Work-Function Metal Pre-Treatment for Oxide-Free Gate Deposition
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Solution Overview
Problem
Existing semiconductor manufacturing processes face challenges in achieving precise work function tuning for metal electrode layers, leading to limited device performance due to issues like poor metal layer deposition causing gaps or voids, and inadequate thickness adjustment.
Innovation Solution
A pre-deposition treatment using chlorine or fluorine-based metal precursors is applied to clean the oxidized surface of work-function layers before atomic layer deposition, followed by in-situ processing to ensure a clean, non-oxidized surface for subsequent metal layer deposition, thereby improving work function tuning and device performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional work function tuning approaches are used (adjusting metal layer thickness), then device performance is limited, but manufacturing complexity remains low
Solution Approach 1:
The patent applies a pre-deposition treatment step before metal layer deposition to clean and activate the surface. This preliminary action modifies the substrate surface properties (removing contaminants, creating nucleation sites) to enable subsequent metal layers to achieve desired work function and adhesion without requiring excessive thickness adjustments or iterative tuning, thereby improving device performance while maintaining manufacturing simplicity
Solution Approach 2:
The patent changes the surface state parameters of the substrate through pre-deposition treatment (surface cleanliness, chemical composition, roughness). By modifying these surface parameters before deposition, the process achieves better work function control and metal layer quality without complicating the overall manufacturing process
2Manufacturing precision
If metal layer thickness is increased to overcome loading effects, then work function tuning capability is improved, but manufacturing precision deteriorates due to gaps and voids
Solution Approach 1:
The pre-deposition treatment prepares the surface by removing contaminants and creating an optimized substrate for metal deposition. This preliminary surface preparation ensures that metal layers deposit uniformly at the intended thickness without forming gaps or voids, achieving both precise work function tuning and high metal layer quality
Solution Approach 2:
The patent replaces the mechanical approach of increasing metal thickness to compensate for poor deposition with a chemical/surface science approach. By using pre-deposition treatment to modify surface properties, the process achieves better metal layer quality and work function precision without relying on increased thickness that would cause gaps and voids
3Manufacturing precision
If metal layer thickness is adjusted for work function tuning, then work function control is improved, but manufacturing complexity increases due to additional process steps
Solution Approach 1:
The patent combines the surface preparation function and the work function tuning function into a single pre-deposition treatment step. This merged approach achieves both surface cleaning/activation and work function control without requiring separate thickness adjustment steps, thereby improving work function control while avoiding additional process complexity
Solution Approach 2:
The pre-deposition treatment serves multiple functions simultaneously: it cleans the surface, activates nucleation sites, and enables work function control. This multi-functional approach consolidates several potential process steps into one, improving manufacturing precision for work function tuning without increasing overall process complexity
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 results in high-quality, conformal metal gate layers with improved threshold voltage and reliability by mitigating gap fill impacts and enhancing device performance, particularly in 10 or 7 nanometer process technologies.
Implementation Method 1
A first in-situ process including a pre-treatment process of the work-function metal layer is performed. The pre-treatment process may include using a chlorine (Cl)-based or fluorine (F)-based metal precursor to clean an oxidized surface of the work-function metal layer
Implementation Method 2
depositing another metal layer over the pre-treated work-function metal layer in a second in-situ process
Data Source
AI summary
A method for providing a pre-deposition treatment (e.g., of a work-function layer) to accomplish work function tuning. In various embodiments, a gate dielectric layer is formed over a substrate, and a work-function metal layer is deposited over the gate dielectric layer. In some embodiments, a first in-situ process including a pre-treatment process of the work-function metal layer is performed. By way of example, the pre-treatment process removes an oxidized layer of the work-function metal layer to form a treated work-function metal layer. In some embodiments, after performing the first in-situ process, a second in-situ process including a deposition process of another metal layer over the treated work-function metal layer is performed.