Interdigitated MOM Capacitor Layout for High-Frequency RF Filtering
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Solution Overview
Problem
Current metal-oxide-metal (MOM) capacitor structures in semiconductor manufacturing face challenges in enhancing their high-frequency filter function and overall performance, particularly in mixed signal radio frequency integrated circuits (RFIC).
Innovation Solution
A semiconductor structure is designed with a first electrode layer featuring a comb handle part and parallel comb tooth parts, and a second electrode layer with crossed comb tooth parts, both layers being connected in a three-terminal capacitor configuration to reduce grounded inductance and improve high-frequency filtering, along with a dielectric layer for electrical isolation and etching selection ratio, and via interconnect structures for signal access.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional MOM capacitor structure is used, then the manufacturing process is simple, but the high-frequency filter function is insufficient due to high grounded inductance
Solution Approach 1:
The capacitor electrodes are segmented into comb-shaped structures with multiple fingers, where the first comb-shaped electrode and second comb-shaped electrode are interdigitated. This segmentation reduces the inductance by distributing the current path across multiple parallel conductors, effectively lowering the overall inductance and improving high-frequency performance.
Solution Approach 2:
The capacitor structure transitions from a conventional planar parallel-plate configuration to a three-dimensional interdigitated comb structure. This dimensional change allows the electrodes to be arranged in multiple layers and orientations, reducing the effective inductance area and improving the high-frequency filter function while maintaining a compact footprint.
2Reliability
If the comb-shaped electrode structure is implemented, then the grounded inductance is reduced, but the manufacturing precision requirements increase
Solution Approach 1:
A dielectric layer with specific etching selection ratio is introduced as an intermediary between the comb-shaped electrodes. This dielectric layer serves as a precise template and spacer during fabrication, enabling accurate positioning and spacing of the interdigitated electrodes. The etching selection ratio allows selective removal of sacrificial layers while preserving the final electrode structures, thereby reducing alignment precision requirements.
3Reliability
If the three-terminal capacitor configuration is used, then the high-frequency performance is improved, but the device area increases
Solution Approach 1:
The three-terminal capacitor configuration merges the functions of multiple electrodes into a compact interdigitated structure where the first and second comb-shaped electrodes share common grounding points. This merging allows the capacitor to achieve low inductance and high-frequency performance while maintaining a reduced footprint by efficiently utilizing the available area through interlaced electrode arrangements.
Data Source
AI summary
A semiconductor structure includes: a base, a first and a second electrode layer, where the first electrode layer is located on the base and includes a first comb handle part and a plurality of first comb tooth parts connected to the first comb handle part and arranged in parallel, one end of the first comb handle part is configured to access an input signal, and the other end is configured to access an output signal; and the second electrode layer is located on the base and located on the same layer with the first electrode layer, and includes a second comb handle part and a plurality of second comb tooth parts connected to the second comb handle part and arranged in parallel, the second comb tooth parts and the first comb tooth parts are parallel in a crossed manner, and the second comb handle part is configured to be grounded.