Overlay Compensation Decomposing Offset Vectors
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Solution Overview
Problem
Conventional semiconductor manufacturing processes face challenges in achieving precise alignment between middle and bottom layers due to large overlay shifts, leading to increased defect rates and manufacturing costs.
Innovation Solution
An overlay compensation method and system that decompose offset vectors into compensable and uncompensable components, using nth-order linear regression equations to compute optimized compensable components and minimize uncompensable components, thereby improving alignment between layers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If overlay compensation is adjusted to a key layer in BEOL process, then alignment between middle and top layers is improved, but manufacturing control over the lithography process deteriorates
Solution Approach 1:
The patent segments the overlay compensation into multiple independent components: translation compensation, rotation compensation, and non-orthogonality compensation. Each component can be calculated and applied separately using offset vectors between overlay marks on different layers, allowing precise control over each aspect of alignment independently
Solution Approach 2:
The patent implements feedback by measuring actual overlay mark positions on middle, bottom, and top layers, calculating offset vectors based on these measurements, and using these vectors to compute compensation parameters that are fed back into the lithography process control system to adjust subsequent processing
2Manufacturing precision
If good alignment is achieved between middle and top layers and between bottom and top layers, then overlay shift between these layers is minimized, but overlay shift between middle and bottom layers increases
Solution Approach 1:
The patent introduces a new dimension of analysis by decomposing the overlay error into multiple independent components (translation, rotation, non-orthogonality) rather than treating it as a single scalar value. This allows simultaneous optimization of alignment between all layer pairs by applying appropriate compensation to each component
Solution Approach 2:
The patent changes the parameters used to describe and control overlay by introducing multiple compensation parameters (translation vectors, rotation angles, non-orthogonality values) that can be independently adjusted. This allows the system to achieve good alignment between middle-top and bottom-top layers while maintaining reliable alignment between middle-bottom layers through coordinated parameter adjustment
3Ease of manufacture
If conventional lithography process is used without overlay compensation, then manufacturing simplicity is maintained, but alignment precision and production yield deteriorate
Solution Approach 1:
The patent implements self-service by using overlay marks that are automatically measured and processed through the existing lithography and metrology systems. The offset vectors are calculated from measured positions, and compensation is applied through standard process control, eliminating the need for separate specialized equipment or manual measurement processes
Data Source
AI summary
An overlay compensation method and a related system are presented. The method includes: acquiring a first offset vector reflecting the relative position between overlay marks of a middle and a bottom target layers; acquiring a second offset vector reflecting the relative position between the overlay marks of a top and the middle target layers; decomposing the first offset vector into a first compensable component and a first uncompensable component; decomposing the second offset vector into a second compensable component and a second uncompensable component; computing minimum values of the first uncompensable component and the second uncompensable component; computing optimized values for the first compensable component and the second compensable component; and computing a third compensable component of a third offset vector reflecting the relative position between the overlay marks of the top and the bottom target layers.