Inverted Trapezoid Active Areas for Contact and Isolation Scaling
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Solution Overview
Problem
As semiconductor structures become more integrated, the reduced size of transistor structures leads to poor contact between the storage node plug and the transistor, affecting performance and potentially causing device failure.
Innovation Solution
A method involving the formation of inverted trapezoid-shaped trenches in a mask layer, followed by filling these with an epitaxy layer to create active areas and then forming regular trapezoid-shaped trenches between these areas, which are filled with a dielectric layer to create an isolation structure, ensuring a large contact area and effective isolation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the integration level of the semiconductor structure is increased, then the size of the transistor structure is reduced, but the contact area between the storage node plug and the transistor becomes smaller resulting in poor contact
Solution Approach 1:
Instead of reducing the contact area proportionally with transistor size reduction, the patent inverts the approach by creating an enlarged contact area through inverse trapezoidal trench structures. The trench width at the upper end is greater than at the lower end, allowing the storage node plug to contact the active area at a larger upper surface area while the transistor size is reduced, thus improving contact quality despite higher integration levels
Solution Approach 2:
The patent addresses the contact area problem by transitioning from a two-dimensional planar contact to a three-dimensional inverted trapezoidal structure. The trench extends vertically into the substrate with varying width, creating additional contact surface area in the vertical dimension that compensates for the reduced planar footprint, thereby maintaining reliable contact at higher integration levels
2Reliability
If the active area contact area is increased to improve contact quality, then the contact between storage node plug and transistor is improved, but the device size increases
Solution Approach 1:
The inverse trapezoidal trench structure is nested within the existing transistor structure footprint. The trench extends downward into the substrate rather than expanding outward at the surface, allowing the contact area to be increased vertically without increasing the horizontal device footprint, thus maintaining compact device size while improving contact quality
Solution Approach 2:
The patent resolves the size conflict by moving the contact area expansion from the horizontal plane to the vertical dimension. The inverted trapezoidal trench creates additional contact surface area through its depth and varying width profile, enabling improved contact quality without increasing the device's planar dimensions
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 method enhances the electrical performance and reliability of semiconductor structures by ensuring good contact between active areas and structures, while maintaining a strong isolation effect without increasing the substrate's size, thus improving the overall performance and reducing power consumption.
Implementation Method 1
An etching process is performed to form a plurality of first trenches in the mask layer
Implementation Method 2
An epitaxy layer is formed on the substrate. The epitaxy layer is filled in each of the first trenches to form an active area
Implementation Method 3
A dielectric layer is filled in the second trench to form an isolation structure
Data Source
AI summary
A method for manufacturing a semiconductor structure includes operations as follows. A substrate is provided, and a mask layer is formed on the substrate. An etching process is performed to form a plurality of first trenches in the mask layer, where the first trench has an inverted trapezoid cross-sectional shape. An epitaxy layer is formed on the substrate, where the epitaxy layer is filled in each of the first trenches to form an active area. The mask layer is removed to form a plurality of second trenches, where the second trench is arranged between adjacent active areas, and the second trench has a regular trapezoid cross-sectional shape. A dielectric layer is filled in the second trench to form an isolation structure.