Programmable Read-Only Memory Cell With Segmented Channel
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Solution Overview
Problem
Conventional one-time programmable (OTP) memory cells are not suitable for use in battery-powered devices due to their inability to be selected for reading or programming operations using low voltage signals, which is necessary for such applications.
Innovation Solution
A transistor with two channel portions of different dopant concentrations is used to protect the selection element from high voltages and currents during programming, allowing for the implementation of a low-voltage transistor that can be switched using low voltage signals, enabling the use of OTP memory cells in battery-powered devices.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If a conventional OTP memory cell uses a single transistor for selection, then the cell can be programmed with high voltage, but the selection element cannot be operated with low voltage signals
Solution Approach 1:
The channel of the transistor is segmented into two distinct portions: a first channel portion with higher dopant concentration and a second channel portion with lower dopant concentration. This segmentation allows different regions of the channel to perform different functions - the first portion provides high breakdown voltage resistance while the second portion enables low-voltage operation, thus resolving the contradiction between operating voltage and breakdown resistance.
Solution Approach 2:
Different regions of the transistor channel are given different dopant concentrations to optimize local properties. The first channel portion has higher dopant concentration for withstanding high programming voltages, while the second channel portion has lower dopant concentration for enabling low-voltage selection operations. This local differentiation allows the single transistor to simultaneously satisfy both high-voltage reliability and low-voltage operability requirements.
2Adaptability or versatility
If the transistor channel has uniform dopant concentration, then the device structure is simple, but it cannot simultaneously withstand high programming voltage and operate with low selection voltage
Solution Approach 1:
The channel is divided into two portions with different dopant concentrations, enabling the transistor to adapt to both high-voltage programming and low-voltage selection operations. This segmentation increases voltage range adaptability while maintaining relatively simple device structure, as the segmentation is achieved through doping concentration variation rather than additional physical structures.
Solution Approach 2:
The channel exhibits local quality variations in dopant concentration, with the first portion having higher concentration for high-voltage withstand capability and the second portion having lower concentration for low-voltage operation. This local differentiation provides versatile voltage range operation without significantly increasing overall device complexity.
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 solution allows for the development of OTP memory cells that can be selected for reading or programming operations using lower voltage signals, making them suitable for battery-powered devices and enabling high-density memory arrays with reduced risk of breakdown damage.
Implementation Method 1
The channel of the transistor comprises a first and a second channel portion. A dopant concentration in the first channel portion is higher than in the second channel portion
Data Source
AI summary
A one-time programmable memory cell having a transistor. The transistor includes a drain, a source, and a channel between the drain and the source. The transistor is connected to a data storage element and to a memory cell selection element. The channel of the transistor includes a first and a second channel portion. A dopant concentration in the first channel portion is higher than in the second channel portion.