SEM Misalignment Measurement for High-Aspect-Ratio Pattern Stacking
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Solution Overview
Problem
In semiconductor device manufacturing, misalignment of high-aspect-ratio patterns during stacking can lead to poor embedding and reduced reliability, and existing methods for measuring misalignment are inefficient, especially when internal stress affects chip layout and device structure.
Innovation Solution
A misalignment measuring apparatus that includes input and output circuits, a control circuit with monitor, dummy, and evaluation pattern calculation circuits, using SEM image data to calculate misalignment amounts and a height coefficient, allowing for accurate measurement of misalignment between patterns without requiring dedicated reticles or additional manufacturing steps.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a dedicated reticle is used for misalignment measurement, then measurement accuracy is improved, but manufacturing cost and device complexity increase
Solution Approach 1:
The patent makes the evaluation pattern serve dual purposes: it is both the actual device pattern to be manufactured and the measurement target for misalignment detection. By integrating the measurement function into the evaluation pattern itself rather than requiring a separate dedicated reticle, the system achieves multi-functionality that reduces device complexity while maintaining measurement accuracy
Solution Approach 2:
The patent creates a virtual model (three-dimensional data) of the evaluation pattern that serves as a reference for measurement. This virtual copy allows the system to compare actual SEM images against the predetermined three-dimensional model, eliminating the need for physical dedicated reticles while maintaining measurement precision
2Measurement precision
If conventional SEM measurement methods are used, then misalignment can be detected, but measurement efficiency and productivity are reduced
Solution Approach 1:
The patent performs preliminary actions by creating a three-dimensional virtual model of the evaluation pattern before actual measurement occurs. This pre-established model serves as a reference framework that enables automated comparison and measurement during production, eliminating the need for time-consuming conventional SEM measurement procedures and significantly improving productivity
Solution Approach 2:
The patent replaces the conventional mechanical/optical SEM measurement system with a computational approach using three-dimensional data processing and image recognition algorithms. By substituting physical measurement mechanisms with digital processing methods, the system achieves both high measurement precision and improved productivity through automated analysis
3Shape
If stacked patterns with high aspect ratio are formed, then desired three-dimensional shapes are achieved, but misalignment occurs due to internal stress leading to poor embedding
Solution Approach 1:
The patent transitions from two-dimensional planar measurement to three-dimensional virtual modeling and measurement. By constructing and measuring the evaluation pattern in three dimensions, the system can accurately assess misalignment in stacked high aspect ratio patterns, enabling proper embedding even when internal stress causes distortion, thus maintaining reliability while achieving desired complex shapes
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Improves misalignment measurement accuracy, reduces product development costs and time by enabling direct measurement of evaluation patterns using monitor and dummy patterns in non-circuit regions, and allows for precise calculation of misalignment variations across the chip surface.
Implementation Method 1
when the misalignment (superposition accuracy) of the patterns is measured, the misalignment may be measured using a scanning electron microscope (SEM)
Data Source
AI summary
According to one embodiment, a misalignment measuring apparatus includes: an input circuit; a storage medium; a first circuit configured to, in a first calibration pattern, calculate a second misalignment amount; a second circuit configured to, using a first image of a second calibration pattern, calculate a third misalignment amount; a third circuit configured to calculate a coefficient indicating; and a fourth circuit configured to, using a second image corresponding to the first and second patterns, calculate a third center position of a third contour and calculate the first misalignment amount between the first pattern and the second pattern based on the fourth misalignment amount and the coefficient.