Selective Bottom-Up Metal Filling for Interconnects
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
As semiconductor device features shrink, it becomes challenging to form diffusion barrier layers with adequate thickness on the sidewalls of vias while providing enough volume for metal layers, especially with copper (Cu) metal, which leads to electrical defects due to high Cu atom mobility in dielectrics.
Innovation Solution
A method for selective bottom-up filling of recessed features with low resistivity metals like ruthenium (Ru), cobalt (Co), and others using a gas phase deposition process that reacts dielectric layer surfaces with hydrophobic functional group-containing gases to prevent metal deposition on these surfaces, allowing for seamless filling of recessed features.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If copper (Cu) metal is used to fill recessed features, then low resistivity is achieved, but Cu atoms diffuse into dielectrics and Si creating electrical defects
Solution Approach 1:
The patent extracts the harmful barrier layer material from the system by using selective bottom-up deposition to fill recessed features with metal directly, without requiring separate barrier layers. The metal is deposited selectively only in the recessed features while avoiding the dielectric sidewalls, eliminating the need for barrier materials that would otherwise be needed to prevent Cu diffusion.
Solution Approach 2:
The patent introduces hydrophobic functional groups as an intermediary mechanism to control metal deposition. By modifying dielectric sidewalls with hydrophobic groups, the process creates a selective interface that allows metal to deposit only in recessed features while preventing deposition on dielectric surfaces, thereby eliminating the need for traditional barrier layers.
2Area of stationary object
If via dimensions are decreased to increase device density, then device area is reduced, but it becomes challenging to form diffusion barrier layers with adequate thickness while providing enough volume for metal layers
Solution Approach 1:
The patent applies local quality by creating different surface properties in different locations: hydrophobic functional groups are applied specifically to dielectric sidewalls, while recessed feature bottoms maintain their original surface chemistry. This local differentiation enables selective metal deposition - the metal fills the recessed features completely while being repelled from the dielectric sidewalls, achieving proper filling in small dimensions without requiring thick barrier layers.
Solution Approach 2:
The patent changes the surface energy parameter of dielectric sidewalls by introducing hydrophobic functional groups. This parameter change creates a stark contrast between the hydrophobic sidewalls and the hydrophilic recessed feature bottoms, enabling selective deposition behavior that works effectively at scaled dimensions where traditional barrier layer approaches fail.
3Reliability
If barrier layers are deposited on trench and via sidewalls and bottoms prior to Cu seed deposition, then Cu atom diffusion is prevented, but process complexity and manufacturing difficulty increase
Solution Approach 1:
The patent merges the barrier layer function with the metal deposition process itself. Instead of performing separate barrier layer deposition and metal filling steps, the selective bottom-up deposition accomplishes both functions simultaneously - the metal deposits selectively in recessed features (providing the barrier function) while filling the features (providing the interconnect function), thereby reducing process complexity.
Solution Approach 2:
The hydrophobic functional group modification provides multi-functionality: it serves as both a deposition control mechanism (directing metal to recessed features only) and a diffusion barrier (preventing metal contact with dielectric sidewalls). This universal approach eliminates the need for separate barrier layers and simplifies the overall process sequence.
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 method effectively fills recessed features with low resistivity metals, reducing the need for barrier layers and preventing electrical defects, while maintaining control over the process sequence, even at smaller feature sizes, and meets International Technology Roadmap for Semiconductors (ITRS) resistance requirements.
Implementation Method 1
reacting the dielectric layer surfaces with a reactant gas containing a hydrophobic functional group to form hydrophobic dielectric layer surfaces
Implementation Method 2
at least substantially filling the recessed feature with a metal in a bottom-up gas phase deposition process that hinders deposition of the metal on the hydrophobic dielectric layer surfaces
Data Source
AI summary
A method for selective bottom-up filling of recessed features with a low resistivity metal for semiconductor devices is described in several embodiments. The method includes providing a substrate containing a patterned dielectric layer having a recessed feature with dielectric layer surfaces and a metal-containing surface on a bottom of the recessed feature, reacting the dielectric layer surfaces with a reactant gas containing a hydrophobic functional group to form hydrophobic dielectric layer surfaces, and at least substantially filling the recessed feature with a metal in a bottom-up gas phase deposition process that hinders deposition of the metal on the hydrophobic dielectric layer surfaces. According to one embodiment, the metal is selected from the group consisting of ruthenium (Ru), cobalt (Co), aluminum (Al), iridium (Ir), iridium (Ir), rhodium (Rh), osmium (Os), palladium (Pd), platinum (Pt), nickel (Ni), and a combination thereof.