Semiconductor Memory Device Dual-Program Operation Strategy
Solution Overview
Problem
Semiconductor memory devices face challenges in maintaining data reliability due to interference between word lines during program operations, particularly with the increasing capacity and integration of memory cells, which can lead to deformation of threshold voltage distributions and data loss.
Innovation Solution
The semiconductor memory device employs a dual-program operation strategy, where a first program operation applies a higher pass voltage to adjacent word lines for a longer time, followed by a second program operation with a lower pass voltage for a shorter time, to diffuse and trap charges effectively, thereby improving retention characteristics and separating threshold voltage distributions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a single program operation is performed with uniform pass voltage, then the program operation is simple and fast, but threshold voltage distributions become deformed and data reliability deteriorates
Solution Approach 1:
The program operation is segmented into multiple distinct program operations (first program operation and second program operation). Each operation applies different pass voltages to adjacent word lines at different timing, thereby separating the charge trapping processes to prevent interference and deformation of threshold voltage distributions, thus improving data reliability without excessive complexity increase
Solution Approach 2:
The patent employs periodic alternating high and low pass voltages to adjacent word lines during the program operation. This periodic voltage application creates distinct charging and verification phases that prevent charge interference between memory cells, ensuring clear threshold voltage distribution separation while maintaining a structured and manageable operation sequence
2Manufacturing precision
If pass voltage is applied to adjacent word lines during program operation, then charge diffusion is improved, but interference between word lines increases and threshold voltage distribution deforms
Solution Approach 1:
The first program operation preliminarily traps charges in memory cells by applying pass voltage to adjacent word lines before the second program operation. This preliminary charge trapping establishes a baseline state that prevents subsequent interference during the second operation, thereby achieving good threshold voltage distribution separation without deformation
Solution Approach 2:
The program operation is divided into two distinct phases: the first program operation applies pass voltage to adjacent word lines for charge diffusion, while the second program operation uses different timing and voltage levels to verify and stabilize the charge distribution. This segmentation prevents interference between word lines while achieving precise threshold voltage control
3Reliability
If program voltage application time is extended, then charge trapping is more complete, but program operation time increases and productivity decreases
Solution Approach 1:
The patent uses periodic application of program voltage with alternating high and low pass voltages to adjacent word lines. This periodic action achieves complete charge trapping through multiple short pulses rather than one long continuous application, thereby improving data retention characteristics while maintaining fast program operation speed and high productivity
Solution Approach 2:
The first and second program operations are performed in continuous sequence without interruption. The first operation initiates charge trapping and the second operation completes and verifies it, ensuring continuous useful action that achieves complete charge trapping efficiently without extending total operation time, thus maintaining high productivity
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach enhances data reliability by preventing interference between word lines and ensuring clear separation of threshold voltage distributions, maintaining data integrity even after program operations are completed.
Implementation Method 1
a first program operation applies a higher pass voltage to adjacent word lines for a longer time, followed by a second program operation with a lower pass voltage for a shorter time, to diffuse and trap charges effectively
Data Source
AI summary
Provided herein is a semiconductor memory device and a method of operating the semiconductor memory device. The semiconductor memory device includes: a memory cell array including a plurality of word lines; a peripheral circuit coupled to the memory cell array through the plurality of word lines and configured to apply a program voltage to a selected word line of the plurality of word lines during a program operation and apply a pass voltage to unselected word lines of the plurality of word lines; and control logic configured to control the peripheral circuit to apply a first pass voltage to word lines adjacent to the selected word line among the unselected word lines during a first program operation of the program operation and apply a second pass voltage to the word lines adjacent to the selected word line during a second program operation of the program operation.