Overlay Error Measurement Using High-Energy Electron Beam
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Solution Overview
Problem
Existing overlay error measurement techniques in integrated circuits face challenges such as lens aberrations and high costs when detecting errors after the top layer is etched, particularly in double patterning processes where features are close together, and current SEM systems are inefficient in capturing tilted images and high aspect ratio holes.
Innovation Solution
A method and system using a primary electron beam to interact with both the top and buried layers in integrated circuits, generating detection signals from secondary and backscattered electrons to determine spatial relationships between features, with a processor analyzing these signals to evaluate overlay errors and send information to scatterometry or diffraction-based overlay apparatuses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If optical instruments are used for overlay measurements, then the measurement process is simple and non-destructive, but lens aberrations reduce measurement precision
Solution Approach 1:
The patent introduces an intermediary layer (e.g., anti-reflective coating or sacrificial layer) between the optical system and the underlying structure to reduce optical aberrations and improve measurement precision while maintaining the simplicity of optical measurement methods
2Measurement precision
If Scanning Electron Microscopy is used to verify optical overlay measurements, then measurement precision is improved, but device complexity and cost increase
Solution Approach 1:
The patent combines optical measurement capabilities with electron beam verification in a single integrated system, allowing the same apparatus to perform both types of measurements without requiring separate equipment, thereby reducing overall system complexity
3Adaptability or versatility
If SEM systems use multiple detectors to capture tilted images, then measurement capability is improved, but device complexity and cost increase
Solution Approach 1:
The patent employs dynamic adjustment mechanisms that allow a single detector to adapt its orientation and positioning in real-time to capture tilted images and high aspect ratio features, replacing the need for multiple fixed detectors
4Manufacturing precision
If double patterning is used to increase feature density, then manufacturing precision is improved, but detecting overlay errors becomes more difficult and costly
Solution Approach 1:
The patent utilizes the depth dimension by employing high-energy electron beams that can penetrate through the top patterned layer to detect overlay errors in buried layers, adding a vertical detection dimension that overcomes the difficulty of measuring closely spaced features in double patterning
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 efficient detection of overlay errors by processing detection signals from secondary and backscattered electrons, improving the accuracy and efficiency of overlay measurements, especially in double patterning processes, and reducing costs associated with post-etching detection.
Implementation Method 1
Once an electron beam hits an inspected object various interaction processes occur. As a result, secondary electrons and Auger electrons are emitted from a very thin information volume
Implementation Method 2
back scattered electrons (BSE) and X-ray electrons can leave the inspected object from a relatively large information volume
Data Source
AI summary
A method, a system and a computer readable medium are provided. The method may include obtaining or receiving first area information representative of a first area of a first layer of an inspected object; wherein the inspected object further comprises a second layer that comprises a second area; wherein the second layer is buried under the first layer; directing electrons of a primary electron beam to interact with the first area; directing electrons of the primary electron beam to interact with the second area; generating detection signals responsive to electrons that were scattered or reflected from at least one of the first and second areas; and determining at least one spatial relationship between at least one feature of the first area and at least one feature of the second area based on the detection signals and on the first area information.