the reaction of a portion of the resin layer
Implementation Method 2
there exist unavoidable electron scattering phenomena (diffraction of the incident beam, different scattering mechanisms within the resin and the adjacent materials)
Implementation Method 3
diffraction of the incident beam
Data Source
AI summary
A method of generating data relative to the writing of a pattern by electronic radiation initially includes the provision of a pattern to be formed which form the work pattern with a single external envelope. The work pattern is broken down into a set of elementary outlines, each including a single external envelope. A set of insolation conditions is defined to model each elementary outline. An irradiated simulation pattern is calculated from the sets of insolation conditions associated with the sets of elementary outlines. The simulation pattern is compared with the pattern to be formed. If the simulation pattern is not representative of the pattern to be formed, shift vectors are calculated. The shift vectors are representative of different intervals existing between the two patterns. The external envelope of the pattern to be formed is modified from displacement vectors determined from the shift vectors. A new iteration is carried out.