Non-Photosensitive Polyimide Passivation Layer Etching

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Solution Overview

Problem

The existing methods for manufacturing non-photosensitive polyimide passivation layers in semiconductor devices face issues such as aluminum corrosion, tapered profiles due to isotropic development, and photoresist residues, which affect device performance and miniaturization.

Innovation Solution

A method involving the deposition of a silicon dioxide thin film between the non-photosensitive polyimide and photoresist layers, followed by a dry etching process using the silicon dioxide as a mask, to prevent direct contact and corrosion, and achieve anisotropic etching for a straight profile.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If the non-photosensitive polyimide layer is developed for a relatively long time to ensure sufficient development, then the development completeness is improved, but aluminum corrosion occurs due to the developer penetrating through thinner portions of the polyimide layer

Engineering Contradiction:

Improvedevelopment completenessVSAvoidaluminum corrosion

Core Design Contradiction:

Manufacturing precisionVSObject-affected harmful factors

Solution Approach 1:

A silicon oxide layer is introduced as an intermediary mask layer between the photoresist and the non-photosensitive polyimide layer. This silicon oxide layer serves as a protective barrier that prevents the developer from directly contacting and corroding the aluminum PAD during the development process, while still allowing the development to proceed completely through the polyimide layer.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Ease of manufacture

If isotropic development is used to develop the non-photosensitive polyimide layer, then the development process is simple, but a tapered and uncontrollable profile is formed affecting device miniaturization

Engineering Contradiction:

Improvedevelopment process simplicityVSAvoidprofile control

Core Design Contradiction:

Ease of manufactureVSManufacturing precision

Solution Approach 1:

The silicon oxide mask layer acts as an intermediary that enables anisotropic etching of the non-photosensitive polyimide layer. By using reactive ion etching (RIE) through the patterned silicon oxide mask, vertical sidewalls are formed with precise profile control, eliminating the tapered profile issue while maintaining process feasibility.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Quantity of substance

If commonly used solvents like NMP are used for non-photosensitive polyimide, then the dissolving capacity is high, but photoresist residues remain in the patterned polyimide layer as the photoresist dissolves into the polyimide layer

Engineering Contradiction:

Improvedissolving capacityVSAvoidphotoresist residues

Core Design Contradiction:

Quantity of substanceVSObject-generated harmful factors

Solution Approach 1:

The silicon oxide layer serves as a physical barrier that prevents direct contact between the photoresist and the non-photosensitive polyimide layer. This intermediary layer stops the photoresist from dissolving into the polyimide layer during spin-coating and baking processes, eliminating photoresist residues while maintaining the high dissolving capacity of NMP for the polyimide layer during development.

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 approach prevents aluminum corrosion, eliminates photoresist residues, and ensures a controlled, non-tapered profile, enhancing the reliability and miniaturization capabilities of semiconductor devices.

Implementation Method 1

depositing a silicon dioxide thin film over the non-photosensitive polyimide layer

Methodology Applied

Scientific EffectPhysical Vapour Deposition: Physical Vapour Deposition

Implementation Method 2

exposing and developing the photoresist layer to form a photoresist pattern

Methodology Applied

Scientific EffectPhotochemical reaction: Photo-oxidation

Implementation Method 3

removing the patterned photoresist layer

Methodology Applied

Scientific EffectChemical dissolution: Solvation

Implementation Method 4

dry etching the non-photosensitive polyimide layer by using the patterned silicon dioxide thin film as a mask

Methodology Applied

Scientific EffectReactive ion etching: Plasma

Implementation Method 5

removing the patterned silicon dioxide thin film

Methodology Applied

Scientific EffectWet etching:

Implementation Method 6

forming an imidized polyimide passivation layer by curing the patterned non-photosensitive polyimide layer

Methodology Applied

Scientific EffectThermal curing: Heat Treatment

Data Source

PatentUS8513142B2Method of manufacturing non-photosensitive polyimide passivation layer

Publication Date: 2013.08.20 SHANGHAI HUAHONG GRACE SEMICON MFG CORP

AI summary

A method of manufacturing non-photosensitive polyimide passivation layer is disclosed. The method includes: spin-coating a non-photosensitive polyimide layer over a wafer and baking it; depositing a silicon dioxide thin film thereon; spin-coating a photoresist layer over the silicon dioxide thin film and baking it; exposing and developing the photoresist layer to form a photoresist pattern; etching the silicon dioxide thin film by using the photoresist pattern as a mask; removing the patterned photoresist layer; dry etching the non-photosensitive polyimide layer by using the patterned silicon dioxide thin film as a mask; removing the patterned silicon dioxide thin film; and curing to form a imidized polyimide passivation layer. The method addresses issues of the traditional non-photosensitive polyimide process, including aluminum corrosion by developer, tapered profile of non-photosensitive polyimide layer and generation of photoresist residues.