Programming method of non-volatile memory cell
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Solution Overview
Problem
Existing programming methods for non-volatile memory cells with P-type transistors face challenges in efficiently injecting hot electrons into the charge trapping layer, leading to inadequate programming and increased power consumption.
Innovation Solution
A programming method that limits the channel current of the memory transistor and uses a ramped-up control signal to gradually adjust the turn-on extent of the memory transistor, ensuring continuous hot electron injection during the program action.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the channel current of the memory transistor is increased to enhance hot electron injection, then the programming efficiency is improved, but the power consumption is increased
Solution Approach 1:
The patent applies periodic action by dividing the programming operation into multiple programming pulses applied in sequence. Each pulse temporarily increases the channel current to enable hot electron injection, then reduces the current. This periodic application allows cumulative programming effect over multiple pulses while limiting the duration of high current flow, thereby improving programming efficiency without proportionally increasing power consumption.
Solution Approach 2:
The patent employs dynamics by adaptively adjusting the voltage levels of the control signal across different programming pulses. The control signal voltage is dynamically modified based on the programming state, allowing the channel current to be optimized for hot electron injection only when necessary. This dynamic adjustment enables efficient programming while minimizing unnecessary power consumption during already-programmed states.
2Device complexity
If a fixed control signal is used during programming, then the circuit operation is simplified, but the hot electron injection becomes inadequate leading to poor programming results
Solution Approach 1:
The patent replaces the fixed control signal with a dynamic control signal whose voltage level changes across different programming pulses. This dynamic control signal adapts to the programming state, ensuring adequate hot electron injection is achieved while maintaining reliable programming results. The added complexity is minimal, involving only voltage level adjustments rather than fundamental circuit changes.
3Reliability
If the control signal voltage is increased to improve hot electron injection, then the programming effectiveness is enhanced, but the channel current increases leading to higher power consumption
Solution Approach 1:
The patent uses periodic application of elevated control signal voltages through multiple programming pulses. Each pulse temporarily increases the voltage to improve hot electron injection effectiveness, then reduces it. This periodic approach achieves reliable programming through cumulative effect while limiting the time duration of high power consumption, thereby decoupling programming effectiveness from continuous high power usage.
Solution Approach 2:
The patent applies partial action by using multiple programming pulses with progressively adjusted voltages rather than continuously applying maximum voltage. Each pulse provides sufficient hot electron injection for incremental programming progress, achieving effective programming through repeated partial actions rather than excessive continuous action, thus reducing overall power consumption.
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 method ensures sufficient hot electron injection for effective programming while reducing power consumption by limiting the channel current and optimizing the control signal waveform.
Implementation Method 1
a channel hot hole induced hot electron injection (CHHIHEI) effect is generated, a greater number of hot electrons are injected into the charge trapping layer of the memory transistor MF
Data Source
AI summary
A programming method of a non-volatile memory cell is provided. The non-volatile memory cell includes a memory transistor. Firstly, a current limiter is provided, and the current limiter is connected between a drain terminal of the memory transistor and a ground terminal. Then, a program voltage is provided to a source terminal of the memory transistor, and a control signal is provided to a gate terminal of the memory transistor. In a first time period of a program action, the control signal is gradually decreased from a first voltage value, so that the memory transistor is firstly turned off and then slightly turned on. When the memory transistor is turned on, plural hot electrons are injected into a charge trapping layer of the memory transistor.