Gate Work Function Layers With Oxygen Treatment for Threshold Voltage
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Solution Overview
Problem
Existing semiconductor devices face challenges in achieving optimal work function layers that enhance device performance, particularly in terms of threshold voltage and speed, due to limitations in integrating oxygen into the work function structures effectively.
Innovation Solution
A method involving the deposition of a p-type work function metal followed by an oxygen treatment to increase oxygen concentration within the work function layers, repeated to achieve a sufficient thickness, thereby enhancing the effective work function and improving the interface with gate dielectric layers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a work function layer is deposited to enhance device performance, then threshold voltage control is improved, but oxygen integration into the work function structure is insufficient
Solution Approach 1:
The patent applies preliminary action by depositing the work function layer before the gate dielectric layer, allowing oxygen to be incorporated into the work function structure during subsequent processing steps. This sequence enables oxygen diffusion into the work function layer without requiring direct oxygen exposure during deposition, thus improving oxygen integration while maintaining threshold voltage control
Solution Approach 2:
The patent utilizes parameter changes by varying the deposition conditions and subsequent thermal processing parameters to optimize oxygen incorporation into the work function layer. By controlling deposition temperature, oxygen partial pressure, and annealing conditions, the oxygen concentration in the work function layer is enhanced without compromising the threshold voltage characteristics
2Reliability
If the work function layer thickness is increased to improve device performance, then effective work function is enhanced, but the interface quality with gate dielectric may deteriorate
Solution Approach 1:
By depositing the work function layer before the gate dielectric, the patent creates a preliminary structure that can be optimized for both thickness and interface quality. The work function layer is deposited to the required thickness, then oxygen is incorporated through subsequent processing, and finally the gate dielectric is deposited to form a high-quality interface without exposing the work function layer to damaging conditions
Solution Approach 2:
The patent employs composite material structures by combining the work function layer with oxygen-containing materials or undergoing oxygenation treatment to create a composite structure that maintains both adequate thickness for performance and high interface quality. The composite nature allows simultaneous optimization of bulk properties (thickness for work function) and interface properties (quality for reliability)
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 increases the flat band voltage and reduces the threshold voltage, leading to improved device speed and performance by increasing the oxygen concentration in the work function layers and at the interface with the gate dielectric.
Implementation Method 1
increasing the oxygen concentration in the work function layers and at the interface with the gate dielectric
Implementation Method 2
depositing a p-type work function metal followed by an oxygen treatment
Data Source
AI summary
A method of forming semiconductor devices having improved work function layers and semiconductor devices formed by the same are disclosed. In an embodiment, a method includes depositing a gate dielectric layer on a channel region over a semiconductor substrate; depositing a first p-type work function metal on the gate dielectric layer; performing an oxygen treatment on the first p-type work function metal; and after performing the oxygen treatment, depositing a second p-type work function metal on the first p-type work function metal.