Nonvolatile Memory Program Method Voltage Control
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Solution Overview
Problem
In nonvolatile memory devices, the local self-boosting scheme for program inhibition can cause hot carrier injection due to large channel voltage differences, leading to errors in programming and read operations.
Innovation Solution
Applying a program voltage to a selected word line and using a series of voltages, including first and second pass voltages, middle voltages, and an isolation voltage to adjacent word lines, to reduce channel voltage differences and prevent hot carrier injection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a local self-boosting scheme is applied to prevent program disturbance, then program inhibition is improved, but hot carrier injection occurs due to large channel voltage differences
Solution Approach 1:
The patent introduces intermediate voltage levels (first middle voltage and second middle voltage) between the isolation voltage and pass voltage to act as mediators. These intermediate voltages are applied to word lines adjacent to those receiving isolation voltage, creating a gradual voltage transition that reduces the abrupt channel voltage difference between turned-off and turned-on memory cells, thereby preventing hot carrier injection while maintaining program inhibition effectiveness
Solution Approach 2:
The patent changes the voltage parameters applied to word lines by introducing multiple intermediate voltage levels (first middle voltage Vmid1 and second middle voltage Vmid2) that are higher than the isolation voltage but lower than the pass voltage. This parameter modification creates a stepped voltage distribution that reduces the voltage difference between adjacent memory cells, eliminating the condition that causes hot carrier injection
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 configuration ensures appropriate channel potential distribution, preventing electron transfer through leakage current and substantially reducing hot carrier injection, thereby maintaining device characteristics during program inhibition operations.
Implementation Method 1
a difference between the boosted local channel voltage and a channel voltage of a turned-off memory cell may be large and thus cause hot carrier injection
Implementation Method 2
electron transfer through leakage current
Data Source
AI summary
A program method of a nonvolatile memory device includes applying a program voltage to a selected word line, applying a first pass voltage to at least one word line adjacent to the selected word line, applying at least one first middle voltage lower than the first pass voltage but higher than an isolation voltage to at least one word line adjacent to the word line receiving the first pass voltage, applying the isolation voltage to a word line adjacent to the word line receiving the first middle voltage, applying at least one second middle voltage higher than the isolation voltage but lower than a second pass voltage to at least one word line adjacent to the word line receiving the isolation voltage, and applying a second pass voltage to at least one word line adjacent to the word line receiving the second middle voltage.