Optical Resonance Detection for Electrical Contact in Semiconductor Layers
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Solution Overview
Problem
Current methods for determining electrical contact between metallic features in different layers of semiconductor devices are limited, particularly at subwavelength pitches, and often require specialized marks or techniques like voltage contrast, which are slow and prone to errors due to unstable charging conditions and surface contamination.
Innovation Solution
A system and method utilizing radiation to detect resonances in reflected radiation from metallic features, where the presence and position of resonances indicate electrical contact, allowing for non-invasive, faster, and more accurate assessment of contact status without relying on diffraction orders or specific illumination directions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional voltage contrast or electron-based inspection methods are used to determine electrical contact between metallic features, then contact status can be detected, but the process is slow and prone to errors due to unstable charging conditions and surface contamination
Solution Approach 1:
The patent replaces electron-based inspection methods with optical radiation-based resonance detection. Instead of using electron beams and voltage contrast techniques, the invention uses radiation (light) to excite plasmonic resonances in metallic features, detecting electrical contact through optical signal changes rather than electrical field measurements. This substitution eliminates the problems of electron beam charging and surface contamination sensitivity.
Solution Approach 2:
The invention changes the detection parameter from electrical properties (voltage contrast) to optical properties (resonance frequency and intensity). By measuring shifts in resonance characteristics when metallic features are in electrical contact, the system achieves both high precision and fast detection speeds, as optical measurements can be performed rapidly without the stability issues plaguing electrical methods.
2Reliability
If specialized marks or electron-based techniques are used for contact detection, then electrical contact can be determined, but the process becomes complex and requires additional manufacturing steps
Solution Approach 1:
The invention uses the metallic features themselves as the detection targets without requiring separate specialized marks. The metallic features' inherent plasmonic properties enable direct optical detection of electrical contact status. This self-service approach eliminates the need for additional mark fabrication and simplifies the inspection system, as the existing device structures serve dual purposes: functional elements and measurement targets.
3Measurement precision
If conventional optical methods relying on diffraction orders or specific illumination directions are used, then some contact information can be obtained, but the method fails at subwavelength pitches
Solution Approach 1:
The invention exploits plasmonic resonances - collective oscillations of free electrons in metallic features when excited by radiation. These resonant vibrations occur at specific frequencies determined by the metallic feature geometry and electrical contact status. By detecting resonance frequency shifts and intensity changes, the system can resolve electrical contact at subwavelength pitches, overcoming the diffraction limit that constrains conventional optical methods.
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
Enables precise determination of electrical contact between metallic features in different layers, facilitating improved semiconductor device manufacturing by providing a faster, more reliable alternative to traditional methods, capable of operating at subwavelength pitches without the need for specialized marks or electron-based inspection.
Implementation Method 1
detect one or more resonances in reflected radiation from the first and second metallic features
Implementation Method 2
detect one or more resonances in reflected radiation from the first and second metallic features
Data Source
AI summary
Optically determining whether metallic features in different layers in a structure are in electrical contact with each other. When the metallic features include different metals and/or have different dimensions, which cause one or more resonances in reflected radiation to be detected, the metallic features in the different layers are determined to be in contact or out of contact with each other based on the spectral positions of the one or more resonances. When the metallic features are formed from the same metal and have the same dimensions, the metallic features in the different layers are determined to be in contact with each other responsive to detection of a single resonance associated with the metallic features and out of contact with each other responsive to detection of two or more resonances associated with the metallic features.