Nonvolatile Semiconductor Device Floating Gate Capacitive Coupling
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Nonvolatile semiconductor devices face challenges with capacitive coupling between floating gates, leading to variations in threshold voltage, and low-permittivity films are prone to hydrogen or water ingress, affecting device functionality.
Innovation Solution
A nonvolatile semiconductor device design featuring gap portions between floating gates and control gates, with insulation films formed to minimize capacitive coupling and prevent moisture ingress, using a method that includes specific film formation conditions to control insulation film thickness and placement, such as adjusting gas flow, N2O/SiH4 ratio, temperature, and plasma power to ensure accurate and reliable operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If gap portions are formed between floating gates to suppress capacitive coupling, then threshold voltage variation is reduced, but insulation films may enter the gap portions and affect device operation
Solution Approach 1:
The patent applies preliminary action by forming the insulation film on the side surfaces of control gates and floating gates before forming the gap portions. This preliminary film formation prevents insulation film material from entering the gap portions during subsequent processing steps, while still allowing the gap portions to effectively suppress capacitive coupling between adjacent floating gates.
Solution Approach 2:
The patent segments the insulation film formation process into distinct stages: first forming insulation films on side surfaces, then forming gap portions, and finally forming additional insulation films to fill and seal the gaps. This segmentation allows each step to be optimized independently, ensuring both capacitive coupling suppression and prevention of insulation film intrusion.
2Manufacturing precision
If low-permittivity films are used between floating gates to reduce capacitive coupling, then threshold voltage stability improves, but hydrogen or water may exude to the gate insulation film and inhibit device function
Solution Approach 1:
The patent uses composite materials by combining low-permittivity insulation film material with hydrophobic or barrier properties. The insulation film is formulated to simultaneously provide low permittivity for capacitive coupling suppression and resistance to hydrogen and water ingress, eliminating the need to choose between performance and reliability.
Solution Approach 2:
The patent introduces an intermediary protective layer or treatment on the gate insulation film that prevents hydrogen and water from reaching the low-permittivity film. This intermediary barrier allows the low-permittivity film to maintain its electrical properties while protecting against harmful chemical ingress.
3Reliability
If insulation film thickness on side surfaces is increased to prevent material entry, then gap portion sealing improves, but capacitive coupling suppression between adjacent floating gates becomes difficult
Solution Approach 1:
The patent applies local quality by varying the insulation film thickness in different regions: thinner insulation films are formed on the side surfaces of control gates and floating gates where capacitive coupling must be suppressed, while thicker insulation films are formed in the gap portions where sealing and prevention of material entry are critical. This spatial variation in film thickness optimizes both functions simultaneously.
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 solution effectively suppresses capacitive coupling and threshold voltage variations, ensuring accurate reading and operation speed while preventing water entry into gap portions, thus maintaining device functionality.
Implementation Method 1
a step of depositing an insulation film by vapor phase epitaxy at a normal pressure
Implementation Method 2
controlling an amount of deposition of the insulation film by adjusting at least one parameter
Data Source
AI summary
A semiconductor substrate having a main surface, first and second floating gates formed spaced apart from each other on the main surface of the semiconductor substrate, first and second control gates respectively located on the first and second floating gates, a first insulation film formed on the first control gate, a second insulation film formed on the second control gate to contact the first insulation film, and a gap portion formed at least between the first floating gate and the second floating gate by achieving contact between the first insulation film and the second insulation film are included. With this, a function of a nonvolatile semiconductor device can be ensured and a variation in a threshold voltage of a floating gate can be suppressed.