Titanium Silicide and Nitride Deposition for FinFET Contact Conformality

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Solution Overview

Problem

In the semiconductor industry, the formation of titanium silicide and titanium nitride layers in high aspect-ratio contact regions of finFETs is challenging due to non-conformal deposition and contamination issues during the transition between physical vapor deposition (PVD) and chemical vapor deposition (CVD) processes, leading to increased fabrication time and parasitic resistance.

Innovation Solution

The use of an in-situ treatment and CVD process to form titanium silicide and titanium nitride layers with controlled thicknesses and improved conformality, allowing for sequential deposition in the same reaction chamber without chamber switching, thereby reducing contamination and enhancing film quality.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If PVD and CVD processes are used separately for forming titanium silicide and titanium nitride layers, then material properties can be optimized, but chamber switching causes contamination and increases fabrication time

Engineering Contradiction:

Improvefilm qualityVSAvoidfabrication time

Core Design Contradiction:

ReliabilityVSLoss of time

Solution Approach 1:

The patent combines PVD and CVD processes into a single reaction chamber, allowing sequential deposition of titanium silicide (via PVD) and titanium nitride (via CVD) without chamber switching. This eliminates contamination from transitions while maintaining the material optimization benefits of using both deposition methods.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The reaction chamber is designed to perform multiple functions: it can operate as a PVD chamber for titanium silicide formation and as a CVD chamber for titanium nitride formation. This multi-functionality eliminates the need for separate chambers while maintaining process quality.

Inventive Principle:

Principle #6Universality (Multi-functionality)

2Reliability

If PVD and CVD processes are used separately for forming titanium silicide and titanium nitride layers, then material properties can be optimized, but chamber switching causes contamination

Engineering Contradiction:

Improvefilm qualityVSAvoidcontamination

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

Inventive Principle:

Principle #5Merging (Combining)

3Ease of manufacture

If conventional deposition methods are used in high aspect-ratio contact regions, then processing is simpler, but non-conformal deposition increases parasitic resistance

Engineering Contradiction:

Improveprocessing simplicityVSAvoiddeposition conformality

Core Design Contradiction:

Ease of manufactureVSManufacturing precision

Solution Approach 1:

The patent uses plasma-enhanced chemical vapor deposition (PECVD) which provides dynamic control over the deposition process. The plasma activation allows for better step coverage and conformal deposition in high aspect-ratio contact regions, improving film uniformity while maintaining process feasibility.

Inventive Principle:

Principle #15Dynamics

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 results in improved conformality, uniformity, and reduced parasitic resistance between the contact layer and the S/D region, while also reducing fabrication time and preventing diffusion of metal atoms into gate structures.

Implementation Method 1

an in-situ treatment and CVD process to form titanium silicide and titanium nitride layers

Methodology Applied

Scientific EffectChemical Vapour Deposition: Chemical Vapour Deposition

Implementation Method 2

The use of an in-situ treatment and CVD process to form titanium silicide and titanium nitride layers

Methodology Applied

Scientific EffectIn-situ treatment:

Data Source

PatentUS11972951B2Selective formation of titanium silicide and titanium nitride by hydrogen gas control

Publication Date: 2024.04.30 TAIWAN SEMICONDUCTOR MANUFACTURING CO LTD

AI summary

The present disclosure relates to a method for fabricating a semiconductor structure. The method includes providing a substrate with a gate structure, an insulating structure over the gate structure, and a S/D region; depositing a titanium silicide layer over the S/D region with a first chemical vapor deposition (CVD) process. The first CVD process includes a first hydrogen gas flow. The method also includes depositing a titanium nitride layer over the insulating structure with a second CVD process. The second CVD process includes a second hydrogen gas flow. The first and second CVD processes are performed in a single reaction chamber and a flow rate of the first hydrogen gas flow is higher than a flow rate of the second hydrogen gas flow.