TiAlC Gate Layer Deposition for Tunable PMOS Work Function
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional gate materials for CMOS devices, such as titanium nitride, fail to meet the need for higher work function values required in PMOS regions, and there is a lack of suitable materials for MIM structures, DRAM capacitors, and VNAND cells.
Innovation Solution
A method for depositing layers comprising titanium, aluminum, and carbon using cyclical deposition processes, where aluminum and transition metal precursors are pulsed with purges in between, forming layers suitable for gate electrodes and other semiconductor applications.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If titanium nitride is used as gate material, then the device can be manufactured with conventional materials, but the work function value is insufficient for PMOS regions
Solution Approach 1:
The patent uses a composite material system consisting of a titanium nitride layer combined with a dipole shifting layer containing aluminum, lithium, and carbon elements. This composite structure allows the gate electrode to achieve higher work function values suitable for PMOS regions while maintaining compatibility with conventional semiconductor manufacturing processes. The dipole shifting layer modifies the electrical properties of the underlying titanium nitride to provide the required work function adjustment.
2Reliability
If conventional gate materials are used, then the manufacturing process is simple, but the material performance is insufficient for aggressively scaled CMOS devices
Solution Approach 1:
The gate electrode is segmented into multiple functional layers: a base titanium nitride layer providing structural foundation and electrical conductivity, and an additional dipole shifting layer containing aluminum, lithium, and carbon elements that provides work function adjustment. This segmentation allows each layer to be optimized independently for its specific function while maintaining overall device reliability in scaled nodes.
3Force
If a dipole shifting layer with aluminum, lithium, and carbon is added, then the work function can be tuned, but the manufacturing process becomes more complex
Solution Approach 1:
The dipole shifting layer is formed using a periodic deposition process where aluminum, lithium, and carbon precursors are deposited in sequential cycles. This periodic action allows precise control over the composition and thickness of each element in the dipole shifting layer, enabling work function tunability while maintaining a systematic and controllable manufacturing approach.
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
The TiAlC layers exhibit low resistivity, stability, and tunable work functions, offering improved performance in CMOS devices, MIM structures, and VNAND cells, with excellent elemental composition uniformity and step coverage.
Implementation Method 1
A method for depositing layers comprising titanium, aluminum, and carbon using cyclical deposition processes
Data Source
AI summary
Disclosed are methods and systems for depositing layers comprising a titanium, aluminum, and carbon. The layers are formed onto a surface of a substrate. The deposition process comprises a cyclical deposition process. Exemplary structures in which the layers may be incorporated include field effect transistors, VNAND cells, metal-insulator-metal (MIM) structures, and DRAM capacitors.