Deep Trench Capacitor Layout for High Density and Low ESR
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Solution Overview
Problem
Trench capacitors in semiconductor devices face challenges in improving capacitance density and equivalent series resistance, and require additional photolithographic steps in their integration into semiconductor device process flows.
Innovation Solution
An integrated trench capacitor is formed in a semiconductor device with a field oxide layer, trenches, a capacitor dielectric, and electrically conductive trench-fill material, where the field oxide layer extends between trenches and covers a portion of the trench-fill material, and substrate contacts are provided on opposite sides of the trenches without any between them, utilizing a silicon-nitrogen compound dielectric and a metal silicide layer to enhance performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If traditional trench capacitor formation methods are used, then the capacitor structure can be formed, but additional photolithographic steps are required and capacitance density is limited
Solution Approach 1:
The patent merges the trench capacitor formation process with the existing semiconductor device fabrication process. The field oxide layer is formed to define both the device regions and the trench capacitor trenches simultaneously, eliminating the need for separate photolithographic steps. The trenches are formed by etching through the field oxide layer at regions where capacitor structures are desired, integrating the capacitor formation into the standard process flow.
Solution Approach 2:
The field oxide layer is formed in advance before the trench etching step. This preliminary oxidation defines the regions where trenches will subsequently be formed, preparing the structure for high-capacitance-density trench capacitors without requiring additional patterning steps later in the process.
2Manufacturing precision
If trench depth is increased to improve capacitance density, then capacitance increases, but equivalent series resistance also increases
Solution Approach 1:
The patent applies different materials and structures at different locations within the trench capacitor. The bottom portion of the trench contains a first dielectric material with different properties than the upper portion, which contains a second dielectric material. This local differentiation allows optimization of capacitance at the bottom while managing resistance in the upper regions. The field oxide layer configuration also varies locally to control electrical characteristics.
Solution Approach 2:
The trench capacitor employs a composite dielectric structure with at least two different dielectric materials stacked vertically within the trench. This composite approach allows the lower layers to provide high capacitance density while upper layers provide optimized electrical characteristics, effectively balancing capacitance density and equivalent series resistance through material composition rather than单纯 increasing depth.
Data Source
AI summary
A semiconductor device includes an integrated trench capacitor in a substrate, with a field oxide layer on the substrate. The trench capacitor includes trenches extending into semiconductor material of the substrate, and a capacitor dielectric in the trenches on the semiconductor material. The trench capacitor further includes an electrically conductive trench-fill material on the capacitor dielectric. A portion of the capacitor dielectric extends into the field oxide layer, between a first segment of the field oxide layer over the trench-fill material and a second segment of the field oxide layer over the semiconductor material. The integrated trench capacitor has a trench contact to the trench-fill material in each of the trenches, and substrate contacts to the semiconductor material around the trenches, with no substrate contacts between the trenches.