Semiconductor Overlay Measurement Using Dual Illumination Systems
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Solution Overview
Problem
The increasing complexity and integration level of semiconductor devices lead to challenges in accurately measuring overlay errors between patterns, due to distortions caused by new materials and complex manufacturing processes.
Innovation Solution
A method for manufacturing semiconductor devices using an overlay measurement process that involves forming a first and second pattern from pre-reticles using different illumination systems, measuring the overlay error between these patterns, and forming a corrected reticle based on the measured error.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If overlay measurement is performed using conventional methods with single illumination system, then the measurement process is simple, but measurement precision deteriorates due to distortions from new materials and complex manufacturing processes
Solution Approach 1:
The measurement process is segmented into multiple independent measurement steps using different illumination systems (first illumination system for lower pattern, second illumination system for upper pattern). This allows each measurement to be optimized for its specific pattern type while maintaining overall process manageability.
Solution Approach 2:
The illumination parameters are changed between measurements - using different illumination systems with different characteristics (e.g., different wavelengths, illumination angles) to measure different patterns. This compensates for material and process-induced distortions by varying the measurement conditions.
2Measurement precision
If multiple illumination systems are used to improve overlay measurement accuracy, then measurement precision improves, but device complexity increases
Solution Approach 1:
The measurement apparatus is designed with multi-functional capability to perform both lower pattern and upper pattern measurements using different illumination systems. This universal design allows a single device to handle multiple measurement tasks that would otherwise require separate specialized equipment.
Solution Approach 2:
The system uses feedback from the measured overlay errors to adjust and optimize the measurement process. By measuring both lower and upper patterns with different illumination systems and comparing results, the system can identify and compensate for distortions, improving overall measurement accuracy.
3Reliability
If conventional overlay measurement methods are used, then the process is simple, but reliability deteriorates due to distortions from complex manufacturing processes
Solution Approach 1:
The system performs preliminary measurements of both lower and upper patterns before final overlay calculation. This preliminary action allows identification of potential measurement issues and distortion effects before they impact the final result, improving reliability.
Solution Approach 2:
The measurement approach combines results from multiple illumination systems and measurement methods to create a composite measurement outcome. This composite approach compensates for the limitations of individual measurement methods, providing more reliable overlay data despite process complexities.
Data Source
AI summary
A method for manufacturing a semiconductor device includes providing a first pre-reticle including a first overlay mark and a first on-cell pattern. A second pre-reticle is provided that includes a second overlay mark and a second on-cell pattern. A first pattern is formed from the first pre-reticle using a first illumination system. A second pattern is formed from the second pre-reticle using a second illumination system. An overlay error is measured between the first pattern and the second pattern. A corrected reticle is formed based on the measured overlay error.