Selective ALD Barrier Layering for Low-Resistance Interconnects
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Solution Overview
Problem
The continuous downscaling of semiconductor devices leads to increased interconnect resistance issues due to diffusion barrier layers formed in trenches, which require either removal or selective formation to prevent metal diffusion into insulating layers, but existing methods are inefficient and leave impurities.
Innovation Solution
A method using atomic layer deposition (ALD) to selectively form layers by employing a reaction inhibitor that acts as both a precursor and a barrier, allowing for the formation of distinct deposition layers on different material regions without reacting with the inhibitor, thereby minimizing impurities and resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a diffusion barrier layer is formed in the entire trench to prevent metal diffusion, then metal diffusion into insulating layers is prevented, but interconnect resistance increases
Solution Approach 1:
The patent applies local quality by forming the diffusion barrier layer selectively only on the insulating layer surface and via wall, while intentionally leaving the trench bottom metal surface without barrier layer coverage. This localized approach prevents metal diffusion where needed (at insulator interfaces) while maintaining low resistance in the metal interconnect region.
Solution Approach 2:
The patent segments the trench into different functional zones: the insulating layer surface and via wall receive diffusion barrier layer protection, while the trench bottom metal region remains exposed. This segmentation allows different parts of the same structure to have different barrier layer configurations based on their specific functional requirements.
2Object-affected harmful factors
If the diffusion barrier layer is removed from the trench bottom to reduce resistance, then interconnect resistance decreases, but metal diffusion into insulating layers may occur
Solution Approach 1:
The diffusion barrier layer is applied locally only where metal diffusion risk exists (at the insulator-metal interface on via walls and insulator surface), while the trench bottom metal region is intentionally left without barrier layer to maintain electrical conductivity.
Solution Approach 2:
The via wall structure acts as an intermediary that provides the necessary diffusion barrier function through its coated surfaces, eliminating the need for a continuous barrier layer at the trench bottom. The barrier layer on the via wall indirectly protects the metal interconnect from diffusion into the insulator.
3Manufacturing precision
If conventional ALD methods are used to form barrier layers, then complete coverage is achieved, but impurities remain and selective formation is difficult
Solution Approach 1:
The patent achieves selective formation by creating local quality differences through surface preparation steps that enable the ALD process to deposit barrier layer material only on specific surfaces (insulator and via wall) while excluding the trench bottom metal surface, thereby avoiding impurity contamination in the metal region.
Solution Approach 2:
Preliminary surface treatment and preparation steps are performed before the ALD barrier layer deposition to create selective surface properties. This preliminary action ensures that subsequent barrier layer formation occurs only on desired surfaces, preventing impurity deposition on metal regions.
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 effectively reduces interconnect resistance by selectively forming diffusion barrier layers only where needed, minimizing impurity presence and enhancing the efficiency of semiconductor device interconnects.
Implementation Method 1
forming a first reaction inhibition layer on the second surface using a reaction inhibitor selectively adsorbed on the second surface
Implementation Method 2
selectively forming a first deposition layer on the first surface using a first precursor and a first reactant, wherein the first reactant reacts with the first precursor to form an atomic layer
Implementation Method 3
converting the first reaction inhibition layer on the second surface into a second deposition layer using a second reactant which reacts with the first reaction inhibition layer to form the atomic layer
Data Source
AI summary
A method of selectively forming a layer according to atomic layer deposition includes providing a substrate which includes a first region consisting of a first material and having a first surface and a second region consisting of a second material and having a second surface, forming a first reaction inhibition layer on the second surface using a reaction inhibitor selectively adsorbed on the second surface, selectively forming a first deposition layer on the first surface using a first precursor and a first reactant, wherein the first reactant reacts with the first precursor to form an atomic layer and does not react with the reaction inhibitor to form the atomic layer, and converting the first reaction inhibition layer on the second surface into a second deposition layer using a second reactant which reacts with the first reaction inhibition layer to form the atomic layer.