Metal Gate De-oxidation Using Reducing Agent

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Solution Overview

Problem

During semiconductor device fabrication, metal gates exposed to oxygen undergo oxidation, leading to performance degradation and unintended consequences in later processing steps, particularly affecting the characteristics and reliability of field-effect-transistors (FETs).

Innovation Solution

A reducing agent is applied to de-oxidize the metal gate surface, removing the oxidation layer and resulting in a substantially non-oxidized surface, which improves the performance of the metal gate by preventing further degradation and ensuring optimal contact formation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If metal gate is exposed to oxygen during fabrication, then oxidation of gate metal occurs, but gate performance deteriorates and reliability decreases

Engineering Contradiction:

Improvegate performanceVSAvoidoxidation

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent applies a reducing agent to convert the harmful oxidation layer into beneficial de-oxidized metal surface. The reducing agent chemically reacts with the oxidized metal gate surface, removing the oxide layer and restoring the metal to its reduced state, thereby converting the harmful oxidation effect into a beneficial de-oxidation process that improves gate performance and reliability

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

2Manufacturing precision

If oxidation layer forms on metal gate, then subsequent processing is affected, but de-oxidation process is required

Engineering Contradiction:

Improvecontact formationVSAvoidunintended consequences in later fabrication steps

Core Design Contradiction:

Manufacturing precisionVSObject-generated harmful factors

Solution Approach 1:

The patent performs de-oxidation as a preliminary action before subsequent fabrication steps such as contact formation. By applying the reducing agent to remove oxidation layers before these critical processing steps, the method prevents unintended consequences and ensures optimal manufacturing precision in later fabrication operations

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

The de-oxidation process enhances the electrical resistance and reliability of the metal gate, reducing the risk of tungsten encroachment and improving the overall performance of the semiconductor device by maintaining a non-oxidized surface, thus ensuring better gate contact formation and device stability.

Implementation Method 1

de-oxidizing, using a reducing agent, an oxidation layer formed on the metal gate

Methodology Applied

Scientific EffectReduction: Reduction

Data Source

PatentUS10854472B2Method for forming a metal gate including de-oxidation of an oxidized surface of the metal gate utilizing a reducing agent

Publication Date: 2020.12.01 GLOBALFOUNDRIES US INC

AI summary

Aspects of the present invention relate to approaches for forming a semiconductor device such as a field-effect-transistor (FET) having a metal gate with improved performance. A metal gate is formed on a substrate in the semiconductor device. Further processing can result in unwanted oxidation in the metal that forms the metal gate. A reducing agent can be used to de-oxidize the metal that forms the metal gate, leaving a substantially non-oxidized surface.