Footed Metal Interconnect Via for Low Resistance Contact

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Advanced semiconductor devices face increased contact resistance due to reduced contact area between contact via structures and underlying conductive structures, which adversely affects semiconductor circuit performance.

Innovation Solution

The implementation of metal interconnect structures with a second metallic nitride liner having a pillar portion with a straight sidewall and a foot portion adjoined to the bottom periphery, which increases the contact area without expanding the contact area, and a method involving the formation of metal oxide plates, selective etching, and deposition of conductive metal nitride and fill materials to create these structures.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Area of moving object

If the contact area is reduced to meet advanced semiconductor device requirements, then the device scaling is achieved, but the contact resistance increases

Engineering Contradiction:

Improvecontact areaVSAvoidcontact resistance

Core Design Contradiction:

Area of moving objectVSReliability

Solution Approach 1:

The invention transitions from a conventional cylindrical contact via structure to a multi-level structure with a foot portion that laterally protrudes from the bottom periphery of the pillar portion. This dimensional change increases the contact area footprint by extending into the lateral dimension while maintaining the vertical scaling benefits, thereby reducing contact resistance without sacrificing device scaling.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

Solution Approach 2:

The contact structure is segmented into distinct functional portions: a pillar portion with straight sidewalls for vertical connection and a foot portion with lateral protrusion for expanded contact area. This segmentation allows each portion to optimize its function - the pillar provides structural integrity and vertical connectivity while the foot portion maximizes the contact interface area with the underlying conductive structure.

Inventive Principle:

Principle #1Segmentation

2Reliability

If the contact area is increased to reduce contact resistance, then the contact resistance decreases, but the contact area footprint expands

Engineering Contradiction:

Improvecontact resistanceVSAvoidcontact area footprint

Core Design Contradiction:

ReliabilityVSArea of stationary object

Solution Approach 1:

The foot portion is strategically positioned at the bottom periphery of the contact structure where lateral protrusion locally expands the contact area without affecting the overall vertical profile. This localized quality enhancement concentrates the area increase at the critical contact interface while maintaining compact dimensions in other regions, thus reducing contact resistance without proportionally increasing the total footprint.

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 configuration reduces contact resistance by increasing the contact area between metal interconnect structures while maintaining the same contact area footprint, thereby enhancing semiconductor device performance.

Implementation Method 1

forming a metal oxide plate by oxidizing a surface region of the first metallic fill material portion

Methodology Applied

Scientific EffectOxidation: Oxidation

Implementation Method 2

depositing a second conductive metal nitride in the expanded second cavity

Methodology Applied

Scientific EffectPhysical Vapour Deposition: Physical Vapour Deposition

Data Source

PatentUS10818545B2Contact via structure including a barrier metal disc for low resistance contact and methods of making the same

Publication Date: 2020.10.27 SANDISK TECHNOLOGIES LLC

AI summary

A first metal interconnect structure embedded in a first dielectric material layer includes a first metallic nitride liner containing a first conductive metal nitride and a first metallic fill material portion. A second metal interconnect structure embedded in a second dielectric material layer overlies the first dielectric material layer. The second metal interconnect structure includes a pillar portion having a straight sidewall and a foot portion adjoined to a bottom periphery of the pillar portion and laterally protruding from the bottom periphery of the pillar portion. The foot portion can be formed by oxidizing a top surface of the first metallic fill material portion, removing the oxidized portion after formation of a cavity through the second dielectric material layer, and depositing a second metallic nitride liner in a volume from which the oxidized portion is removed.