Non-volatile Memory Body Bias Temperature Compensation
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Solution Overview
Problem
Non-volatile memory devices face performance variations due to temperature changes, leading to read errors and widened threshold voltage distributions, as existing compensation techniques are inadequate in addressing these issues.
Innovation Solution
A non-volatile storage system that applies a temperature-dependent body bias to compensate for temperature variations, adjusting voltages and bias levels to maintain consistent device parameters across different temperatures, including threshold voltage, sub-threshold slope, and 1/f noise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If temperature compensation is applied using conventional techniques, then threshold voltage stability is improved, but read errors persist due to widened threshold voltage distributions
Solution Approach 1:
The patent applies body bias voltage to change the electrical parameters of the memory device, specifically adjusting the threshold voltage and sub-threshold slope to compensate for temperature-induced variations. This resolves the contradiction by dynamically modifying device parameters to maintain consistent performance across temperature ranges, reducing read errors while preventing threshold voltage distribution widening.
Solution Approach 2:
The patent implements dynamic body bias adjustment based on temperature conditions, transitioning from static compensation to adaptive control. The body bias voltage is modified in response to temperature changes, enabling the device to dynamically maintain optimal operating characteristics and prevent threshold voltage distribution widening that occurs with conventional fixed compensation techniques.
2Measurement precision
If body bias is applied to compensate for temperature variations, then sensing accuracy is improved, but device complexity increases
Solution Approach 1:
The patent employs self-service mechanisms where the memory device monitors its own temperature conditions and automatically adjusts body bias to maintain optimal sensing accuracy. This reduces the need for external complex control circuits, as the device autonomously compensates for temperature variations, thereby improving sensing accuracy without proportionally increasing device complexity.
Solution Approach 2:
The body bias control circuitry serves multiple functions simultaneously: temperature compensation, threshold voltage adjustment, and sub-threshold slope optimization. By consolidating these functions into a single control mechanism, the patent improves sensing accuracy while minimizing the increase in device complexity that would result from separate circuits for each function.
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 reduces read errors and maintains consistent device performance by compensating for temperature-induced changes in memory device parameters, improving sensing accuracy and reliability across varying temperatures.
Implementation Method 1
the body bias is set to vary with temperature to compensate at least one temperature-varying characteristic of a set of non-volatile storage elements
Implementation Method 2
Both the traditional EEPROM and the flash memory utilize a floating gate that is positioned above and insulated from a channel region in a semiconductor substrate. The threshold voltage (VTH) of the transistor thus formed is controlled by the amount of charge that is retained on the floating gate.
Data Source
AI summary
A non-volatile storage system in which a body bias is applied to a non-volatile storage system to compensate for temperature-dependent variations in threshold voltage, sub-threshold slope, depletion layer width and/or 1/f noise. A desired bias level is set based on a temperature-dependent reference signal. In one approach, a level of the biasing can decrease as temperature increases. The body bias can be applied by applying a voltage to a p-well and n-well of a substrate, applying a voltage to the p-well while grounding the n-well, or grounding the body and applying a voltage to the source and/or drain of a set of non-volatile storage elements. Further, temperature-independent and/or temperature-dependent voltages can be applied to selected and unselected word lines in the non-volatile storage system during program, read or verify operations. The temperature-dependent voltages can vary based on different temperature coefficients.