Negative Capacitance FET Ferroelectric HfO2 Doping
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Solution Overview
Problem
Current semiconductor technologies face challenges in reducing operating voltage and leakage current, particularly due to limitations in ferroelectric material polarity in miniaturized gate structures, which restricts the development of high-density integrated circuits.
Innovation Solution
A negative capacitance field effect transistor (NCFET) is developed with a gate insulating dielectric structure comprising an HfO2 layer, a doping material layer, and a ferroelectric HfxA1-xO2 layer, where A represents a doping element such as Si, Zr, Al, or Y, to enhance ferroelectric material polarity and stability, allowing for improved crystal lattice and grain size changes through lattice strain or metal element induction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional ferroelectric materials (PZT, PbTiO3, BST) are used in miniaturized gate structures, then good ferroelectric effect is achieved, but processing complexity increases and compatibility with traditional CMOS processes decreases
Solution Approach 1:
The patent changes the material parameters by using HfO2-based ferroelectric materials with specific compositions (HfxA1-xO2 where A is Si, Zr, Al, or Y and 0.1≤x≤0.9) and controlled thickness (5-50 nm), which allows achieving good ferroelectric effect while maintaining compatibility with traditional CMOS processes and simpler processing requirements
Solution Approach 2:
The patent employs composite material structures including the ferroelectric HfO2 layer combined with gate insulating dielectric layers and metal gate stack layers, creating a multi-layer composite structure that achieves both ferroelectric performance and process compatibility
2Length of moving object
If ferroelectric material thickness is reduced for miniaturization, then device scaling is achieved, but ferroelectric polarity and stability deteriorate
Solution Approach 1:
The patent optimizes the thickness parameter of the ferroelectric HfO2 layer to be between 5-50 nm, and controls the composition parameter (x in HfxA1-xO2) to achieve the right balance between miniaturization and maintaining sufficient ferroelectric polarity and stability
Solution Approach 2:
The patent applies different doping elements (Si, Zr, Al, or Y) at specific locations and concentrations within the HfO2 structure to locally enhance ferroelectric properties while maintaining overall device miniaturization
3Use of energy by moving object
If operating voltage VDD is reduced below 0.5V, then power consumption decreases, but the Boltzmann limit (SS≥60 mV/dec) prevents further performance improvement
Solution Approach 1:
The patent utilizes the ferroelectric phase transition properties of HfO2-based materials, where the inversion of ferroelectric domains produces negative capacitance effect that amplifies internal potential, enabling the transistor to break the Boltzmann limit and achieve sub-60 mV/dec sub-threshold swing at low operating voltages
Solution Approach 2:
The patent introduces a ferroelectric capacitance layer as an intermediary element between the gate electrode and the channel, which provides negative capacitance effect and internal potential amplification, enabling the transistor to overcome the Boltzmann limit while operating at reduced voltages
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 NCFET achieves increased ferroelectric material polarity and reliability, breaking the Boltzmann limit and enabling larger current gains, thus addressing the limitations of existing ferroelectric materials in miniaturized semiconductor devices.
Implementation Method 1
A ferroelectric capacitance based on a ferroelectric material is integrated in a gate structure... A negative capacitance is formed when a ferroelectric domain is inverted, and an internal potential is amplified
Implementation Method 2
A negative capacitance is formed when a ferroelectric domain is inverted, and an internal potential is amplified under suitable operation conditions
Implementation Method 3
orthorhombic HfO2 crystal can also exhibit ferroelectricity. The orthorhombic HfO2 crystal is simple in structure and compatible with a traditional HkMG (high-k and metallic gate) technique
Implementation Method 4
By doping with elements such as Si, Y, Zr, and Al, the ferroelectricity of HfO2 can be greatly improved, and materials with strong polarity such as HfZrOx (HZO), HfSiOx, and HfAlOx can be formed
Data Source
AI summary
A negative capacitance field effect transistor (NCFET) and a manufacturing method thereof. The NCFET includes: a substrate structure, including a MOS region; a gate insulating dielectric structure, covering the MOS region; and a metal gate stack layer, covering the gate insulating dielectric structure. The gate insulating dielectric structure includes an interface oxide layer, a HfO2 layer, a doping material layer, and a ferroelectric material layer, which are sequentially stacked along a direction away from the substrate structure. A ferroelectric material in the ferroelectric material layer is HfxA1-xO2, A represents a doping element, and 0.1≤x≤0.9. A material forming the doping material layer is AyOz or A, and a ratio of y/z is equal to 1/2, 2/3, 2/5 or 1/1. Ferroelectric characteristics, material stability, and material reliability of the NCFET are improved by increasing domain polarity of the ferroelectric material.