Mask Fabrication Model for Lithographic Correction
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Solution Overview
Problem
Current lithography process models do not effectively address mask fabrication effects, leading to sub-optimal designs in advanced technology nodes with shorter wavelengths and smaller geometries, where effects like stochastic defect mechanisms and line edge roughness become significant.
Innovation Solution
Incorporating a separate mask fabrication model into the correction process to account for systemic impacts during mask fabrication, rather than lumping these effects with general process models, improving the accuracy of mask design and reducing manufacturing defects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a conventional lumped process model is used that combines mask fabrication effects with general lithography process effects, then the model complexity is reduced and easier to calibrate, but the accuracy of predicting mask fabrication effects deteriorates
Solution Approach 1:
The patent segments the lithography process model into distinct components: a mask fabrication model that specifically models e-beam exposure, resist processing, and etching effects, and a separate general lithography process model. This segmentation allows each model to be optimized for its specific function, improving the accuracy of mask fabrication effect predictions while maintaining manageable complexity through modular design.
2Productivity
If lithography moves to shorter wavelengths and smaller geometries to increase productivity, then the resolution and feature size are improved, but sensitivity to mask fabrication effects increases causing more defects
Solution Approach 1:
The patent applies preliminary action by using the mask fabrication model to predict and correct mask pattern deviations before the actual lithography process. The model estimates how the mask fabrication process will alter the intended mask design, and correction patterns are applied in advance to compensate for these effects, thereby maintaining high reliability at advanced technology nodes.
Solution Approach 2:
The patent implements feedback by using measured data from actual mask fabrication processes to calibrate and refine the mask fabrication model. This calibrated model then provides accurate predictions of mask pattern deviations, enabling continuous improvement of correction algorithms and reducing defect rates in subsequent lithography runs.
3Ease of operation
If mask correction is applied based on inaccurate process models, then the mask design is modified, but the correction accuracy deteriorates leading to sub-optimal results
Solution Approach 1:
The patent introduces an intermediary mask fabrication model that acts as a bridge between the intended mask design and the actual lithography process. This model accurately predicts how mask fabrication will alter the design, enabling precise correction calculations that account for specific mask fabrication effects rather than using generic process models.
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 results in more accurate mask corrections, reducing defect counts and stochastic variations, leading to improved yield and uniform device performance by handling mask variations systematically.
Implementation Method 1
this is an electron-beam (e-beam) process, which includes e-beam exposure of resist on a mask blank
Implementation Method 2
processing of the exposed resist to form patterned resist
Data Source
AI summary
A lithography process is described by a design for a lithographic mask and a description of the lithography configuration, which may include the lithography source, collection/illumination optics, projection optics, resist, and/or subsequent fabrication steps. The actual lithography process uses a lithographic mask fabricated from the mask design, which may be different than the nominal mask design. A mask fabrication model models the process for fabricating the lithographic mask from the mask design. Typically, this is an electron-beam (e-beam) process, which includes e-beam exposure of resist on a mask blank, processing of the exposed resist to form patterned resist, and etching of the mask blank with the patterned resist. The mask fabrication model, usually in conjunction with other process models, is used to estimate a result of the lithography process. Mask correction is then applied to the mask design based on the simulation result.