Electron Beam Overlay Measurement for 3D Distortion Detection
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Solution Overview
Problem
Current overlay measurement technologies fail to accurately detect 3D distortion in lower patterns during semiconductor manufacturing, leading to incomplete defect detection and reduced yield.
Innovation Solution
An overlay measurement method using electron beam scanning and voltage contrast imaging to generate a defect function, followed by self-cross correlation analysis to determine accurate overlay values and quantify asymmetry, reflecting the effects of 3D distortion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If 2D image measurement at the top of the overlay key is used, then the measurement process is simple, but the effect of 3D distortion of the lower pattern cannot be detected
Solution Approach 1:
The patent transitions from 2D image measurement to 3D topography measurement by capturing height information of the overlay mark. The measurement apparatus acquires three-dimensional topographical data including the lower pattern's surface profile, enabling detection of 3D distortion effects that 2D measurement cannot capture. This dimensional expansion resolves the contradiction by maintaining measurement simplicity while achieving precise overlay measurement that accounts for 3D distortion.
2Ease of manufacture
If overlay analysis is based only on top surface measurement, then the measurement method is straightforward, but incomplete defect detection occurs
Solution Approach 1:
The patent employs three-dimensional topography measurement to capture the complete structure of the overlay mark including the lower pattern's height and shape information. By measuring the vertical dimension in addition to horizontal positions, the system achieves comprehensive defect detection while maintaining a straightforward measurement process. The 3D topographical data enables reliable identification of defects that would be invisible in 2D measurements.
3Productivity
If conventional overlay measurement methods are used, then the process is simple, but the overlay value accuracy is insufficient due to undetected 3D distortion
Solution Approach 1:
The patent implements three-dimensional topography measurement that captures the vertical profile of the overlay mark, enabling accurate overlay measurement that accounts for 3D distortion effects. The measurement apparatus obtains height information and uses it to calculate the true overlay value, maintaining measurement efficiency while significantly improving accuracy compared to conventional 2D methods that cannot detect 3D distortion.
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 measurement of overlay values and asymmetry, identifying the cause of 3D distortion and improving defect margin and yield in semiconductor manufacturing.
Implementation Method 1
The overlay mark is scanned with an electron beam to obtain a voltage contrast image. Secondary electrons that are emitted from the overlay mark are detected to obtain voltage contrast data.
Data Source
AI summary
In an overlay measurement method, an overlay mark having programmed overlay values is provided. The overlay mark is scanned with an electron beam to obtain a voltage contrast image. A defect function that changes according to the overlay value is obtained from voltage contrast image data. Self-cross correlation is performed on the defect function to determine an overlay.