Test Line Letter Trenches Prevent Residue Contamination
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Solution Overview
Problem
The topography of traditional test line letters on integrated chips can cause protectant layers to collect residue from high-k metal gate processes, leading to contamination of processing tools during semiconductor fabrication.
Innovation Solution
The use of trenches within the test line letter structure instead of positive relief, with dummy structures to maintain a uniform protectant layer topography and prevent residue accumulation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional positive relief test line letters are used, then the test line identification is clear and visible, but the protectant layer collects residue from high-k metal gate processes causing contamination
Solution Approach 1:
The patent inverts the traditional positive relief test line letter structure into a negative relief structure by forming trenches within the test line letter. This inversion allows the protectant layer to be deposited over the trenches, creating a planarized surface that prevents residue accumulation while maintaining test line identification through the trench patterns.
Solution Approach 2:
The patent applies different local qualities to different regions of the test line letter structure. The trenches are selectively formed in specific regions to create local variations in topography that guide protectant layer deposition, while maintaining identification visibility in other regions. This localized modification prevents contamination without compromising overall functionality.
2Object-generated harmful factors
If trenches are formed within the test line letter structure, then residue accumulation is prevented and contamination is reduced, but the manufacturing process complexity increases
Solution Approach 1:
The patent segments the test line letter structure by dividing it into multiple trenches rather than using a solid positive relief form. This segmentation creates a structured pattern that prevents residue accumulation while maintaining identification capability through the segmented trench patterns.
Solution Approach 2:
The patent changes the topographic parameter of the test line letter from positive relief to negative relief (trenches). This parameter change fundamentally alters how the protectant layer interacts with the structure, enabling planarized deposition that prevents contamination while maintaining manufacturing feasibility through standard semiconductor fabrication processes.
3Object-generated harmful factors
If dummy structures are added to maintain uniform protectant layer topography, then residue accumulation is prevented, but the device complexity and manufacturing steps increase
Solution Approach 1:
The patent introduces dummy structures to create homogeneity in the protectant layer topography. These dummy structures fill in gaps and variations in the trench patterns, ensuring uniform deposition of the protectant layer across the entire test line letter region. This homogenization prevents residue accumulation by eliminating topographic variations that would otherwise trap contaminants.
Solution Approach 2:
The dummy structures act as intermediary elements between the trenches and the protectant layer. They mediate the interaction by providing a uniform surface for protectant layer deposition, preventing direct contact between the protectant layer and the trench regions that would otherwise cause residue accumulation.
Data Source
AI summary
The present disclosure, in some embodiments, relates to a method of forming an integrated chip. The method includes forming a test line letter structure having one or more sidewalls continuously extending along a path that defines a shape of an alpha-numeric character from a top-view. The test line letter structure is formed by forming a first polysilicon structure over a substrate and forming a second polysilicon structure over the substrate at a location laterally separated from first polysilicon structure by a dielectric layer.