Deep Trench Capacitor Profile for Higher Capacitance and Structure Strength
Find Innovative SolutionsGenerate Solutions
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, achieving a relatively uniform overall width by forming a trench with a first portion surrounded by a silicon-containing layer and a second portion surrounded by a nitride layer, where the second width is greater than the first width, using a multilayered stack of 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 trench is divided into multiple sections along its height, with each section having a different width. The bottom portion has a larger width for structural strength, the middle portion has a reduced width, and the top portion has an enlarged width. This segmentation allows the trench to achieve both high capacitance (through increased height) and structural strength (through widened bottom and top sections).
Solution Approach 2:
Different portions of the trench are given different local qualities in terms of width. The bottom portion is widened to provide structural support, the middle portion is narrowed to maximize capacitance density, and the top portion is enlarged to provide mechanical stability. This local differentiation resolves the contradiction between overall height and local width requirements.
2Quantity of substance
If the trench width is reduced at the bottom to increase capacitance density, then the capacitance value improves, but the structure becomes weak
Solution Approach 1:
The trench width is segmented into multiple zones: a bottom zone with larger width for structural strength, a middle zone with reduced width for capacitance density, and a top zone with enlarged width for mechanical stability. This segmentation allows each zone to optimize for its specific function while collectively resolving the strength-capacitance contradiction.
Solution Approach 2:
Instead of maintaining a uniform width in the horizontal dimension, the invention introduces variation in the width dimension at different heights. This dimensional variation allows the trench to achieve both structural strength (through wider bottom and top sections) and high capacitance (through the overall increased height and optimized middle section).
3Ease of manufacture
If the trench tapers from top to bottom to reduce manufacturing complexity, then the manufacturing process is simplified, but the bottom space is limited reducing capacitance
Solution Approach 1:
The trench fabrication process is segmented into multiple etching stages, each creating a specific width profile at different heights. This segmented approach, while more complex than a single etch, enables precise control over the width at each level, maximizing the bottom space for capacitance while maintaining manufacturability through standardized multi-step processes.
4Device complexity
If the trench has a uniform width throughout, then the structure is simplified and manufacturing is easier, but the capacitance value is reduced due to limited height
Solution Approach 1:
The trench is segmented into multiple width zones to simultaneously achieve structural simplicity and high capacitance. The bottom portion is widened to provide structural foundation, the middle portion is optimized for capacitance density, and the top portion is enlarged for mechanical stability. This segmentation allows the trench to exceed the height of uniform-width trenches while maintaining manageable complexity through standardized fabrication steps.
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.