Deep Trench Capacitor Structure With Asymmetric Sidewall Slopes
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Solution Overview
Problem
Deep trench capacitors in semiconductor structures often have a top width that exceeds the bottom width, leading to lower capacitance values and a weak structure due to tapering, which limits the space at the bottom and results in a non-uniform trench width.
Innovation Solution
A method is introduced to protect the upper portion of the trench, allowing the lower portion to be widened uniformly, resulting in a relatively uniform overall trench width, by forming a multilayered stack with specific nitride and silicon-containing layers and performing controlled etching operations to expand the trench while maintaining the integrity of the nitride and silicon-containing layers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the trench capacitor has a great height and a short width, then the capacitance value increases, but the bottom portion width becomes small leading to weak structure
Solution Approach 1:
The patent applies asymmetry by creating different slope angles for the first and second lateral surfaces of the trench capacitor. The first lateral surface (at the bottom) has a first slope angle, while the second lateral surface (at the top) has a second slope angle that is different from the first. This asymmetric design allows the bottom portion to be wider for structural strength while the top portion can be narrower, resolving the contradiction between capacitance and structural strength.
2Quantity of substance
If the trench capacitor has a great height and a short width, then the capacitance value increases, but the structure becomes weak due to small bottom width
Solution Approach 1:
The asymmetric slope design ensures that the bottom portion of the trench capacitor has a wider width (due to the first slope angle) compared to the top portion (with the second slope angle). This provides structural reliability and prevents weakness at the bottom while maintaining the high aspect ratio needed for increased capacitance value.
3Ease of manufacture
If the trench width is non-uniform with top width exceeding bottom width, then manufacturing is simplified, but the capacitance value decreases and structure becomes weak
Solution Approach 1:
Instead of using a simple uniform or tapered trench, the patent employs asymmetric slopes on opposite sides of the trench. The first lateral surface has a first slope angle and the second lateral surface has a second slope angle, creating a controlled non-uniform width profile that optimizes both capacitance and structural integrity while remaining manufacturable through standard etching processes.
4Ease of manufacture
If the trench width is non-uniform with top width exceeding bottom width, then manufacturing is simplified, but the structural strength decreases
Solution Approach 1:
The asymmetric slope configuration ensures that at least one of the lateral surfaces has a slope angle that maintains adequate width at critical portions of the trench. This provides structural strength while still allowing the trench to be formed through standard manufacturing processes, balancing ease of manufacture with structural requirements.
Data Source
AI summary
A semiconductor structure and a method for forming the same are provided. The semiconductor structure includes a substrate having a first surface, a plurality of layers disposed on the first surface of the substrate. The plurality of layers includes a first nitride layer disposed on the first surface of the substrate, a first silicon-containing layer disposed on the first nitride layer, an intermediate nitride layer disposed on the first silicon-containing layer, a second silicon-containing layer disposed on the intermediate nitride layer, and a second nitride layer disposed on the second silicon-containing layer. In addition, the semiconductor structure includes a trench capacitor penetrating the plurality of layers and in contact with the substrate. The trench capacitor has a first portion having a first lateral surface and a second portion having a second lateral surface, and the first lateral surface has a slope different from that of the second lateral surface.