U1+V+U2 Isolation Trench Structure for Semiconductor Devices
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Solution Overview
Problem
In semiconductor integrated circuits, the shrinking size and increased density of components lead to challenges in maintaining effective electrical isolation between high-voltage and low-voltage regions, as traditional trench isolation structures often result in voids and keyholes during dielectric material deposition, limiting the achievable depth of isolation trenches and voltage differential isolation.
Innovation Solution
The implementation of a U1+V+U2 isolation trench structure, where the first isolation trench portion has perpendicular sidewalls, followed by an obliquely angled V portion, and then a third U2 portion with perpendicular sidewalls, allows for deeper trench etching without pinch-off, reducing voids and keyholes by facilitating faster dielectric fill and maintaining isolation efficacy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the trench depth is increased to isolate high-voltage regions, then voltage differential isolation is improved, but voids and keyholes develop during dielectric material deposition
Solution Approach 1:
The trench is divided into three distinct portions (U1, V, U2) with different sidewall angles. The upper U1 and lower U2 portions have perpendicular sidewalls for voltage isolation, while the middle V portion has oblique sidewalls that widen toward the surface to facilitate dielectric material flow and prevent void formation during deposition.
Solution Approach 2:
Different portions of the trench have different sidewall geometries optimized for different functions: the U1 and U2 portions provide vertical isolation for voltage blocking, while the V portion provides a tapered geometry that facilitates dielectric material deposition and prevents void formation in the critical fill region.
2Area of stationary object
If component density is increased to reduce circuit size, then area utilization is improved, but trench width decreases leading to constrictions during dielectric flow
Solution Approach 1:
The trench structure is segmented into three portions with the middle V portion specifically designed to address the constriction problem. This V portion creates a tapered geometry that widens toward the surface, allowing dielectric material to flow smoothly without forming voids even when the overall trench width is reduced for higher density.
3Manufacturing precision
If trench depth is limited to avoid voids, then dielectric fill quality is improved, but voltage differential isolation capability is reduced
Solution Approach 1:
The trench is divided into three portions where the upper U1 and lower U2 portions maintain perpendicular sidewalls for effective voltage isolation, while the middle V portion with oblique sidewalls is specifically designed to prevent void formation during dielectric deposition, allowing the trench to achieve both depth and fill quality.
Solution Approach 2:
Different portions of the trench have different sidewall geometries optimized for different functions: the U1 and U2 portions provide vertical isolation for voltage blocking, while the V portion provides a tapered geometry that facilitates dielectric material deposition and prevents void formation in the critical fill region.
Data Source
AI summary
Among structures, methods, devices, and systems for isolation trenches, a semiconductor device is provided that includes a substrate and an isolation trench structure. One such isolation trench structure includes a first isolation trench portion associated with a surface of the substrate and having a first pair of opposing sidewalls that are each substantially perpendicular to the surface of the substrate. A second isolation trench portion includes a second pair of sidewalls within the substrate that are each angled obliquely with respect to the surface of the substrate, where the second isolation trench portion has a separation between the second pair of sidewalls that decreases as a distance from the first isolation trench portion increases. A third isolation trench portion includes a third pair of sidewalls within the substrate that are each substantially perpendicular to the surface of the substrate.