Protecting Layer for Semiconductor Interconnects

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Solution Overview

Problem

As semiconductor technology advances, the shrinking dimensions of interconnect metal lines lead to signal un-reliabilities and failures due to electromigration phenomena, and existing precursor soak and plasma treatment processes damage low-K dielectric layers through metal ion diffusion and plasma conversion.

Innovation Solution

A protecting layer, typically 15 Å thick and composed of materials like carbon-doped nitride or silicon nitride, is applied to prevent metal ion diffusion and plasma conversion into low-K dielectric layers, reducing damage during prolonged capping processes and enhancing the reliability of interconnects.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If precursor soak and plasma treatment processes are used to improve electromigration resistance, then interconnect reliability is improved, but low-K dielectric layer is damaged due to metal ion diffusion

Engineering Contradiction:

Improveinterconnect reliabilityVSAvoidmetal ion diffusion damage

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

A protecting layer comprising carbon-doped nitride or silicon nitride is introduced as an intermediary barrier between the interconnect metal line and the low-K dielectric layer. This protecting layer prevents metal ion diffusion from the interconnect into the dielectric during precursor soak and plasma treatment processes, while still allowing the capping layer to provide electromigration protection. The protecting layer acts as a mediator that enables the harmful process (precursor soak/plasma treatment) to proceed without damaging the sensitive low-K dielectric material.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The capping structure is segmented into multiple functional layers: a protecting layer (carbon-doped nitride or silicon nitride) directly contacting the low-K dielectric, and a capping layer (metal oxide, metal nitride, or metal oxynitride) providing electromigration protection. This segmentation allows each layer to perform its specific function independently - the protecting layer prevents metal ion diffusion while the capping layer provides EM resistance, resolving the contradiction between improving reliability and preventing dielectric damage.

Inventive Principle:

Principle #1Segmentation

2Reliability

If capping layer formation time is prolonged to enhance protection, then electromigration resistance is improved, but damage to low-K dielectric layer increases

Engineering Contradiction:

Improveelectromigration resistanceVSAvoidcapping process duration

Core Design Contradiction:

ReliabilityVSDuration of action of stationary object

Solution Approach 1:

The protecting layer serves as a protective intermediary that enables prolonged precursor soak and plasma treatment processes to proceed without damaging the low-K dielectric. By introducing this barrier layer, the process duration can be extended to achieve better electromigration protection in the capping layer while the protecting layer prevents metal ion diffusion into the dielectric, thus resolving the time-duration contradiction.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Reliability

If plasma treatment is applied to improve capping layer quality, then interconnect reliability is improved, but plasma conversion damages the low-K dielectric layer

Engineering Contradiction:

Improveinterconnect reliabilityVSAvoidplasma conversion damage

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The protecting layer comprising carbon-doped nitride or silicon nitride acts as a plasma-resistant intermediary barrier during plasma treatment. It protects the low-K dielectric layer from plasma conversion and damage while allowing the plasma treatment to effectively improve the capping layer quality and electromigration resistance. The protecting layer absorbs or blocks the harmful plasma effects from reaching the sensitive dielectric material.

Inventive Principle:

Principle #24Intermediary (Mediator)

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 protecting layer effectively reduces and eliminates electromigration effects and metal ion diffusion, protecting low-K dielectric layers from damage, thereby improving the reliability and electrical performance of semiconductor structures.

Implementation Method 1

a protecting layer, typically 15 Å thick and composed of materials like carbon-doped nitride or silicon nitride, is applied to prevent metal ion diffusion and plasma conversion into low-K dielectric layers

Methodology Applied

Scientific EffectDiffusion barrier: Diffusion Barrier

Implementation Method 2

Methodology Applied

Scientific EffectPlasma resistance: Plasma

Data Source

PatentUS9859152B2Protecting layer in a semiconductor structure

Publication Date: 2018.01.02 TAIWAN SEMICONDUCTOR MANUFACTURING CO LTD

AI summary

A method for forming a protecting layer includes determining an expected concentration of metal ions in a dielectric layer. The method also includes determining a thickness of the protecting layer based on the expected concentration of metal ions. The method also includes forming the protecting layer at the determined thickness and in contact with the dielectric layer. The protecting layer can include at least one of silicon doped nitride, carbon nitride, silicon nitride, or silicon carbon.