Overlay Displacement Correction via Thermal Expansion Compensation
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Solution Overview
Problem
Current methods for measuring overlay displacement between layers in semiconductor manufacturing, such as using SEM, face challenges in accuracy due to thermal expansion of substrates, leading to discrepancies between alignment mark and body pattern measurements.
Innovation Solution
A method that involves measuring temperature distributions during pattern formation and measurement, calculating expansion/contraction amounts, and correcting positional displacement amounts using expansion coefficient information to accurately determine overlay displacement between patterns.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If SEM is used to measure overlay displacement, then measurement precision is improved, but substrate damage increases and observation conditions become difficult to set
Solution Approach 1:
The patent introduces a simulation step that performs preliminary calculation of overlay displacement using process condition data obtained before actual exposure. This preliminary action provides an expected overlay displacement value that can guide subsequent measurement and reduce the need for repeated high-resolution SEM measurements that cause substrate damage.
Solution Approach 2:
The patent uses process condition data (exposure conditions, development conditions, etching conditions) as an intermediary to calculate expected overlay displacement through simulation. This intermediary approach allows obtaining overlay information without directly using high-energy electron beams that damage the substrate.
2Ease of manufacture
If alignment mark is used for overlay measurement, then measurement process is simplified, but measurement accuracy diverges from body pattern alignment
Solution Approach 1:
The patent replaces direct physical measurement of alignment marks with a simulation-based calculation system. By using process condition data to simulate and calculate overlay displacement, the system substitutes mechanical/optical measurement with computational analysis, maintaining simplicity while improving accuracy to match body pattern alignment.
Solution Approach 2:
The patent changes the measurement approach from direct spatial measurement of alignment marks to parameter-based calculation using process conditions (exposure, development, etching parameters). This parameter transformation allows deriving overlay displacement information that accurately reflects body pattern alignment without the limitations of alignment mark measurement.
3Object-affected harmful factors
If indirect measurement method is used, then substrate damage is reduced, but thermal expansion causes positional relationship changes
Solution Approach 1:
The patent replaces direct physical measurement of positional relationships with simulation-based calculation. By computing overlay displacement from process condition data rather than measuring actual positions after thermal expansion occurs, the system avoids the accuracy degradation caused by thermal effects while maintaining low substrate damage.
Solution Approach 2:
The patent performs preliminary simulation calculation of overlay displacement using process conditions obtained before final measurement. This preliminary action captures the expected positional relationships before thermal expansion during measurement can alter the actual positions, thereby preserving measurement accuracy.
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 overlay displacement measurement by correcting for thermal expansion errors, ensuring precise alignment between layers in semiconductor devices.
Implementation Method 1
the positional relationship between the alignment mark and the body pattern is changed due to the thermal expansion of the substrate
Implementation Method 2
a first expansion/contraction amount of the substrate between the first process and the second process is calculated based upon the first temperature distribution and the second temperature distribution
Data Source
AI summary
In an overlay displacement amount measuring method according to an embodiment, a temperature distribution of a substrate during a pattern forming process and a temperature distribution of the substrate during a measuring process for measuring a positional displacement amount between patterns on the substrate by an electron microscope are measured. An expansion/contraction amount of the substrate between two processes is calculated based upon the two temperature distributions, and the positional displacement amount is corrected based upon the expansion/contraction amount. An overlay displacement amount between the pattern and a pattern formed on a layer different from the pattern is measured by an optical measuring apparatus, and the overlay displacement amount is corrected based upon the corrected positional displacement amount.