Bottom-Up Contact Plug Filling for High-Aspect-Ratio Backside Holes

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Solution Overview

Problem

The formation of metal contact plugs on the backside of semiconductor wafers with high aspect ratios leads to voids and seams due to incomplete filling, resulting in high electrical resistance.

Innovation Solution

A method of bottom-up metal growth is employed, involving the formation of a silicide layer, a metal seed layer, and a protective metal nitride layer to facilitate complete filling of the contact hole, preventing voids and seams.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If conventional metal filling methods are used for high aspect ratio contact holes, then the contact hole can be filled, but voids and seams form resulting in high electrical resistance

Engineering Contradiction:

Improvefilling completenessVSAvoidelectrical resistance

Core Design Contradiction:

Manufacturing precisionVSReliability

Solution Approach 1:

The patent inverts the conventional filling approach by using bottom-up growth instead of top-down deposition. Metal layers are grown from the bottom of the contact hole upward, ensuring complete filling without voids or seams that plague conventional methods. This inversion of the filling direction resolves the contradiction between achieving complete filling and maintaining low electrical resistance.

Inventive Principle:

Principle #13The other way round (Inversion)

Solution Approach 2:

The patent applies preliminary action by first forming a seed layer at the bottom of the contact hole before growing the metal contact layer. This seed layer serves as a foundation that enables controlled bottom-up metal growth, ensuring that the contact hole is completely filled from the bottom up without forming voids or seams, thereby achieving both complete filling and low electrical resistance.

Inventive Principle:

Principle #10Preliminary action

2Adaptability or versatility

If the contact hole aspect ratio is high, then backside contact formation is enabled, but incomplete filling occurs leading to voids and seams

Engineering Contradiction:

Improvebackside contact capabilityVSAvoidfilling completeness

Core Design Contradiction:

Adaptability or versatilityVSManufacturing precision

Solution Approach 1:

The patent inverts the filling direction to bottom-up growth, which is particularly effective for high aspect ratio contact holes. This inversion allows metal to be deposited from the bottom where it can flow and fill the entire height of the contact hole completely, overcoming the filling completeness issues that arise in high aspect ratio structures with conventional top-down methods.

Inventive Principle:

Principle #13The other way round (Inversion)

Solution Approach 2:

The patent transitions from conventional planar deposition to vertical bottom-up growth, adding a dimensional aspect to the filling process. By growing metal vertically from the bottom of the contact hole upward, the process accommodates high aspect ratio structures while ensuring complete filling, thus enabling backside contact formation without sacrificing filling completeness.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

3Reliability

If metal layer is deposited to fill high aspect ratio contact holes, then connectivity is achieved, but voids and seams form reducing electrical performance

Engineering Contradiction:

ImproveconnectivityVSAvoidelectrical performance

Core Design Contradiction:

ReliabilityVSManufacturing precision

Solution Approach 1:

The patent inverts the deposition sequence to grow metal from the bottom upward rather than depositing from the top down. This bottom-up approach ensures that metal completely fills the contact hole volume without forming voids or seams, achieving both reliable connectivity and high electrical performance by eliminating defects that would otherwise form in high aspect ratio structures.

Inventive Principle:

Principle #13The other way round (Inversion)

Solution Approach 2:

The patent uses a seed layer as a template or copy at the bottom of the contact hole that guides the subsequent metal growth. This seed layer copying approach ensures that the metal contact layer replicates the desired complete filling pattern from the bottom up, achieving both connectivity and excellent electrical performance without voids or seams.

Inventive Principle:

Principle #26Copying

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

This approach ensures low electrical resistance and reliable connectivity by avoiding voids and seams in the contact plug, enhancing the electrical performance of semiconductor devices.

Implementation Method 1

a silicide layer is formed over the silicon-containing feature

Methodology Applied

Scientific EffectSilicidation: Chemical Bonding

Implementation Method 2

chemical vapor deposition (CVD) is used to deposit a metal contact layer over the metal seed layer

Methodology Applied

Scientific EffectChemical Vapor Deposition: Chemical Vapour Deposition

Data Source

PatentUS20250357203A1Method for forming a contact plug by bottom-up metal growth

Publication Date: 2025.11.20 TAIWAN SEMICONDUCTOR MANUFACTURING CO LTD

AI summary

A method is provided for forming a contact plug by bottom-up metal growth. In one step, a substrate is etched to form a contact hole that exposes a silicon-containing feature in the substrate. In one step, a silicide layer is formed on the silicon-containing feature. In one step, a metal seed layer is formed over the silicide layer. In one step, a metal contact layer is deposited over the metal seed layer to form the contact plug in the contact hole.