Semiconductor Memory Device Program Voltage Control
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing semiconductor memory devices face challenges in efficiently managing the threshold voltage of memory cells due to deterioration over multiple write and erase operations, leading to increased operating times and reduced data accuracy.
Innovation Solution
The semiconductor memory device employs a program voltage control operation that adjusts the initial program voltage based on the degree of deterioration of memory cells, and also adjusts erase and verify parameters to optimize operations, ensuring accurate data storage and retrieval.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If multiple write and erase operations are performed on memory cells, then data storage capacity is improved, but threshold voltage deterioration increases leading to reduced data accuracy
Solution Approach 1:
The patent adjusts the initial program voltage as a parameter based on the number of write and erase operations performed. By dynamically changing the voltage parameter in response to operational wear, the system compensates for threshold voltage deterioration and maintains data accuracy throughout the memory device's lifecycle
2Productivity
If program voltage is increased to improve write speed, then productivity is improved, but threshold voltage deterioration accelerates reducing long-term reliability
Solution Approach 1:
The patent implements a dynamic voltage adjustment mechanism where the initial program voltage is not fixed but is modified based on operational history. The control circuit dynamically determines the appropriate voltage level by considering the number of previous write and erase operations, thereby optimizing the balance between write speed and long-term reliability
Solution Approach 2:
By changing the program voltage parameter adaptively based on wear levels, the system prevents excessive threshold voltage deterioration that would occur with consistently high voltage operations, while still maintaining sufficiently fast write speeds through optimized voltage selection
3Device complexity
If fixed program voltage is used to simplify control circuit, then device complexity is reduced, but data accuracy deteriorates due to threshold voltage shifts
Solution Approach 1:
The patent modifies the initial program voltage parameter based on the count of write and erase operations. This parameter change approach maintains data accuracy by compensating for threshold voltage shifts without requiring complex real-time monitoring circuits, as the adjustment is based on simple operation counting
4Reliability
If write operation time is extended to improve data accuracy, then reliability is improved, but productivity decreases due to increased operating time
Solution Approach 1:
By adjusting the initial program voltage parameter based on operational wear, the patent achieves high data accuracy without requiring extended write times. The optimized voltage selection ensures sufficient data accuracy is reached more quickly, thereby maintaining high write operation throughput while ensuring reliability
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 effectively manages the threshold voltage of memory cells, reducing the time required for write operations and improving data erasure accuracy by adapting to the cell's deterioration, thus enhancing overall memory device performance.
Implementation Method 1
The program voltage control operation includes a plurality of first write loops. Each of the plurality of first write loops includes a first program operation that applies a first program voltage to a first conductive layer as one of the plurality of conductive layers and applies a write pass voltage smaller than the first program voltage to a second conductive layer as one of the plurality of conductive layers. The first program voltage increases by a first offset voltage together with an increase in a number of times of execution of the first write loop.
Implementation Method 2
The erase operation includes: a program voltage control operation; and an erase voltage supply operation that applies an erase voltage to the first wiring after performing the program voltage control operation.
Data Source
AI summary
A semiconductor memory device performs a write operation and an erase operation. The write operation includes a first program operation that applies a first program voltage to a first conductive layer. The first program voltage increases by a first offset voltage together with an increase in an execution count of a first write loop. An erase operation includes a program voltage control operation and an erase voltage supply operation that applies an erase voltage to a first wiring. The program voltage control operation includes a second program operation that applies a second program voltage to a third conductive layer. The second program voltage increases by a second offset voltage together with an increase in a number of times of execution of a second write loop. A magnitude of the first program voltage is adjusted according to a magnitude of the second program voltage.