Lithography Process Window Prediction for Pattern-Driven Defect Prevention
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Solution Overview
Problem
Current lithographic processes face challenges in detecting defects before substrates are irreversibly processed, due to limitations in inspection tools, leading to potential defects going undetected until it's too late.
Innovation Solution
A computer-implemented method that identifies processing window limiting patterns (PWLPs) and determines processing parameters to predict the existence, probability, and characteristics of defects, allowing for adjustments to prevent or reduce defect severity before irreversible processing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If standard inspection tools are used to detect defects before substrate processing, then defect detection capability is limited, but inspection coverage and reliability are insufficient
Solution Approach 1:
The system performs preliminary simulation of the lithographic process to predict potential defects before actual substrate processing occurs. By identifying processing window limiting patterns and simulating their behavior under various processing parameters, the system can predict defects such as necking, line pull back, and resist top loss in advance, enabling preventive actions to be taken before irreversible processing happens.
Solution Approach 2:
The system creates a virtual copy of the lithographic process through simulation. Instead of physically inspecting substrates at multiple stages, the system uses computational models to replicate the processing behavior and predict outcomes. This virtual copying allows comprehensive defect analysis without requiring extensive physical inspection infrastructure.
2Reliability
If extensive substrate inspection is performed to ensure quality, then defect detection rate increases, but processing time and cost increase
Solution Approach 1:
The system extracts only the critical patterns that limit the processing window from the complete set of patterns on the substrate. By identifying and focusing analysis on these processing window limiting patterns (PWLPs), the system avoids the need to inspect or simulate every pattern, significantly reducing computational requirements and processing time while maintaining defect detection effectiveness.
Solution Approach 2:
The system performs defect prediction as a preliminary step before actual substrate processing. By simulating and identifying potential defects in advance using processing parameters determined immediately before processing, the system can prevent defects from occurring or minimize their impact, eliminating the need for extensive post-processing inspection and rework.
3Manufacturing precision
If processing parameters are adjusted to prevent defects, then defect severity is reduced, but process complexity increases
Solution Approach 1:
The system establishes a feedback loop where simulation results of processing window limiting patterns are used to adjust processing parameters. The system determines processing parameters based on simulated outcomes, and these parameters are then applied to actual processing. This closed-loop feedback mechanism enables automatic optimization of processing conditions to prevent defects while maintaining manageable process complexity through algorithmic control.
Solution Approach 2:
The system optimizes processing parameters such as focus, dose, and other lithographic parameters based on simulation results. By adjusting these parameters within their valid ranges to match the characteristics of processing window limiting patterns, the system can prevent defects like necking and line pull back without requiring fundamental changes to the manufacturing process.
Data Source
AI summary
A defect prediction method for a device manufacturing process involving processing a pattern onto a substrate, the method comprising: identifying a processing window limiting pattern (PWLP) from the pattern; determining a processing parameter under which the PWLP is processed; and determining or predicting, using the processing parameter, existence, probability of existence, a characteristic, or a combination thereof, of a defect produced from the PWLP with the device manufacturing process.