Surface-Mount MOS Capacitor Structure for Low Insertion Loss
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Solution Overview
Problem
Metal-oxide-semiconductor (MOS) capacitors exhibit poor high-frequency performance due to wirebond connections, which cause electrical perturbations and affect their performance at high frequencies.
Innovation Solution
A MOS capacitor design featuring a substrate with a semiconductor material, an oxide layer, and conductive layers connected in series, with terminals exposed for surface mounting, eliminating wirebond connections and enhancing high-frequency performance by reducing insertion loss.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If wirebond connections are used to connect MOS capacitor terminals, then the capacitor can be manufactured with conventional processes, but the high-frequency performance deteriorates due to electrical perturbations
Solution Approach 1:
The patent extracts and eliminates the wirebond connection from the capacitor structure. By integrating the terminals directly into the capacitor body and exposing them on the same surface, the invention removes the external wirebond connection that causes electrical perturbations, thereby resolving the contradiction between ease of manufacture and high-frequency performance
Solution Approach 2:
The patent merges the terminal structures with the capacitor body by forming both on the same semiconductor substrate. The first terminal connects to the substrate and the second terminal connects to the conductive layer, with both terminals exposed on the same surface, eliminating the need for separate wirebond connections and integrating all functional elements into a unified structure
2Device complexity
If wirebond connections are used for terminal connections, then the capacitor structure remains simple, but insertion loss increases at high frequencies
Solution Approach 1:
The invention extracts the wirebond connection that causes energy loss and replaces it with direct surface-mounted terminals. This elimination of the intermediate connection structure reduces insertion loss while maintaining structural simplicity through direct integration
Solution Approach 2:
The patent transitions from a three-dimensional wirebond connection (extending above the capacitor surface) to a two-dimensional surface-mounted terminal configuration. Both terminals are exposed on the same surface plane, eliminating the vertical wirebond structure that contributes to insertion loss while keeping the overall structure simple
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The MOS capacitor achieves improved high-frequency performance with insertion loss greater than −0.75 dB for frequencies ranging from 5 GHz to 40 GHz, demonstrating enhanced performance compared to prior art MOS capacitors.
Implementation Method 1
The oxide layer can be connected in series between the substrate and the conductive layer to form a capacitor between the first terminal and the second terminal
Data Source
AI summary
A metal-oxide-semiconductor (MOS) capacitor can include a substrate including a semiconductor material, an oxide layer formed on a surface of the substrate, a conductive layer formed over at least a portion of the oxide layer, a first terminal connected with the surface of the substrate, and a second terminal connected with the conductive layer. The oxide layer can be connected in series between the substrate and the conductive layer to form a capacitor between the first terminal and the second terminal. Each of the first terminal and the second terminal can be exposed along the surface of the substrate for surface mounting the capacitor. The MOS capacitor can exhibit excellent high frequency performance. For example, an insertion loss of the MOS capacitor can be greater than about −0.75 dB for frequencies ranging from about 5 GHz to about 40 GHz.