Non-Volatile Memory Programming Voltage Slope Control
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Solution Overview
Problem
Existing methods for programming non-volatile memory, such as NAND-type flash memory, face challenges in controlling the slope of programming pulses, leading to potential program disturb effects and inefficiencies in voltage application.
Innovation Solution
A method and controller that apply a pass voltage to a selected word line and increment it with a single step value to reach a program voltage, maintaining a controlled slope to avoid program disturb and ensure accurate programming.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a steep voltage slope is used during programming, then programming speed is improved, but program disturb effect increases
Solution Approach 1:
The voltage ramping process is segmented into multiple discrete steps rather than a continuous steep slope. The controller applies voltage in controlled increments (e.g., 0.5V steps) from pass voltage to program voltage, allowing the slope to be adjusted at each step. This segmentation enables the system to achieve programming speed while preventing program disturb by avoiding excessively steep voltage transitions.
Solution Approach 2:
The voltage slope is made dynamic and adjustable rather than fixed. The controller adapts the voltage ramping rate based on the specific programming requirements, memory cell state, and detected disturbances. This dynamic control allows optimization of the voltage slope to balance programming speed with prevention of program disturb effects.
2Adaptability or versatility
If different programming voltages are applied, then programming flexibility is improved, but control complexity increases
Solution Approach 1:
The system manages programming flexibility through parameter changes in the voltage ramping process. The controller adjusts parameters such as voltage increment size, ramping rate, and holding time based on the target program voltage. This allows support for multiple programming voltages (e.g., 3.3V, 5V, 12V) without proportionally increasing control complexity, as the same basic ramping mechanism adapts to different voltage levels through parameter modification.
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 approach simplifies the control of voltage slope during programming, prevents program disturb, and allows for precise programming across varying programming voltages, ensuring reliable data storage in non-volatile memory.
Implementation Method 1
The programming operation is performed by driving a strong positive voltage on the control gate to force a current to flow from the channel through the floating gate to the control gate, a phenomenon known as the 'Fowler Nordheim Tunnelling' effect.
Data Source
AI summary
A method is provided for programming a non-volatile memory having a plurality of word lines, the method comprising: applying a pass voltage to a selected word line among the plurality of word lines; and applying one of first and second program voltages to the selected word line by increasing the pass voltage, wherein the applying of one of the first and second program voltages increases the pass voltage with a single increment.