Tungsten Gapfill Without Nucleation Layer for Lower Resistivity
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
As semiconductor device geometries shrink, the decreased metal volumes in gapfill processes lead to higher resistivity in metal interconnects, particularly due to the use of nucleation layers like silicon or boron in tungsten gapfill, which form high resistance stacks between PVD liners and bulk fills.
Innovation Solution
A method involving a nucleation presoak to form a silicon or boron underlayer on a substrate feature, followed by physical vapor deposition of a tungsten liner and subsequent tungsten gapfill, eliminating the need for a traditional nucleation layer and reducing resistivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a nucleation layer (silicon or boron) is deposited on PVD tungsten liner before bulk fill, then adhesion and bulk fill formation are promoted, but resistivity increases due to formation of high resistance stacks (BW and WSi)
Solution Approach 1:
The patent removes the traditional nucleation layer (silicon or boron layer) from the stack configuration. Instead of having PVD liner + nucleation layer + bulk fill, the invention directly deposits bulk fill metal onto the PVD liner, eliminating the high-resistance intermediate layer while maintaining adhesion through optimized deposition parameters and surface preparation
Solution Approach 2:
The patent modifies deposition parameters including using lower deposition rates, controlling substrate temperature, and adjusting gas flow ratios during PVD and CVD processes to enable direct bulk fill deposition on PVD liner without nucleation layer, achieving both adhesion and low resistivity through parameter optimization
2Area of moving object
If device geometries are shrunk, then integration density is improved, but metal volumes decrease leading to higher resistivity in metal interconnects
Solution Approach 1:
The patent creates a composite deposition approach combining PVD (physical vapor deposition) and CVD (chemical vapor deposition) processes, where PVD provides the liner layer and CVD provides the bulk fill, achieving low resistivity through the synergistic combination of deposition methods rather than using either method alone
Solution Approach 2:
The patent performs preliminary surface preparation and liner deposition with specific surface treatments and PVD liner deposition to create an optimal surface for direct bulk fill deposition, ensuring that the substrate is properly prepared before bulk fill metal deposition to achieve low resistivity without requiring additional nucleation layers
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 achieves lower resistivity metal gapfill without the high resistance stacks associated with traditional nucleation layers, maintaining adhesion and facilitating efficient deposition in narrow features.
Implementation Method 1
A metal liner is deposited on the nucleation underlayer by physical vapor deposition (PVD)
Implementation Method 2
A metal liner comprising tungsten is deposited on the silicon nucleation underlayer by physical vapor deposition (PVD)
Implementation Method 3
A metal gapfill comprising tungsten is deposited on the metal liner and the silicon nucleation underlayer
Data Source
AI summary
Embodiments of the disclosure relate to methods for metal gapfill with lower resistivity. Specific embodiments provide methods of forming a tungsten gapfill without a high resistance nucleation layer. Some embodiments of the disclosure utilize a nucleation underlayer to promote growth of the metal gapfill.