Memory Device Program Pulse Duration Temperature Compensation
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Solution Overview
Problem
Program disturb in memory devices, particularly in erased-state memory cells, occurs due to capacitive coupling and channel boosting, leading to incorrect data readbacks and reduced bit error rate and reliability, especially under varying temperature conditions.
Innovation Solution
The solution involves optimizing channel boosting by adjusting program pulse duration based on temperature and memory hole width, increasing the minimum allowable program pulse duration with temperature, and optionally increasing the bit ignore number and reducing verify voltage for higher target data states to minimize program disturb.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If program pulse duration is shortened to reduce program disturb, then bit error rate improves, but threshold voltage distribution broadens at high temperatures
Solution Approach 1:
The patent applies dynamics by making the program pulse duration adjustable rather than fixed. The system dynamically adapts the pulse duration based on detected temperature conditions, using shorter pulses at high temperatures to reduce program disturb while maintaining reliable threshold voltage distribution through temperature-compensated programming sequences
Solution Approach 2:
The patent changes the parameter of program pulse duration based on temperature. By detecting temperature and selecting from multiple pulse duration values (e.g., first, second, third durations), the system optimizes the balance between reducing program disturb and maintaining threshold voltage distribution narrowness under varying thermal conditions
2Manufacturing precision
If program pulse duration is lengthened to maintain threshold voltage distribution, then manufacturing precision improves, but program disturb increases at high temperatures
Solution Approach 1:
The patent changes the program pulse duration parameter based on temperature detection. At high temperatures, shorter pulse durations are used to minimize program disturb, while at lower temperatures, longer durations can be used to ensure proper programming, thus adapting to thermal conditions to balance both objectives
Solution Approach 2:
The system dynamically adjusts program pulse duration according to real-time temperature conditions. This dynamic adaptation allows the system to optimize programming parameters for current thermal states, reducing program disturb when hot while maintaining distribution quality when cooler
3Reliability
If temperature increases, then program disturb increases, but fixed program pulse duration fails to compensate for temperature variations
Solution Approach 1:
The patent implements feedback by detecting the temperature of the memory device and using this information to adjust the program pulse duration. The temperature detection circuit provides feedback to the control logic, which then selects appropriate pulse durations from multiple options to compensate for temperature-induced variations in program disturb
Solution Approach 2:
The system transitions from a fixed program pulse duration to a dynamic, temperature-adaptive duration. By detecting temperature and selecting from multiple pulse duration values, the system adapts its programming behavior to current thermal conditions, improving reliability across varying operating temperatures
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 reduces program disturb, maintaining narrow threshold voltage distributions and improving the bit error rate and reliability of memory devices across different operating temperatures.
Implementation Method 1
Program disturb in memory devices, particularly in erased-state memory cells, occurs due to capacitive coupling and channel boosting
Data Source
AI summary
Techniques are provided for reducing program disturb in a memory device. The techniques include compensating for a temperature in the memory device to reduce the upshift in the threshold voltage (Vth) of erased-state memory cells. A minimum allowable program pulse duration increases with temperature to account for an increase in the attenuation of a program pulse along a word line. A program pulse duration which accounts for reduced channel boosting at relatively high temperatures is reduced as the temperature increases. An optimum program pulse duration is based on the larger of these durations. The optimum program pulse duration can also be based on factors such as a measure of program disturb or a memory hole width. Program disturb can also be reduced by easing the requirements of a verify test for the highest data state.