Source/Drain ILD and CESL Structure for Oxidation-Resistant Contacts

Solution Overview

Problem

Existing semiconductor manufacturing processes face challenges in forming inter-layer dielectrics and etch stop layers that adequately adhere to underlying layers and protect them from oxidation, particularly when using low reactive sticking coefficient deposition methods like FCVD, leading to potential oxidation and contamination of source/drain regions.

Innovation Solution

A combination of nitridation treatment for the contact etch stop layer (CESL) and oxide curing process for the inter-layer dielectric (ILD) is employed to enhance adhesion and barrier properties, reducing oxidation and contamination risks by increasing nitrogen concentration in the CESL and improving the quality of the ILD.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If low reactive sticking coefficient deposition methods like FCVD are used to form inter-layer dielectric layers, then deposition efficiency is improved, but adhesion to underlying layers deteriorates and oxidation protection is insufficient

Engineering Contradiction:

Improvedeposition efficiencyVSAvoidadhesion and oxidation protection

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

A contact etch stop layer (CESL) is introduced as an intermediary layer between the underlying source/drain region and the inter-layer dielectric (ILD) layer. The CESL serves as a mediator that provides both adhesion promotion and oxidation barrier functions, allowing the use of FCVD for ILD deposition while preventing direct contact between the ILD and underlying layers, thus solving the adhesion and oxidation protection problems.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The contact etch stop layer is formed as a composite structure with multiple materials having different etch selectivities and functional properties. This composite approach allows the CESL to simultaneously provide adhesion enhancement, oxidation barrier protection, and etch stop functionality, resolving the contradiction between deposition efficiency and reliability.

Inventive Principle:

Principle #40Composite materials

2Reliability

If conventional deposition methods are used for inter-layer dielectric layers, then adhesion to underlying layers is maintained, but deposition time and manufacturing complexity increase

Engineering Contradiction:

ImproveadhesionVSAvoidmanufacturing process complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The contact etch stop layer is designed to perform multiple functions simultaneously: adhesion promotion, oxidation barrier protection, etch stop functionality, and deposition rate control. This multi-functionality reduces the need for separate specialized layers, simplifying the overall manufacturing process while maintaining adhesion reliability.

Inventive Principle:

Principle #6Universality (Multi-functionality)

3Device complexity

If the inter-layer dielectric layer is deposited directly on source/drain regions, then manufacturing steps are reduced, but oxidation and contamination of source/drain regions occur

Engineering Contradiction:

Improvenumber of manufacturing stepsVSAvoidoxidation and contamination

Core Design Contradiction:

Device complexityVSObject-affected harmful factors

Solution Approach 1:

The contact etch stop layer is deposited preliminarily on the source/drain regions before the inter-layer dielectric layer is formed. This preliminary action creates a protective barrier that prevents oxidation and contamination during subsequent processing steps, while still maintaining a relatively simple manufacturing process.

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 proposed method improves the adherence and barrier properties of the ILD, preventing oxidation and contamination of underlying layers, thereby enhancing the performance and reliability of semiconductor devices.

Implementation Method 1

A combination of nitridation treatment for the contact etch stop layer (CESL) and oxide curing process for the inter-layer dielectric (ILD) is employed to enhance adhesion and barrier properties, reducing oxidation and contamination risks by increasing nitrogen concentration in the CESL

Methodology Applied

Scientific EffectNitridation: Nitriding

Implementation Method 2

A combination of nitridation treatment for the contact etch stop layer (CESL) and oxide curing process for the inter-layer dielectric (ILD) is employed to enhance adhesion and barrier properties, reducing oxidation and contamination risks by increasing nitrogen concentration in the CESL and improving the quality of the ILD

Methodology Applied

Scientific EffectOxide curing:

Data Source

PatentUS20250344435A1Inter-layer dielectrics and etch stop layers for transistor source/drain regions

Publication Date: 2025.11.06 TAIWAN SEMICONDUCTOR MANUFACTURING CO LTD

AI summary

In an embodiment, a device includes: a gate structure over a substrate; a gate spacer adjacent the gate structure; a source/drain region adjacent the gate spacer; a first inter-layer dielectric (ILD) on the source/drain region, the first ILD having a first concentration of an impurity; and a second ILD on the first ILD, the second ILD having a second concentration of the impurity, the second concentration being less than the first concentration, top surfaces of the second ILD, the gate spacer, and the gate structure being coplanar; and a source/drain contact extending through the second ILD and the first ILD, the source/drain contact coupled to the source/drain region.