Gate-Based Alignment Marks for Residue-Resistant Overlay Accuracy
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Solution Overview
Problem
The precise alignment of layers in semiconductor devices is crucial for high yield and low rework rate in manufacturing, but existing alignment marks can become obscured by residual material during semiconductor processing, leading to alignment errors and degraded overlay performance.
Innovation Solution
Incorporating a gate-based alignment pattern in the alignment mark region of semiconductor devices, which includes a plurality of gate structures etched to form a specific pattern, reduces the likelihood of obscuration by residual material and maintains alignment accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If conventional alignment marks are used in semiconductor devices, then alignment marks can be easily formed, but alignment marks become obscured by residual material during processing, leading to alignment errors
Solution Approach 1:
The patent introduces an intermediary structure (the gate-based alignment pattern formed by etching gate structures) that mediates between the conventional alignment mark and the residual material. This alignment pattern is positioned and structured to be less susceptible to obscuration by residual material while still serving the alignment function, thus resolving the contradiction between ease of manufacture and measurement precision
Solution Approach 2:
The patent applies local quality by creating a specific gate-based alignment pattern in a particular region of the semiconductor device. The alignment mark region has different structural characteristics (gate structures with specific geometries) compared to other regions, providing localized alignment functionality that is resistant to residual material obscuration while maintaining overall manufacturing simplicity
2Ease of operation
If alignment marks are placed in processing paths, then alignment can be performed, but residual material obscures the alignment marks, degrading overlay performance
Solution Approach 1:
The gate-based alignment pattern is formed preliminarily through etching gate structures before subsequent processing steps. This preliminary formation creates a robust alignment reference that is less susceptible to later residual material deposition, maintaining alignment capability and overlay performance throughout the manufacturing process
Solution Approach 2:
Instead of placing traditional alignment marks that are directly exposed to processing paths and susceptible to obscuration, the patent inverts the approach by using the gate structures themselves (formed by etching) as the alignment pattern. This inverted approach creates an alignment reference that is inherently more resistant to residual material while maintaining alignment functionality
3Device complexity
If traditional alignment marks are used, then manufacturing process is simple, but alignment errors occur due to obscuration by residual material
Solution Approach 1:
The gate structures serve multiple functions: they act as both the functional gate elements of the semiconductor device and as the alignment pattern for manufacturing. This multi-functionality eliminates the need for separate alignment mark structures, maintaining simple device complexity while achieving high alignment precision through the gate-based alignment pattern
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
The gate-based alignment pattern enhances scanning accuracy and reliability of laser-based illumination systems, reduces alignment errors, and improves overlay performance, leading to increased semiconductor device yield and productivity.
Implementation Method 1
enhances scanning accuracy and reliability of laser-based illumination systems
Data Source
AI summary
Implementations described herein provide various implementations of gate based alignment patterns for semiconductor process alignment of a substrate on which semiconductor devices are manufactured. In some implementations described herein, a gate based alignment pattern may be included in an alignment mark region in a semiconductor device that is manufactured on the substrate. The alignment mark region may include a plurality of gate structures that are etched to form gate based alignment pattern. The use of the gate based alignment pattern may reduce the likelihood of and/or may prevent the gate based alignment pattern from becoming obscured or covered by residual material byproducts from one or more semiconductor processing operations that are performed to form various layers and/or structures of the semiconductor device.