Memory Program Method Using Multiple Precharge Steps
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Solution Overview
Problem
As critical dimensions of devices in integrated circuits shrink, program disturbance during memory cell programming operations becomes increasingly serious, necessitating a method to reduce this disturbance while maintaining storage capacity and lowering costs per bit.
Innovation Solution
A program method for memory devices that includes multiple precharge and program steps, with specific voltage applications to selected and unselected memory cells, followed by verification, to inhibit programming of unselected cells and ensure proper programming of selected cells, thereby reducing program disturbance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multiple precharge steps are performed before program steps, then program disturbance is reduced, but programming time is increased
Solution Approach 1:
The programming operation is segmented into multiple precharge steps and program steps. Each precharge step applies a precharge voltage to the bit line, followed by a program step that applies a program voltage to the word line. This segmentation allows controlled charging of the bit line to reduce program disturbance while maintaining efficient programming throughput.
Solution Approach 2:
Multiple precharge steps are performed as preliminary actions before the actual program steps. The precharge voltage is applied to the bit line in advance to prepare the memory cell for programming, reducing program disturbance by ensuring proper voltage conditions are established before the program voltage is applied to the word line.
2Reliability
If precharge voltage is applied to bit line connected to unselected memory cells, then program disturbance is inhibited, but voltage control complexity is increased
Solution Approach 1:
The precharge voltage is applied locally to specific bit lines that are electrically connected to unselected memory cells. This local quality approach ensures that only the necessary bit lines receive the precharge voltage, thereby inhibiting program disturbance in adjacent unselected cells while avoiding unnecessary voltage applications to other parts of the memory device, thus managing voltage control complexity.
Solution Approach 2:
The precharge voltage acts as an intermediary measure between the program voltage application and the memory cells. By applying the precharge voltage to the bit line as an intermediate step, the system prepares the electrical conditions to prevent program disturbance without directly applying the program voltage, thus reducing the harmful effects on unselected cells.
3Reliability
If multiple program steps with different program voltages are performed, then programming reliability is improved, but operation time is increased
Solution Approach 1:
The programming operation uses periodic action by alternating between precharge steps and program steps. Each cycle consists of applying precharge voltage to the bit line followed by applying program voltage to the word line. This periodic pattern ensures reliable programming by maintaining proper voltage conditions throughout the operation while managing the overall operation time through structured repetition.
Solution Approach 2:
The program voltage is changed across different program steps, with each subsequent program step using a different program voltage level. This parameter change approach improves programming reliability by progressively adjusting the voltage conditions to ensure complete and accurate programming of the selected memory cell while managing the total operation time.
Data Source
AI summary
A program method for a memory device is provided. The memory device includes a plurality of memory cells, a bit line and word lines electrically connected to the plurality of memory cells. The plurality of memory cells includes a selected memory cell and unselected memory cells when the memory device is in a program operation. The program method including performing precharge steps, performing program steps and performing a verification step to the selected memory cell after the precharge steps and the program steps. Each of the precharge steps includes applying a precharge voltage to the bit line electrically connected to the unselected memory cells. Each of the program steps includes applying a program voltage to a word line of the word lines electrically connected to the selected memory cell.