Selective Transition Metal Precursors for Nanoscale Via Deposition
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The semiconductor industry faces challenges in manufacturing smaller vias and transistors due to limitations in lithographic processes, particularly with via pitches below 70 nanometers and critical dimensions below 35 nanometers, where overlay tolerances and critical dimension uniformity are difficult to control, and current photoresists do not improve rapidly enough to keep up with shrinking dimensions.
Innovation Solution
The development of inherently selective precursors for the deposition of second or third row transition metal thin films, such as tungsten or ruthenium, using specific ligand frameworks that allow for selective atomic layer deposition or chemical vapor deposition on metal surfaces without contaminating adjacent dielectric layers, enabling conformal metal film growth and reducing the need for complex lithographic masks and processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If conventional lithographic processes are used to pattern smaller vias, then via sizes and spacing can be reduced, but overlay tolerances and critical dimension uniformity become difficult to control
Solution Approach 1:
The precursor molecules self-assemble on metal surfaces through inherent chemical selectivity, with the metal surface itself directing the deposition process. The precursor's ligand framework automatically orients and binds to exposed metal, eliminating the need for external alignment systems or complex lithographic patterning to achieve precise spatial control.
Solution Approach 2:
The invention changes the chemical parameters of the deposition process by using precursors with specific ligand frameworks (diazabutadiene, pyrazolate, triazolate) that alter the reaction kinetics and selectivity. This enables deposition at lower temperatures and provides inherent selectivity for metal surfaces over dielectric materials, improving precision without relying on lithographic capabilities.
2Length of moving object
If photoresist layers are used for patterning, then via openings can be defined, but line width roughness and critical dimension uniformity deteriorate as dimensions shrink
Solution Approach 1:
The invention replaces the mechanical lithographic patterning system with a chemical self-assembly system. Instead of using photoresist layers that require lithographic exposure and development, the process uses precursor molecules that automatically assemble on metal surfaces through chemical affinity, eliminating LWR and CDU issues associated with photoresist.
3Length of moving object
If multiple lithographic masks are used to achieve smaller via pitches, then resolution capabilities can be extended, but manufacturing complexity and costs increase
Solution Approach 1:
The metal surfaces serve as self-aligned templates that automatically define the spatial positions of deposited features. Subsequent layers deposit only on the previously deposited metal, creating a self-aligned multi-layer structure without requiring additional lithographic alignment steps or masks.
Solution Approach 2:
The first metal layer is deposited as a preliminary template that pre-defines the pattern for subsequent layers. This preliminary action eliminates the need for additional lithographic patterning steps, as the template itself guides the formation of overlying structures.
4Reliability
If selective deposition is achieved through complex passivation processes, then selectivity can be obtained, but process complexity and manufacturing steps increase
Solution Approach 1:
The invention changes the chemical parameters of the precursor molecules by incorporating specific ligand frameworks that provide inherent selectivity. The diazabutadiene, pyrazolate, and triazolate ligands are designed to have specific chemical affinity for metal surfaces, enabling selective deposition without complex passivation or surface preparation steps.
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 enables precise and conformal metal deposition, improving overlay tolerances and critical dimension uniformity, reducing manufacturing steps, and allowing for the production of smaller features without compromising film quality or increasing costs, thus addressing the scaling challenges in semiconductor manufacturing.
Implementation Method 1
enabling conformal metal film growth and reducing the need for complex lithographic masks and processes
Implementation Method 2
using specific ligand frameworks that allow for selective atomic layer deposition or chemical vapor deposition on metal surfaces
Implementation Method 3
Each of the precursor molecules includes a second or third row transition metal center complexed with three heteroleptic bidentate ligands, and the method includes depositing a second or third row transition metal layer on the metal surface by thermally dissociating the ligands from the precursor molecules
Data Source
AI summary
Inherently selective precursors for deposition of second or third row transition metal (e.g., tungsten or ruthenium) thin films are described. In an example, a ligand framework for second or third row transition metal complex formation includes a lithium complex.