Semiconductor Overlay Evaluation via Scanning Charged Particle Microscopy
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current methods for evaluating overlay deviations between patterns on semiconductor wafers, especially in double patterning techniques, face challenges in achieving high accuracy due to mask manufacturing errors, exposure position deviations, and pattern deformation, making it difficult to stably measure deviations at multiple positions with high precision.
Innovation Solution
A method using a scanning charged particle microscope to automatically determine evaluation points and imaging sequences based on pattern layout information, allowing for accurate overlay position evaluation by considering imaging deviations, pattern deformation, and invisibility, and enabling the selection of optimal evaluation points and processing methods to ensure high-resolution imaging without position deviation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If overlay evaluation is performed using normal circuit patterns without dedicated patterns, then measurement can be performed on existing structures, but measurement precision and stability deteriorate due to difficulty in deciding evaluation points and pattern deformation
Solution Approach 1:
The patent applies preliminary action by pre-defining evaluation points based on pattern layout information before actual overlay measurement. The system determines optimal evaluation point positions in advance considering pattern shapes and locations, then uses these predetermined points for consistent measurement across multiple wafers and process steps, eliminating the need to manually select evaluation points during measurement
Solution Approach 2:
The patent introduces pattern layout information as an intermediary element that mediates between the evaluation system and the actual patterns on the wafer. This layout information serves as a reference model that guides the automatic determination of evaluation points, enabling precise measurement without requiring complex manual intervention or dedicated evaluation patterns
2Measurement precision
If multiple evaluation points are measured to account for mask manufacturing errors and exposure position deviations, then overlay evaluation accuracy improves, but measurement time and processing complexity increase
Solution Approach 1:
The system performs preliminary determination of optimal evaluation point positions based on pattern layout information before actual measurement. By pre-calculating where to measure based on expected pattern locations and shapes, the system identifies the most informative evaluation points in advance, enabling accurate overlay measurement with fewer points and reduced measurement time
Solution Approach 2:
The patent dynamically adjusts evaluation point positions and imaging parameters based on pattern layout information and expected deviations. The system modifies measurement parameters such as evaluation point coordinates, imaging magnification, and field of view to optimize measurement efficiency while maintaining accuracy across different pattern configurations
3Measurement precision
If imaging deviation is not considered in evaluation point selection, then the evaluation process is simpler, but measurement precision deteriorates due to position deviation in imaging
Solution Approach 1:
The patent incorporates imaging deviation considerations by dynamically adjusting evaluation point position parameters based on expected imaging errors. The system calculates corrected evaluation point coordinates that compensate for anticipated imaging deviations, ensuring that measurements are taken at positions that will accurately represent the true pattern locations even when imaging imperfections occur
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
This approach enables precise and stable overlay deviation measurement across multiple positions on semiconductor wafers, improving exposure pattern accuracy and process margins by accounting for imaging deviations and pattern deformations, thus enhancing the reliability of semiconductor manufacturing.
Implementation Method 1
image obtained by imaging an evaluation point on the sample by a scanning charged particle microscope
Data Source
AI summary
An pattern evaluation method includes a step of estimating imaging deviation allowed to evaluate an overlay position on one or more evaluation point candidates based on pattern layout information, a step of deciding one or more evaluation points from among the evaluation point candidates based on the allowed imaging deviation, a step of deciding an imaging sequence for imaging the selected evaluation point, and a step of evaluating an overlay position between first and second patterns based on an image obtained by imaging the evaluation point according to the imaging sequence.