Tungsten Film Formation Preventing Substrate Etching

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Solution Overview

Problem

The existing methods for forming metal films on substrates, such as tungsten films, often result in etching of the substrate surface due to fluorine from precursor gases, leading to film peeling and degradation of insulation properties in films like aluminum oxide or hafnium oxide.

Innovation Solution

A method involving alternating cycles of supplying fluorine-free and fluorine-containing precursor gases with reducibility, where a first film is formed using a chlorotungsten precursor and then a second film using hexafluorotungsten, both with diborane as the reactant gas, to laminate and prevent substrate etching and diffusion.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If fluorine-containing precursor gas (WF6) is supplied to form metal film, then film formation efficiency is improved, but substrate surface is etched and film peeling occurs

Engineering Contradiction:

Improvefilm formation efficiencyVSAvoidsubstrate etching

Core Design Contradiction:

ProductivityVSObject-affected harmful factors

Solution Approach 1:

The film formation process is segmented into multiple stages: initial film formation without fluorine-containing gas, followed by subsequent film formation with fluorine-containing gas. This segmentation allows the substrate to be protected during initial stages while enabling efficient film formation in later stages, resolving the contradiction between productivity and substrate damage.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

A preliminary film layer is formed using non-fluorine-containing precursor gas before introducing fluorine-containing gas. This preliminary action creates a protective barrier that prevents substrate etching while allowing subsequent efficient film formation with fluorine-containing gases.

Inventive Principle:

Principle #10Preliminary action

2Productivity

If fluorine-containing precursor gas (WF6) is supplied to form metal film, then film formation efficiency is improved, but insulation film properties are degraded due to fluorine diffusion

Engineering Contradiction:

Improvefilm formation efficiencyVSAvoidinsulation film property

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The process is segmented into stages where fluorine-containing gas is introduced only after a sufficient metal film layer is formed. This ensures the metal film acts as a diffusion barrier, preventing fluorine from reaching and degrading the insulation film while maintaining high formation efficiency.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

A preliminary metal film layer is formed using non-fluorine-containing precursor gas to establish a diffusion barrier before introducing fluorine-containing gas. This preliminary barrier prevents fluorine diffusion into the insulation film while allowing subsequent efficient film formation.

Inventive Principle:

Principle #10Preliminary action

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 reduces substrate etching, enhances film uniformity and flatness, and maintains insulation properties by acting as a fluorine diffusion barrier, improving the conductivity and reducing impurity concentration in the tungsten film.

Implementation Method 1

forming a first film containing a metal element on a substrate by performing a cycle a predetermined number of times, the cycle including: (a-1) supplying a first precursor gas being a fluorine-free inorganic gas containing the metal element to the substrate

Methodology Applied

Scientific EffectChemical Vapour Deposition: Chemical Vapour Deposition

Implementation Method 2

supplying a first reactant gas having reducibility to the substrate

Methodology Applied

Scientific EffectReduction: Reduction

Implementation Method 3

forming a second film containing the metal element on the first film by performing a cycle a predetermined number of times, the cycle including: (b-1) supplying a second precursor gas containing the metal element and fluorine to the substrate

Methodology Applied

Scientific EffectChemical Vapour Deposition: Chemical Vapour Deposition

Implementation Method 4

supplying a second reactant gas having reducibility to the substrate

Methodology Applied

Scientific EffectReduction: Reduction

Implementation Method 5

forming a film containing the metal element and obtained by the first film and the second film being laminated on the substrate

Methodology Applied

Scientific EffectDiffusion Barrier: Diffusion Barrier

Data Source

PatentUS9558937B2Method of manufacturing semiconductor device, substrate processing apparatus, and non-transitory computer-readable recording medium

Publication Date: 2017.01.31 KOKUSAI DENKI KK

AI summary

A method of manufacturing a semiconductor device includes: (a) forming a first film containing a metal element on a substrate by performing a cycle a predetermined number of times, the cycle including: (a-1) supplying a first precursor gas being a fluorine-free inorganic gas containing the metal element to the substrate; and (a-2) supplying a first reactant gas having reducibility to the substrate; (b) forming a second film containing the metal element on the first film by performing a cycle a predetermined number of times, the cycle including: (b-1) supplying a second precursor gas containing the metal element and fluorine to the substrate; and (b-2) supplying a second reactant gas having reducibility to the substrate; and (c) forming a film containing the metal element and obtained by the first film and the second film being laminated on the substrate by performing the (a) and (b).