Tungsten Interconnect Step Coverage via Selective Deposition
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current methods for fabricating integrated circuitry face challenges in efficiently forming conductive interconnect lines, particularly in achieving desirable step coverage and interface properties in small openings and high aspect ratio structures, using traditional physical vapor deposition techniques like sputter-depositing titanium and titanium nitride.
Innovation Solution
The method involves forming a first conductive line with elemental tungsten deposited selectively against the outer surface, followed by dielectric material formation and via creation, and then non-selectively depositing additional tungsten within the via to electrically couple with the first conductive line, allowing for the formation of a second conductive line that bypasses the need for direct titanium deposition against copper.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If traditional physical vapor deposition techniques (sputter-depositing titanium and titanium nitride) are used, then conductive interconnect lines can be formed, but step coverage and interface properties in small openings and high aspect ratio structures are insufficient
Solution Approach 1:
The patent changes the material parameter from traditional titanium/titanium nitride to tungsten, which has superior step coverage properties. This material substitution resolves the contradiction by providing adequate step coverage in high aspect ratio structures while maintaining fabrication feasibility through established tungsten deposition and etch processes
Solution Approach 2:
The patent introduces an intermediary tungsten layer deposited selectively on the conductive line surface before via formation. This intermediary layer serves as a foundation for subsequent non-selective tungsten deposition in vias, ensuring proper interface properties and electrical coupling while simplifying the overall fabrication process
2Reliability
If traditional titanium deposition against copper is used, then conductive interconnect lines can be formed, but interface properties in high aspect ratio structures are limited
Solution Approach 1:
The patent changes the deposition material from titanium to tungsten, which provides superior interface properties with copper and better performance in high aspect ratio structures. This material parameter change improves reliability while the selective and non-selective deposition sequence maintains process simplicity
Solution Approach 2:
The patent performs preliminary selective deposition of tungsten on the conductive line surface before forming vias. This preliminary action ensures proper interface properties are established in advance, facilitating subsequent via formation and non-selective tungsten deposition without requiring complex in-situ process adjustments
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 enhances the fabrication process by improving step coverage and interface properties without the limitations of traditional methods, enabling more effective electrical coupling and reducing the complexity of using titanium and titanium nitride in high aspect ratio structures.
Implementation Method 1
using traditional physical vapor deposition techniques like sputter-depositing
Implementation Method 2
non-selectively depositing additional tungsten within the via to electrically couple with the first conductive line
Data Source
AI summary
A method of fabricating integrated circuitry includes forming a first conductive line. First elemental tungsten is deposited directly against an elevationally outer surface of the first conductive line selectively relative to any exposed non-conductive material. Dielectric material is formed elevationally over the first conductive line and a via is formed there-through to conductive material of the first conductive line at a location where the first tungsten was deposited. Second elemental tungsten is non-selectively deposited to within the via and electrically couples to the first conductive line. A second conductive line is formed elevationally outward of and electrically coupled to the second tungsten that is within the via.