Lithography Image Simulation via Regional Stitching
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current lithographic technologies face challenges in accurately projecting small feature sizes and high feature densities due to proximity effects and finite feature heights, which can result in pattern deformation and reduced process windows, making it difficult to achieve precise image fidelity and increased manufacturing costs.
Innovation Solution
A method of image simulation that identifies regions of uniform optical properties on substrates or patterning devices, obtains images for these regions, stitches them according to location, and applies adjustments to correct for finite sizes and scattering effects, allowing for more accurate modeling of optical properties and improved image fidelity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional lithographic methods are used to project small feature sizes and high feature densities, then manufacturing process can be maintained with standard equipment, but image fidelity deteriorates due to proximity effects and finite feature heights causing pattern deformation
Solution Approach 1:
The substrate or patterning device surface is divided into multiple discrete regions, each characterized by uniform optical properties. This segmentation allows independent modeling and correction of optical effects in each region, thereby improving overall image fidelity while accounting for local variations in proximity effects and finite feature heights.
Solution Approach 2:
Different regions of the substrate or patterning device are assigned different optical properties based on their local characteristics. This local quality approach enables tailored correction for proximity effects and finite feature heights in each region, rather than applying a uniform model across the entire surface, thus improving manufacturing precision.
2Manufacturing precision
If standard image projection is used without regional optimization, then device complexity remains low, but manufacturing precision deteriorates due to inability to account for varying optical properties across the substrate
Solution Approach 1:
The complex problem of modeling the entire substrate is segmented into multiple simpler regional models with uniform optical properties. Each region can be modeled independently with lower computational complexity, and the results are stitched together to form the complete image, thereby achieving high manufacturing precision without overwhelming device complexity.
Solution Approach 2:
The problem is solved by transitioning from a continuous full-surface model to a discrete regional model approach. This dimensional change from continuous to discrete representation simplifies the computational complexity while maintaining or improving pattern formation accuracy through the stitching of regional images.
3Manufacturing precision
If uniform optical properties are assumed across the entire substrate, then processing and modeling are simplified, but image fidelity deteriorates due to neglect of local optical variations and scattering effects
Solution Approach 1:
The substrate is segmented into regions with locally uniform optical properties, allowing accurate modeling of local variations while maintaining computational tractability. This segmentation resolves the contradiction by capturing local optical variations without requiring a fully complex continuous model across the entire substrate.
Solution Approach 2:
Each region is assigned its own uniform optical properties that reflect local characteristics, enabling accurate image projection that accounts for local variations in scattering effects and optical behavior. This local quality approach improves image projection accuracy without the complexity of a fully heterogeneous model.
4Manufacturing precision
If finite feature heights are not accounted for in the model, then computational processing is faster and simpler, but manufacturing precision deteriorates due to uncorrected scattering effects and pattern deformation
Solution Approach 1:
The computational model is segmented into regional models that can be processed independently and parallelized. This segmentation reduces the overall computation time compared to a single comprehensive model, while still accounting for finite feature heights and scattering effects in each region to maintain pattern fidelity.
Solution Approach 2:
Regional images are pre-computed with adjustments for finite feature heights and scattering effects before final stitching. This preliminary action allows optimization of each region independently, reducing total computation time while ensuring pattern fidelity is maintained through pre-applied corrections.
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 enhances the accuracy of image projection, expands process windows, and reduces manufacturing costs by accounting for finite feature heights and scattering effects, leading to more precise and reliable pattern formation on substrates.
Implementation Method 1
a patterning device (e.g., a mask) may contain or provide a circuit pattern corresponding to an individual layer of the IC, and this circuit pattern can be transferred onto a target portion (e.g. comprising one or more dies) on a substrate (e.g., silicon wafer) that has been coated with a layer of radiation-sensitive material (resist), by methods such as irradiating the target portion through the circuit pattern on the patterning device
Implementation Method 2
a projection system (e.g., reflective or catadioptric) configured to project the pattern onto a target portion of the substrate
Data Source
AI summary
Disclosed herein is a computer-implemented method of image simulation for a device manufacturing process, the method comprising: identifying regions of uniform optical properties from a portion or an entirety of a substrate or a patterning device, wherein optical properties are uniform within each of the regions; obtaining an image for each of the regions, wherein the image is one that would be formed from the substrate if the entirety of the substrate or the patterning device has the same uniform optical properties as that region; forming a stitched image by stitching the image for each of the regions according to locations of the regions in the portion or the entirety of the substrate of the patterning device; forming an adjusted image by applying adjustment to the stitched image for at least partially correcting for or at least partially imitating an effect of finite sizes of the regions.