Semiconductor Conductive Feature Interface Mixing to Cut Resistance

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Solution Overview

Problem

The semiconductor industry faces challenges in reducing the resistance of conductive features in FinFETs and other electronic devices due to seam merging and thermal expansion, which affects yield and reliability.

Innovation Solution

The formation of conductive features using a liner layer and a filler layer that can form a homogeneous mixture, with a thermal process to create a smoother interface and reduce resistance, and a capping layer to increase contact area and reduce contact resistance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a single conductive material is used to fill the conductive feature, then the manufacturing process is simpler, but seam merging and thermal expansion cause increased resistance and reduced reliability

Engineering Contradiction:

Improvereliability of conductive featureVSAvoidcomplexity of conductive feature structure

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The conductive feature is formed using a composite structure with a liner layer of first conductive material and a filler layer of second conductive material. The liner layer materials (e.g., tungsten, cobalt, copper) are specifically selected to mitigate seam merging and thermal expansion effects, while the filler layer provides bulk conductivity. This composite approach resolves the contradiction by improving reliability through material selection without requiring overly complex manufacturing processes.

Inventive Principle:

Principle #40Composite materials

2Reliability

If the conductive feature uses a larger contact area, then contact resistance is reduced, but the device area increases

Engineering Contradiction:

Improvecontact resistanceVSAvoidarea of conductive feature

Core Design Contradiction:

ReliabilityVSArea of stationary object

Solution Approach 1:

The liner layer is applied selectively at the interfaces and contact regions where electrical connection is critical. This localized approach concentrates the resistance-reducing effect at the contact interfaces without expanding the overall conductive feature area. The filler layer then provides the bulk conductive path, achieving low contact resistance while maintaining compact device dimensions.

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

This approach improves the reliability and yield of conductive features by reducing resistance and contact resistance, addressing issues related to seam merging and thermal expansion.

Implementation Method 1

a thermal process to create a smoother interface and reduce resistance

Methodology Applied

Scientific EffectThermal diffusion: Diffusion

Implementation Method 2

addressing issues related to seam merging and thermal expansion

Methodology Applied

Scientific EffectThermal expansion: Thermal Expansion

Data Source

PatentUS20240379425A1Conductive feature of semiconductor device and method of forming same

Publication Date: 2024.11.14 TAIWAN SEMICONDUCTOR MANUFACTURING CO LTD

AI summary

A method includes forming a device region over a substrate; forming a first dielectric layer over the device region; forming an opening in the first dielectric layer; conformally depositing a first conductive material along sidewalls and bottom surfaces of the opening; depositing a second conductive material on the first conductive material to fill the opening, wherein the second conductive material is different from the first conductive material; and performing a first thermal process to form an interface region extending from a first region of the first conductive material to a second region of the second conductive material, wherein the interface region includes a homogeneous mixture of the first conductive material and the second conductive material.