Memory System Partial Page Program Verify Voltage Control

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Existing memory systems face challenges in maintaining data reliability and uniformity of threshold voltage distribution when writing data in units smaller than a page, leading to potential decreases in data retention characteristics and operation reliability.

Innovation Solution

The memory system employs a controller that issues specific commands to the semiconductor memory device to execute write operations in modes such as the 4 Partial Page Program (PPP) mode, where data is written in zones within a page, and pre-verify operations are performed to align the threshold voltage distribution uniformly across all zones.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If data is written in units smaller than a page (partial page program mode), then writing efficiency and flexibility are improved, but data reliability and threshold voltage distribution uniformity deteriorate

Engineering Contradiction:

Improvewriting efficiencyVSAvoiddata reliability

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The patent divides a page into multiple zones (e.g., 4 zones) and performs separate program operations on each zone. This segmentation allows the system to maintain the flexibility of partial page programming while managing threshold voltage distribution more effectively across different zones, thereby preserving data reliability.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent performs a pre-verify operation before the main program operation to identify memory cells that require additional programming. This preliminary action ensures that all cells are properly programmed before final verification, preventing data reliability issues even when writing partial pages.

Inventive Principle:

Principle #10Preliminary action

2Adaptability or versatility

If data is written in units smaller than a page, then operation flexibility is improved, but threshold voltage distribution uniformity deteriorates

Engineering Contradiction:

Improveoperation flexibilityVSAvoidthreshold voltage distribution uniformity

Core Design Contradiction:

Adaptability or versatilityVSManufacturing precision

Solution Approach 1:

The patent applies different verify voltages to different zones based on their specific programming status and characteristics. By using a first verify voltage for some zones and a second verify voltage (higher than the first) for other zones, the system achieves uniform threshold voltage distribution across all zones while maintaining the flexibility to program partial pages.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The pre-verify operation identifies cells that need additional programming before the main program operation. This preliminary assessment ensures that subsequent programming operations achieve uniform threshold voltage distribution across all zones, even when only partial pages are programmed.

Inventive Principle:

Principle #10Preliminary action

3Device complexity

If verify operations use a single verify voltage, then operation simplicity is maintained, but data retention characteristics deteriorate

Engineering Contradiction:

Improveoperation simplicityVSAvoiddata retention characteristics

Core Design Contradiction:

Device complexityVSDuration of action of stationary object

Solution Approach 1:

The patent changes the verify voltage parameter by using different verify voltages for different zones. Specifically, it uses a first verify voltage for some zones and a second verify voltage (higher than the first) for other zones. This parameter variation ensures that all memory cells achieve the required threshold voltage levels for reliable data retention, while the controller manages the complexity through automated voltage selection based on zone identification.

Inventive Principle:

Principle #35Parameter changes

Data Source

PatentUS20250037771A1Memory system having semiconductor memory device that performs verify operations using various verify voltages

Publication Date: 2025.01.30 KIOXIA CORP

AI summary

A memory system includes a semiconductor memory device having memory cells arranged in rows and columns, and a controller configured to issue a write command with or without a partial page program command to the semiconductor memory device. The semiconductor memory device, in response to the write command issued without the partial page command, executes a first program operation on a page of memory cells and then a first verify operation on the memory cells of the page using a first verify voltage for all of the memory cells of the page, and in response to the write command issued with the partial page command, executes a second program operation on a subset of the memory cells of the page and then a second verify operation on the memory cells of the subset using one of several different second verify voltages corresponding to the subset.