Semiconductor Memory Cell Trench Isolation and Sidewall Capacitor
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Solution Overview
Problem
Current semiconductor devices face challenges in reducing the area occupied by memory cells to increase integration density, as existing capacitor structures and isolation techniques are inefficient in minimizing the space required for transistors and capacitors.
Innovation Solution
The semiconductor device incorporates a semiconductor substrate with active regions that include both transistor and capacitor sub-regions, featuring trenches and insulating layers to reduce the area occupied by each component, with a trench isolation structure around the capacitor sub-region and a conductive layer on the capacitor's sidewall, enhancing capacitance and reducing noise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If a planar or trench capacitor structure is used, then the capacitor can be formed with existing processes, but the area occupied by the memory cell increases
Solution Approach 1:
The capacitor structure transitions from a planar (2D) configuration to a three-dimensional configuration by forming the capacitor on the sidewall of the trench. This vertical utilization of space allows the capacitor to occupy less horizontal area while maintaining sufficient capacitance, directly resolving the contradiction between minimizing memory cell area and preserving capacitor performance
Solution Approach 2:
The isolation trench and capacitor structure are merged into a single integrated feature. The trench that serves to isolate the transistor also provides the substrate for forming the capacitor on its sidewall. This dual-purpose design eliminates the need for separate capacitor area, reducing the total memory cell footprint while maintaining both isolation functionality and capacitor performance
2Productivity
If the capacitor area is reduced to increase integration density, then more memory cells can be integrated, but the capacitance value decreases
Solution Approach 1:
The capacitor geometry changes from a planar plate to a vertical sidewall structure. This dimensional change allows the capacitor to achieve sufficient capacitance in a smaller horizontal footprint by utilizing the vertical dimension, enabling higher integration density without sacrificing capacitance value
Solution Approach 2:
The capacitor structure is nested within the trench structure. The insulating layer is formed on the trench sidewall, and the electrodes are positioned within the trench volume. This nested configuration maximizes the use of available space within the memory cell footprint, achieving high capacitance in a compact form factor
3Reliability
If isolation structures are added around transistors, then transistor performance is improved, but the manufacturing process complexity increases
Solution Approach 1:
The isolation trench and capacitor formation processes are merged into a single sequence of operations. The same trench etching and filling steps that create the isolation structure also provide the substrate for capacitor formation. This integration reduces the number of separate process modules required, thereby simplifying the overall manufacturing process while maintaining transistor performance benefits
Data Source
AI summary
A semiconductor device includes a semiconductor substrate, an active region formed in the semiconductor substrate and extending in a first direction, the active region including a transistor sub-region and a capacitor sub-region, a first trench extending around the transistor sub-region, an isolation layer disposed in the first trench, a second trench extending around the capacitor sub-region, a first transistor including a first insulating layer disposed on the transistor sub-region, the first transistor including a first conductive layer disposed on the first insulating layer, and a first capacitor including a second insulating layer extending over the capacitor sub-region and a sidewall of the second trench, the first capacitor including a second conductive layer disposed on the second insulating layer, the active region having an end portion in the first direction opposite to the transistor sub-region and extending across the first capacitor.