Metal Hard Mask Structure for Reducing Dielectric Line Bending

Solution Overview

Problem

The reduction in line widths and spacings between metal lines in integrated circuits leads to distortion of the dielectric layer, causing issues in gap-filling processes and potential line-breaking during the formation of metal lines and vias.

Innovation Solution

A metal hard mask layer with a high Young's modulus and high tensile stress is used to reduce distortion of the dielectric layer between trenches, improving gap-filling and reducing line-width roughness by adjusting deposition conditions such as plasma power to achieve optimal tensile stress.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If line widths and spacings between metal lines are reduced to increase circuit density, then productivity and integration density are improved, but the dielectric layer between trenches becomes distorted and manufacturing precision deteriorates

Engineering Contradiction:

Improvecircuit densityVSAvoiddielectric layer distortion

Core Design Contradiction:

ProductivityVSManufacturing precision

Solution Approach 1:

The patent changes the mechanical parameters of the hard mask layer by selecting materials with high Young's modulus (e.g., tungsten, ruthenium, osmium, iridium, rhodium, palladium, platinum) to reduce dielectric layer distortion. This parameter change allows the hard mask to maintain structural integrity and provide sufficient mechanical support during trench formation, enabling reduced line widths and spacings without compromising manufacturing precision

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent employs composite structures combining the metal hard mask layer with the dielectric layer. The hard mask layer acts as a reinforcing composite material that provides mechanical support to the dielectric layer, preventing distortion while allowing high-density interconnect structures to be formed

Inventive Principle:

Principle #40Composite materials

2Productivity

If the dielectric layer between trenches becomes narrower, then circuit density is improved, but gap-filling process reliability deteriorates due to distortion

Engineering Contradiction:

Improvecircuit densityVSAvoidgap-filling process

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The patent changes the mechanical parameters of the hard mask layer by selecting materials with high Young's modulus (e.g., tungsten, ruthenium, osmium, iridium, rhodium, palladium, platinum) to reduce dielectric layer distortion. This parameter change allows the hard mask to maintain structural integrity and provide sufficient mechanical support during trench formation, enabling reduced line widths and spacings without compromising manufacturing precision

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The hard mask layer is deposited beforehand to provide mechanical support and cushioning to the dielectric layer before trench formation. This prior cushioning prevents distortion from occurring during subsequent processing steps, ensuring reliable gap-filling even when dielectric regions are narrowed

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

3Productivity

If metal lines are formed with smaller dimensions, then productivity is improved, but line-breaking occurs during formation due to distortion

Engineering Contradiction:

Improveline width reductionVSAvoidline-breaking

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The patent changes the mechanical parameters of the hard mask layer by selecting materials with high Young's modulus (e.g., tungsten, ruthenium, osmium, iridium, rhodium, palladium, platinum) to reduce dielectric layer distortion. This parameter change allows the hard mask to maintain structural integrity and provide sufficient mechanical support during trench formation, enabling reduced line widths and spacings without compromising manufacturing precision

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The hard mask layer is deposited beforehand to provide mechanical support and cushioning to the dielectric layer before trench formation. This prior cushioning prevents distortion from occurring during subsequent processing steps, ensuring reliable gap-filling even when dielectric regions are narrowed

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

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 high modulus and tensile stress of the metal hard mask layer enhances the integrity of trenches, resulting in improved gap-filling and reduced line-width roughness, particularly for line widths smaller than 20 nm.

Implementation Method 1

the metal hard mask layer has a high Young's modulus and a high tensile stress

Methodology Applied

Scientific EffectYoung's modulus:

Implementation Method 2

the metal hard mask layer has a high Young's modulus and a high tensile stress

Methodology Applied

Scientific EffectTensile stress:

Data Source

PatentUS20250336675A1Metal hard masks for reducing line bending

Publication Date: 2025.10.30 TAIWAN SEMICONDUCTOR MANUFACTURING CO LTD

AI summary

A method includes forming a metal-containing hard mask layer over a dielectric layer, wherein the metal-containing hard mask layer has a Young's modulus greater than about 400 MPa and a tensile stress greater than about 600 MPa, patterning the metal-containing hard mask layer to form an opening in the metal-containing hard mask layer, and etching the dielectric layer using the metal-containing hard mask layer as an etching mask. The opening extends into the dielectric layer. The opening is filled with a conductive material to form a conductive feature. The metal-containing hard mask layer is then removed.