Cobalt Gap-Fill via Cyclic Deposition and Annealing
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Solution Overview
Problem
The challenge in semiconductor manufacturing lies in reliably depositing metal layers into features with high aspect ratios, as conventional methods suffer from poor step coverage, overhangs, voids, and adhesion issues, particularly at sub-half micron dimensions, leading to increased contact resistance and device failures.
Innovation Solution
A cyclic metal deposition process involving a precursor gas mixture, followed by plasma treatment or hydrogen annealing, is employed to deposit a metal layer, with optional barrier and wetting layers, ensuring conformal step coverage and seamless gap-fill without seams or voids, using cobalt as a low-resistivity material.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional PVD process is used to deposit metal layer, then deposition speed is maintained, but step coverage is poor and voids are formed in high aspect ratio features
Solution Approach 1:
The patent employs a cyclic deposition process where the metal layer is deposited in multiple periodic cycles rather than continuously. Each cycle deposits a thin conformal layer followed by annealing, which enables the metal to refow and fill high aspect ratio features seamlessly without voids, while maintaining acceptable overall deposition speed
Solution Approach 2:
The patent changes the deposition parameters by using atomic layer deposition (ALD) instead of conventional PVD, and introduces intermediate annealing steps at specific temperatures to enable metal refowing. This parameter change transforms the deposition mechanism to achieve superior step coverage in high aspect ratio structures
2Reliability
If thick barrier layers are used to prevent metal diffusion, then diffusion barrier is improved, but contact resistance increases
Solution Approach 1:
The patent changes the material parameter from conventional tungsten to cobalt, which has inherently lower contact resistance. The process parameters are also changed to deposit ultra-thin barrier layers (1-3 nm) that provide sufficient diffusion protection without significantly increasing contact resistance, achieving both reliability and low resistance
Solution Approach 2:
The patent uses a composite structure with multiple thin layers including ultra-thin TiN or TaN barrier layers combined with cobalt metal layer. This composite approach provides effective diffusion barrier while maintaining low contact resistance through the cobalt material properties
3Manufacturing precision
If metal layer is deposited to fill high aspect ratio features, then gap-fill is achieved, but adhesion is poor and peeling occurs
Solution Approach 1:
The patent performs preliminary surface treatment and deposits ultra-thin adhesion promoter layers before depositing the main metal layer. This preliminary action ensures strong adhesion between the metal layer and underlying structures, preventing peeling while enabling complete gap-fill in high aspect ratio features
Solution Approach 2:
The patent introduces intermediate annealing steps during the deposition process to enhance adhesion. The temperature and timing parameters are optimized to create strong interfacial bonding without causing metal agglomeration or void formation
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 enables seamless cobalt gap-fill with low contact resistance, improved adhesion, and reduced surface roughness, suitable for advanced transistor technology nodes, allowing for efficient metal gate, contact, and interconnect fill without the need for thick barrier layers.
Implementation Method 1
exposing the substrate to a deposition precursor gas mixture to deposit a portion of the metal layer in the feature definition
Implementation Method 2
exposing the portion of the metal layer to either a plasma treatment process
Implementation Method 3
exposing the portion of the metal layer to either a plasma treatment process or a hydrogen annealing process
Implementation Method 4
exposing the portion of the metal layer to either a plasma treatment process or a hydrogen annealing process
Implementation Method 5
annealing the metal layer
Data Source
AI summary
Methods for depositing a metal layer in a feature definition of a semiconductor device are provided. In one implementation, a method for depositing a metal layer for forming a semiconductor device is provided. The method comprises performing a cyclic metal deposition process to deposit a metal layer on a substrate and annealing the metal layer disposed on the substrate. The cyclic metal deposition process comprises exposing the substrate to a deposition precursor gas mixture to deposit a portion of the metal layer on the substrate, exposing the portion of the metal layer to either a plasma treatment process or hydrogen annealing process and repeating the exposing the substrate to a deposition precursor gas mixture and exposing the portion of the metal layer to either a plasma treatment process or hydrogen annealing process until a predetermined thickness of the metal layer is achieved.