Integrated Overlay and Critical Dimension Measurement Structure
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Solution Overview
Problem
In semiconductor manufacturing, existing methods for critical dimension and overlay measurement require large areas for measuring patterns, which hinders precision and efficiency, especially with the increasing complexity of nanoscale transistor integration and the need for accurate alignment and dimension measurement across multiple layers.
Innovation Solution
A structure that combines overlay and critical dimension measurement patterns on the scribe line around the wafer, utilizing a first target pattern for overlay measurement and a second target pattern for linewidth, line density, and line semi-density measurement, where both patterns share a common orthogonal bar structure, allowing for reduced area usage and accurate measurement in multiple directions, including the use of optical and scanning electron microscopes for precise analysis.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If separate overlay targets and critical dimension targets are disposed in different areas, then measurement functions are fulfilled, but the total area of measuring patterns is large
Solution Approach 1:
The patent combines overlay measurement function and critical dimension measurement function into a single integrated target structure. The overlay target includes both outer bar structures (for overlay measurement) and inner bar structures (for critical dimension measurement), allowing both measurements to be performed on the same target area, thus reducing the total area required while maintaining measurement precision
Solution Approach 2:
The integrated target structure serves multiple measurement functions simultaneously. The same target can be used for both overlay measurement (comparing positions of outer bars from different layers) and critical dimension measurement (measuring dimensions of inner bars), making the measurement system universal and reducing the need for separate measurement areas
2Productivity
If conventional separate target structures are used, then measurement coverage is comprehensive, but measurement efficiency is reduced due to large area
Solution Approach 1:
By merging overlay and critical dimension measurement functions into one integrated target, the patent enables both measurements to be performed within a single measurement cycle and area, significantly improving measurement efficiency and productivity while reducing the total area occupied by measuring patterns
3Adaptability or versatility
If multiple separate measurement targets are disposed, then all measurement requirements are met, but the complexity of pattern layout increases
Solution Approach 1:
The integrated target structure provides universal measurement capability for both overlay and critical dimension measurements. By designing the target with both outer bars and inner bars that can serve dual purposes, the patent reduces pattern layout complexity while maintaining comprehensive measurement adaptability
Data Source
AI summary
The invention provides a structure for critical dimension and overlay measurement including a measuring unit, a first measurement pattern for measuring overlay and a second measurement pattern for measuring linewidth, line density and/or line semi-density. The first target pattern includes an outer bar structure disposed on a first layer and an inner bar structure disposed on a second layer; the outer bar structure and/or the inner bar structure has a same shared pattern structure with the second target pattern. The pattern structure includes four bars with the same shape positioned orthogonally and closely to each other, and at least two orthogonally positioned bars include N equally spaced rectangular lines of the same width, wherein, N is an odd number; the N rectangular lines include one central rectangular line and N−1 auxiliary rectangular lines.