Contact Structure Fabrication for Uniform Small-Opening Fill

Solution Overview

Problem

The scaling down of feature sizes in semiconductor devices has made it difficult to fill small openings with conductive materials, leading to damaged contact structures or contact plugs with high resistance and yield loss issues.

Innovation Solution

A method of fabricating a contact structure involves forming a conductive material layer with a top section having a greater thickness than a bottom section, followed by a gradient metal removal cycle that includes oxide treatments and etching steps to equalize the thickness of the conductive material layer, thereby improving gap filling capability and reducing damage.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If feature sizes are scaled down to increase device density, then device integration is improved, but filling small openings with conductive materials becomes difficult

Engineering Contradiction:

Improvedevice integrationVSAvoidopening filling

Core Design Contradiction:

ProductivityVSEase of manufacture

Solution Approach 1:

The method performs preliminary actions by forming a mandrel structure and depositing conductive material with intentional overhang before removing the mandrel. This preliminary configuration allows the conductive material to be supported during deposition, enabling successful filling of small openings that would otherwise be too difficult to fill directly

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The mandrel structure serves as an intermediary element that facilitates the filling process. The mandrel provides a scaffold that supports the conductive material during deposition, allowing the material to be placed in the opening without requiring direct filling of the small opening itself

Inventive Principle:

Principle #24Intermediary (Mediator)

2Device complexity

If conventional opening filling methods are used, then manufacturing process is simple, but contact structures are damaged and resistance is high

Engineering Contradiction:

Improvemanufacturing processVSAvoidcontact structure integrity

Core Design Contradiction:

Device complexityVSReliability

Solution Approach 1:

The method performs preliminary actions by forming a mandrel structure and depositing conductive material with intentional overhang before removing the mandrel. This preliminary configuration allows the conductive material to be supported during deposition, enabling successful filling of small openings that would otherwise be too difficult to fill directly

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The overhang portion of the conductive material serves as a cushioning element that prevents damage during the mandrel removal process. The extra material extends beyond the opening edges, providing structural support and preventing the conductive material from collapsing or damaging the contact structure when the mandrel is removed

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

3Device complexity

If conventional opening filling methods are used, then manufacturing process is simple, but yield loss increases

Engineering Contradiction:

Improvemanufacturing processVSAvoidyield

Core Design Contradiction:

Device complexityVSProductivity

Solution Approach 1:

The method performs preliminary actions by forming a mandrel structure and depositing conductive material with intentional overhang before removing the mandrel. This preliminary configuration allows the conductive material to be supported during deposition, enabling successful filling of small openings that would otherwise be too difficult to fill directly

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The overhang portion of the conductive material serves as a cushioning element that prevents damage during the mandrel removal process. The extra material extends beyond the opening edges, providing structural support and preventing the conductive material from collapsing or damaging the contact structure when the mandrel is removed

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 method results in contact structures with lower resistance and more reliable electrical connections, reducing the likelihood of damage and improving the overall yield of semiconductor devices.

Implementation Method 1

A first treatment is performed on the conductive material layer to form a first oxide layer on the bottom section and on the top section of the conductive material layer

Methodology Applied

Scientific EffectOxidation: Oxidation

Implementation Method 2

A second treatment is performed to remove at least portions of the first oxide layer and at least portions of the conductive material layer

Methodology Applied

Scientific EffectEtching:

Data Source

PatentUS12237218B2Method of fabricating contact structure

Publication Date: 2025.02.25 TAIWAN SEMICONDUCTOR MANUFACTURING CO LTD

AI summary

A method of fabricating a contact structure includes the following steps. An opening is formed in a dielectric layer. A conductive material layer is formed within the opening and on the dielectric layer, wherein the conductive material layer includes a bottom section having a first thickness and a top section having a second thickness, the second thickness is greater than the first thickness. A first treatment is performed on the conductive material layer to form a first oxide layer on the bottom section and on the top section of the conductive material layer. A second treatment is performed to remove at least portions of the first oxide layer and at least portions of the conductive material layer, wherein after performing the second treatment, the bottom section and the top section of the conductive material layer have substantially equal thickness.