Substrate Curvature Dose Mapping for Overlay Distortion Compensation
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Solution Overview
Problem
Existing substrate fabrication processes face challenges in controlling out-of-plane distortion (OPD), which leads to in-plane distortion (IPD) and overlay errors in lithographic operations, due to stress buildup and complex patterns of OPD across the wafer.
Innovation Solution
The approach involves determining a substrate OPD map to extract global and residual curvature components, applying a uniform stress compensation layer to address global OPD, and using a dose map with a patterning energy source to correct residual OPD patterns, thereby reducing IPD.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional fabrication processes are used without stress compensation, then manufacturing simplicity is maintained, but out-of-plane distortion accumulates causing in-plane distortion and overlay errors
Solution Approach 1:
The patent applies stress compensation layers and dose mapping treatments before lithographic operations to pre-correct out-of-plane distortion. By measuring substrate curvature and calculating compensation patterns in advance, the method eliminates OPD-induced IPD before it affects overlay alignment, rather than attempting to correct errors after they occur.
Solution Approach 2:
The patent modifies physical parameters of the substrate by depositing stress compensation layers with specific stress characteristics and applying localized dose maps with varying energy concentrations. These parameter changes alter the substrate's mechanical properties to counteract existing stress patterns and flatten the substrate surface, thereby improving overlay precision.
2Manufacturing precision
If stress compensation layers and dose mapping are applied to correct OPD, then overlay alignment precision is improved, but manufacturing process complexity increases
Solution Approach 1:
The patent implements a feedback loop where substrate curvature is measured using interferometry or other measurement techniques, the measured data is used to calculate customized dose maps and compensation layer parameters, and these corrections are applied in subsequent processing steps. This closed-loop approach automatically adapts to each substrate's specific distortion pattern, maintaining high precision while systematizing the complexity.
Solution Approach 2:
The patent introduces stress compensation layers as intermediary elements between the substrate and subsequent processing steps. These layers act as a mediator that absorbs and redistributes stress, preventing it from propagating to the device structures. The intermediary layer simplifies the overall process by decoupling substrate distortion from device fabrication precision requirements.
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 effectively minimizes IPD and improves the accuracy of subsequent device fabrication by compensating for both global and residual OPD, ensuring precise overlay alignment and reducing overlay misalignment issues.
Implementation Method 1
a dose map is determined for ion beam processing of the substrate based on the residual curvature map
Implementation Method 2
a uniform stress compensation layer is applied to the substrate to reduce the global OPD
Data Source
AI summary
A method may include generating a residual curvature map for a substrate, the residual curvature map being based upon a measurement of a surface of the substrate. The method may include generating a dose map based upon the residual curvature map, the dose map being for processing the substrate using a patterning energy source; and applying the dose map to process the substrate using the patterning energy source.