MOSCAP Shielding for Eddy Current Reduction

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Solution Overview

Problem

MOSCAP structures in semiconductor devices suffer from low quality factor values due to eddy currents generated by inductors, and existing solutions often require complex multi-layer structures, increasing costs and complexity.

Innovation Solution

A semiconductor device with a MOSCAP structure incorporating a polysilicon layer, an oxide definition layer, and two metal layers, where the patterned shielding structure is connected to ground to prevent eddy currents and reduce mutual inductance, utilizing a simpler two-metal-layer configuration.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a complex multi-layer structure is used to shield against eddy currents, then the quality factor value is improved, but the device complexity and manufacturing cost increase

Engineering Contradiction:

Improvequality factor valueVSAvoidstructure complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent extracts and isolates the shielding function into a separate patterned shielding structure that is selectively positioned only where eddy currents are generated. This separates the shielding function from the entire multi-layer structure, allowing only the necessary portions to be shielded, thereby reducing overall structural complexity while maintaining quality factor improvement.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The shielding structure is segmented into specific patterned regions rather than using a continuous multi-layer shield. The shielding is divided into discrete segments that are strategically placed to interrupt eddy current paths, reducing the amount of shielding material and structural complexity required while still achieving the desired quality factor improvement.

Inventive Principle:

Principle #1Segmentation

2Reliability

If more metal layers are added to the MOSCAP structure, then the quality factor value is improved, but the manufacturing cost and process complexity increase

Engineering Contradiction:

Improvequality factor valueVSAvoidmanufacturing cost

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The first metal layer serves dual functions: it acts as both the upper electrode of the MOSCAP structure and part of the shielding configuration. The polysilicon layer simultaneously functions as the control electrode and provides shielding when connected to ground. This multi-functionality eliminates the need for additional dedicated shielding layers, reducing manufacturing cost and process complexity.

Inventive Principle:

Principle #6Universality (Multi-functionality)

Solution Approach 2:

The patent merges the MOSCAP electrode function with the shielding function into the same structural elements. The first metal layer and polysilicon layer are used for both capacitor operation and eddy current shielding, combining multiple functions into fewer layers and reducing manufacturing complexity.

Inventive Principle:

Principle #5Merging (Combining)

3Reliability

If a patterned shielding structure is added over the MOSCAP, then eddy currents are reduced and quality factor is improved, but the device complexity increases

Engineering Contradiction:

Improvequality factor valueVSAvoidstructure complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The shielding is applied locally only where eddy currents are generated, rather than uniformly across the entire device. The patterned shielding structure is selectively positioned in specific regions to interrupt eddy current paths, providing targeted shielding where needed while leaving other areas unchanged, thus minimizing added structural complexity.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patterned shielding structure acts as an intermediary element that is strategically inserted between the inductor and the MOSCAP structure. This intermediary selectively blocks eddy current paths without requiring complete multi-layer shielding, reducing the overall structural complexity while still achieving quality factor improvement.

Inventive Principle:

Principle #24Intermediary (Mediator)

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

This configuration effectively increases the quality factor value of semiconductor devices by reducing eddy currents and parasitic capacitance, while maintaining a low-cost and simplified structure.

Implementation Method 1

MOSCAP structures in semiconductor devices suffer from low quality factor values due to eddy currents generated by inductors

Methodology Applied

Scientific EffectEddy currents: Eddy Currents

Implementation Method 2

low quality factor values due to eddy currents generated by inductors

Methodology Applied

Scientific EffectElectromagnetic induction: Electromagnetic Induction

Data Source

PatentUS11557535B2Semiconductor device and metal-oxide-semiconductor capacitor structure

Publication Date: 2023.01.17 REALTEK SEMICON CORP

AI summary

A semiconductor device is disposed below an inductor. The semiconductor device includes a metal-oxide-semiconductor capacitor structure and a patterned shielding structure. The metal-oxide-semiconductor capacitor structure includes a polysilicon layer, an oxide definition layer, and a first metal layer. The first metal layer is connected to the polysilicon layer and the oxide definition layer. The patterned shielding structure is disposed over the metal-oxide-semiconductor capacitor structure and includes a second metal layer.