Semiconductor Memory Device Programming with Dual-Step Voltage Increments
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Solution Overview
Problem
Conventional semiconductor memory devices, such as flash memory devices, experience malfunction due to shifts in threshold voltage distribution during programming operations, leading to increased programming time and wider threshold voltage widths, which affect operation characteristics.
Innovation Solution
A semiconductor memory device and method that program memory cells through temporary states using step-wise increasing program voltages in two distinct steps: first, to temporary states with a larger incremental value, and second, to target states with a smaller incremental value, thereby narrowing the threshold voltage distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional programming methods are used with single-step voltage increases, then programming operation can be completed, but threshold voltage distribution becomes wide and programming time increases
Solution Approach 1:
The programming operation is divided into multiple stages with different voltage increment patterns. The method segments the programming process into initial programming with larger voltage increments and final programming with smaller voltage increments, allowing efficient programming while achieving narrow threshold voltage distribution.
Solution Approach 2:
The programming method employs periodic voltage pulse applications with varying increment patterns. By alternating between larger and smaller voltage increments in periodic cycles, the method achieves both fast programming and precise threshold voltage control, resolving the contradiction between speed and precision.
2Productivity
If programming voltage is increased to accelerate programming, then programming speed improves, but threshold voltage shifts due to interference increase causing malfunction
Solution Approach 1:
The programming voltage increment is made dynamic rather than fixed. The method adjusts voltage increment size based on programming stage: larger increments during initial programming for speed, and smaller increments during final programming to prevent interference and ensure reliability. This dynamic adjustment resolves the contradiction between speed and reliability.
Solution Approach 2:
The method changes the voltage increment parameter throughout the programming process. By transitioning from large voltage increments to small voltage increments, the system maintains high programming speed while preventing threshold voltage shifts caused by interference, thus improving both productivity and reliability.
3Manufacturing precision
If programming is performed page by page sequentially, then all pages can be programmed, but total programming time becomes excessively long
Solution Approach 1:
The programming process is segmented into two distinct phases: a first programming phase that quickly programs all pages using larger voltage increments, and a second programming phase that refines the programming using smaller voltage increments. This segmentation allows complete programming of all pages while significantly reducing total programming time.
Solution Approach 2:
The method maintains continuous programming action across all pages without idle transitions. By applying the two-phase voltage increment strategy continuously across all pages, the system achieves complete programming of all pages efficiently, eliminating time losses associated with sequential page-by-page processing.
Data Source
AI summary
The semiconductor memory device includes a memory cell array configured to include a plurality of blocks, wherein each of the blocks has pages and each of the pages includes memory cells, and a peripheral circuit configured to program the memory cells to target program states. Here, the peripheral circuit programs the memory cells to temporary program states by applying program voltages increasing step-by-step by a first incremental value, and then programs the memory cells to the target program states by applying program voltages increasing step-by-step by a second incremental value.