Optical Metrology Test Substrate for Lithography Error Characterization
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Solution Overview
Problem
The increasing complexity of semiconductor manufacturing requires more accurate alignment, overlay, and critical dimension control in lithographic processes, as errors in these aspects can lead to device malfunction or electrical issues, necessitating improved metrology techniques to characterize and minimize errors.
Innovation Solution
A method involving a product test substrate with a non-zero sensitivity to changes in radiation characteristics, allowing for the measurement of optical response parameters, which are used to determine physical characteristics and adjust the patterning process accordingly, utilizing a metrology apparatus to illuminate and measure the substrate and generate electronic instructions for process optimization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional metrology techniques are used to measure alignment, overlay, and critical dimension, then measurement capability is maintained, but measurement precision is insufficient to characterize errors in advanced lithographic processes
Solution Approach 1:
The patent changes the physical parameters of the test substrate by creating a stack of layers with specific optical properties (refractive indices, thicknesses) that are sensitive to radiation characteristics. This allows the substrate to produce measurable optical responses that characterize errors in alignment, overlay, and critical dimension with higher precision than conventional techniques.
Solution Approach 2:
The patent creates a simplified test substrate that copies the essential optical interaction characteristics of complex product substrates without the complexity of actual device patterns. This test substrate replicates the optical response behavior needed for metrology measurements while being easier to manufacture and interpret.
2Measurement precision
If complex product substrates are used for metrology testing, then measurement accuracy is improved, but manufacturing complexity and cost increase
Solution Approach 1:
The patent extracts the essential optical measurement function from complex product substrates by creating a simplified test substrate with a specific stack of layers. This extraction maintains the necessary optical response characteristics for metrology while removing the complexity of actual device patterns and structures.
Solution Approach 2:
The patent creates a test substrate that is simpler and less expensive than product substrates, designed specifically for metrology testing. This disposable-like test substrate can be manufactured cost-effectively and discarded after use, avoiding the need to invest in complex product substrates for testing purposes.
3Reliability
If existing metrology approaches are used, then process monitoring is maintained, but the ability to characterize and minimize errors in advanced lithography is insufficient
Solution Approach 1:
The patent enables feedback by measuring optical responses from the test substrate to characterize errors in alignment, overlay, and critical dimension. These measurements provide information that can be used to adjust and optimize the lithographic process, improving manufacturing precision and reliability.
Solution Approach 2:
The patent performs preliminary characterization of the test substrate's optical response before actual production runs. By pre-measuring the substrate's sensitivity to radiation characteristics and error conditions, the system can establish baseline data and detection thresholds for monitoring process quality in advance.
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 enables precise characterization of errors and adjustments in the lithographic process, enhancing the accuracy and reliability of semiconductor device manufacturing by providing a robust and cost-effective metrology solution.
Implementation Method 1
measuring at least a part of the radiation redirected by the product test substrate
Data Source
AI summary
A method including illuminating a product test substrate with radiation from a component, wherein the product test substrate does not have a device pattern etched therein and yields a non-zero sensitivity when illuminated, the non-zero sensitivity representing a change in an optical response characteristic of the product test substrate with respect to a change in a characteristic of the radiation; measuring at least a part of the radiation redirected by the product test substrate to determine a parameter value; and taking an action with respect to the component based on the parameter value.