Composite Metal Nitride Film Work Function Control
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Solution Overview
Problem
Existing semiconductor manufacturing techniques fail to effectively control the work function of metal films, which is crucial for optimizing the performance of devices like NMOS transistors, particularly in reducing power consumption.
Innovation Solution
A method involving a substrate processing apparatus that alternately supplies a first metal source, a second metal source with an ethyl ligand, and a nitrogen-containing gas to form a composite metal nitride film, specifically a TiHfN film, with controlled process temperatures to achieve crystallinity and modulate the work function.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If a traditional TiN film is used as a gate electrode, then the device structure is simple and manufacturing is easy, but the work function cannot be sufficiently reduced to decrease power consumption in NMOS transistors
Solution Approach 1:
The patent forms a composite metal nitride film containing multiple metal elements (e.g., Ti, Hf, Ta) and nitrogen, where each metal element contributes differently to the work function. By adjusting the composition ratios of these metal elements, the work function can be precisely controlled to achieve lower values than traditional TiN films, thereby reducing power consumption in NMOS transistors while maintaining structural integrity.
Solution Approach 2:
The patent employs atomic layer deposition (ALD) to precisely control the composition and thickness of the metal nitride film at the atomic level. By adjusting deposition parameters such as precursor flow rates, temperature, and cycle numbers, the work function can be tuned to specific values. The process also controls crystallinity through temperature management, which further influences the electrical properties and work function of the film.
2Use of energy by moving object
If the work function of a metal film is reduced to decrease power consumption, then power consumption decreases, but the metal film composition becomes more complex requiring multiple metal sources
Solution Approach 1:
The patent introduces separate supply systems for different metal sources (first metal source and second metal source) into the process chamber. The first metal source supplies a first metal element, while the second metal source supplies a second metal element with an ethyl ligand. This segmentation allows independent control of each metal element's deposition, enabling precise composition adjustment to achieve desired work function values while maintaining systematic organization.
Solution Approach 2:
The patent implements periodic alternation between supplying the first metal source and the second metal source during the film formation process. This periodic action allows controlled incorporation of different metal elements in alternating layers or sequences, enabling fine-tuning of the composite film's composition and work function. The cyclic supply pattern ensures uniform distribution of multiple metal elements throughout the film structure.
3Manufacturing precision
If multiple metal sources are supplied alternately to form a composite metal nitride film, then the work function can be precisely controlled, but the manufacturing process becomes more complex
Solution Approach 1:
The patent utilizes atomic layer deposition (ALD) as a universal manufacturing platform that can deposit multiple metal elements and form nitride films through a standardized process sequence. The same ALD equipment and basic process steps (precursor supply, purge, reactive gas exposure) are used for all metal elements in the composite film, reducing the need for different specialized equipment or fundamentally different process approaches. This multi-functionality simplifies the overall manufacturing complexity despite the multi-element composition.
Solution Approach 2:
The patent achieves precise work function control by adjusting deposition parameters within the ALD process, such as temperature, precursor flow rates, and exposure times. By changing these parameters, the composition ratios of different metal elements in the composite film can be precisely tuned. The process also controls the degree of crystallinity through temperature management, which further refines the electrical properties and work function without requiring fundamentally different manufacturing approaches.
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 allows for precise control of the work function of the metal film, achieving lower values than traditional TiN films, thereby enhancing device performance and reducing power consumption while preventing integration and thermal stability issues.
Implementation Method 1
supplying a first metal source including a first metal element to a substrate accommodated in a process chamber and exhausting the first metal source from the process chamber; supplying a second metal source including an ethyl ligand and a second metal element different from the first metal element to the substrate and exhausting the second metal source from the process chamber; supplying a reactive gas containing nitrogen to the substrate and exhausting the reactive gas containing nitrogen from the process chamber
Implementation Method 2
(a) through (c) are repeated a plurality of times to form a metal nitride film including the first metal element, a second metal element and nitrogen
Data Source
AI summary
Provided is a technique of controlling a work function of a metal film. A composite metal nitride film is formed on a substrate present in a process chamber by alternately supplying a first source and a second source to the substrate, wherein the first source contains a first metal element, the second source contains an ethyl ligand and a second metal element that is different from the first metal element, and a bond between the second metal element and a nitrogen element in the composite metal nitride film has crystallinity.