Fluoride Metal Gate Layer for Semiconductor NBTI Reduction
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Solution Overview
Problem
Conventional poly-silicon gates in semiconductor devices face performance issues due to boron penetration and depletion, leading to reduced gate capacitance and electrical unreliability, while work function metal gates approach physical and electrical limitations, complicating process controls and efficiency in CMOS technology.
Innovation Solution
A semiconductor structure with a fluoride work function metal layer is introduced, where fluorine ions from the layer diffuse into the dielectric layer, improving the work function value and reducing negative bias temperature instability (NBTI), thereby enhancing electrical reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If work function metal gates are used to replace poly-silicon gates, then gate capacitance and driving force are improved, but electrical unreliability increases due to degradation of NBTI values
Solution Approach 1:
The patent modifies the work function metal gate by forming a fluoride metal layer and introducing fluorine ions to change its electrical parameters. The fluorine doping adjusts the work function value and improves NBTI characteristics, transforming the gate's electrical properties to achieve both high capacitance and reliability
Solution Approach 2:
The patent creates a composite structure by combining work function metal with fluoride ions, forming a fluoride metal layer that integrates the high work function advantage with the electrical stability of fluorinated materials. This composite approach merges beneficial properties to overcome the limitations of pure work function metals
2Ease of manufacture
If conventional poly-silicon gates are used, then manufacturing simplicity is maintained, but performance deteriorates due to boron penetration and depletion effect
Solution Approach 1:
The patent fundamentally changes the material parameter from poly-silicon to work function metal with fluoride doping, enabling higher gate capacitance and driving force while maintaining compatibility with existing semiconductor manufacturing processes through established deposition and annealing techniques
3Reliability
If work function value of gate structures is increased to improve electrical performance, then NBTI values improve, but process complexity increases due to need for dual work function metal gates in CMOS
Solution Approach 1:
The patent makes the work function metal gate with fluoride doping universally applicable to both NMOS and PMOS transistors. By achieving appropriate work function values through fluorine doping, a single gate structure design can serve dual purposes in CMOS technology, eliminating the need for different metal gates for different transistor types
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 fluoride work function metal layer achieves a work function value closer to the bandwidth, reducing NBTI and increasing electrical reliability, thus addressing the limitations of conventional gate structures in semiconductor devices.
Implementation Method 1
a part of the fluorine ions in the fluoride work function metal layer is to diffuse into a dielectric layer below
Data Source
AI summary
A semiconductor structure includes a substrate, a dielectric layer and a fluoride metal layer. The dielectric layer is located on the substrate. The fluoride metal layer is located on the dielectric layer. Furthermore, the present invention also provides a semiconductor process to form said semiconductor structure.