Lithographic Overlay Correction via Substrate Displacement Feedback
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Solution Overview
Problem
Current lithographic processes face challenges in accurately compensating for process-induced distortions in semiconductor device manufacturing, which can lead to overlay errors and complex corrections that exceed the capabilities of existing lithographic apparatuses.
Innovation Solution
A method that involves exposing a first substrate to form patterned layers, determining displacements of features from their nominal positions, calculating corrections to compensate for these displacements, and applying these corrections during the exposure of subsequent substrates to minimize distortions and overlay errors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If complex corrections are applied to compensate for process-induced distortions, then overlay accuracy is improved, but device complexity and process difficulty increase
Solution Approach 1:
The patent applies preliminary action by determining displacements and calculating corrections for the first substrate before exposing the second substrate. The correction is calculated based on measured displacements of first features from their nominal positions, and this correction is then applied during the exposure of the second substrate to compensate for process-induced distortions before they affect subsequent layers.
Solution Approach 2:
The patent implements feedback by measuring the actual positions of first features after processing the first substrate, comparing them to nominal positions to determine displacements, and using this information to calculate corrections that are applied to subsequent substrate exposures. This closed-loop approach continuously refines overlay accuracy.
2Manufacturing precision
If advanced lithographic apparatus are used to apply complex corrections, then overlay precision is improved, but manufacturing cost and process complexity increase
Solution Approach 1:
The patent uses copying by creating a correction model based on measurements from the first substrate that can be applied to subsequent substrates. The correction calculated from the first substrate serves as a template or copy that compensates for systematic process-induced distortions across multiple substrates, reducing the need for expensive advanced lithographic apparatus on every substrate.
3Reliability
If multiple pattern layers are formed with strict overlay limits, then device functionality is improved, but process difficulty and time increase
Solution Approach 1:
The patent applies preliminary action by calculating and applying corrections during the exposure of the second substrate based on displacement measurements from the first substrate. This proactive correction approach prevents overlay errors from accumulating across multiple pattern layers, ensuring device functionality without requiring excessive process time for repeated measurements and adjustments.
Data Source
AI summary
A device manufacturing method includes: exposing a first substrate using a lithographic apparatus to form a patterned layer having first features; processing the first substrate to transfer the first features into the first substrate; determining displacements of the first features from their nominal positions in the first substrate; determining a correction to at least partly compensate for the displacements; and exposing a second substrate using a lithographic apparatus to form a patterned layer having the first features, wherein the correction is applied for or during the exposing the second substrate.