Tapered Contact Plug Structure for Low Resistance and Dielectric Strength

Solution Overview

Problem

The challenge in semiconductor devices is the trade-off between high contact resistance and reduced dielectric strength due to the diameter of the contact plug, which affects the performance of wiring connections.

Innovation Solution

A contact plug design with a larger diameter at the bottom and a smaller diameter at the top, combined with a spacer insulating film, reduces contact resistance and increases dielectric strength by optimizing the plug's cross-sectional dimensions.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the diameter of the contact plug is increased, then the contact resistance is reduced, but the dielectric strength between adjacent wiring patterns and the contact plug is reduced

Engineering Contradiction:

Improvecontact resistanceVSAvoiddielectric strength

Core Design Contradiction:

ReliabilityVSStrength

Solution Approach 1:

The contact plug employs a non-uniform diameter design where the lower portion (in contact with first wiring patterns) has a larger diameter to reduce contact resistance, while the upper portion (near second wiring patterns) has a smaller diameter to maintain dielectric strength. This local differentiation of dimensions optimizes both electrical and insulating performance in different spatial zones.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The contact plug features an asymmetric cross-sectional shape, being elongated in the first direction where wiring patterns are spaced farther apart (requiring larger diameter for low resistance) and narrower in the second direction where wiring patterns are closer (requiring smaller diameter for high dielectric strength). This asymmetric geometry resolves the contradiction between contact resistance and dielectric strength.

Inventive Principle:

Principle #4Asymmetry

2Strength

If the diameter of the contact plug is decreased, then the dielectric strength is improved, but the contact resistance becomes high

Engineering Contradiction:

Improvedielectric strengthVSAvoidcontact resistance

Core Design Contradiction:

StrengthVSReliability

Solution Approach 1:

The contact plug employs a non-uniform diameter design where the lower portion (in contact with first wiring patterns) has a larger diameter to reduce contact resistance, while the upper portion (near second wiring patterns) has a smaller diameter to maintain dielectric strength. This local differentiation of dimensions optimizes both electrical and insulating performance in different spatial zones.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The contact plug features an asymmetric cross-sectional shape, being elongated in the first direction where wiring patterns are spaced farther apart (requiring larger diameter for low resistance) and narrower in the second direction where wiring patterns are closer (requiring smaller diameter for high dielectric strength). This asymmetric geometry resolves the contradiction between contact resistance and dielectric strength.

Inventive Principle:

Principle #4Asymmetry

3Ease of manufacture

If a uniform diameter contact plug is used, then the manufacturing process is simplified, but both contact resistance and dielectric strength cannot be simultaneously optimized

Engineering Contradiction:

Improvecontact plug fabricationVSAvoidelectrical performance

Core Design Contradiction:

Ease of manufactureVSReliability

Solution Approach 1:

The contact plug employs a non-uniform diameter design where the lower portion (in contact with first wiring patterns) has a larger diameter to reduce contact resistance, while the upper portion (near second wiring patterns) has a smaller diameter to maintain dielectric strength. This local differentiation of dimensions optimizes both electrical and insulating performance in different spatial zones.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The contact plug features an asymmetric cross-sectional shape, being elongated in the first direction where wiring patterns are spaced farther apart (requiring larger diameter for low resistance) and narrower in the second direction where wiring patterns are closer (requiring smaller diameter for high dielectric strength). This asymmetric geometry resolves the contradiction between contact resistance and dielectric strength.

Inventive Principle:

Principle #4Asymmetry

Data Source

PatentUS12581940B2Semiconductor device having contact plug

Publication Date: 2026.03.17 MICRON TECHNOLOGY INC

AI summary

An apparatus that includes a first conductive pattern positioned at a first wiring layer and extending in a first direction, a second conductive pattern positioned at a second wiring layer located above the first wiring layer and extending in a second direction, and a contact plug connecting the first conductive pattern with the second conductive pattern. The contact plug includes a lower conductive section contacting the first conductive pattern and an upper conductive section contacting the second conductive pattern. The width of the lower conductive section on a first boundary between the lower and upper conductive sections in the first direction is greater than the width of the upper conductive section on the first boundary in the first direction and the width of the second conductive pattern on a second boundary between the contact plug and the second conductive pattern in the first direction.