Semiconductor Device Pre-Programming Voltage for Data Retention
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Solution Overview
Problem
Semiconductor memory devices face challenges in maintaining data retention due to charge loss caused by holes in space regions between memory cells, which affects the operational characteristics and reliability of nonvolatile memory devices like flash memory.
Innovation Solution
A semiconductor device and method that apply a pre-program voltage to a selected word line and adjacent unselected word lines to remove holes in the space region, minimizing charge loss by generating a fringe field that injects electrons and improves data retention characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional programming is applied directly without pre-programming, then the programming process is simpler and faster, but charge loss occurs due to holes in space regions between memory cells, degrading data retention and operational reliability
Solution Approach 1:
A pre-programming step is performed before the main programming operation. This preliminary action applies a first program voltage to remove holes from the space region between memory cells, preparing the structure for subsequent programming. This prevents charge loss during the main programming operation, thereby improving data retention without significantly complicating the overall process flow.
2Reliability
If a pre-program voltage is applied to remove holes in the space region, then data retention and operational reliability are improved, but additional voltage application steps and control logic are required, increasing device complexity
Solution Approach 1:
The control logic is designed to automatically execute a pre-programming sequence before main programming. This preliminary action applies appropriate voltages to selected and unselected word lines to remove holes from space regions. By embedding this preparation step into the control logic, operational reliability is improved while the complexity is managed through automated sequencing rather than manual intervention.
Solution Approach 2:
Different voltage levels are applied at different stages: a first program voltage is applied during pre-programming to remove holes, and a second program voltage is applied during main programming to program the memory cells. By changing voltage parameters according to the programming stage, the system achieves improved reliability while using a single integrated control logic unit that manages multiple voltage conditions.
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
The solution effectively improves data retention and operational reliability by removing holes in the space region before programming, thereby enhancing the program operation and maintaining the integrity of stored data.
Implementation Method 1
generating a fringe field that injects electrons
Data Source
AI summary
A semiconductor device includes strings each having a plurality of memory cells. The strings are coupled between a common source line and a bit line. A method of operating the semiconductor device includes applying a pre-program voltage to a selected word line coupled to a selected memory cell and to an unselected word line coupled to an unselected memory cell adjacent to the selected memory cell among the plurality of memory cells. The method further includes applying a first program voltage to the selected word line.