Trench Memory Gate Structure for Non-Volatile Storage in Power MOSFETs
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Solution Overview
Problem
There is a need for improved non-volatile memory solutions in power MOSFETs and integrated circuits with increased storage capacity to store chip IDs and adjust circuit properties post-assembly, enhancing product accuracy and user customization.
Innovation Solution
A semiconductor device is fabricated with a control gate and a floating gate insulated from each other, along with source, body, and drain regions of specific conductivity types, within a trench structure in a semiconductor substrate, allowing for charge storage and readout as memory information.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If a memory device is added to power MOSFETs and integrated circuits, then storage capacity and product accuracy are improved, but device complexity and manufacturing difficulty increase
Solution Approach 1:
The patent implements a nested structure where the control gate is positioned within the trench and the floating gate is placed above it, with both gates nested within the same vertical space. This nesting approach allows the memory device to store information while occupying minimal additional area, thereby increasing storage capacity without proportionally increasing device complexity
Solution Approach 2:
The patent transitions from a planar two-dimensional layout to a three-dimensional vertical structure by forming trenches that extend into the semiconductor substrate and positioning gates at different vertical levels. This dimensional change enables the memory device to achieve higher storage capacity while maintaining a compact footprint, effectively resolving the contradiction between storage capacity and device complexity
2Reliability
If a trench structure with control gate and floating gate is formed, then memory functionality is improved, but manufacturing precision requirements increase
Solution Approach 1:
The patent divides the gate structure into two distinct segments: a control gate positioned in the lower portion of the trench and a floating gate positioned above it. This segmentation allows each gate to be formed and positioned independently with specific precision requirements, making the overall manufacturing process more controllable and reducing the cumulative precision demands compared to a single complex gate structure
Solution Approach 2:
The patent introduces an insulating layer as an intermediary between the control gate and floating gate, which not only provides electrical isolation but also serves as a reference for positioning and alignment during manufacturing. This intermediary structure simplifies the manufacturing process by providing clear dimensional references, thereby reducing the overall manufacturing precision requirements while ensuring reliable memory functionality
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 configuration enables efficient storage and retrieval of information, improving the accuracy and adaptability of integrated circuits by precisely controlling the charging state of the floating gate, thus enhancing memory functionality.
Implementation Method 1
a floating gate disposed in the first trench above the control gate and insulated from the control gate
Data Source
AI summary
A semiconductor device is formed in a semiconductor substrate comprising a first main surface and includes a control gate disposed in a lower portion of a first trench formed in the first main surface, a floating gate disposed in the first trench above the control gate and insulated from the control gate, a source region of a first conductivity type, a body region of a second conductivity type, and a drain region of the first conductivity type.