Buried Optical Alignment Structures in Semiconductor Carriers
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Solution Overview
Problem
Common alignment marks used in lithographic processes for semiconductor manufacturing degrade in quality and accuracy due to material coverage and high processing temperatures, leading to overlay errors and the need for frequent refreshment.
Innovation Solution
A method involving the formation of recess structures in a carrier, followed by annealing to create hollow chambers that serve as buried optical alignment structures, allowing accurate alignment even under material coverage using an infrared alignment system.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional alignment marks are used during lithographic processes, then alignment can be performed initially, but the alignment marks degrade in quality and accuracy due to material coverage and high processing temperatures, requiring frequent refreshment
Solution Approach 1:
The patent extracts the alignment function from surface-level marks that are exposed to degrading conditions, and relocates it to subsurface hollow chambers that are protected from material coverage and high temperatures. The hollow chambers are formed below the carrier surface, separating the alignment reference from the harmful processing environment.
Solution Approach 2:
The alignment structure is nested within the carrier substrate itself, with hollow chambers formed inside the carrier material. This nesting provides protection from external degrading factors while maintaining the alignment function. The hollow chambers are embedded within the carrier, creating a hierarchical structure where the alignment feature is contained within the substrate.
2Ease of manufacture
If alignment marks are covered with additional material during processing, then subsequent layers can be formed, but the alignment marks become undetectable and alignment accuracy is lost
Solution Approach 1:
The patent introduces an optical intermediary effect where infrared light interacts with the hollow chambers to produce detectable signals. The hollow chambers act as optical mediators that reflect or refract infrared light in a detectable manner, allowing alignment detection through overlying material layers. This intermediary optical effect enables alignment marks to remain detectable even when covered.
Solution Approach 2:
The patent utilizes optical property changes by employing infrared wavelengths that interact differently with the hollow chamber structures. The hollow chambers create specific optical signatures or contrast patterns when illuminated with infrared light, enabling detection through material layers. This optical contrast mechanism allows the alignment structure to remain visible despite coverage.
3Temperature
If conventional alignment marks are exposed to high processing temperatures, then processing can proceed, but the alignment marks become unstable and inaccurate
Solution Approach 1:
The hollow chambers are formed within the carrier substrate before the high-temperature processing steps. This preliminary formation of the alignment structure protects it from thermal degradation, as the chambers are already embedded in the substrate and shielded from direct thermal exposure and material coverage during subsequent high-temperature processes.
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
Maintains alignment accuracy and reduces the need for frequent alignment mark refreshment by ensuring the buried alignment structures remain detectable through material layers, minimizing overlay errors and process complexity.
Implementation Method 1
annealing the at least one recess structure such that at least one hollow chamber is formed by material of the at least one recess structure
Data Source
AI summary
A method for processing a carrier may include forming at least one recess structure at least one of over and in the carrier; and annealing the at least one recess structure such that at least one hollow chamber is formed by material of the at least one recess structure, wherein the at least one hollow chamber may form an optical alignment structure.