Memory Device Programming With Segmented Word Line Voltage Waveforms
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Solution Overview
Problem
Existing memory device programming methods face interference issues between programming voltage and pass voltages, which can lead to programming failure or memory cell breakdown due to inappropriate voltage changes during the programming process.
Innovation Solution
The method involves providing different two-stage voltage waveforms to word lines at deselected states, with specific preliminary and step voltages, to effectively support the programming voltage on the selected word line, thereby optimizing voltage settings and preventing overshoot or programming failure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a programming voltage is applied to a selected word line during programming, then memory cells can be programmed, but voltage interference occurs between the programming voltage and pass voltages on other word lines
Solution Approach 1:
The patent segments the word lines into different groups based on their physical positions relative to the selected word line. Word lines are divided into first groups (above the selected word line) and second groups (below the selected word line), allowing different voltage waveforms to be applied to different segments. This segmentation enables precise control of voltage interference by treating each segment independently with appropriate voltage waveforms.
Solution Approach 2:
The patent applies different voltage waveform characteristics to different local regions (word line groups) based on their specific positions. First groups receive voltage waveforms with first characteristics while second groups receive voltage waveforms with second characteristics. This local quality approach ensures that each region receives the optimal voltage waveform for its specific position, minimizing interference while maintaining programming effectiveness.
2Reliability
If voltage waveforms are applied to deselected word lines to prevent interference, then programming reliability improves, but voltage control complexity increases
Solution Approach 1:
The patent employs dynamic voltage waveform generation where the voltage characteristics are adjusted based on the selected word line position. The voltage waveform generation unit dynamically changes the voltage waveforms applied to different word line groups depending on which word line is currently selected for programming. This dynamic approach allows the system to adapt to different programming scenarios while maintaining manageable control complexity through systematic waveform generation.
Solution Approach 2:
The patent changes voltage parameters (amplitude, duration, timing) of the waveforms applied to different word line groups. By adjusting these parameters based on the selected word line position and the specific group being addressed, the system optimizes programming reliability without requiring overly complex control circuits. The parameter changes are systematically applied to different groups to achieve the desired interference prevention.
Data Source
AI summary
A memory device and a programming method thereof are provided. The memory device includes a memory array, a plurality of word lines and a voltage generator. During a programming procedure, one of the word lines is at a selected state and others of the word lines are at a deselected state. Some of the word lines, which are at the deselected state, are classified into a first group and a second group. The first group and the second group are respectively located at two sides of the word line, which is at the selected state. The voltage generator provides a programming voltage to the word line, which is at the select state, during a programming duration. The voltage generator provides a first two-stage voltage waveform to the word lines in the first group and provides a second two-stage voltage waveform to the word lines in the second group.