Trench Isolation Layout for Coplanar Multi-Voltage Device Regions
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Solution Overview
Problem
The height differences between semiconductor device regions with different threshold and operation voltages cause manufacturing yield issues in integrated circuits.
Innovation Solution
A semiconductor structure with trench isolation structures having coplanar bottom and top surfaces between device regions, combined with varying gate oxide layer thicknesses to accommodate different voltage requirements, is fabricated using a method involving etching, oxidation, and deposition processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If thicker gate oxide layers are used to enhance operation voltage in higher voltage areas, then voltage requirements are met, but height differences are generated between device regions
Solution Approach 1:
The patent applies local quality by making different parts of the gate oxide layer have different thicknesses according to the specific voltage requirements of each device region. High voltage devices receive thicker gate oxide layers while low voltage devices receive thinner layers, allowing each region to have optimized local properties without creating manufacturing problems.
Solution Approach 2:
The patent resolves the height difference problem by transitioning to a planarized surface structure. Instead of allowing vertical height variations, the invention introduces a flattened top surface dimension that accommodates different gate oxide thicknesses underneath, effectively moving the variation from the vertical dimension to the horizontal/subsurface dimension.
2Adaptability or versatility
If different gate oxide layer thicknesses are used for different voltage requirements, then device performance is optimized, but manufacturing yield decreases due to height differences
Solution Approach 1:
The patent applies equipotentiality by creating a planarized surface that provides a uniform reference plane across all device regions. This flattened surface ensures that subsequent manufacturing processes operate from a consistent baseline, eliminating the yield-reducing height differences while preserving the necessary variations in gate oxide thickness underneath.
3Manufacturing precision
If coplanar top surfaces are maintained in trench isolation structures, then manufacturing yield is improved, but device region flexibility is reduced
Solution Approach 1:
The patent applies segmentation by dividing the gate oxide structure into region-specific segments with different thicknesses. Each device region can have its gate oxide layer independently optimized for its voltage requirements, while the overall structure maintains a coplanar top surface through the trench isolation design.
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 structure addresses manufacturing yield issues by ensuring consistent surface levels and appropriate gate oxide thicknesses, enhancing the manufacturing process efficiency and yield.
Implementation Method 1
A first trench isolation structure is formed in the substrate between the first device region and the second device region
Implementation Method 2
a first gate oxide layer on the top surface of the substrate within the first device region; and a second gate oxide layer on the top surface of the substrate within the second device region
Data Source
AI summary
A semiconductor structure includes a substrate having a first device region and a second device region in proximity to the first device region. A first trench isolation structure is disposed in the substrate between the first device region and the second device region. The first trench isolation structure includes a first bottom surface within the first device region and a second bottom surface within the second device region. The first bottom surface is lower than the second bottom surface. The first trench isolation structure includes a first top surface within the first device region and a second top surface within the second device region. The first top surface is coplanar with the second top surface.