NAND Flash Memory Page Programming and Verification Sequence
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Solution Overview
Problem
Existing semiconductor memory devices, particularly NAND-type flash memories, face challenges in enhancing operating speed and reducing consumption current due to inefficient programming and verification processes, which involve frequent changes in word line voltages and stabilization waiting times.
Innovation Solution
A semiconductor memory device configuration that consecutively programs and verifies data in multiple pages shared by the same word line, minimizing changes in selected word line voltages and reducing waiting times for word line stabilization, thereby improving operational speed and reducing power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If programming and verification are performed sequentially for each page, then data reliability is ensured, but operating speed decreases due to frequent word line voltage changes and stabilization waiting times
Solution Approach 1:
The control unit performs preliminary actions by consecutively programming multiple pages (first page, second page, third page) before performing verification. This preliminary programming sequence allows the word line voltage to be stabilized once and maintained throughout the verification process, eliminating the need for repeated voltage changes and stabilization waiting times during verification operations.
Solution Approach 2:
The patent implements continuity of useful action by maintaining the word line voltage in a high state throughout the entire verification process for multiple pages. Instead of returning to low state between verification operations, the voltage remains high, enabling continuous verification without interruption or waiting time for voltage stabilization.
2Manufacturing precision
If word line voltage is changed frequently for each programming and verification operation, then programming precision is maintained, but power consumption increases
Solution Approach 1:
The control unit performs preliminary programming of multiple pages while the word line voltage is in the high state. By completing the programming of the first page, second page, and third page before verification begins, the system maintains programming precision without requiring frequent voltage changes, thereby reducing power consumption.
Solution Approach 2:
The word line voltage is maintained in a continuous high state throughout the verification process, eliminating repeated voltage transitions. This continuous action reduces the energy consumption associated with frequent voltage changes while maintaining the programming precision achieved during the preliminary programming phase.
Data Source
AI summary
A semiconductor memory device includes memory cells which are laminated on a semiconductor substrate and include charge storage layers and control gates, a plurality of word lines each of which is commonly connected to the control gates of a plurality of the memory cells, and a control unit which performs programming and verification of data in units of a page of memory cells. The control unit consecutively performs programming of data in two or more pages of memory cells connected to the same word line, and then consecutively performs verification of the data programmed in the two or more pages of memory cells connected to the same word line.