Optical Coating Detection of Tungsten CMP Nanoparticles
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Solution Overview
Problem
Conventional optical scan methodologies fail to detect nano-sized tungsten particles during semiconductor manufacturing due to their deep subwavelength size, leading to yield-limiting defects and delayed process corrections.
Innovation Solution
Implementing an optical detection method that includes coating nano-sized tungsten particles with an optical enhancement layer, such as TiN or titanium oxide, to enhance visibility and detect these particles using bright-field or dark-field illumination, allowing for automated comparison with reference dies.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional optical scan methodologies are used to detect particles, then the detection process is simple and fast, but nano-sized tungsten particles cannot be detected due to their deep subwavelength size
Solution Approach 1:
An optical enhancement layer is introduced as an intermediary between the nano-sized tungsten particles and the optical detection system. This layer, composed of materials with high refractive index contrast (such as silicon dioxide, silicon nitride, or silicon oxynitride), mediates the interaction between light and the particles, enhancing their optical visibility without requiring changes to the particles themselves.
Solution Approach 2:
The invention utilizes optical property changes through refractive index contrast. The optical enhancement layer modifies the optical characteristics of the substrate, creating enhanced contrast that makes nano-sized particles visible under bright-field or dark-field illumination. This approach transforms undetectable particles into detectable features through optical property modification rather than physical size change.
2Measurement precision
If an optical enhancement layer is deposited on the substrate, then nano-sized particles become detectable, but the manufacturing process becomes more complex and time-consuming
Solution Approach 1:
The optical enhancement layer is deposited in advance, before particle detection and before subsequent manufacturing steps. This preliminary action ensures that the detection capability is established upfront, allowing for early identification of contamination issues without delaying the overall manufacturing schedule. The layer is prepared as part of the substrate fabrication process rather than as a separate post-processing step.
Solution Approach 2:
The optical enhancement layer serves multiple functions: it enhances particle detection capability, provides a protective barrier during subsequent processing, and can serve as part of the final device structure. This multi-functionality reduces the need for additional separate layers or processes, thereby minimizing the impact on manufacturing throughput.
3Productivity
If tungsten particles are present on the wafer surface, then manufacturing can proceed quickly, but yield-limiting defects occur and process corrections are delayed
Solution Approach 1:
The optical detection system provides real-time feedback about the presence of tungsten particles on the wafer surface. This feedback mechanism enables immediate identification of contamination, allowing for prompt process corrections before defective devices are manufactured. The system creates a closed-loop control where detection results directly inform process adjustments.
Solution Approach 2:
Particle detection is performed at an early stage in the manufacturing process, before subsequent processing steps that would make later detection difficult or impossible. This preliminary detection allows for early intervention and process correction, preventing yield losses rather than identifying defects after they have already impacted product quality.
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 effective detection and reduction of nano-sized tungsten particles, facilitating process optimization and reducing manufacturing defects, thereby improving yield and efficiency.
Implementation Method 1
detect these particles using bright-field or dark-field illumination
Implementation Method 2
coating nano-sized tungsten particles with an optical enhancement layer, such as TiN or titanium oxide, to enhance visibility
Data Source
Figure 1
Figure 2A~2B
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AI summary
Chemical mechanical polish processes on surfaces of semiconductor devices comprising tungsten layers can create nano-sized particles of tungsten. These particles can create manufacturing yield reductions. These particles can also be difficult to detect optically. Etched surfaces coated with a layer of material that can provide optical detection enhancement provide an ability to optically detect nano-sized particles.