Capacitive Isolation Barrier for High Voltage IC Breakdown

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Solution Overview

Problem

Existing high voltage isolation structures for integrated circuits face challenges in providing reliable voltage isolation and breakdown voltage, as they are prone to voltage breakdown due to secondary paths and interactions between circuitry and isolation structures.

Innovation Solution

The integrated circuit isolator device employs capacitive coupling with complementary metal oxide semiconductor (CMOS) processes to create isolation barrier structures with insulative material between metal layers, forming isolation capacitors that distribute voltage and charge across two die structures, and uses bonding wires to connect these structures, along with polyimide keep-out regions and metallic unity rings to enhance breakdown voltage.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If a single isolation barrier structure is used, then the device complexity is reduced, but the breakdown voltage is insufficient

Engineering Contradiction:

Improvebreakdown voltageVSAvoidisolation structure complexity

Core Design Contradiction:

StrengthVSDevice complexity

Solution Approach 1:

The isolation barrier is divided into two separate structures located on different dies. Each die contains one isolation barrier structure with capacitive coupling plates, allowing the breakdown voltage to be distributed across multiple structures rather than requiring a single high-voltage structure.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The isolation function is extended from a single-die structure to a multi-die configuration. By placing isolation barriers on separate dies and coupling them through capacitive plates and bond wires, the solution adds the dimension of spatial distribution across multiple semiconductor substrates.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

2Reliability

If isolation barrier structures are added to provide voltage isolation, then the voltage isolation reliability is improved, but the device complexity increases

Engineering Contradiction:

Improvevoltage isolation reliabilityVSAvoidisolation structure complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The isolation barrier structure combines multiple functions into a single integrated design. The capacitive coupling plates serve both as electrical isolation barriers and as signal coupling elements, while also functioning as bonding pads for wire bonding. This multi-functionality reduces the need for separate structures.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The top plate of the isolation barrier structure serves multiple purposes: it acts as the capacitive coupling element for voltage isolation, functions as a bonding pad for electrical connection via bond wire, and provides structural support for the isolation barrier. This universal design reduces overall device complexity.

Inventive Principle:

Principle #6Universality (Multi-functionality)

3Reliability

If traditional isolation structures are used, then the manufacturing process is simpler, but secondary breakdown paths occur

Engineering Contradiction:

Improvebreakdown protectionVSAvoidmanufacturing complexity

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

Capacitive coupling plates are introduced as intermediary elements between the circuitry on different dies. These plates provide a controlled coupling mechanism that prevents direct electrical contact and potential breakdown paths, while still allowing signal transmission through capacitive coupling.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The isolation barrier utilizes thin film insulative materials deposited on the semiconductor dies to create electrically isolating layers. These thin films provide effective voltage isolation while maintaining compatibility with standard semiconductor manufacturing processes.

Inventive Principle:

Principle #30Flexible shells and thin films

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 doubles the breakdown voltage by distributing voltage and charge across two isolation structures, reducing the likelihood of secondary breakdown paths and enhancing the overall isolation voltage, thereby providing reliable voltage isolation between signal inputs and outputs.

Implementation Method 1

The first isolation barrier structure includes a combined top plate/bonding pad, a bottom plate, and insulative material therebetween... The second isolation barrier structure includes a combined top plate/bonding pad, a bottom plate, and insulative material therebetween

Methodology Applied

Scientific EffectCapacitance: Capacitance

Implementation Method 2

A bond wire couples the combined top plate/bonding pad of the first isolation barrier structure to the combined top plate/bonding pad of the second isolation barrier structure, such that a signal propagates from the first circuitry

Methodology Applied

Scientific EffectElectrical Conduction: Conduction (electrical)

Data Source

PatentUS8643138B2High breakdown voltage integrated circuit isolation structure

Publication Date: 2014.02.04 SKYWORKS SOLUTIONS INC

AI summary

A high breakdown voltage integrated circuit isolator device communicates a digital signal from a signal input on one semiconductor die to a signal output on another semiconductor die while providing high voltage isolation between the signal input and the signal output. Each die may include a respective capacitive isolation barrier structure that couple together via a bonding wire between combined top metal/bonding pads of the capacitive isolation barrier structures.