Lithography Pre-Biasing for Overlay Precision
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The challenge in semiconductor device manufacturing is the strict limits on overlay errors between successive layers in lithographic processes, which are difficult to control due to differences in capabilities between various lithographic apparatus, especially when using different types of equipment with varying control inputs, leading to inefficiencies and reduced manufacturing flexibility.
Innovation Solution
The method involves using a first lithographic apparatus with more control inputs to pre-bias parameters, allowing for corrections in parameters that are non-correctable in a second apparatus, by determining coupling between parameters and applying pre-biasing to achieve desired characteristics, such as improved overlay and focus, through a process of metrology data analysis and feedback loops.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If different types of lithographic apparatus are used for successive layers, then manufacturing flexibility is improved, but overlay precision deteriorates due to differences in control inputs and capabilities
Solution Approach 1:
The patent applies parameter changes by pre-biasing control parameters in the first lithographic apparatus to compensate for the limited control capabilities of the second apparatus. This involves adjusting exposure parameters, focus settings, and other controllable variables in advance to achieve desired overlay and focus characteristics despite using equipment with different control inputs.
Solution Approach 2:
The patent implements preliminary action by determining and setting pre-bias values for control parameters before performing the second exposure. The system calculates required compensations based on the known limitations of the second lithographic apparatus and applies these pre-bias settings in advance, allowing the second apparatus to produce acceptable results despite its reduced control capabilities.
2Manufacturing precision
If parameters are pre-biased in the first lithographic apparatus, then achievable characteristics in the second exposure are improved, but control complexity increases
Solution Approach 1:
The patent employs feedback mechanisms by using metrology data from exposed layers to determine and adjust pre-bias values for subsequent exposures. The system measures actual overlay and focus results, compares them against targets, and uses this information to refine control parameter settings, creating a closed-loop control system that manages complexity through data-driven adjustments.
Solution Approach 2:
The patent applies dynamics by making pre-bias values adjustable and adaptable rather than fixed. The system can modify pre-bias settings based on measured performance, allowing dynamic optimization of control parameters. This enables the control system to adapt to varying conditions and maintain precision without requiring overly complex static control mechanisms.
3Reliability
If strict overlay limits are enforced between successive layers, then device functionality is improved, but manufacturing efficiency deteriorates due to additional corrections and measurements
Solution Approach 1:
The patent applies preliminary action by pre-calculating and setting control parameter values before exposure steps. By determining appropriate pre-bias values in advance based on expected performance requirements, the system reduces the need for extensive post-exposure adjustments and rework, thereby maintaining strict overlay limits while improving manufacturing throughput.
Solution Approach 2:
The patent uses feedback from metrology measurements to efficiently enforce overlay limits. Rather than requiring multiple iterative exposures, the system measures overlay performance and uses this information to adjust subsequent exposures, enabling rapid convergence to acceptable results and reducing total manufacturing time while maintaining device functionality.
Data Source
AI summary
A device manufacturing method including: performing a first exposure on a substrate using a first lithographic apparatus to form a first patterned layer including first features; processing the substrate to transfer the first features into the substrate; and performing a second exposure on the substrate using a second lithographic apparatus to form a second patterned layer including second features, wherein: the first lithographic apparatus has first and second control inputs effective to control first and second parameters of the first features at least partly independently; the second lithographic apparatus has a third control input effective to control the first and second parameters of the second features together; and the first exposure is performed with the first and/or second control input set to pre-bias the first and/or second parameter.