Phase-Stabilized Metal Nitride Films for Uniform Gate Electrodes
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Solution Overview
Problem
Existing thin-film deposition techniques for semiconductor devices face challenges in achieving uniformity and stability of metal gate electrodes, particularly as feature sizes decrease, leading to performance variations due to domain-specific work function differences and difficulties in depositing desirable metastable phases of metal nitride films.
Innovation Solution
The formation of phase-stabilized nitrogen-containing films using a phase stabilizer and a matrix material precursor, where a nitrogen-containing reactant reacts with active species on the substrate to form a metal nitride film, stabilizing the matrix material into a selected solid phase, such as TaxTi(1−x)N, which improves film uniformity and properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If traditional PVD or CVD techniques are used to deposit metal gate electrode films, then the deposition process is simple and straightforward, but the film uniformity and phase stability deteriorate, leading to domain-specific work function differences
Solution Approach 1:
A phase stabilizer layer is introduced as an intermediary between the substrate and the metal gate electrode material. This stabilizer layer prevents the formation of unwanted crystalline phases and domains in the metal gate electrode, ensuring uniform work function across the film while maintaining a relatively simple deposition process
Solution Approach 2:
The gate electrode structure is formed as a composite material system consisting of a phase stabilizer layer combined with metal gate electrode material. This composite structure leverages the stabilizer to control the phase and domain formation of the metal gate material, achieving both manufacturing simplicity and film uniformity
2Adaptability or versatility
If metal gate electrode films are deposited on three-dimensional gate dielectric supporting structures, then the device architecture is achieved, but step coverage and film thickness uniformity deteriorate
Solution Approach 1:
The phase stabilizer layer is deposited first as a preliminary layer before the metal gate electrode material. This pre-formed stabilizer layer provides a uniform surface and structural template that improves the step coverage and thickness uniformity of subsequent metal gate electrode deposition on three-dimensional gate dielectric structures
3Productivity
If high energy PVD processes are used to deposit metal gate electrode material, then the deposition rate is high, but the material equilibrates into a thermodynamically stable phase with less desirable work function properties
Solution Approach 1:
The phase stabilizer layer is deposited beforehand to counteract the tendency of high-energy PVD processes to drive the metal gate electrode material into thermodynamically stable phases. The stabilizer layer acts as a barrier that prevents unwanted phase transformation, allowing high deposition rates to be maintained while preserving desirable work function properties
4Manufacturing precision
If CVD processes are used to form metastable phases of material, then the desired phase can be formed, but incomplete conversion and compositional non-uniformities occur
Solution Approach 1:
The phase stabilizer serves as an intermediary that promotes complete and uniform conversion to the desired metastable phase. By providing a stabilizing environment at the interface with the substrate, it ensures thorough phase transformation without the incomplete conversion and compositional non-uniformities that plague direct CVD 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 results in films with improved electrical and morphological characteristics, reducing gate-to-gate work function variations and enhancing device performance by stabilizing otherwise metastable phases, thus addressing the limitations of traditional PVD and CVD techniques.
Implementation Method 1
supplying a nitrogen-containing reactant to the reactor so that the nitrogen-containing reactant reacts with active species on the exposed surface of the substrate to form the phase-stabilized film
Implementation Method 2
mass transport phenomena inherent in physical vapor deposition (PVD) and chemical vapor deposition (CVD) techniques
Data Source
AI summary
Nitrogen-containing phase-stabilized films, methods of forming phase-stabilized films, and structures and devices including the phase-stabilized films are disclosed. The phase-stabilized films include a matrix material and a phase stabilizer, which provides a morphologically stabilizing effect to a matrix material within the films. The phase-stabilized films may be used as, for example, gate electrodes and similar films in microelectronic devices.