Semiconductor Test Structure for Layer Misalignment Detection
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Solution Overview
Problem
Misalignment of layers during semiconductor device manufacturing can lead to short circuits and device failure, necessitating a method to check layer alignment effectively.
Innovation Solution
A test structure and method are provided to check layer alignment by measuring electrical resistance between contacts on a floating gate, distinguishing between normal and abnormal control gate overlays, allowing for identification of misalignment before further processing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If layer alignment is not tested during manufacturing, then manufacturing process continues without interruption, but short circuits and device failure occur due to misalignment
Solution Approach 1:
The patent implements preliminary alignment testing by forming test structures (first conductive layer, second conductive layer with opening, third conductive layer) before complete device fabrication. This allows measurement of electrical resistance to detect misalignment between layers early in the manufacturing process, preventing defective devices from proceeding to subsequent processing steps.
Solution Approach 2:
The patent segments the manufacturing process by separating alignment testing from the main fabrication flow. Test structures are formed in specific regions of the semiconductor substrate independently from the device regions, allowing dedicated alignment verification without interrupting the overall manufacturing timeline for non-defective devices.
2Measurement precision
If alignment testing is performed on all devices, then misalignment is detected early, but manufacturing complexity and processing time increase
Solution Approach 1:
The patent applies local quality by forming test structures only in specific test regions of the semiconductor substrate, not across the entire wafer. The first conductive layer, second conductive layer with opening, and third conductive layer are created locally to perform alignment verification in targeted areas, reducing overall process complexity while maintaining detection accuracy where needed.
Solution Approach 2:
The patent introduces an intermediary measurement mechanism using electrical resistance through the conductive layer structure. Instead of complex optical or physical alignment measurements, the invention uses electrical properties as an intermediary to indirectly detect misalignment between layers, simplifying the measurement process while maintaining precision.
3Loss of time
If misalignment is detected late in manufacturing, then fewer devices are affected, but additional processing steps are required to correct defects
Solution Approach 1:
The patent performs alignment verification at an early stage by forming test conductive structures before complete device fabrication. Measuring electrical resistance through the second conductive layer opening allows detection of misalignment between the first and third conductive layers before subsequent processing steps are applied, enabling early intervention to prevent material waste and rework.
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
This approach enables early detection of misalignment, reducing the risk of short circuits and improving semiconductor device yield by identifying and correcting alignment issues during manufacturing.
Implementation Method 1
measuring electrical resistance between contacts on a floating gate
Data Source
AI summary
Bridging testing method between adjacent semiconductor devices includes forming patterned diffusion region on semiconductor substrate, and forming first conductive layer over diffusion region. First conductive layer is patterned in same pattern as patterned diffusion region. Second conductive layer formed extending in first direction over first conductive layer. Second conductive layer is patterned to form opening extending in first direction in central region of second conductive layer exposing portion of first conductive layer. First conductive layer exposed portion is removed exposing portion of diffusion region. Source/drain region is formed over exposed portion of diffusion region, and dielectric layer is formed over source/drain region. Third conductive layer is formed over dielectric layer. End portions along first direction of second conductive layer removed to expose first and second end portions of first conductive layer. Electrical resistance across first conductive layer between first and second end portions of first conductive layer is measured.