Carbon-Rich Copper Layer Structure for Strain Reduction

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Solution Overview

Problem

The semiconductor industry faces challenges in manufacturing copper layers for integrated circuits due to self-annealing and grain growth issues, leading to defects like hump and pit defects, which result in increased sheet resistance over time.

Innovation Solution

Incorporating a carbon-rich copper layer between copper main layers to block grain growth, thereby reducing strain and preventing defects, using an electroplating technique with specific carbon concentration and thickness ratios to form the copper layer structure.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If copper layers are formed using conventional electroplating, then copper layers can be deposited to fill vias and trenches, but self-annealing and grain growth occur leading to hump and pit defects and increased sheet resistance

Engineering Contradiction:

Improvecopper layer uniformityVSAvoidsheet resistance stability

Core Design Contradiction:

Manufacturing precisionVSReliability

Solution Approach 1:

The copper layer is segmented into multiple sub-layers by introducing carbon-rich copper layers at specific positions within the copper structure. These carbon-rich layers act as barriers that divide the continuous copper layer into discrete segments, preventing uncontrolled grain growth across the entire layer while maintaining electrical connectivity.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Carbon-rich copper layers are introduced as intermediary layers between the main copper layers. These intermediary layers serve as grain growth barriers that mediate the interaction between adjacent copper grains, preventing direct grain boundary formation and the associated defects while maintaining the overall copper layer integrity.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Productivity

If copper grain growth is allowed to proceed naturally, then copper layers can be formed efficiently, but hump and pit defects occur reducing manufacturing quality

Engineering Contradiction:

Improvecopper layer formation efficiencyVSAvoiddefect density

Core Design Contradiction:

ProductivityVSManufacturing precision

Solution Approach 1:

Carbon-rich copper layers are strategically positioned within the copper structure to preemptively counteract grain growth before it can lead to defect formation. These preliminary barrier layers prevent the development of hump and pit defects by blocking grain boundary migration at critical stages of grain growth.

Inventive Principle:

Principle #9Preliminary anti-action

Solution Approach 2:

The copper layer structure is transformed into a composite material system consisting of copper matrix with embedded carbon-rich copper layers. This composite structure combines the electrical conductivity of copper with the grain growth inhibition properties of carbon-rich layers, achieving both productivity and precision requirements.

Inventive Principle:

Principle #40Composite materials

3Reliability

If carbon-rich copper layers are added to block grain growth, then sheet resistance stability improves, but manufacturing process complexity increases

Engineering Contradiction:

Improvesheet resistance stabilityVSAvoidcopper layer structure complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

Rather than uniformly modifying the entire copper layer, carbon-rich copper layers are introduced only at specific local positions where grain growth control is most critical. This localized approach maintains sheet resistance stability while minimizing the overall structural complexity and maintaining compatibility with existing manufacturing processes.

Inventive Principle:

Principle #3Local quality

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 carbon-rich copper layer structure effectively slows down the drop in sheet resistance, reducing defects and maintaining performance over time, thus enhancing the reliability and efficiency of copper layer manufacturing.

Implementation Method 1

the carbon-rich copper layer between the copper layers can block or eliminate the growth of copper grains in the copper layer structure

Methodology Applied

Scientific EffectGrain boundary blocking:

Implementation Method 2

using an electroplating technique with specific carbon concentration and thickness ratios to form the copper layer structure

Methodology Applied

Scientific EffectElectroplating: Electroplating

Data Source

PatentUS10840184B2Formation of copper layer structure with self anneal strain improvement

Publication Date: 2020.11.17 TAIWAN SEMICONDUCTOR MANUFACTURING CO LTD

AI summary

In a method for manufacturing an interconnect structure, a dielectric layer is removed to form a first recess and a second recess. The first recess is below the second recess. A first metal layer is deposited to fill the first recess and a first portion of the second recess. A carbon-containing layer is deposited over the first metal layer to fill a second portion of the second recess, which is over the first portion. A second metal layer is deposited over the carbon-containing layer to fill a third portion of the second recess, which is over the second portion. A carbon concentration of the carbon-containing layer is greater than a carbon concentration of the first metal layer and a carbon concentration of the second metal layer, and the carbon concentration of the first metal layer is substantially the same as the carbon concentration of the second metal layer.