Passive Element Structure With Tunable Parasitic Capacitance

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Solution Overview

Problem

Semiconductor devices operating in frequency bands exceeding 100 GHz face challenges due to manufacturing variations affecting passive elements, leading to significant deterioration of high-frequency characteristics, particularly in analog and high-frequency circuits.

Innovation Solution

The semiconductor device incorporates embedded semiconductors with low- and high-concentration impurity regions beneath passive elements, allowing for independent adjustment of parasitic capacitance through controlled voltage application, thereby stabilizing the characteristic impedance and improving high-frequency performance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If a correction circuit is added to adjust impedance of passive elements, then manufacturing variations can be corrected, but the correction circuit affects analog circuit performance and high-frequency characteristics deteriorate

Engineering Contradiction:
Improveimpedance adjustmentVSAvoidhigh-frequency characteristics
Core Design Contradiction:
Manufacturing precisionVSReliability

Solution Approach 1:

The patent extracts the impedance adjustment function from a separate correction circuit and integrates it directly into the passive element structure itself. By forming variable capacitance regions within the interlayer insulating film beneath the passive element, the impedance adjustment capability is embedded within the passive element, eliminating the need for external correction circuits that would affect analog circuit performance.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The patent merges the impedance adjustment function with the passive element structure by combining the variable capacitance regions with the interlayer insulating film. This integration allows the passive element to self-adjust its impedance characteristics without requiring separate correction circuitry, thereby maintaining high-frequency performance while achieving manufacturing variation compensation.

Inventive Principle:
Principle #5Merging (Combining)

2Object-affected harmful factors

If the p-type layer is maintained at high resistance without wells, then substrate noise is reduced, but manufacturing variations still affect passive element performance at high frequencies

Engineering Contradiction:
Improvesubstrate noiseVSAvoidpassive element performance
Core Design Contradiction:
Object-affected harmful factorsVSManufacturing precision

Solution Approach 1:

The patent applies local quality by creating variable capacitance regions with specific dielectric constant variations in localized areas within the interlayer insulating film, directly beneath the passive element. This allows impedance adjustment in the specific region affecting passive element performance while maintaining high resistance of the p-type layer overall, thus reducing substrate noise while compensating for manufacturing variations.

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The patent changes the physical parameters of the interlayer insulating film by introducing variable capacitance regions with different dielectric constants. This parameter change enables dynamic adjustment of the electric field distribution and impedance characteristics of passive elements, compensating for manufacturing variations without requiring changes to the p-type layer resistance structure.

Inventive Principle:
Principle #35Parameter changes

3Productivity

If pattern miniaturization is advanced for logic circuits, then device density increases, but passive element performance deteriorates at frequencies above 100 GHz

Engineering Contradiction:
Improvedevice densityVSAvoidhigh-frequency characteristics
Core Design Contradiction:
ProductivityVSReliability

Solution Approach 1:

The patent addresses high-frequency performance deterioration by moving the impedance adjustment mechanism from the planar dimension to the vertical dimension. By forming variable capacitance regions within the interlayer insulating film structure, the solution utilizes the third dimension (film thickness direction) to control electromagnetic field distribution, enabling effective impedance adjustment for miniaturized passive elements operating at frequencies above 100 GHz without compromising device density.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

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 mitigates the impact of manufacturing variations on high-frequency characteristics by dynamically adjusting parasitic capacitance, ensuring stable operation in frequency bands of several tens of GHz and beyond.

Implementation Method 1

embedded semiconductors with low- and high-concentration impurity regions beneath passive elements, allowing for independent adjustment of parasitic capacitance through controlled voltage application

Methodology Applied
Scientific EffectParasitic capacitance: Parasitic Capacitance

Data Source

PatentEP4708362A1Semiconductor device
Publication Date: 2026.03.11 MITSUBISHI ELECTRIC CORP
  • EP4708362A1 patent drawingFigure 1
  • EP4708362A1 patent drawingFigure 2
  • EP4708362A1 patent drawingFigure 3

AI summary

A semiconductor device includes: a semiconductor substrate (1); a first oxide film (2) formed on a surface of the semiconductor substrate (1); a first oxide film (3) formed on a surface of the first oxide film (2); a passive element (10) formed inside the first oxide film (3); and embedded semiconductors (21) to (23) embedded in a surface of the first oxide film (2) directly below the passive element (10) and including low-concentration impurity regions (21a) to (23a) in which an interface is formed with a back surface of the first oxide film (3), and high-concentration impurity regions (21b) to (23b) bonded to bottom surfaces of the low-concentration impurity regions (21a) to (23a) and having contact surfaces which are exposed to a surface of the first oxide film (3) and to which a voltage is applied, respectively.