Moisture-Barrier Coating for Polymer-Substrate Semiconductor Devices

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Solution Overview

Problem

The existing semiconductor devices with silicon-on-insulator (SOI)-CMOSFETs experience fluctuations in electrical characteristics when operated in moist environments, due to distortion in the semiconductor layer caused by moisture absorption and expansion of the polymer substrate.

Innovation Solution

A semiconductor device is designed with a support substrate made of a polymer or filler-containing polymer, an insulating layer made of inorganic material, a circuit formation layer with semiconductor elements, and a coating film covering the lower and side surfaces of the support substrate. The coating film is made of a material with lower moisture permeability than the support substrate, effectively suppressing moisture penetration and expansion.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If a polymer substrate is used to support the insulating layer and semiconductor element, then the device structure is simplified and manufacturing is easier, but the polymer substrate absorbs moisture and expands causing distortion in the semiconductor layer and fluctuation in electrical characteristics

Engineering Contradiction:

Improveease of manufactureVSAvoidelectrical characteristics stability

Core Design Contradiction:

Ease of manufactureVSReliability

Solution Approach 1:

A coating film is introduced as an intermediary layer between the polymer substrate and the external environment. This coating film acts as a moisture barrier that mediates the interaction between moisture and the polymer substrate, preventing moisture penetration while allowing the polymer substrate to maintain its structural support function. The coating film thus resolves the contradiction by enabling the use of polymer substrates without suffering from their moisture absorption issues.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The device structure is transformed into a composite material system consisting of the polymer substrate combined with a moisture-barrier coating film. This composite structure combines the advantages of the polymer substrate (ease of manufacture, flexibility) with the moisture-blocking properties of the coating film, thereby achieving both ease of manufacture and electrical characteristics stability simultaneously.

Inventive Principle:

Principle #40Composite materials

2Adaptability or versatility

If the polymer substrate is exposed to moisture environment, then the device can operate in various conditions, but the polymer substrate expands due to moisture absorption causing distortion in the semiconductor layer

Engineering Contradiction:

Improveoperability in moist environmentVSAvoidsemiconductor layer distortion

Core Design Contradiction:

Adaptability or versatilityVSShape

Solution Approach 1:

The coating film serves as a protective intermediary that allows the device to operate in moist environments while preventing moisture from reaching the polymer substrate. This intermediary layer enables adaptability to various operating conditions without causing shape distortion to the semiconductor layer, as it blocks moisture penetration while allowing thermal and mechanical stress dissipation.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Device complexity

If no additional protective layer is added to the polymer substrate, then the device structure remains simple, but moisture penetrates into the support substrate causing expansion and semiconductor layer distortion

Engineering Contradiction:

Improvedevice structure complexityVSAvoidelectrical characteristics stability

Core Design Contradiction:

Device complexityVSReliability

Solution Approach 1:

A thin coating film is applied to the polymer substrate to provide moisture protection. This thin film approach maintains the simplicity of the device structure while effectively preventing moisture penetration. The coating film is sufficiently thin to minimize added complexity but thick enough to provide adequate moisture barrier protection, thus resolving the contradiction between structural simplicity and reliability.

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

The semiconductor device exhibits reduced fluctuations in electrical characteristics, as the coating film prevents moisture-induced distortion in the semiconductor layer, thereby enhancing the reliability of the device under humid conditions.

Implementation Method 1

The coating film is formed of a material having lower moisture permeability than the support substrate

Methodology Applied

Scientific EffectMoisture permeability barrier: Permeation

Implementation Method 2

expansion of the support substrate due to moisture absorption

Methodology Applied

Scientific EffectMoisture absorption and expansion: Absorption (physical)

Data Source

PatentUS20250132269A1Semiconductor device

Publication Date: 2025.04.24 MURATA MFG CO LTD

AI summary

An insulating layer made of an inorganic insulating material is provided on an upper surface which is one surface of a support substrate made of a polymer or a filler-containing polymer. A circuit formation layer including a semiconductor element is provided on the insulating layer. A lower surface on an opposite side from the upper surface and a side surface of the support substrate are covered with a coating film formed of a material having lower moisture permeability than the support substrate.