Continuous Copper Contact Formation in Semiconductor Devices

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Solution Overview

Problem

The existing methods of forming semiconductor devices result in increased resistance due to the use of two different contacts, which is exacerbated as technology scales.

Innovation Solution

A method is developed to form a continuously formed copper contact across multiple levels by creating a sacrificial layer, aligning and removing it, and depositing a liner and copper layer within contact holes, allowing for an interface-free metal layer across multiple levels.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If two different contacts are used in separate contact holes, then the manufacturing process is simple, but the contact resistance increases

Engineering Contradiction:

Improvecontact resistanceVSAvoidcontact structure

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent merges two separate contacts into a single continuous copper contact that extends from the first contact hole through the second contact hole. This is achieved by forming a sacrificial layer in the first contact hole, depositing a liner layer, filling with copper, and then forming a second contact hole aligned with the first. The continuous copper structure eliminates the interface between two separate contacts, thereby reducing contact resistance while maintaining manufacturing feasibility.

Inventive Principle:

Principle #5Merging (Combining)

2Reliability

If a continuous copper contact is formed across multiple levels, then contact resistance is reduced, but the manufacturing process complexity increases

Engineering Contradiction:

Improvecontact resistanceVSAvoidmanufacturing process

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The patent applies preliminary action by forming a sacrificial layer in the first contact hole before forming the second contact hole. This sacrificial layer (e.g., silicon nitride) is deposited and patterned in advance to define the first contact hole region. The liner layer is also deposited conformally on the sacrificial layer and sidewalls before copper filling. These preliminary steps enable the subsequent formation of a continuous copper structure across multiple levels while maintaining manufacturing control and simplicity.

Inventive Principle:

Principle #10Preliminary action

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 reduces contact resistance by creating a continuous copper contact from the active area to the upper surface of the dielectric layer, eliminating the need for separate contacts and providing a low-resistance interface-free metal layer across multiple levels.

Implementation Method 1

forming a copper contact in the first and second contact holes

Methodology Applied

Scientific EffectPhysical Vapour Deposition: Physical Vapour Deposition

Implementation Method 2

a reflowed copper layer formed in the first and second contact holes

Methodology Applied

Scientific EffectReflow:

Data Source

PatentUS10256145B2Semiconductor device and method of forming the semiconductor device

Publication Date: 2019.04.09 INTERNATIONAL BUSINESS MACHINE CORPORATION

AI summary

A method of forming a semiconductor device includes forming a sacrificial layer in a first contact hole of a first dielectric layer, forming a second dielectric layer on the first dielectric layer, and forming a second contact hole in the second dielectric layer, the second contact hole being aligned with the first contact hole, removing the sacrificial layer from the first contact hole, and forming a copper contact in the first and second contact holes.