Nitrogen-Rich Silicon Nitride MIM Capacitor Dielectric
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Solution Overview
Problem
The reduction of dielectric layer thickness in MIM capacitors to increase capacitance leads to increased leakage current and deteriorated breakdown voltage, resulting in decreased reliability and production yield, limiting their application in semiconductor devices.
Innovation Solution
A silicon nitride film with a ratio of silicon-hydrogen bonds to nitride-hydrogen bonds equal to or smaller than 0.5 is used as the dielectric layer, formed through a PECVD process, to enhance the breakdown voltage of MIM capacitors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If the thickness of the dielectric layer is reduced to increase capacitance, then the capacitance increases, but the leakage current increases and breakdown voltage deteriorates
Solution Approach 1:
The patent changes the chemical composition parameters of the silicon nitride film by controlling the atomic percentage of silicon-hydrogen bonds and nitride-hydrogen bonds. Specifically, it reduces silicon-hydrogen bonds to ≤15% and increases nitride-hydrogen bonds to ≥10%, with their ratio ≤1.5. This parameter optimization improves film density and reduces defects, enabling thinner dielectric layers to maintain high breakdown voltage while achieving increased capacitance.
Solution Approach 2:
The patent creates a composite dielectric structure using silicon nitride film combined with oxide layers (forming ONO structure). This composite material approach leverages the high dielectric constant of silicon nitride while the oxide layers provide protective interfaces, resulting in improved reliability and breakdown voltage characteristics even at reduced thickness.
2Force
If the thickness of the dielectric layer is reduced to increase capacitance, then the capacitance increases, but the leakage current increases
Solution Approach 1:
The patent optimizes the chemical bond composition parameters of the silicon nitride film, specifically controlling silicon-hydrogen bonds to ≤15% and nitride-hydrogen bonds to ≥10%. This parameter control improves the film's density and reduces pinhole defects, thereby suppressing leakage current generation even when the dielectric layer thickness is reduced for higher capacitance.
3Ease of manufacture
If a silicon nitride film with high silicon-hydrogen bonds is used, then the film formation is easier, but the breakdown voltage decreases
Solution Approach 1:
The patent identifies and controls critical parameters of the silicon nitride film deposition process, specifically the atomic percentages of silicon-hydrogen bonds (≤15%) and nitride-hydrogen bonds (≥10%). By optimizing these chemical composition parameters, the patent achieves a balance where the film remains manufacturable through PECVD while attaining superior breakdown voltage characteristics through improved film density and reduced defects.
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 nitrogen-rich silicon nitride film with compressive stress improves the breakdown voltage and capacitance of MIM capacitors, providing better film quality and reliability, while allowing for thinner dielectric layers without compromising performance.
Implementation Method 1
formed through a PECVD process
Data Source
AI summary
A method for fabricating a metal-insulator-metal (MIM) capacitor includes providing a substrate comprising a bottom electrode, forming a dielectric layer positioned on the bottom electrode, and forming a top electrode positioned on the dielectric layer. The dielectric layer includes a silicon nitride film, the silicon nitride film has a plurality of Si—H bonds and a plurality of N—H bonds, and a ratio of Si—H bonds to N—H bonds being equal to or smaller than 0.5.