SiO2 Intermediate Film for Semiconductor Resist Ashing

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Solution Overview

Problem

The three-layered resist process in semiconductor fabrication faces challenges with ashing resistance and hygroscopicity issues, leading to pattern failure and poor mass productivity, particularly when removing and re-building the upper resist film, which affects the micro-fabrication of interconnect trenches and viaholes.

Innovation Solution

A method involving the formation of a SiO2 intermediate film using a compound expressed by the general formula Si(OR1)(OR2)(OR3)(OR4) through chemical vapor deposition at temperatures not exceeding 300°C, with R1, R2, R3, and R4 being carbon-containing groups or hydrogen atoms, enhancing ashing resistance and reducing hygroscopicity, and optionally using TEOS as the film-forming gas, along with oxidative gases like O2 to prevent nitrogen-induced resist poisoning.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If O2 ashing is used to remove the upper resist film, then the upper resist film can be removed, but the intermediate film (SOG) degrades and absorbs moisture

Engineering Contradiction:

Improveremoval of upper resist filmVSAvoidintegrity of intermediate film

Core Design Contradiction:

Ease of manufactureVSReliability

Solution Approach 1:

The patent introduces a protective film formed from Si(OR1)(OR2)(OR3)(OR4) compound as an intermediary layer between the resist film and the SOG intermediate film. This protective film acts as a mediator that shields the SOG layer from degradation during O2 ashing, allowing the upper resist film to be removed while preserving the intermediate film's integrity and preventing moisture absorption.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The protective film formed from Si(OR1)(OR2)(OR3)(OR4) compound serves as a disposable protective layer that is intentionally designed to be temporary. It provides protection during the ashing process and can be easily removed afterward, sacrificing itself to protect the more valuable SOG intermediate film from irreversible damage.

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

2Manufacturing precision

If the upper resist film is removed and re-built, then misalignment can be corrected, but productivity decreases

Engineering Contradiction:

Improvealignment accuracyVSAvoidmass production efficiency

Core Design Contradiction:

Manufacturing precisionVSProductivity

Solution Approach 1:

The protective film formed from Si(OR1)(OR2)(OR3)(OR4) compound provides beforehand cushioning by creating a stable, protective barrier before any potential misalignment issues arise. This allows for easy removal and re-building of the upper resist film without worrying about damaging the underlying SOG layer, thus enabling correction of alignment errors without sacrificing productivity.

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

3Ease of manufacture

If SiH4 gas and N2O gas are used to form the intermediate film, then the film can be formed, but ashing resistance is insufficient

Engineering Contradiction:

Improveformation of intermediate filmVSAvoidashing resistance

Core Design Contradiction:

Ease of manufactureVSStrength

Solution Approach 1:

The patent changes the chemical composition parameters of the intermediate film by using Si(OR1)(OR2)(OR3)(OR4) compound instead of SiH4 and N2O gases. This parameter change in the film's chemical structure results in significantly improved ashing resistance while maintaining the ability to form the film at low temperatures (not higher than 300°C).

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The protective film formed from Si(OR1)(OR2)(OR3)(OR4) compound can be considered a composite material that combines the benefits of low-temperature deposition with high ashing resistance. The specific chemical composition (with R1-R4 being carbon-containing groups or hydrogen atoms) creates a material structure that is inherently more resistant to ashing degradation than conventional SiO2 films.

Inventive Principle:

Principle #40Composite materials

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 improves ashing resistance and reduces hygroscopicity of the intermediate film, allowing for reliable removal and reformation of the resist film without degrading the underlying layers, thereby enhancing the resolution and productivity in forming interconnect trenches and viaholes.

Implementation Method 1

forming, on the insulating film, an intermediate film by the chemical vapor deposition process, at a temperature not higher than 300° C., using a compound expressed by the general formula (1) below

Methodology Applied

Scientific EffectChemical vapor deposition: Chemical Vapour Deposition

Implementation Method 2

optionally using TEOS as the film-forming gas, along with oxidative gases like O2 to prevent nitrogen-induced resist poisoning

Methodology Applied

Scientific EffectOxidation: Oxidation

Data Source

PatentUS8598044B2Method of fabricating a semiconductor device

Publication Date: 2013.12.03 RENESAS ELECTRONICS CORP

AI summary

An intermediate film 222 in a three-layered resist film 225 is formed by the chemical vapor deposition process at a temperature not higher than 300° C., using Si(OR1)(OR2)(OR3)(OR4), where each of R1, R2, R3 and R4 independently represents a carbon-containing group or a hydrogen atom, excluding the case where all of R1 to R4 are hydrogen atoms.