FinFET Barrier Layer Thickness Control via TiN TaN Segmentation
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Solution Overview
Problem
In semiconductor manufacturing, particularly for nanometer technology process nodes, the challenge lies in controlling the threshold voltage of Fin FET devices as the gate length decreases, due to difficulties in accurately controlling the thickness of the barrier layer, which affects the performance and efficiency of the metal gate structure.
Innovation Solution
A method is developed to form a barrier layer with high uniformity in thickness by using a combination of TiN and TaN layers, where the TiN layer is deposited and etched to achieve a thickness of 0.2-3.0 nm, and the TaN layer is also deposited and etched to ensure a uniform barrier layer, allowing for precise control of the threshold voltage as the gate length varies from 5-15 nm.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the gate length is decreased to increase device density, then the device density is improved, but the manufacturing precision of the barrier layer thickness deteriorates
Solution Approach 1:
The barrier layer is segmented into multiple sub-layers (first barrier layer and second barrier layer) with different materials and functions. The first barrier layer (e.g., TiN) provides initial barrier functionality, while the second barrier layer (e.g., TaN) provides enhanced barrier functionality and better thickness control. This segmentation allows each layer to be optimized independently, improving overall manufacturing precision while maintaining compatibility with scaled-down gate lengths for higher device density.
2Manufacturing precision
If the barrier layer thickness is controlled to improve threshold voltage control, then the threshold voltage control is improved, but the device complexity increases
Solution Approach 1:
The invention changes the material parameters of the barrier layer by using a combination of different materials (e.g., TiN and TaN) with distinct properties. The TiN layer provides good adhesion and initial barrier properties, while the TaN layer provides superior barrier performance and easier thickness control. By adjusting the thickness and material composition parameters of each sub-layer, precise threshold voltage control is achieved without requiring overly complex structural configurations.
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 enables the control of threshold voltage to a desirable value by maintaining a thickness variation of less than 10% of the average thickness, improving the performance and efficiency of Fin FET devices by ensuring consistent gate structure formation.
Implementation Method 1
the TiN layer is deposited and etched to achieve a thickness of 0.2-3.0 nm
Implementation Method 2
the TaN layer is also deposited and etched to ensure a uniform barrier layer
Data Source
AI summary
A field effect transistor includes a channel layer made of a semiconductor and a metal gate structure. The metal gate structure includes a gate dielectric layer, a barrier layer formed on the gate dielectric layer, a work function adjustment layer formed on the barrier layer and made of one of Al and TiAl, a blocking layer formed on the work function adjustment layer and made of TiN, and a body metal layer formed on the blocking layer and made of W. A gate length over the channel layer is in a range from 5 nm to 15 nm, and a thickness of the first conductive layer is in a range of 0.2 nm to 3.0 nm. A range between a largest thickness and a smallest thickness of the first conductive layer is more than 0% and less than 10% of an average thickness of the first conductive layer.