Ferroelectric Capacitor Oxide Stack for Oxygen Diffusion Control
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Solution Overview
Problem
The miniaturization of semiconductor devices requires high-k materials with low leakage current and ferroelectricity for capacitors, but existing technologies face issues with increased power consumption and reduced endurance due to interfacial defects from oxygen diffusion during the manufacturing process.
Innovation Solution
A method involving the formation of a stacked structure with alternating layers of hafnium oxide and zirconium oxide, where the lowermost layers are thicker than subsequent layers, reducing oxygen diffusion and preventing interfacial defects, thereby enhancing the endurance of the capacitor.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If thin oxide layers are used to miniaturize the capacitor, then the device size is reduced, but oxygen diffusion increases causing interfacial defects and reduced endurance
Solution Approach 1:
The dielectric layer is segmented into multiple alternating oxide layers (first oxide layer and second oxide layer) with different compositions and thicknesses. This segmentation allows each layer to serve specific functions: the thicker lowermost first oxide layer prevents oxygen diffusion, while the alternating structure maintains overall miniaturization.
Solution Approach 2:
Different regions of the dielectric layer have different local qualities - the lowermost first oxide layer has greater thickness specifically at the interface region to prevent oxygen diffusion, while other layers maintain uniform alternating thickness. This local variation in thickness and composition optimizes both protection and miniaturization.
2Use of energy by moving object
If high-k ferroelectric material is used to reduce power consumption, then negative capacitance effect is achieved, but interfacial defects from oxygen diffusion increase power consumption and reduce endurance
Solution Approach 1:
The thicker lowermost first oxide layer is formed beforehand to cushion and prevent oxygen diffusion from the electrode into the dielectric layer during subsequent processing and operation. This preventive measure eliminates interfacial defects that would otherwise increase power consumption and reduce endurance, allowing the ferroelectric material to maintain its low power consumption benefits.
3Ease of manufacture
If uniform thickness oxide layers are formed by repeating deposition cycles, then manufacturing simplicity is maintained, but oxygen diffusion occurs at interfaces reducing capacitor performance
Solution Approach 1:
The deposition process maintains simplicity through repeated cycles, but introduces local quality variation by forming the lowermost first oxide layer with greater thickness than subsequent first oxide layers. This local thickness variation prevents oxygen diffusion at the critical electrode interface while maintaining the overall alternating layer structure.
Solution Approach 2:
The thicker lowermost first oxide layer is formed as a preliminary action before subsequent alternating layers are deposited. This preliminary layer establishes an oxygen diffusion barrier at the electrode interface, protecting the entire capacitor structure from interfacial defects during manufacturing and operation.
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 proposed method increases the endurance of capacitors by minimizing interfacial defects, leading to improved remnant polarization and reduced power consumption.
Implementation Method 1
oxygen diffusion from the electrode into the dielectric layer
Implementation Method 2
when the high-k material has ferroelectricity, power consumption of the electronic device including the capacitor can be greatly reduced due to a negative capacitance effect
Implementation Method 3
power consumption of the electronic device including the capacitor can be greatly reduced due to a negative capacitance effect
Data Source
AI summary
A method for fabricating a semiconductor device includes: forming a first oxide layer containing a first element over a first electrode layer; forming a second oxide layer containing a second element over the first oxide layer; forming a stacked structure in which a plurality of first oxide layers and a plurality of second oxide layers are alternately stacked by repeating the forming of the first oxide layer and the forming of the second oxide layer a plurality of times; and forming a second electrode layer over the stacked structure, wherein a thickness of a lowermost first oxide layer among the plurality of first oxide layers is greater than a thickness of each of other first oxide layers.