Tunnel Insulating Film Structure for Nonvolatile Memory
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Solution Overview
Problem
Existing semiconductor memory devices face challenges in achieving high-speed writing and erasing characteristics and excellent charge retention while also reducing parasitic capacitance between floating gates, which affects operating voltage and memory performance.
Innovation Solution
A method of manufacturing a semiconductor device involving the formation of a tunnel insulating film with a high dielectric constant silicon nitride film sandwiched between low dielectric constant silicon oxinitride films, achieved through oxidizing and nitriding processes using nitrogen monoxide, which reduces parasitic capacitance and enhances film quality and interface characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If a high dielectric constant film is sandwiched between low dielectric constant films to achieve high-speed writing and erasing, then writing and erasing speed is improved, but parasitic capacitance between floating gates increases
Solution Approach 1:
The patent applies local quality by creating a tunnel insulating film with spatially varying dielectric constant. The first insulating film has higher dielectric constant than the second insulating film, which is positioned at the interface with the floating gate electrode. This local variation reduces parasitic capacitance at the critical interface while maintaining high-speed writing and erasing characteristics through the overall high dielectric constant structure.
Solution Approach 2:
The patent employs composite materials by forming a tunnel insulating film comprising multiple insulating films with different dielectric constants. Specifically, it combines a first insulating film (higher dielectric constant) with a second insulating film (lower dielectric constant) to create a composite structure that simultaneously achieves high-speed operation and reduced parasitic capacitance between adjacent floating gates.
2Ease of manufacture
If conventional methods are used to form tunnel insulating film, then manufacturing process is simple, but film quality and interface characteristic are insufficient
Solution Approach 1:
The patent applies preliminary action by performing oxidizing treatment on the floating gate electrode film before forming the tunnel insulating film. This preliminary oxidation creates a foundation for subsequent nitriding processes, ensuring excellent interface characteristics between the tunnel insulating film and floating gate electrode. The sequence of oxidation followed by nitriding prepares the surface in advance for optimal film formation.
Solution Approach 2:
The patent employs parameter changes by controlling the nitriding conditions including temperature (500-800°C), nitrogen source (NH3, N2O, or plasma), and treatment time. These parameter variations enable precise control over the nitride film formation process, achieving excellent film quality and interface characteristics while maintaining manufacturing feasibility through standardized process parameters.
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 high-speed writing and erasing operations while maintaining excellent charge retention characteristics, reducing operating voltages, and preventing malfunctioning due to decreased parasitic capacitance between adjacent floating gates, resulting in a reliable and high-performance nonvolatile memory.
Implementation Method 1
exposing the first structure to an atmosphere containing an oxidizing agent; oxidizing that part of the floating gate electrode film which corresponds to a boundary between the first insulating film and the floating gate electrode film using the oxidizing agent
Implementation Method 2
forming a first insulating film on a semiconductor substrate containing silicon, the first insulating film having a first dielectric constant and constituting a part of a tunnel insulating film
Data Source
AI summary
A semiconductor device manufacturing method includes forming a first insulating film on a semiconductor substrate containing silicon, the first insulating film having a first dielectric constant and constituting a part of a tunnel insulating film, forming a floating gate electrode film on the first insulating film, the floating gate electrode film being formed of a semiconductor film containing silicon, patterning the floating gate electrode film, the first insulating film, and the semiconductor substrate to form a first structure having a first side surface, exposing the first structure to an atmosphere containing an oxidizing agent, oxidizing that part of the floating gate electrode film which corresponds to a boundary between the first insulating film and the floating gate electrode film using the oxidizing agent, to form a second insulating film having a second dielectric constant smaller than the first dielectric constant and constituting a part of the tunnel insulating film.