Ferroelectric Gate Stack Crystallization for Low-Voltage NCFETs
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Solution Overview
Problem
As the semiconductor industry continues to reduce minimum feature sizes to increase integration density, challenges arise in the manufacturing of semiconductor devices, particularly in forming reliable and efficient field effect transistors with improved switching characteristics at lower voltages.
Innovation Solution
The manufacturing process involves forming negative capacitance field effect transistors (NCFETs) using ferroelectric materials with a metal layer to seed crystallization and control grain size, combined with a conductive gate stack, to achieve lower voltage switching and improved transistor performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If minimum feature sizes are reduced to increase integration density, then integration density is improved, but manufacturing reliability deteriorates
Solution Approach 1:
The gate structure is segmented into multiple thin film layers (ferroelectric layer, metal layer, semiconductor layer) rather than using a single thick layer, allowing each layer to be formed with precise thickness control through atomic layer deposition, thereby maintaining manufacturing reliability at reduced feature sizes
Solution Approach 2:
The invention changes the physical and chemical parameters of the gate stack by using specific ferroelectric materials (e.g., hafnium zirconium oxide, hafnium aluminum oxide) with controlled compositions and thicknesses, enabling reliable operation at lower voltages and smaller dimensions while maintaining device performance
2Ease of manufacture
If conventional transistors are used, then manufacturing is simpler, but switching characteristics at lower voltages deteriorate
Solution Approach 1:
The invention changes the electrical parameters by introducing ferroelectric materials with high dielectric constants into the gate stack, enabling enhanced charge control and lower voltage switching operation while maintaining compatibility with existing semiconductor manufacturing processes
Solution Approach 2:
The gate stack uses composite materials combining ferroelectric layers (e.g., hafnium zirconium oxide), metal layers (e.g., tungsten, titanium nitride), and semiconductor layers, creating a multi-material structure that achieves superior switching characteristics while remaining manufacturable through sequential deposition processes
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 production of transistors with enhanced switching characteristics at lower voltages, improving integration density and device performance while maintaining reliability.
Implementation Method 1
a crystallized ferroelectric layer in physical contact with the interfacial layer, the crystallized ferroelectric layer comprising multiple crystalline regions with grain boundaries between adjacent ones of the multiple crystalline regions
Implementation Method 2
using ferroelectric materials with a metal layer to seed crystallization and control grain size
Data Source
AI summary
A semiconductor device and method of manufacture are provided which utilizes metallic seeds to help crystallize a ferroelectric layer. In an embodiment a metal layer and a ferroelectric layer are formed adjacent to each other and then the metal layer is diffused into the ferroelectric layer. Once in place, a crystallization process is performed which utilizes the material of the metal layer as seed crystals.