Semiconductor Memory Page Buffer Voltage Control
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Solution Overview
Problem
Semiconductor memory devices face challenges in maintaining consistent current characteristics during program verify and read operations, leading to reliability issues due to variations in memory cell back patterns and temperature effects.
Innovation Solution
The semiconductor memory device incorporates a voltage supply unit and page buffers controlled by a logic unit to adjust operating voltages and sensing signals based on the program sequence, page position, and temperature, ensuring optimal current characteristics and reliability during operations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a nonvolatile memory device is used to maintain data regardless of power supply state, then data retention capability is improved, but read and write speeds deteriorate
Solution Approach 1:
The memory device is divided into multiple pages that can be independently programmed and verified. The control logic sequentially selects and programs specific pages within a block, allowing targeted data writing without affecting other pages. This segmentation enables efficient data retention for specific pages while maintaining overall system reliability.
2Manufacturing precision
If multiple pages are programmed sequentially with increased program turns, then programming completeness is improved, but current characteristic variations worsen
Solution Approach 1:
Before programming each page, the control logic performs a read operation to detect the current state of memory cells. Based on this preliminary detection, the system determines the appropriate number of program turns needed for each page. This preliminary action prevents over-programming and ensures that each page receives the exact number of programming cycles required, maintaining current characteristic consistency across all pages.
Solution Approach 2:
The control logic continuously monitors the programming status of each page through read operations and adjusts the number of program turns accordingly. If a page is already programmed to the desired state, the system reduces or stops further programming for that page. This feedback mechanism prevents excessive programming that would cause current characteristic variations and ensures uniform performance across all pages in the block.
3Reliability
If the number of program turns is increased to ensure programming completeness, then programming reliability is improved, but operation time deteriorates
Solution Approach 1:
The control logic performs preliminary read operations on each page before initiating programming to detect the initial state of memory cells. Based on this detection, the system determines the minimum number of program turns required for each page. This preliminary assessment prevents unnecessary programming cycles, reducing operation time while ensuring that each page is programmed sufficiently to achieve the desired reliability.
Solution Approach 2:
The number of program turns for each page is dynamically adjusted based on its initial state and programming progress. Pages that are already close to the desired state receive fewer program turns, while pages requiring more programming receive additional turns. This dynamic adjustment optimizes the total programming time while maintaining programming reliability across all pages in the block.
Data Source
AI summary
Provided herein is a semiconductor memory device. The semiconductor memory device may include: a memory cell array including a plurality of pages; a voltage supply unit configured to provide operating voltages to the plurality of pages; a plurality of page buffers coupled to a plurality of bit lines of the memory cell array and configured to control and sense currents flowing through the plurality of bit lines in response to a page buffer sensing signal; and a control logic configured to control the voltage supply unit and the plurality of page buffers such that the plurality of pages are successively programmed, and to control a potential level of the page buffer sensing signal depending on a program sequence of the plurality of pages during a program verify operation of a program operation.