Capacitive Sidewall Insulating Films for Nonvolatile Semiconductor Storage
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Solution Overview
Problem
Conventional non-volatile semiconductor memory devices with ONO films as capacitive insulating films have insufficient breakdown voltage characteristics and unstable capacitor characteristics due to continuous high voltage application, leading to complex configurations and inability to downsize due to multiple power supplies required for different capacitive elements.
Innovation Solution
A non-volatile semiconductor memory device with a capacitive element using sidewall spacers made of insulating material as capacitive sidewall insulating films, allowing for improved breakdown voltage and stabilized capacitor characteristics without the need for separate power supplies, by integrating the sidewall spacers into the charge pump circuit on a semiconductor substrate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If ONO film is used as capacitive insulating film in charge pump circuit, then manufacturing process is simplified, but breakdown voltage characteristic is insufficient and capacitor characteristic becomes unstable
Solution Approach 1:
The patent applies different insulating films to different functional regions: ONO film is used in memory cell regions where charge storage is needed, while silicon oxide film is used in charge pump circuit regions where high breakdown voltage is required. This local differentiation allows each region to have optimal properties for its specific function, resolving the contradiction between manufacturing simplicity and reliability.
Solution Approach 2:
The insulating film structure is segmented into different material layers (silicon oxide and ONO) in different spatial locations. The charge pump circuit uses silicon oxide film for capacitive insulating layers, while memory cells use ONO film. This segmentation allows the system to simultaneously achieve high reliability in charge pumping and effective charge storage in memory cells.
2Ease of manufacture
If ONO film is used as capacitive insulating film, then manufacturing is easier, but device complexity increases due to multiple power supplies required
Solution Approach 1:
By using silicon oxide film with superior breakdown voltage characteristics in the charge pump circuit, the patent eliminates the need for multiple power supplies and complex voltage management. The enhanced reliability of silicon oxide film allows single-power-supply operation, reducing device complexity while maintaining manufacturing simplicity.
3Reliability
If higher breakdown voltage is achieved through thicker insulating film, then reliability improves, but device area increases
Solution Approach 1:
The patent employs a composite insulating film structure combining silicon oxide and ONO materials. Silicon oxide provides high breakdown voltage with thin film thickness, while ONO provides charge storage functionality. This composite approach achieves both high reliability and compact area by leveraging the complementary strengths of different materials rather than increasing film thickness uniformly.
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 use of sidewall spacers as capacitive sidewall insulating films enhances breakdown voltage and stabilizes capacitor characteristics, simplifying the device configuration and enabling downsizing by eliminating the need for multiple power supplies, while maintaining efficient charge injection and storage operations.
Implementation Method 1
the capacitive elements C101, C102, C103, and C104 repeat charging and discharging at the timings of voltage change between high and low levels of the first clock φ1 and the second clock φ2. The charge pump circuit 100 outputs, as the output voltage V2 from the output electrode, a voltage obtained by multiplying a voltage having the amplitude of the first clock φ1 or the second clock φ2 by the number of stages of the capacitive elements C101, C102, C103, and C104.
Implementation Method 2
The charge injection into the charge storage layer of the memory cell is achieved by applying a low bit voltage to a channel layer of the memory gate structure and applying a high charge storage gate voltage to a memory gate electrode to cause a quantum tunneling effect due to a voltage difference between the bit voltage and the memory gate voltage.
Data Source
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AI summary
In a non-volatile semiconductor memory device (1) according to the present invention, a capacitive sidewall insulating film (21) of a capacitive element (C1, C2) is made of a layer same as that of a sidewall spacer (13a, 13b) of a memory cell (2), the film qualities and thicknesses of which are adjusted mainly for breakdown voltage. The configuration leads to an improved breakdown voltage characteristic and a stabilized capacitor characteristic of the capacitive element (C1, C2). The non-volatile semiconductor memory device (1) does not need a conventionally needed power supply for achieving low voltage application to a capacitive element, thereby achieving a simplified and downsized configuration accordingly.