Nonvolatile Memory Bit Line Current Control for Temperature Compensation
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Solution Overview
Problem
Semiconductor devices with polycrystalline silicon channels face challenges in maintaining reliable electrical properties across temperature variations, leading to reduced sensing margins and increased failure rates during read, program, and erase operations due to decreased current flow at lower temperatures.
Innovation Solution
A nonvolatile memory device with a bit line current controlling circuit that increases current supply to the bit line when temperature decreases, using a control signal generator to adjust the voltage and ensure consistent current flow through memory transistors, thereby compensating for temperature-induced current reductions without adjusting gate voltages.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If gate voltage is adjusted to compensate for temperature-induced current reduction, then current flow through memory transistors is improved, but read disturbance properties deteriorate
Solution Approach 1:
The patent introduces a bit line current controlling circuit as an intermediary component that regulates current flow through the memory transistors. This circuit includes a current mirror structure with compensation transistors that actively adjust the bit line current based on temperature conditions, thereby compensating for temperature-induced current reduction without directly adjusting gate voltages, thus avoiding read disturbance
Solution Approach 2:
The patent changes the control parameter from gate voltage to bit line current. By monitoring temperature and adjusting the bit line current accordingly through the current controlling circuit, the system compensates for temperature effects on current flow while maintaining gate voltages at safe levels that prevent read disturbance
2Reliability
If temperature decreases, then current flow through polycrystalline silicon channel decreases, but sensing margin is reduced
Solution Approach 1:
The patent implements a feedback mechanism where the bit line current controlling circuit monitors temperature conditions and adjusts the current flow accordingly. The circuit uses temperature-dependent current adjustment to maintain consistent electrical properties and sensing margins across varying temperatures, compensating for the inherent temperature sensitivity of polycrystalline silicon channels
Data Source
AI summary
According to example embodiments, a nonvolatile memory device includes a substrate, at least one string extending vertically from the substrate, and a bit line current controlling circuit connected to the at least one string via at least one bit line. The at least one string may include a channel containing polycrystalline silicon. The bit line current controlling circuit may be configured to increase the amount of current being supplied to the bit line according to a decrease in a temperature such that a current flowing through the channel of the at least one string is increased when a temperature decreases.